Contract No. W-7405-eng-26 Instrum i entation and Controls Division MS RE DESIGN AND OPERATIONS REPORT Part IIA. Je« R. Tallackson " LEGA as an account of racy, completeness, of any information, privately owned rights; or B. Assumes any 1iabilities use of any information, apparatus, As used in the above, ployee oF contractor guch employee or contractor of the disseminates, with the Commission, with respect or his employment with such FEBRUARY 1968 OAK Ré[)l;l(iE IETATIONAL LABORATORY R(l)dge » Tennessee perated b UNION CARBIDE CORPgRATION .S, ATO for the . MIC ENERGY COMMISSION Government acting on be expres sed to the use of, method, OF process disclol ting on behalf or employee of 8¢ or employes any information pursusnt contractoT. Nucl ear and Process Instrumentatio n or for damages resulting from the sed in this report. of the Comm.\sslon" {ncludes any em~ ch contractor, ORNL-TM-729, Fart tl A to the extent that of such contractor prepares, o his employment of contract -::V‘. T B \u ry CONTENTS ACmOWIED(mNT..“.V..D.....l'...‘.........l...................l.... 1. MSEE INSTRUMENTATION AND CONTROL SYSTEM — CGENERALeasececsecaens 1.1 1.2 1.3 Introductol‘y. RemarkS..IlC.........O‘.......0.............. Desigl ConsiderationSIIl.O......‘...O....’...l..‘...l..... 1.2.1 1.2.2 1.2.3 1.2.4 102.5 102.6- 1.2.7 1.2.8 Introduction....................‘.....ll....Ol..l. Operational RequirementS.ceesccscesssssssccscsnes 10720201 o d POV - » . o & . ° ® ® LW o o W Ww o O FHEEHE VOH DN e3.3 0 Compatibility with Centralized Control ”Philosopl]y..‘.'....0................... Fase of Operation..cssececsscececcceses Flexibilityeeescesesosestsscccscssonsnae Experimental DatB.seesecscosccsccssccsse Remote MaintenancCe.c.ceecscescccscscceces Maintainability.ceeeesessssccesossnnces y Req_uirements.l..‘.l......l...'..l.......‘l. Containmentlio_.......'..........‘....l. Redundancy, Separation, and Identifi- cation.ili.....'....Ol......'.......... Hazards to Operating Persomnel..cececes erformance CharacteristicCSeeccesvecsssssecsscsnae PHEPRREE PERY e 0] ot FRHHFY PR HPE _ 3 0n o LN Wb E O'V-era\ll Accwacy. LI B B B RN RN BN BN L BN NN B NN BN N BN Reliabili‘ty. S &0 & 6O 0 020888 s SO E B eSO SSE eSS Fai 1 uI‘e MOdeS LR BN R RE B BN RN BN B B B BN BN B BN AR B BN B BN A I of Process ConditionNSeescesseseccsssccsse Operating TemperaturCsiescoescsesessecscce Operating PressurC.cceccsssssosesscscns COrrosiON.isecssesessesssscncsccsanccnsns Salt Plugging and Vapor Depositiones... Electrical Resistivity of Molten Salts. ntal Effectsl.l......'.I.l.l............ Anbient TemperatuUrCecsecsesscscessesass Am.bient Pressure..........0.-.......... RadiationDamalge.l.....I.O.I.I.l.‘..... Requlrements...'..-...‘..........'l..... Weld.-sea.led COIlS'bI'LlCthIl.-.o..-...-.... RUuggednesSS.eeesescosccssssccecsssscscsnas S1Z€eccesescnssscecsssscssncssscssccsne Materials of ConstructioNe.esececscesss CleanlineSSeecescssccacsssoncosssscassces ‘Cost.....-...l....'.....l..'......'......-......... Plant Instrumentation Layoubl.ceeceevcescsceccsscosscccssnnss 1.3.1 1.3.2 %neral Description.ro...l..ll.'..;......OOOOOUOOO. Main contI'Ol Area..l’..........l'..l............'. iii 17 17 17 17 19 20 20 20 21 27 27 27 27 27 28 29 29 29 30 30 31 32 32 32 33 35 35 35 35 35 36 36 37 37 37 1l.4 1.5 1.3.3 1.3.4 1.3.5 1.3.6 1.3.7 iv Auxiliary Control Are€f.ceccecccccccccssosccnscsss Transmitter ROOMeceeceeoccesevecssseaseosssesncanne Field PanelSceeeccccsscccossassscsesssascsnsnsncanse InterconmnectionS..eececsssseesescessessssacncacns Data- Room....o.o.l'olool...oooono.oc.ooo.oo.o-.oo Plant contrOl System.....0.0.'.0...0..'l..l....l!l.l..l.. Safety Systemoot.0.0.0-.-.00........l..o..o.oc.bo.o.ooooo 1.5.1 1.5.2 105.3 1.5.4 1.5.5 1'5.6 Reactor Fi]—]- md Dralin System..........‘...Q.O..O Helium Pressure Measurements in the Fuel Salt LOOP.00......00...'..0....‘.00...0!..0......0.... Afterheat Removal Systelleeeececccecesccccesconsosnecs Containment System Instrumentationecscececccceass 1.5.4.1 Helium Supply Block ValveSe.seeeecosecoss 1.5.4.2 Off-Gas System Monitoringe.ceeeescececees 1.5.4.3 1In-Cell Liquid Waste and Instrument Air Block ValVeS.eeeeesssesssccssssccnce 1.5.4.4 In-Cell Cooling Water Block ValveS..... Underpressure Protection for the Secondary Con- tainment Cells..........I.....'ll'...OO'QDC.I'.'. Fuel Salt Sampler-Enricher Containment Instru- mentation'l..II.....l'..'...'..l.......'II'....'I 2. SAF'ETY mSTleTATIONANDmACTOR CONTROL......'.......'.‘...' 2.1 2.2 2.3 Nuclear Instrumentation: Installation and LocatioNeeeess BF3 Instrmentation-oo....0...00..-...0oooooooc-lo.t..ooo 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6 2.2.7 2.2.8 GeNeralescecessoccsssccscesccssssscsscocssnsssnsse BF3 COUnberieceecesccncccocoscrscscscccccoscscacncsns High-Voltage Power SUpPPlYescscesossccccsocsacases Preamplifier, ORNL Model Q-1857.ccccceevsccccccss Pulse Amplifier, ORNL Model Q-1875.cccesecscccecs Scaler, ORNL Model Q=1743.ccescessecscoassesasnas Logarithmic Count Rate Meter, ORNL Model Q-751... ConfidenCe Trips..o.o...00..'..C..C...D0.00C..'.O Wide-Ra.nge Comting Cha:nnels-ool'.tOcl.t....oo.o....'oono 2.3.1 2.3.2 Principle of OperatioN.ececsceccceseccccessacsnns Fission Chamber and Preamplifier Assembly.sececececss 2:3.2.1 Introductioneceececcccccsceccescccccsee 2:3.2.2 Preamplifiercieseccecssssccscscscsccscosse 2.3.2.3 TFlexible CBbleSeveccsersccccocosssccncss 37 38 38 39 39 55 67 69 70 71 72 72 76 76 77 77 7 97 106 106 106 107 107 107 108 108 108 111 115 116 116 118 2.3.3 2.3.4 2.3.5 2.3.6 2.3.7 2.3.8 oA PO * : Electrical Shielding Layoub.eecseescees Low Pickup-Noise Performasnce of the Assembly.l..'...‘....I.l....ll..l....‘. ifier Power SUDPPlY eececccscesssnscsssscsncs GENEraleseeercesecsesssssssssssosassese ConstructioNeeeessecscscscsscssscnscnne Applicalionicesesecscesscsascacccensacee SpecificabionS,scscacscscscesccssnsscnonse Circuit Description of the —22-v SUPDlY seseorssvsesscctncsssncnsccsacssnsns Circuit Description of the +300-v and +110-V SUPDlYceeoesosscssossnssssasccssse Plllse A@llfler...-....‘.....‘..'..‘.I'...‘...... w»&}&k MWL - » P)P)h)h)b)fi‘ LWLWLWLW < DOV O DD M 8 . H ot . 0n - -* * . 0\?\0\0\0\0\ . B oD DD LVWLWLL WVWW Q LMLV HFG MWD E o P o ™~ e » * - . | WLWwWW UJb)th)h)h)g WWwWww - L I o0 '0101019101018"QFQ'Q'Q B HWoHI LMW H o DO General.ceeccecscesnsccsnsscsncssnsnsoccs ConstructioNseesseccessocvossscoccccnss ApplicatioNeesssececcecsscossssscaccsnne OpecificationSesececescsescccsocsnsnnse Theory of Operation.cceescsccccessaces . P Sel"VO AmplifiEI‘, ORNL MOdel Q,"2615. es s e v Genersal.cssccsccosccscsosscscosnsansnancs ConstructioNeesecsecssesscsceccnccconse AppPlicalionessscscessesesorscscssensoces SpecificationSeessceseescsosssscscessncee Theory of OperatioNesescecccccesssosccsns a...................................I.... GeNEr8l.cevscsssasassossssnsannssnssssse ConstructioNeceecessscsssecncesssnesanes Applicationeseecsesscescescescnscnscone SpecificationSeecseccssssccscccscsccssee Applicable DrawingSeescescescsscsscensce Theory of OperatlONeiecesssessoscssassss Amplifier..-............................. T GENEYBLlessecessosnsessssssesssenssssasns Specifications.eccececcenss sscecssscses Amplifier BalanCingeeceseesesscscssccacs Theory of Operation.cesceccccesscscenes Chember DriVeeseesssssessosassssscssssnes Description.sceececscscesscceccsosrecanase Drive MOtOTesesessseescoossccsssnsssons Lead SCreWeesssesesscosssescccsscssosses Position-Sensing Potentiometer...eeees. SYyNChYOesescossscssssnsssssessncscsscnes Auxiliary Position-Sensing Potenti- OMELEr e s eosensesssscosssesscosascasnses Vernistat Interpolating Potentiometer,. Gear RedUCerS.ccesscssctcoscscsscscccns S1IP CLUBCH .t eeeeeeonncereasaosnncnnans Limit SwitcheS.eeessececrsssscssnnasnnsns 119 119 120 120 120 120 120 121 122 123 123 123 123 124 125 135 135 135 135 135 136 138 138 138 139 139 139 139 140 140 141 141 141 146 146 147 147 147 147 148 148 148 148 148 2.4 2.5 2.6 vi Linear Power ChannelSDOCC...l......‘..l....'l......‘..l.. 2.4'1 2.4.2 24,3 2obrots 2.4.5 2.4.6 Description...................O.....-....'C...... Visual Readout Device, Series 360..cccesevccescse Keithley Model 418-20 Picoammeter: Specifica- tions mld- Description...l........................ Procedure for Field Testing and Compensating Compensated Chamber Q-l045..ceececscccccccscsccasns 24441 Descriptionicesccccsssescsossscescessnnsns 2eietee2 TestiNgeeessvssesscacesscesscssecssonns The Use of a Colloidsal Dispersion of Boron in 0il to Obtain a Uniform and Easily Applied coating Of Boron..‘........'.I.....-.l.....l.'... High Current Saturation Characteristics of the ORNL Compensated Ionization Chamber (Q-1045)..... ROd. Scram. Safew System.........l...................l.l'. 2.5.1 2.5.2 2.5.3 2.5.4 2.5.5 2.5.6 2.5.7 2.5.8 Rod Scram Safety Channel — Input Instrumen- tation.oo.o.o.oooo.oo.-cooooon.oon..ooooo-.ccooo-- Rod Scram Safety Channel — Output Instrumen- tation..I.............................‘l‘.ll.l... Safety C}lmbers.l...............'........Q....... Period Safety Module, ORNL Model Q=2635.cccecssee 2eD.4.l DescripbiONeececcesscscsscessssscnsocns 2.5.4.2 Theory of Operation.cesescesacscsscesss 2.5.4.3 Operating InstructionS..cceeeccsccessnns Flux Amplifier and Ion Chamber High-Voltage Supply, ORNL Model Q-2602..cccesssscccscsssssccsne 2.5.5.1 DescripbioNeecececceccssesscscesccscnnsns 5.2 Theory of OperatioN.ecscccescccscscsveses 5.3 Operating InstructionSeececsssccessosess 5.4 Maintenance InstructionS.cecscceccsseces NIQN Ux\n\.n * & & TeSt MOd-lfl.e, ORNII MOdel Q"2634..0000.0000.00 .1 DescriptionO............-‘..'........'. .2 Theory of Operationesccesssecccossososs 3 r Operating InstructionS.cecececcccecscss NE\JN Ut W\ * NV Oy Fast-Trip Comparator, ORNL Model Q-=2609..scevssse 2.5,7.1 DescriptioN.ecececescesescesscscescccons 2.5.7.2 Theory. Of Operation..fll..........l.'.'. 2.5.7.3 Operating InstructionS.eceescsssscsscns Coincidence Matrix Monitor, ORNL Model Q-2624.... 2.5‘8.1 Description..............'...‘.......... 2.5.8.2 Theory of Operationecececcececessssccess 2.5.8.3 Operating InstructionS.cecececcccesenas Shim and REglfl-ating ROd. contrOl System. * 0 60 9 8 6000 EN B 163 163 164 164 165 165 165 168 168 177 177 178 180 181 181 183 184 185 185 187 189 190 191 191 192 195 196 196 199 201 203 203 204 205 221 2.7 2.6.1 2.6.2 2.6.3 2.6.4 2.6.5 2.6.6 Control 2.7.1 2.7.2 2.7.3 2.7.4 2.7.5 2.7.6 2.7.7 2.7.8 2.7.9 DPVDVDDDN N3 =1-2-~1-31-1-3 vii Introduction..l..C....l.....l............ll.'... Rod Control CircultSessiecccececessscosccscnsessns The Automatic Rod Controller.ecceceecescssscscss .o 2.6.3,1 Basic Rod Control Circuitecsccscscscses 2.6.3.2 Temperature Control.csscssscssscssssss 3 TFlux Demand Limiting.ecesecscscsccecaes ating Rod Limit Switch Assembly, Q-2586.... .l Range Switching...'.........‘........I 2 RaIlge Seal]-.............'.............‘ 2 D - % O W o O > nent Descriptions.'..-.......... oooooooo se oo .l SerVO MO'EOI'................--...-....- g . AR ON O Ut Q Aplifierececescecssscscesssssccsccacessne 3 Clubch-BraKe.seeeessscsscececssscsssss 4 Shim-Locating MotOreseeseesccssceacess 5 Mechanical Differentialecceccecceccveces 6 Size 15 Control TransformMerecsccecesse .7 Size 31 Torque Transmitterececeececececsse L ] L] . Operational Situations Involving the Regulating Rod Limit Switch and the Regulating Rod Servo... Rods and ROd DriveSeeesssssscsnsesccscesscscsses General ArrangemenNt..cecssscscscssssncescscsscsse Position IndicabioN.ececesecsscscsscscscocescncse Shock ADSOIDEerececossovssssessssicssncssssccssccss Cooling Air Flow and Temperature Mbnitoring..... Limit SwitcheSeeeesecsossssocssessccccsscsocnnns Control ROAS.sseeseasossssscsssosssoscscsssascass Rod Drop Timerececeessecsssccsassascesrscscsnsssasns Performance CharacteristicSessccccscscscccvens . . Component Descriptions and SpecificationsS.ceevee 2.7.9.1 Rod Drive Motor Assembly.cceesccccccss Electromechanical Clutcheececcssecccss Overrunning Clutchessscccessssvasnases Position-Indicating SynchroS.sseascses ' Position-Indicating Potenticmeter..... Limit SwitcheSeeessessvsessscscecccscns Electrical Wiringeeeceeessasosescssccssce LubricatioNeesescccscsoccscsscscscnssne Thermostatic SWwitCheS.ecesscsccoscsscne 2.7.9.10 GCBIS.evescossoscscssccsssoscasssansscs 0 00 ~1 0" Ut I * -~J . o . :0\0\0\0\0\0\0\0 2.8 'Load Control System........V............l".;.l.‘......... 2.8‘1 2.8.2 Blower Operation..'.;to.........O.......O..C0.0. Door Operation........ll...'....l.l.........l.... 221 221 228 228 229 230 231 234 235 236 236 236 237 237 237 237 238 238 263 263 264 265 265 266 267 268 268 269 269 269 270 270 271 271 271 271 272 272 301 302 302 2.9 2,10 2.11 2.12 2.13 viii 2.8.3 Automatic Load Programming..ceccecescccsccocsess 2.8.4 Manual Control.eeecssccsscsscscscsscoesassssssnass 2.8.5 INterloCKkS.eessecsssoscscsssscosasosssscnssoncas 2.8.6 Load SCrall...ecessseessccsssesssssossescsasasnsss Health Physics Monitoring.ececesesccssssssccscscsscsscsscse 2.9.1 Introduction..ceccesscescsccecesssssscsccnsscoses 2.9.,2 Tacility Radiation and Contamination System..... 2.9.2.1 IntroductioNecesccecscescccccacanssese 2.9.2.2 System Descriptioneeeccecssacecssscccse 3 ComponentSecececcscssccscsasossscnsnsons 2.9.3 General SySteMeseecccccccasscessssccasescsscases 1 IntroductiONecesceescecsscsccocasnnnns .2 Beta-Gamma Monitors, Q-2091........... 3 Hand-and-Foot Beta-Gamma Monitor, Q=1939-Bicseesssssssscscocscsccssssssss 2.9.3.4 Beta and Alpha Sample CountersS.csseces Process Radiation Monitors.secececscescccsscscccoscsssane 2.10.1 IntroductioNececsccscsscssossccscscsstssscsnscsasns 2.10,2 System DescripbioON.eccececececscscsccsccsssscosssvse Stack Monitoring SystemM.eeseecccccasessecssscescsscsnacee 2.,11.1 IntroductioN.ceeececscsccscsscessscsccsscsnsscns 2.11.,2 System DescriptioN.scesscscesssscccsccsscscsscss 2.11.2,1 Flow Channel FT-Sleceeccoccsscsssscces 2.11.2.2 In-Stack Sampler.ccececssscescscssnsscs 2.11.2.3 Particulate MonitorS.ceeeceecsseccceces 2.11.2.4 Todine Monitor, RE~SlCecescesssocaccecs 2.11.3 ORNL Drawing List for the MSRE Stack Monitoring SySteMeceeeceossosssecenvecscsssssssssscsnsssanne Data Logger-Compulerececeecvecscesssscssccsscssesossnnsae 2.12.1 IntroductioONisscessscscssessscssosesssssscssssosssns 2.12.2 Basic System Equipment DescriptioNessecccescscse 2.12.3 Peripheral Equipment DescriptioNececcsecscesessecss 2.12.4 System Operation.cecececcccscescccesscsocsssesssse 2.12.4.1 Collection and Processing of Analog and Digital Input SignalS.ceccecscecsss 2.12.4.2 Logging FunctionS.ccececccesacossccsacs 2.12.4.3 CalculationSeeeeesssosesscssasssansnns 2.12.4,4 Miscellaneous FunctionSeceeeceesccccss 2.12.5 References and ORNL DravwingSecceccccscscsssscase MSRE BerlliUIIl Monitoring SyStemooooooooo-oooooooaoo.ooo 304 308 308 308 331 331 331 331 332 334 339 339 339 340 341 351 351 351 367 367 367 368 368 368 368 372 379 379 379 381 382 382 384 385 386 393 ACKNOWLEDGMENT This report represents the collective efforts of many more persons than the authors of record, who, in some areas, served as editors, not writers. We gratefully acknowledge the contributions of the following.?! H. R. Brashear for checking and final editing of the section on Process Radiation Monitoring. G. H. Burger2 for preparing the sections on Process Radiation Mon- itoring, Health Physics Monitoring, Stack Monitoring, and the Data Log- ger-Computer. S, J. Ditto and E. N. Fray® for assistance in writing and checking large portions of the sections on the nuclear and electronic instru- mentation. P. G. Herndon, C. E. Mathews, J. L. Redford, and R. W. Tucker for continuous and invaluable assistance in gathering information and in reviewing the drawings and text material. D. J. Knowles and J. A. Russell for help with reviews of the Health Physics and Stack Monitoring sections. R. H. Guymon, Chief of MSRE Operations, and his staff for giving generously of their time to review the sections on control and safety. M. Richardson for help with the section discussing the control rod and the drive unit. lExcept as noted, those listed below are members of the ORNL In- strumentation and Controls Division. 2Formerly with the Instrumentation and Controls Division, ORNL, now with Union Carbide Corporation, Mining and Metals Division, Niagara Falls, N.Y. 3Formerly with the Instrumentation and Controls Division, ORNL, now with General Electric Co., San Jose, Calif. ix 1. MSRE INSTRUMENTATION AND CONTROL SYSTEM — GENERAL 1.1 -INTRODUCTORY REMARKS Instrumentation is required by the MSRE to provide information and control for routine operations, to obtain experimental data, and to protect against hazard or damage to persomnel or equipment resulting from abnormel conditions. Both nuclear and nonnuclear instrumentation are used for measure- ment, for control, and for protection; however, because of the nature of the system, nonnuclear instrumentation predominates. Vital oper- ational instrumentation on the MSRE is that which measures and controls levels, flows, and temperatures of molten salts, helium gas, cooling air, and water and which is required for opersation and control of the auxil- iary systems. - Two grades of instrumentation, control grade and safety grade, are found in the MSRE. Control-grade instrumentation is used where a fail- ure of control or a loss of information or protective action (though undesirable) can be tolerated. Safety-grade instrumentation is used where such failures or losses cannot be accepted. The choice between the two systems is based on considerations of cost vs consequences. Safety-grade systems involve the use of redundant, reliable instruments and interconnections and tend to be much more expensive than control- grade systems. Hence safety-grade instruments are used only where nec- essary; control-grade instrumentation predominates. The experimental nature of the reactor has increased the instrumen- tation requirements if compared to a power reactor. In some cases eX- perimental data are obtained from instrumentation required for operation; however, in many cases, additional instrumentation was installed pri- marily for data. A second-generation, nonexperimental version of the MSRE will require less instrumentation. The MSRE system,’ the components comprising the system, and its nuclear and operating characteristics have been fully described pre- viously.2‘5 It is not inappropriate to introduce & description of the 1The MSRE has been operating since June 1, 1965, and as of May 9, 1967, had developed & total of 32,654 Mwhr. ?S. E. Beall et al., MSRE Design and Operations Report, Part V, Reactor Safety Analysis, ORNL-TM-732 (August 1964). 3R. E. Wintenberg and J. L. Anderson, Trans. Am. Nucl. Soc. 3, 454~55 (1960). 4J. L. Anderson and R. E. Wintenberg, Instrumentation and Controls Div. Ann. Progr. Rept. July 1, 1959, CORNL-2787, p. 145. °P. N. Haubenreich, "Safety Aspects of the Molten-Salt Reactor Ex- periment,"” Nucl. Safety 8(3), 226~-33 (Spring, 1967). MSRE instrumentation and control system by repeating some of the essen- tial features of the MSRE. Figure l1.1.1 is a pictorial drawing of the reactor installation, and Fig. 1l.1.2 is a schematic drawing of the primary and secondary molten-salt loops in which nuclear power is generated and transferred. The primary (fuel) salt is a mixture of fluorides of lithium, beryllium, and zirconium with sufficient uranium fluoride to achieve criticality at the desired temperature. Several compositions of salt are under con- sideration for the MSRE,2 differing principally in the concentration of UF§ as a consequence of the degree of enrichment in 235y, The use of 233y is also being studied. These variations or changes in composition are not expected to affect the design of the instrumentation and con- trols. The coolant salt, containing no uranium, is similar to the fuel salt in its nonnuclear characteristics. The use of sodium fluoroborate coolant salt®:7 is under consideration, but this experiment is expected to have little or no effect on the instrumentation. Teble l.1l.1 gives the composition and characteristics of the fuel and coolant salts currently (March 1966) being used in the MSRE. ®P. N. Haubenreich et al., Consideration of Substituting Uranium-233 in the MSRE Fuel, ORNI-CF-66-12-28. 7R. E. Brooksbank, P. N. Haubenreich, and J. H. Shaffer, "Study of the Use of U?33 in MSRE," MSR-66-21 (internal memorandum). Table l.1l.1. Fuel Salt Coolant Salt Composition (mole %) IiF 65 66 BeF» 29.2 34 UF; (33% 23°U), approx 0.8 Physical properties (at 1200°F) Density, 1b/ft?> 134 120 Viscosity, 1b ft~% hr~t 20 24 Heat capacity, Btu 1b~1 (°F)~% 0.47 0.53 Liquidus- temperature, °F 840 850 &' Since these salts are frozen below 840°F, it is necessary to apply heaters to the tanks and the piping throughout the salt systems. Figure 1.1.3 shows the reactor core vessel after assembly. The re- actor is graphite-moderated, with the graphite in the form of long vertical bars, or stringers. These stringers are essentially square in cross section with grooves cut into the four faces to channel the flow. Figure l.1l.4 is a horizontal cross section through the axial center line of the core, showing the shape of the graphite moderator bars and the location of the control rods. Whereas the fuel is a homogeneous salt, the core itself has many of the nuclear characteristics of a heterogeneous reactor. Table 1l.1.2 lists some of the nuclear parameters of interest to the control and safety system designer.z' Table 1.1.2. Core size 141 cm diam X 200 cm long Neutron lifetime, £*% ' 240 Hsec Temperature coefficient of reactivity In fuel salt . 10> (8k/k)/°F 4.0 X In graphite 3.3 x 10™° (8k/k)/°F Total 7.3 x 10™° (8k/k)/°F Effective delayed neutron fraction Stationary fuel 0.0067 Circulating fuel 0.0045 Power density (fuel) at 7.5 Mw Maximum 29.0 w/cm? Average in core 13.3 w/cm? Maximum slloweble rod drop time 1.35 sec Control rods are employed for both safety and routine operational control. Nuclear excursions are not incredible, but none have been postulated that cannot be averted by well-established techniques using a reliable protective system. ' Both the fuel and coolant salt loops are blanketed and purged with flowing helium at a slight positive pressure, nominally 5 psig. This is accomplished in the salt pumps, which are designed to provide &a gas space for the helium; see Fig. 1l.1.5. The volute around the pump im- peller is enclosed in a larger tank, the pump bowl. The pump bowl is ~ 8g, W. Allin and H. J. Stripling, Jr., Instrumentation and Controls Div. Ann. Progr. Rept. Sept. 1, 1963, ORNL-3578, pp. 11l4-15. kept about half filled with fresh circulating salt by means of a bypass ng flow of 50 to 65 gpm (~5.0%) around the pump. The salt, at pump outlet pressure, is delivered to the relatively quiescent volume in the pump bowl through a toroidal spray ring which allows the escape of gaseous materials from the salt. These released gases, composed mainly of fission products and, perhaps, hydrocarbons, are carried to the off-gas system by a continuous flow of helium which sweeps across the free salt surface in the pump bowl. Hydrocarbons, if present, will originate with small leaks in the lubricating oil seals in the pumps. While MSRE fuel at 1200°F has & vapor pressure of only 4.47 X 1073 mm Hg, the 5-psig overpressure substantially reduces the amount of long- term salt carry-over into the off-gas system; it also helps to prevent large-scale contamination of the pump itself by salt deposition. The gas spaces in the pump bowl and the overflow tank provide extra volume for fuel expansion from excessive temperature should the need arise. A second helium flow is used to purge the lubricating and cooling 0il passages in the pump to prevent the entry of contaminants from the pump bowl. Helium is used as a cover gas in the fuel and coolant salt drain and storage tanks and, by increasing the pressure, becomes the driving force used to fill the circulating loops. The off-gas system conveys the helium from the tanks and the pump bowls to particle traps, filters, charcoal beds, etc., and thence to discharge via the off-gas stack. In addition to the main nuclear heat rejection system, described in Sect. 2.8, auxiliary cooling is required in the reactor and drain tank cells. The ambient air temperature in these cells is maintained at 150°F kaj or less by two air-to-water space coolers. Direct forced air cooling is used on the freeze valves and on the control rods and their drives. This forced air pumping system is also used to evacuate the reactor and drain tank cells to their operating pressure of —2.0 psig. The in-cell cooling water system is used to cool such in-cell components as the thermal shield, salt pump motors, and space coolers. Fuel additions and the removal of samples for analyses are made with the sampler-enricher. This is a device connected with a pipe to the fuel salt pump bowl and which, of necessity, penetrates all containment barriers. Freeze valves are used in the interconnecting salt pipelines between the various tanks and the reactor vessel. A length of flattened pipe that can be cooled and heated is a conceptual and perhaps oversimplified description of a freeze valve. Valve closure is obtained by freezing a salt plug in the flattened portion of the pipe. The complex of reliable instrumented subsystems used solely for pro- tection forms the MSRE safety system. In the MSRE the protection may be categorized as (1) protection against nuclear excursions, (2) protection against loss of containment, and (3) protection of vital equipment. From the standpoint of extent and quantity, & majority of the safety system instrumentation is in category 2. These are process-type instru- ments based on measurements of pressure and radiation level. Their out- put actions are to close valves, shut down pumps, etc., in lines which are possible escape routes for contamination. The preceding paragraphs highlight those features of the MSRE that are of particular interest to the instrumentation and controls designer. Qfifi Two of the major problem areas created by the reactor system's design are containment and temperature (its measurement, control, display, and recording). The first containment barrier, cladding, always present in a heterogeneous reactor, is missing. This placed more stringent require- ments on the instruments used to measure pressures and levels inside the reactor loop. The problems were magnified by the higher than usual tem- peratures encountered in this service. Obtaining high-grade satisfactory measurements of important flows, pressures, levels, and temperatures is complicated by the general requirement that the number of primary con- tainment penetrations be minimum and, even more so, by the environments of molten salt, fission products, and radiation inside the primary con- tainment or in the coolant salt loop, where measurements involve either molten fuel or coolant salt. It is impossible to operate the MSRE and not breach the primary snd secondary containment volumes with process lines for helium, air, and water (Fig. 1.1.6). In many cases these containment penetrations violate design criteria unless they are capable of being relisbly blocked with instrumented systems when potential hazards are detected; hence the ex- tent of the process-type instruments in the safety systems and the extensive use of sensors and transducers designed to meet containment requirements. In addition, wide variations of reactor and drain tank cell temperatures and pressures complicated the containment aspects of pressure-measuring instruments since this large and convenient contained volume could not serve as a stable reference. To a degree the apparent emphasis on problems of contalnment is & result of the inherent characteristics of unclad, fluid-fueled reactor systems. BHowever, the design of the MSRE was complicated by having to shoehorn it into an existing facility with size and general configuration less than ideal. This housing situation generated additional design problems with both the reactor system and the instrumentation and con- trols. Auxiliary systems for air, oil, water, helium, and emergency power are of necessity spread out and remotely located, cable and piping runs tend to be long and tortuous, power and signal cables could not be properly separated, and it was not feasible to put all the controls in one central area. Instead, some of the auxiliaries are provided with local control panels that are periodically supervised by the operators. These problems of interconnecting and integrating the various subsystems into an operating entity would have been substantially reduced in a facility engineered specifically for the MSRE. In particular, problems of containment and the amount of instrumentation for containment could have been substantially reduced. Temperatures throughout the two salt systems are the most numerous and possibly the most vital single type of measurement in the MSRE. Both salt systems (freeze valves excepted) must be maintained above the freezing temperature (850°F) and should not exceed 1300°F. This upper temperature 1imit® is based on stress and metallurgical considerations and, depending on location, a reasonable and safe allowance for fuel expansion caused by °R. B. Briggs, Effects of Irradiation on Service Life of MSRE, ORNL-CF-66-5-16. any unscheduled temperature excursion. Stress producing temperature o gradients are to be avoided. If salt freezes, it may rupture the con- Q_, taining pipe or vessel on remelting. The coolant salt radiator is par- ticularly vulnerable in this respect. Accurate, reliasble temperature information is essential to successful operation of the afterheat removal system, to freeze valve operation, to heat balance calculations, to re- activity balance calculations, to all operations involving criticality, to routine operational controls, and as input information to the safety system. There are over 1050 thermocouples installed on the MSRE. A prepon- derance of these are on the salt loops, on the storage and drain tanks, and on associated piping. These salt systems are equipped with many manually controlled heaters; safe and effective control is only possible if the operators have a clear, relisble picture or profile of temperatures in the system and if they are assisted by suitable off-limit interlocks and alarms. For these reasons, high-speed temperature scanning and dis- play and continuous data logging are extensively used. These logging and displey systems also provide off-limit alarms. It is worth while to note that these temperature instrumentation systems are most intensively used when the salt loops are being heated prior to filling or before teking the reactor to power. When the reactor is on line and generating power, the loop temperatures become more uniform and certain; hence the control and monitoring problem is sharply reduced. Other areas which called for more than usual care in design or for nonroutine solutions are: 1. measuring and controlling low flows of helium and off-gas to and . from the cover-gas system, Lfi“ 2. measuring helium cover-gas pressure in the fuel salt pump bowl, 3. measuring salt level in the pump bowls, 4. measuring coolant salt flow rate, 5. measuring and controlling salt levels in the drain tanks, 6. designing containment penetrations for instrument lines, 7. designing in-cell instrumentation end related disconnects, piping, and wiring to accommodate remote maintenance requirements. It was recognized at the onset of the MSRE design that suitable and eminently satisfactory instrumentation for some of these measurements was nonexistent. Therefore, in some cases the methods and components now in use have developmental status. Sections 1.2 to 1.5 are concerned with broad and quite general —descriptions which are intended to convey design philosophy and criteria. Detailed descriptions of MSRE instrumentation and control are contained in Sects. 2 to 8. The outline which follows will give the reader an idea as to the scope and the arrangement of this report. REAGCTOR CONTROL ROOM / REMOTE MAINTENANCE CONTROL ROOM ORNL-DWG 63-1209R Fig. 1.1l.1. . FREEZE FLANGE . COOLANT PUMP MSRE Iayout. 8 . REACTOR VESSEL 7. RADIATOR . HEAT EXCHANGER 8. COOLANT DRAIN TANK . FUEL PUMP 9. FANS 10. FUEL DRAIN TANKS . THERMAL SHIELD 11, FLUSH TANK 12. CONTAINMENT VESSEL 13. FREEZE VALVE ORNL-LR-DWG 59158AR COOLANT " PUMP !| - | PUMP I “ ! | HEAT | EXCHANGER 4 !11012°F 820 gpm ) I I} hcwz°r cooLant i FREEZE OVERFLOW | CELL || FLANGE | I REACTOR | VESSEL Il |} f H71°F 1200 gpm I ) Il 1 ) i - I ' l CORE | ' o RADIATOR | L) | | REACTOR CELL H i I | —_— —C “ AR i 220,000 b o ———=—=—=m7 o= ————-=—mm--=——====L ¢fnm il I i 40 °F I | ORAIN TANK i I |V ceLL il TEMPERATURES AND 1 | 1 FLOWS ARE TYPICAL (| 1 FREEZE 1 FOR REACTOR AT I i I I 1 I Il I I il (///,//J' GOOLANT SPARE FILL FILL AND FLUSH TANK gy K AND DRAIN DRAIN TANK (73#3) (a4n= TANK (73t3) (73 t3) Fig. 1.1.2. MSRE Primary and Secondary Molten-Salt Loops. ORNL-LR-DWG 61097 R2 FLOW DISTRIBUTOR ~MODERATOR SUPPORT GRID ACCESS PORT COOLING JACKETS REACTOR ACCESS PORT JAYAYAVAYAYAYAYA =t Y Y2 24 .wll il - ’ \ EeTy P T o . - \Mll. _ _EQE?N D000 VESSEL DRAIN LINE: » w + ] : W = » .ulu = nE R % o ¥ 5 S N V \ < - o wl L S W -7 o L -l w o - o 0 D x x 2 o 14 o W o W S w.ow 3 < xz o z R OR OG w o 1 o =2 Q x - - w ) - > o = o Z = o O L o o w ¥ - , 2 b= o [+ MSRE Reactor Core Vessel After Assembly. Fig. 1.1.3. 10 RN G oh-eaa TYPICAL FUEL PASSAGE NOTE: STRINGERS NOS. 7, 60 AND 61 (FIVE) ARE REMOVABLE. |_—CONTROL ROD =AWA7—6uipe Tuee l - e LN “-GUIDE BAR = “ (¢} REACTOR / CENTERLINE 9 e \ | THREE GRAPHITE AND INOR-8 REMOVABLE SAMPLE BASKETS Fig. 1.1.4. Lattice Arrangement of MSRE Control Rods. 11 ORNL-LR-DWG-56043-BRi SHAFT WATER COUPLIN COOLED MOTOR SHAFT SEAL LEAK DETECTOR LUBE OIL IN UBE OIL BREATHER BALL BEARINGS (Face to Face) BEARING HOUSING BALL BEARINGS (Back to Back) GAS PURGE IN SHAFT SEAL SHIELD COOLANT PASSAGES (!n Parallel With Lube Oil) SHIELD PLUG GAS PURGE OUT LUBE OIL OUT SEAL OIL LEAKAGE DRAIN LEAK DETECTCR SAMPLER ENRICHER GAS FILLED EXPANSION (Out of Section) SPACE N STRIPPER HELIUM (Spray Ring) SPRAY OPERATING LEVEL ol PUMP BOWL HELIUM BUBBLER CONFIGURATION To Overflow Tank Fig. 1.1.5. MSRE Fuel Pump. TMEMBLZANE SEAL ' 7777 ORNL DWG. 67-2688 SHIELD BLOCKS N RN m 1100). 3. The range selectors in the linear power channels (Sect. 2.4) must be in the 1.5-Mw position. 4. At least one wide-range counting channel must provide "confidence" ‘and indicate that reactor power is above 0.5 Mw and that the reactor period is over 30 sec. Once Operate-Run has been established, most of the requirements listed in the preceding paragraphs are bypassed by & seal, as shown in Fig. 1.4.5. When reactor power reaches 1 Mw the "confidence" interlock (Sect. 2.6) is bypassed and, insofar as the mode control circuitry is involved, the only requirement for continuing reactor operation in this mode is that the fuel salt pump be running, one main blower be on, the transfer freeze valves be frozen, at least one drain line freeze valve be thawed, and no safety system jumpers be used. The data logger-computer, adjacent to the main control area, oc- cupies a singular position in the hierarchy of MSRE instrument and control systems. It is added to the MSRE as an experiment intended to evaluate the merit of such devices in reactor systems. Therefore, the MSRE control system continues to operate whether or not the data logger is in service. Although no direct reactor system control functions are vested in the logger-computer, it is capable of exerting consider- able influence on reactor system operations. This is because it pro- vides the reactor operator with a large amount of current information on system status and gives alarms for off-limit conditions., The available space in the main and auxiliary control areas re- stricted their use to instrumenting the functions shown in Fig. l.4.1. It was necessary, and for no other reason, to obtain the additional space required for the remaining instrumentation by decentralization with local control systems. In many cases, and regardless of available space considerations, local control was a preferred choice for one or more of the following reasons: 1. it results in control loops which are less costly to build and are more reliable, 2., 1it eliminates problems of data transmission or retransmission over long lines with consequent improvement in accuracy, 3. it improves operation by locating the control system directly ad- jacent to the controlled equipment. 49 These decentralized controls, whose location has been discussed in Sect. 1.3, are in categories 4 and 5 (listed previously in this section) and are not needed continuously by the reactor operator. Monitoring by annuncistion is augmented by scheduled, routine inspection (the "walking log") as required. ORNL—-DWG 67-8147 MAIN CONTROL BOARD 1 CORTROL ORS 1. Jumper Poard 2. Offgas System: (a) Stack Fans ---- On - Off (v} Miock Valves High Bay Ventilation and Pressure Helium Supply: (a) Purge Flows to Salt Pups and pump bowls (b} Flows and pressure in Drain Tanks II _ TWFORMATION: (1) As required for operator surveillance to support control functions. (2) Anmunciation fram all major con- trolled ¢omponents and systema. (¢) ¥lows and pressures to Iube Gil Tanks Salt Tranefers: (a) See (k) above (t) Freeze Valves - Thaw and Preeze Reactor F111 end Drain: (a) See also (4b) and (5) above (b) Drain tank pressure venting to offgas system {c) Pump Bowl -~ Drain Tank pressure difference Icad Ceontrol (a) Main blowers: (v) Bypass damper Inbe 011 Systems (a) See (Le) above (b) 0%l Pumps: Auxiliaries: (a) Treated Hg0 Pumps: (v} Cooling Tower Hz0 Pumps: {¢) Cooling Tower Fans: (4} Component Cooling Pumps (e) Cell Cooling Elowers (f) Air Compressors (g) Rediator Anmulus Blowers (k) Anti-Packflow Dempers on Main and Anrmulus Blowers Cn - Off Marual positioning On - Off g g88888¢% R838888% 3 DIRECT / SURVEILLANCE AND IMMEDIATE CONTROL ACTION DIRECT SURVEILLANCE ] ALARMS AND INFORMATION NEARLY je— IMMEDIATE CONTROL REACTOR OPERATOR ACTION OPERATORS CONSOLE CONTROL oxs 1. Operating Mode Selecticn 2. Reactivity: (a) Mamual Bhirming, all rods (b) Bervo Control of Flux () Servo Control of Outlet Temperature () Mamal Rod Scram 3. Reactor load: (a)} Mamual Individual Control of Radiator Doors and Bypass Demper (b} Automatically Programmed Control of Doors, Demper, and 1 Blower (¢} Load Scram L, Emergency Drain, Manual 5. Fission Chamber Position by Manual Operaticn of Wide-Range Counting Chanmels 6. Drain Tank Selection for Houtine Fill and Transfer. I INFORMATICN As required for operator survelllance to support sbove cortrol functicns. ALARMS AND INFORMATION INSTRUCTIONS INFORMATION ASSISTANT OPERATORS AND oW e 10. AUXILIARY CONTROL BOARDS Antunciators Safety System Instrumentation Process Radiastioz Monitering Instrumentation Health-Physics Radiation Alarm Instrumentation Freeze Valve Temperature Control and Monitoring Instrumentatlion Salt Loop Temperature Instruments Flux Instruments: (a) ¥, Chammel {b) Wide-Range Ccunting Channels (¢) Red Control Servo Flectrical Power System Tnstruments and Controls (a} Voltage, Current, and Pover Indication (b} TVA Bus Transfer Control (c) Diesel Start - Stop Fuel and Coolant Salt Pump Monitoring Instruments (a) BHoise Level (b) Power and Current Thermocouple Patch Panel — INFORMATION MANUAL OPERATIONS AND CONTROL ADJUSTMENTS ALARMS, DIRECT - AND INDIRECT SLIGHTLY DELAYED CONTROL ACTION Fig. 1.4.1. ALARMS INFORMATION DATA LOGGER - COMPUTER Information from all aress of the system, Diagram of Instrumentation in and Directly Adjacent to the Main Control Room. C 7 A PREFERRED FEEDER TVA ALTERNATE FEEDER A 234, /3.81Y NO. 294, I2.B XV ORNL-DWG 67-5890 N 7vA _ - { w ] j , I 500 AVA 2.8 KV‘?BOV DIESEL ‘ GEN. *5 AR AAAS /000 KW l DIESEL o) C .. . GEN. "7 DIESEL JOOKW GEN. 74 o JO0 KW . 440y AC SWITCHGEAR | | BUs _ . W ° AL :),.,f ; i . . SW/ mHG‘EAR BUsS "4 fT ‘ o« 1ESKVA, o SWITCHEFAR BUS 5 @ reIuva ! EMERGENCY HCV-92.54 é RADIATOR e ' g esoroc § sus I , [ e J9d0vAC] Ge MOTOR CONTROL CEN e, pocR O ! ‘ I s ’ CONTROL POWER ‘ I) ‘éJ-IO )C NTER goca TO SWITCHGEAR INDUCTION =ity NORMAL REG m f;w PWF VER To: = B0V 34 ST KvA a8/ 20/1t0 YAC & 5“’&’7 “”"g"’”i" anal. —I:.._ I : INST. POWER & 7&mp Scapners INVERTER = = savoir | SBY/RO- 20811 TRANSF. %3 (d) Television = 62,5 KVA.250V OC = BATTERY 2EW, &Y JoxvA ro: ey, Keajeosy = € SAW, 28 : o ¢ (3) Sempler-enricher ! (o) Health Physics instrunent's N 70 DATA LOGGER t 180V AC t Nstanusl trenster sw /120 ¥V AC £ . £8¥ 9C BUS . { 180 V AC INST. POWER TO: : - 3 (8) Ssfety chts,chen'l 7O 48¢ DC b0 o { () Rod Jrive control SAFETY SYSTEM &) Freeze valres CIRCULI TS, CHAN. *3 (@) Annuncistors 701 INVERTER (e} Sartety chis,chan *l. 1AW - gngf (b} Frecze valve femp. sw CIRCUIT, — N . and cooling &ir control. 5 te) Fuel & coclant sslt femp., 7O 120V AC Flow & level instruments. st SAFETY SYSTEM &) Sarnpler-enricher insts, CIROUITS, CHAN. *3 (@) Lube Ol Sysrems insts. r—re————— 70 diese/ start elfreuits. Fig. 1.4.2. 7o off pUmps in fobe oil Systems, MSRE Instrument Power Distribution. 1S ORNL-DWG €7-4549 FUEL SALT MAIN BLOWER STATUS OF ROD L,E:f.',; ‘;‘OL':E | Sts CONTROLLER ON" OR “OFF JB‘:’O"::%R t. REACTOR POWER (FLUX) : 2. INSTRUMENT STATUS PRESSURE PUMP SPEED OF HELIUM REACTOR POWER, (FLUX) COVER GAS RADIATOR STATUS OF STATUS OF SAFETY LoD AILSTING (POSITION) SYSTEM JUMPERS, ST RUMENTS ("IN" OR "OUT™) AUTOMATIC FUEL COOLANT ROD CONTROLLER PUMP PUMP TOTAL WEIGHT Il— HEAT OF SALT IN I EXCHANGER TANKS I | —rop orives FUEL STORAGE TANK OVERFLOW FV-112 FV-#3 TEMPERATURES t e OF FREEZE VALVES Fv-107 DIFFERENTIAL PRESSURE CONTROLLER COOLANT DRAIN TANK FLUSH SALT u TANK TEMPERATURES TEMPERATURE OF FREEZE OF REACTOR VALVES DRAIN VALVE FUEL SALT DRAIN TANKS Fig. 1.4.3. MSRE Instruments and Instrument Signals for Mode Control. (4] L i, L 53 ORNL-DWG 67-6435 PREFILL . REACTOR 1S EMPTY . REACTOR FILL AND DRAIN VALVES FROZEN . PERMITS SALT TRANSFERS AMONG DRAIN TANKS . PERMITS HELIUM CIRCULATION IN FUEL AND COOLANT LOOPS . PERMITS BYPASSING THE SAFETY SYSTEM WITH THE JUMPER BOARD FOR SYSTEM TESTING Fig. 104'4. CPERATE 1. PROHIBITS FUEL TRANSFERS AMONG DRAIN TANKS 2. ALLOWS REACTOR FILL 3. NO JUMPERED SAFETY SYSTEM CONTACTS START RUN H UM - . DRAIN VALVE FROZEN . REACTOR FULL 2. REACTOR FULL . LOW POWER, <1.5 MW 3. POWER ABOVE t MW OR ABOVE . ONE MAIN RADIATOR . SERVO CONTROLS 4, FUEL SALT PUMP "ON" . DRAIN VALVE FRQZEN 200 kW WITH GOOD COUNT BLOWER MAY BE "ON" RATE INFORMATION ( “CONFIDENCE") FLUX ONLY 5. ONE OR BOTH MAIN RADIATOR BLOWERS "ON" 6. SERVO CONTROLS REACTOR OUTLET SALT TEMPERATURE MSRE Control System Modes. 3 e T e ogu.?o-[' .3';& NOT IN PREFILL no*orfF"|__ _J| "OFF" MODE REQUEST REQUEST i x | NOT IN OPERATE REACTOR _ MODE EMPTY INTERTANK TRANSFER | VALVES FROZEN FILL AND DRAIN VALVES FROZEN AT LEAST ONE FILL AND DRAIN VALVE THAWED NO SAFETY SYSTEM JUMPERS IN USE No |l ___t REQUEST REQUEST OPERATE MODE SEAL |« REQUEST NO PREFILL MODE || || REQUEST I SEAL I PREFILL MODE r—— 1 I | DRAIN VALVE FROZEN | REACTOR FULL NOT IN RUN MODE START MODE @RATE MODE ORNL-DWG 67-4609 LINEAR NUCLEAR POWER INSTRUMENTATION IN POWER RANGE "CONFIDENCE" ESTABLISHED IN AT LEAST ONE CHANNEL OF WIDE RANGE NUCLEAR INSTRUMENTATION | REACTOR POWER GREATER THAN 0.5 MW PER WIDE RANGE CHANNEL WITH "CONFIDENCE" | REACTOR PERIOD GREATER THAN 30 sec PER WIDE RANGE CHANNEL WITH "CONFIDENCE" —+i| NO REQUEST rRUN MODE REQUEST] l - | NO LIMIT SWITCHES ACTUATED REGULATING ROD UNDER MANUAL - [oxqu0) SPON Bupgessdy FMSW JO WeIBETd BY REGULATING ROD CONTROC TROD SERVO “OFF 7 AUTOMATIC PERMISSIVE CONDITION COMPUTED FLUX DEMAND BY TEMPERATURE SERVO NOT MORE THAN ONE (1.0) MW b — MOMENTARY SWITCH ACTUATION WITH SPRING RETURN IN DIRECTION OF ARROW NO DEMAND FOR LOAD INCREASE LOAD OK FOR "RUN" MODE OPERATION OF SYSTEM REACTOR CONTROL MODE REACTOR LOAD UNDER MANUAL CONTROL — REACTOR POWER GREATER THAN ONE (1.0) MW SAME INSTRUMENTS OR BOTH WIDE RANGE NUCLEAR INSTRUMENT CHANNELS "CONFIDENCE" ESTABLISHED IN EITHER REACTOR POWER GREATER THAN 0.2 MW ] | EITHER OR BOTH MAIN RADIATOR BLOWERS TURNED "ON" FUEL PUMP SPEED ABOVE {100 rpm fuo "OFF" REQUESTJ‘-—["OFF" REQUEST] bS 55 1.5 SAFETY SYSTEM The MSRE safety system is composed of instrumentation which must be highly reliable because it augments the containment or protects vital and expensive equipment, or both. This section is confined to a broad, overall description of the reliable protective subsystems in the MSRE and the basic principles which guided their design. Reliable protective systems for reactor installations have, in the past, been focused principally on the reactor core, and their operation has been centered on the behavior of the flux. In designing the MSRE the use of reliable protective instrumentation was not limited to pro- tecting the reactor core from the immediate effects of excessive flux. It will be seen, as we review and describe the protective subsystems, that safety-grade instrumentation is extensively employed to enhance the primary and secondary containment and to ensure a reactor drain. It is worth while to describe, briefly, some of the characteristics of the MSRE that are responsible for the safety-grade protective instru- mentation with which it is provided. 1. The MSRE, being liquid-fueled, does not have fuel cladding as the first, unpenetrated containment barrier. The core vessel, heat ex- changer, fuel salt storage tanks, and all interconnecting piping become the primary contaimment barrier to the molten salt. In addition, this primary contalnment is pierced by inlet and outlet lines carrying helium used for sweep gas across the pump bowl, for bubbler level instruments, and for drain tank pressurization. These lines violate the primary con- tainment barrier unless they are reliably blocked. 2. In common with solid-fueled reactors the MSRE uses conventional poison rods for control and safety. Analyses,l tests, and operating experience have shown that this reactor 1s a very docile and stable me.- chine having a relatively long neutron lifetime, & large heat capacity, and an effective negative temperature coefficient of reactivity. All hypothetical nuclear excursions in the MSRE proceed slowly and do not develop high transient vapor pressures; undesirably high temperatures are the consequence. The control rods are not capable of providing absolute reactor shutdown under all conditions. The shutdown worth in the rods, at re- actor operating temperature, 1s lost because of the negative temperature coefficient if the fuel salt 1n the core vessel is cooled sufficiently. Transference ¢f fuel to the drailn tanks is the certain method of ‘obtaining absolute shutdown, and the abillty to effect such a transfer (reactor drain) must be assured. - 13, E. Beall et al., MSRE Design and Operatlons Report, Part V, Reactor Safety Analysis, ORNL~TM~732 (August 1964). 2P, N. Haubenreich et al., MSRE Design and Operations Report Part III, Nuclear Analysis, ORNL-TM-730 (Feb. 3, 1964). 3J. R. Engel, P. N, Haubenreich, and S. J. .Ball, Analysis of Fill- ing Accidents in MSRE, ORNL-TM-497 (Aug. 16, 1966). 56 3. The chemistry of the fuel salt does not disallow segregation4’5 of the different fluorides with a consequent increased concentration of uranium in one of the segregated phases. OSegregated salt has been pro- duced in the laboratory under very carefully controlled conditions. The accidental and undetected segregation of salt in a drain tank is highly improbable bhut has not been demonstrated to be incredible. Filling the reactor with segregated salt may produce a nuclear excursion during the filling operation which, ultimately, exceeds the limiting capacity of the control rods. Rigid, reliable control of the reactor filling operation is & necessity. 4. A temperature excursion will cause the fuel salt to expand faster than its containment. The volume available for such expansion is limited; therefore, it is essential to have rigid, reliable control of temperature and fuel salt level. ©See also No. 3 above, 5. Fuel and coolant salts freeze at temperatures in the region of 840 to 850°F. Freezing the salt is not harmful, but remelting is accom- panied by expansion, which is capable of rupturing the piping. The coolant salt radiator is particularly vulnerasble. Loss of the radiator would be costly and would be an intolerable setback to the MSR program. Reliable protective measures (see Sect. 2.8) are included in the MSRE. Principles employed in achieving reliability in reactor safety sys- tems® 28 have been applied extensively to the MSRE. These principles are summarized as follows: 1. Redundancy is employed so that no single failure of an instru- ment, component, or wiring having a reasonable probability of faillure could cause system failure. A single failure could involve all con- ductors in a single conduit, all contacts of a switch, or, unless special barriers are provided, the entire contents of an enclosure. 2. Testing is employed, preferably on line and without disconnecting equipment or otherwise impairing the ability to protect during the test. Each channel is tested separately so as to dlsclose a failed component which would prevent protective action or a failure which could intercon- nect two otherwise independent channels and thereby destroy channel in- dependence and redundancy. 3. Diversity is employed wherever feasible; that is, unlike channels are palred to accomplish a desired result. For example, a flow loss caused by stopping the coolant salt pump is detected by both the pump speed mon- itors and the flowmeters in the coolant salt piping. 4. Safety and control are separated so that loss of control result- ing in an excursion will not occur simultaneously with loss of protection. Separation is also employed so that improvements intended to enhance con- trol or other functions unrelated to safety willl not be made, unwittingly, to the detriment of safety. These precepts constitute recommended design practices for what are now thought to be the best safely systems we know how to build. Figure “R, E. Thoma and H. A. Friedman, "Se§regation of the MSRE Fuel Salt in Drain Tanks," MSR-65-15 (Mar. 17, 1965) (internal memorandum). °H, A, Friedman, "Segregation of LiF-BeF,-UF; Fuel Salt on Freezing in Drain Tenks, MSR-66-19 (July 12, 1966) (internal memorandum). 57 1.5.1 shows an example of & three-channel, high-relisbility subsystem in the MSRE. This is a simplified diagram of the instrumentation which closes the block valves in the instrument air lines to the secondary containment cell if the pressure in the cell rises sbove 2 psig. It is a representative example of a safety subsystem in the MSRE. The follow- ing description of its design and operation is included here to i1llus- trate how these general precepts have been reduced to practice. The instrumentation is simple; three high-grade pressure switches provide the switching contacts which operate the solenold valves in the valve matrix. This matrix is arranged so that, if any two of the three pressure switches are actuated, the pneumatic actuators (diaphragms) of the block valves are vented to the atmosphere, the air supply to the valves is shut off, and the spring-loaded valves close and block the in- strument air lines. 63, H, Hanauer, "Design Precepts for Engineered Safeguards,” Nucl. Safety §fi4), 408-11 (Summer 1965). 7E. P. Epler, "Dangers in Safety Systems," IRE Trans. Nucl. Sci NS-8(4), 51-55 (October 1961). 85, H, Hansuer, "Instrumentation for Conteinment,"” Nucl. Safety 3(1), 4146 (September 1961). 9T, M. Jacobs, "Safety Systems for Nuclear Power Reactors," Trans. Am. Inst. Elec. Engrs., Pt. I, 76, 67073 (November 1957). 105, J, Ditto, "Redundancy and Coincidence in Reactor Safety Sys- tems," Nucl. Safety 2(4), 16-17 (June 1961); M. A, Schultz, "Reactor Safety Instrumentation,” Nucl. Safety 4(2), 1-13 (December 1962). 1lc, G, Lennox, A. Pearson, and P, R. Tunnicliffe, Re%gégtion and Protective System Design for Nuclear Reactors, AECL-1495 \April 1962). 121, M. Jacobs, "Safety System Technology," Nucl. Safety 6(3), 231- 45 (Spring 1965). 135, J. Ditto, "Effect of Operating Experience on Safety System De- sign," Nucl. Safety 6(2), 183-84 (Winter 1964-1965). | 145, P, Epler, "Reliability of Reactor Systems," Nucl. Safety 4(4), 7276 (June 1963). 15K, W. West, "Instrument System Testing for In-Pile Loops," Nucl. Safety 5(4), 374—76 (Summer 19633’. 16K, W. West, "Relative Functions of Loop Contalnment and Instrumen- tation," Nuel. Safety 4(4), 180-8L (June 1963). 175, J. Ditto, "Failures of Systeus Designed for High Reliability," Nucl. Safety 8(1), 35-37 (Fall 1966). 185, P, Epler, "Safety System Reliability vs. Performance,” Nucl. Safety 6(4), 411-14 (Summer 1965). 58 The two-out-of-three redundancy permits on-line testing without oy system perturbation. The completeness of the test procedure employed \hw; is an operational decision and is not limited by the design of the in- strumentation. Testing is done by simulating an increase in cell pres- sure by using the nitrogen cylinder(Fig. 1.5.1) as the source of pres- sure and noting the response of the pressure gages in the valve matrix or, if desired, by actually closing the block valves. A typical test in channel A proceeds thus: 1. The hand valve in the line which connects the nitrogen cylinder to the line from PSS-RC-B to the reactor cell is opened, and the pres- sure is adjusted to the 2-psig set point. The sintered disk snubbers provide sufficient flow restriction to maintain this pressure without wdue loss*? of nitrogen to the reactor cell. 2. The increase in pressure actuates pressure switch PSS-RC-B and this, in turn, deenergizes solenoid valves ESV-1Al and ESV-1A2. 3. These valves, ESV-1Al and ESV-1A2, in the valve matrix change their aspect, but not so as to affect the pressure in the 80-psig air header; valve ESV-1A2 vents pressure gage PI-1A5. During normal opera- tion pressure gages PI-1Al, PI-1A4, and PI-1A5 indicate header pressure, 80 psig. Pressure gage PI-1A5 will now go to zero. The block valves will be unaffected since there is still no open line or lines between the block valve operators and the vent line and because the connection between the 80-psig header and the valve operators is still maintained through ESV-1B2, ESV-1Al, ESV-1Bl, and ESV-1C. This test, steps 1 to 3 above, can be conducted with any channel and without disturbing reactor operation. It does not test the actual closure of the block valves. Now, suppose any two channels are tested ‘Ej coincidentally. For example, if channels 1 and 2 are tested simulta- neously, solenoids ESV-1Al, ESV-1A2, ESV-1Bl, and ESV-1B2 will be de- energized, and, referring to the valve matrix in Fig. 1.5.1, the block valve operators will be opened to atmospheric pressure through ESV-1CL to ESV-1Bl1 to ESV-1C2 to ESV-1Al to ESV-1B2 to vent. Valves ESV-1A1 and ESV-1B2 now prevent transmission of pressure from the 80-psig air supply to the block valve diaphragms, and the spring-loaded valves will close. Such a two-channel test checks operation of the entire system. Failure of any block valve to close can be detected by observing the response, or lack of response, of the in-cell instruments supplied via the block valve. This same hasic scheme is used for protection elsewhere in the MSRE. The protective instruments which close block valves in the inlet helium lines operate when the pressure in line 500 falls below 28 psig (see Figs. 1.5.7 and 1.5.2). In this situation, where protective action is initiated by an undue reduction in pressure, testing is accomplished 19Me containment is normally held at -2.0 psig, and the test pres- sure needs only to produce a differential across the snubbers of 4 psig. The nitrogen cylinder has & volume of approximately 2 £t3 at 2000 psi. Should this entire volume be introduced into the secondary containment, with a volume of 18,000 ft3, the pressure rise in the containment would be negligible. Also, the cell atmosphere is specified to be more than 95% nitrogen and would not be degraded. £;; 59 by venting the pressure switches to atmospheric pressure by opening an individual hand valve and, as above, by observing the response of the pressure gages in a valve matrix or the block valves themselves. This same design is used for protecting against too great a re- duction in reactor cell pressure below atmospheric (see input No. XII, Fig. 1.5.2). 1In this particular system the pressure switches are en- closed in bhoxes which are vented to atmospheric pressure through snubbers. Testing is accomplished by pressurizing the boxes. This increases the differential pressure across the pressure switches and thereby simulates a reduction of pressure within the cell. It is worth while to examine this particular safety subsystem from the standpoint of the "recommended practices" previously cited. Up to but not including the output elements (block valves), redundancy and testing requirements are completely satisfied by the design. It should be pointed out that an on-line test of this particular subsystem which includes closing the instrument air line block valves 1s operationally intolerable. The addition of a second valve in each line would improve the reliability of the instrumented blocking system but, of course, would not improve the on-line testing situation. It was established while the MSRE was being designed that the c¢losed system of instrument air lines, tanks, and compressors, with associated valves, etc., con- stituted the second effective containment barrier (see Sect. 1.5.4). This particular system does not employ diverse channels in obtain- ing redundant input channels. In this particular case there is no suit- able and reliable substitute for the simple, direct measurement of cell pressure as it is done. The use of diverse sources of control power substantially reduces the likelihood of spurious action caused by failed or faulty power sources. The pressure switches are installed in the north electric service area and are within 10 £t of the cell wall. The piping to and from the switches is of autoclave tubing with autoclave fittings. The electrical interconnections are run in separate conduits, channel by channel, and contain no other wiring. The solenoid valve matrix is located in the north electric service area in a safety instrumentation cabinet. As the MSRE design proceeded, a few situations and conditions de- veloped which resulted in departures from the ideal recommended practices outlined previously in this section. Two examples, with reasons, follow: 1. All three of our safety system neutron sensors are located in a single penetration because both the amount of space and its configura- tion absolutely prohibit three separate penetrations at different loca- tions (see Sect. 2.1). 2. In some cases the reliable instrumentation which automatically closes block valves closes only one valve in each line rather than two separate, independent valves in series. MSRE system design established a criterion that a single block valve in series with a pair of check valves was a necessary and sufficient alternate for two block valves in series (see, for instance, Sect. 4.8). On-line testing of the "load scram" system (refer to Sect. 2.8) con- flicts, seriously, with reactor operating schedules and will produce highly undesirable thermal transients. These, in turn, produce thermal stress cycles which reduce the life of the system. In order to test the door drive mechanism and the ability of the doors to scram when the re- actor is down and the coolant system drained, it is necessary to bypass 60 the safety instruments that scram the doors since these same instruments prevent raising the doors to perform the test. This dilemma is solved by using the jumper board to bypass these safety instruments. The jumper board circuitry (refer to Sect. 4.11) is interlocked so that safety system bypassing is permitted only when the reactor is empty, Safety system jumpering is resorted to only when absolutely necegséry and, where em- ployed on the MSRE, was adopted only when no altgfnate method could be found. In this particular case the ability totest was retained by this compromise. It is ususl and obvious practice to ggerate relays, solenoids, tem- perature switches, etc., so that power losses cause them to change state toward safety;?° e.g., safety system relays are operated "energized," and their contacts break circuits to produce the safety action. The relay contacts which stop the component cooling pump motors (see Sect. 1.5.5) must be closed to energize the battery-powered "Stop" trip coil in the motor starter. Motor starters, typically, operate this way, and it is not in the best interests of reliability to attempt to redesign or modify well-engineered, time-tested equipment of this type for reverse- mode operation. Furthermore, this particular sgfety action is diverse in that protection is also obtained by closing a valve (see outputs XI and XII, Fig. 1.5.2). - Because of the very strong incentive to keep the primary containment simple and structurally uncomplicated, the MSRE does not have a multi- plicity of fuel salt drain lines, each with an individual drain valve, controlled by the safety system. The foregoing is intended to provide a broad, overall view of the _ application of relisble, safety-grade instrumentation to the MSRE. De- : (EJ tailed descriptions of the design and operation of these reliable sub~ systems are contained either in the remainder of this section or else- where in this report and may be located by referring to the "Supplemen- tary Information" column in Teble 1.5.1, or the last columa in Fig. 1.5.2. Much of the text which immediately follows is an updated ver- sion of similar material, now partially obsolete, originally presented in ORNL-TM-732 (ref. 1). Figure 1.5.2 shows input-output diagrams of the MSRE protective in- strument system. Figure 1.5.3 is an expanded signal flow diagram of the reactor drain instrumentation (described in Sect. 1.5.1), and Table 1.5.1 elaborates and augments the information in the figures. The more detailed descriptions which follow are referenced to the particular regions in the reactor system which are principally involved. e 20The reader is referred to sect. 1.2, "Design Considerstions," for a discussion of instrument failure modes. gfiy Table 1.5.1 (continued) Input Ref. No. Condition or Situation Which Indicates a Real or Potential Hazard Causes of the Hazard, the Consequences, and the Cotrective Action Supplementary Information VII. VIII. X Helium pressure in the pump bowl greater than 25 psig Helium pressure in the fuel pump bowl greater than “fill permit’’ valve. Excess radioactivity in reactor cell atmosphere 1. 1. . Cattses a, Rapid unchecked expansion of fuel salt by excess temperature; see [ " and 11 above and Supplementary Information b. Plugging of off-gas system. . Con sequences a. If unchecked, damage to pump seals, which are rated at 100 psig, and possible overstressing of primary loop b. Exceed capacity of off-gas system, with resulting threat to containment ¢. Possible loss of primary containment . Corrective actions a. Drain reactor vessel b. Vent pump bowl to the auxiliary charcoal bed Causes _ 8. Excess filling rate or overfill. b. Temperature excursion during fill (see II and III, this table) c. Closing of HCV-533A1 nomally maintained open by administrative control, during the filling operation. . Consequences Not of itself a hazard; a release of positive pressute may produce a sud- den tise in fuel level during fill and, possibly, a nuclear excursion if the fuel salt is segregated. See VI, this table. . Corrective action Drain reactor vessel Causes ) Rupture or leak in the primary containment . Consequences Contamination of secondary containment and increased possibility of contamination of area in the event that secondary containment fails. . Corrective action a. Drain reactor vessel b. Close cell evacuation valve which vents cooling air loop to the off-gas stack (valve No. HCV-565A1) c. Close HCV-915A1 which blocks cooling air line to rod drives and con- trol rod thimbles d. Close block valves in the lines to and from in-cell O, analyzer e Close block valves in steam dome condensate drain lines NSO unAwh . System design provides 5.0 ft? of overflow capacity, and power level scram and fuel overflow tank level sys- tems (see I and IV, this table) protect against fuel salt expansion caused by power excursion; safety system holds bypass valves (Fig. 1.5.4) open during operation, in which case the pressure rise will be moderate until all the overflow volume is filled. Redundancy: Two pressure channels, one in the pump bowl and one in the overflow tank. . Testing: Test procedure checks entire channel, with exception of transmitter bellows (see Fig. 1.5.5). Monitoring: Loss of helium flow to bubblers caused by either low inlet pressure or line blockage is alarmed. . Safety only?: Yes Coincidence: Either of the two inputs will produce cortective action. . Draining (see Figs. 1.5.2 and 1.5.4) ensures immediate opening of the bypass valves to back up administrative control. Venting to the auxiliary charcoal bed is less effective but useful backup. This uses same instrumentation as VII (this table). NN oW Redundancy: Two channels are used; one in the pump bowl and the other in the overflow tank. . Testing: See VII, this table. Monitoring: See VII, this table, . Safely only?: Yes. . Coincidence: Either of the two inputs will produce corrective action. 1 Red: . y Tw.o' . t ch ] . P . Testing: Complete testing of each channel is possible. . Monitoring: Certain system failures produce alarms. . Safety only?. Yes. . Coincidence: Either of the two inputs will produce corrective action. €9 Table 1.5.1 (continued) Input R:f. Condition or Situation Which Indicates Causes of the Hazard, the Consequences, and the Corrective Action Supplementary Information No. a Real or Potential Hazard X. Supply pressure less than 28 psig in L. Causes 1. Redundancy: Three independent channels. helium line 500 which supplies Loss of supply helium caused by: 2. Testing: Complete testing possible. helium to all reactor cell components, a. Empty tank 3. Monitoring: Testing meets requirements. drain tank cell, and fuel processing b. Previous overpressure which operates relief valve and breaks rupture 4. Safety only?: Yes. system disk 5. Coincidence: Any two-out-of-three. c. Malfunction of pressure-regulating valve PCV-500C (or alterately, 6. Block helium lines to coolant salt system (pump bowl and drain tank) PCV 605) which maintains supply at design-point value of 35 psig 2. Consequences Possible loss of secondary containment (see 1b above) 3. Corrective action Block all helium lines to reactor and fuel selt drain tank cells X1, High radiation activity in helium linege 1. Causes 1. Redundancy: Three independent channels. supplying fuel salt level bubblers or Reversal of flow in these lines (or back diffusion) from pump bowl, 2. Testing: Complete testing of each channel is possible, in dead-ended helium lines to zero drein tanks, overflow tanks 3. Monitoring: Indicated, logged and alarmed. psi, reference chambers connected 2. Conasequences 4. Safety only?: Yes. to pressure transmitters Radioactivity inside the helium piping in normally safe areas. This 8. Coincidence: Any two-out-of-three. activity will be contained as long as piping is not breached. 6. Flow rate, in either direction, is limited by capillaries; check valves, two in series, are used to back up 3. Corrective action block valves. The capillaries provide a long flow path at high velocity end hence reduce back diffusion, Close block valves in helium lines to fuel salt pump bow! and overflow tank. X1 Pressure in secondary containment 1. Causes 1. Redundancy: Three independent channels, less than 10.7 psia. a. Malfunction of the secondary containment pressure control system 2. Testing: Complete testing of each channel is possible. which results in excessive pump-down of the secondary containment 3. Monitoring: Not applicable, b. Misoperation of pumps and coolers during non-routine tests and 4. Salety only?: Yes. equipment checkouts. 5. Coincidence: Either of two will initiate safety action. 2. Consequences 6. Pressure in the secondary contsinment is normally maintained approximately 2 psi below atmospheric (12.7 psia). Possible collapse of the secondary containment because of excessive 7. The blowers are of the positive displacement type and are, therefore, capable of reducing the pressure well extemal pressure below the value which endangers the containment vessel. 3. Corrective action a. Close cell evacuation valve, HCV-565A1, in the line which is used to evacuate secondary containment to maintain pressure at 12.7 psia. b. Shut off both component pumps. ’ XIIL. Pressure in the secondary contain- 1. Causes 1. Redundancy: Three independent channels. ment greater than two (2) psig. a. A rupture or leak in the primary containment which allows hot fuel salt 2. Testing: Complete testing is possible. to mix with water in the secondary containment; in the worst version 3. Monitoring: Indicated, logged and alamed. this is the maximum credible accident. 4. Safety only?: Yes 2 b. A malfunction in or misoperation of the pressure control system 5. Coincidence: Any two-out-of-three, 2, Consequences Not, of itself, a direct hazard; during normal operation the reactor cell is mainteined at a negative pressure of -2 psig (12.7 psia) to ensure inflow in the event of a leak; the existence of positive pressure is evidence that & malfunction or misoperation exists; a loss of secondary contain- ment is a possible result. ’ 3. Corrective action a. Close instrument air block valves b. Close liquid waste system block valves from reactor cell sump and drain tank cell sump to waste tank. . Close block valves to and from in-cell oxygen analyzer . Close block valves to and from off-gas sampler m® e . Close steam dome condensate drain valves . Close block valves in lines to the hook gage used for cell tank rate checks ¥9 Table 1.5.1 (continyed) S9 Input Ri;f. Condition ot Situation Which Indicates Couses of the Hazard, the Consequences, and the Corrective Action Supplementary Information No. a Real or Potentiel Hazard XIv. High radioactivity in the ventilation . Causes 1. Redundancy: Two independent channels. line from off-gas sampler enclosure Leak in the off-gas sampler 2. Testing: Complete testing is possible. . Conseguences 3. Monitoring: Indicated, logged and alarmed. This is a loss of primary containment 4. Salety only?: Yes. . Carrective action ' 5. Coincidence: Either of two inputs will initiate safety action. Close block valves in lines to and from the off-gas sampler XV. Helium pressure in fuel salt pump . Causes 1, Redundancy: Two independent channels bowl greater than ten (10) psig. a. Same as VII, this table. 2. Testing: Complete testing of each channel is possible, b. Clogging of off-gas system during normal operation requiring opetation 3. Monitoring: Certain system failures produce alarms. Pressure is indicated and logged. ) at higher than usual pump bowl pressure 4, Safety only?: Yes. c. Blowback as an operational procedure to open clogged offgas system 5. Coincidence; Either of two channels will initiate safety action. {see b above) ‘ 6. The maximum pressure rating (rupture) of some components in the sampler is less than the 150% of maximum . Conseguences pressute (75 psig) normally required for primary containment components. This value of pressure, 10 psig, will not endanger reactor system. This interlock to protect the off-gas sampler and guard against a loss of containment . Corrective action a. Close block valves in off-ges lines to and from the off-gas sampler b. Prevents opening operational and maintenance valves in fuel salt sampler-enticher (maintains containment) XVI. High radiation activity in line No. 557 . Causes 1. Redundancy: Two independent channels. carrying off-gas from all charcoal " a. Charcoal beds not operating comrectly (overloaded, see III above) or 2. Testing: Complete testing possible. beds and from the coolant pump, and pump seal failure allowing discharge of activity to lube-oil system 3, Monitoring: Certain system failures are alarmed, radiation level is indicated and logged. from the lube oil systems b. Activity in the coolant salt loop; see also V, this table. 4. Safety only?: Yes. . Conseguences 5. Coincidence; Either of two channels will initiate safety action Radioactive gases discharged up stack . .Corrective action a. Close off-gas block valve b. Close lubq-pfl systems vent valves XVII. High radiation activity in in-cell . Causes’ Redundancy: Three independent ch 1s treated water system a. Maximum credible accident with coincident rupture of in-cell water system piping . b. Induced activity in treated water. . Consequences a. Local contamination by radioactive water leak b. Loss of secondary containment, with accompanying contamination if radioactive material is discharged from the treated water system . Corrective action a. Closes block valves in water lines which are extensions of the second- ary containment and which are outside the containment cell b. Closes valve in degassing tank vent which is located outside of secondary containment cell s . Testing: Complete testing of each channel is possible. . Monitoring: Certain system failures initiate alarms. Radiation level is indicated and logged. . Safety only?: Yes. . Coincidence: Either of two channels will initiate safety action. . The water lines and vent tank are extensions of the secondary containment.. Table 1.5.1 {continved) Input Rpef. Condition or Situation Which Indicates Causes of the Hazard, the Consequences, and the Corrective Action Supplementary Information No. a Real or Potential Hazard XVINl. Low temperature of coolant salt in . Causes 1. Redundancy: Three independent channels. outlet from radiator (line 202) a, Malfunction of load control system (complex of doors, blowers, and 2. Testing: A complete test of each input channel is possible; complete testing requires dropping doors, bypass damper) which disturbs operation. ) b. Cessation of power generation in core from any cause (scram, drain, 3. Monitoring: Thermocouple break or detachment from pipe will produce safety action in that channel. Tem- rupture in primary containment, etc,) perature is indicated and logged. c. Loss of coolant flow (see XIX, this table) 4. Safety only?: Input channels used solely for safety. , Consequences S. Coincidence: Any two-out-of-three. No hazard; warns that potential radiator freezeup may be developing (see 6. The corrective actions constitute a ‘‘load scram.”’ XIX, this table) . Corrective action a. Close radiator doors b. Shut down main blowers, MB-1 and MB-3 ¢, Drain coclant salt system XI1X. Loss of coolant salt flow . Causes 1. Redundancy: Two direct flow channels which receive information from a common primary element, a venturi, a. Coolant pump stoppage plus two independent pump speed channels. b. Line break 2. Testing: Partial testing possible; a test which includes dropping radiator doors will perturb operation; input c. Unscheduled coolant salt drain elements not tested. d. Plug in line or radiator 3. Monitoring: By surveillance and comparison; flow and pump speed are indicated and logged. . Consequences 4. Salety only?: Yes. Unless accompanied by undetected contamination of the coolant salt, 5. Coincidence: Refer to Section 2.8. see V, this table, no hazard exists. Unless action is taken a costly 6. These corrective actions constitute a ‘‘load scram’’; refer to Section 2.8. radiator freezeup will ensue, . Corrective action 2. Close radiator doors b. Shut down main blowers, MB-1 and MB-3 XX. Either or both doors at final upper . Causes 1. Redundancy: Two independent limit switch channels which are cross connected so that if either door is at limit Failure of first upper limit switches and/or any circuit or circuit element the final upper limit both doors ere stopped. See also XIX, this teble. Only one motor starter; it must work. associated with these switches 2. Testing: Complete testing is possible at some inconvenience. . Consequences 3. Monitoring: Not applicable. a. Damage to the doors 4. Safety only?: Yes. b. Damage to the drive mechanism 5. Coincidence: See (1) above. c. Loss of ability to scram the doors because of cable snarling or other damage per 2a and 2b above. . Cortective actions a. Stops door drive motor b. Disengages clutches in drive train between motor and cable sheave c. Applies brakes XXI. Door drive motor current at overload . Causes 1. Redundancy: Only one primary element, the overcurrent relay. Otherwise this interlock is composed of two value a. Anything which jams the doors or the drive mechanism (2) separate channels. See XX, this table, and (5) below. b. A failure of both first and final upper limit switches and/or any circuit 2. Testing: During shutdown only. or any circuit element associated with these switches 3. Monitoring. Wot applicable. . Consequences 4. Safety only?: Yes. Same as for XX, this table. 5. a. Insofar as preventing damage caused by forcing the door and drive mechanism against the hard, fixed . Corrective action Same as for XX, this table. upper limit, this interlock provides diverse redundancy with the final upper limit interlock, XX, this table. b. Prevention of damage at other doot positions than the final upper limits depends on the reliability of a single overcurrent relay and the reliability of & single motor starter-relay. 99 67 1.5.1 Reactor Fill and Drain System A pimplified diagram is shown in Fig. 1.5.4 of the reactor vessel, the drain tanks, the interconnecting piping, and the control elements required to fill and drain the reactor system with fuel salt in a safe, orderly way. The control rods are essential to a safe filling procedure but are omitted from this diagram in the interest of simplification. The reactor is filled by applying helium pressure to the gas space in the selected drain tank and forcing the molten fuel salt up and into the core vessel. As a typical example, if the reactor is to be filled from fuel drain tank 1 (FDI'-1), pressurizing helium is admitted via lines 517 and 572 (see Fig. 1.5.4). The filling pressure is controlled by pressure-regulating valve PCV-517-Al. The pressure setting of this valve is controlled by the operator. The upstream capillary flow re- strictor in line 517 limits the maximum inlet flow rate of pressurizing helium. Valves HCV-544-Al and HCV-573-Al in the pipes which connect the gas space in FDI-1 to the pump bowl and to the charcoal beds are closed. Since the net pressure head available to produce flow decreases as the fuel level rises in the core vessel, the fill rate becomes progressively slower as the fill proceeds if constant inlet helium pressure is main- tained and if the pump bowl pressure remains constant. Helium pressure in the pump bowl is the second component of the differential pressure that drives fuel salt into the core vessel. A sudden reduction in pump bowl pressure during the reactor filling op- eration would cause an unscheduled rise in salt level in the core. If, at this time, the reactor is on the verge of becoming critical, an un- expected nuclear excursion cannot be ruled out. The safeguard provided is to allow filling only when the positive pressure in the pump bowl is equal to or less than +2 psig and thus keep the maximum possible increase in net filling pressure within safe limits. Two causes for a sudden de- crease in pump bowl pressure are considered. First, opening valve HCV- 533-A1 after reactor filling has started would vent the pump bowl to the auxiliary charcoal beds, which normally operate at close to atmospheric pressure. The resultant pressure change in the pump bowl would be —2 psi. Administrative control is used to maintain HCV-533-Al open just before and during filling. ©Second, a rupture or leak would allow the escape of pump bowl helium to the reactor cell atmosphere, which is held at —2 psig (12.7 psia). This condition would cause a meximum pressure decrease in the pump bowl of 4 psi. If the fuel pump bowl pressure ex- ceeds 2 psig, the safety equipment (1) initiates a drain by opening by- pass valves HCV-544-Al, HCV-545-Al, and HCV-546-Al, thereby equalizing helium pressure in the drain tanks and pump bowl, and (2) shuts off the supply of pressurizing helium by closing valves PCV-517-Al, HCV-572-A2, HCV-574-A1, and HCV-576-Al, This is the helium valve condition shown in Fig. 1.5.4 and is required by normal operation with the pump bowl at 5 psig; therefore, the 2-psig channel need not be disabled during normal operation. Additional safety considerations involving pressure in the fuel salt system and the instrumentation used for measuring helium pres- sures are discussed in the following section. ' Excessive pressure, 25 psig, in the pump bowl is relieved by opening HCV-533-Al.. During reactor operation, with the bypass lines open, one or more of the drain tanks would be subjected to this pressure. The input signal used to open HCV-533-Al originates in either of a redundant pair 68 of pressure transmitters, PT-592B and PT-589B, on inlet lines to the pump bowl and overflow tank respectively. These same input channels provide the +2-psig safety signal discussed above. - As a further safeguard during filling, the safety system requires that all three control rods be partially withdrawn in order to pressurize the drain tanks. The weigh cells on the drain tanks provide information used to monitor the total amount of fuel salt moved into the core vessel. The possible filling accidents are discussed in ref. 1. Briefly, these accidents are (1) premature criticality during filling caused by an overly high concentration of uranium brought about by selective freez- ing®t+?2 in the Arain tank; (2) premature criticality during filling of low-temperature (900°F) fuel salt of normal concentration, whose normal critical temperature with the rods withdrawn approximately half stroke is 1200°F; and (3) premature criticality during filling of normal fuel salt at normal temperature with all control rods fully withdrawn. Pro- tective action is the same for all three cases: the control rods are scrammed, and the reactor vessel 1s drained to ensure permanent shut- down. Rod scram is produced and vent valves HCV-573-Al1, HCV-575-A1, and HCV-577-Al are opened by the excess flux signal. ©Since a premature criticality occurs before loop circulation is attained, the outlet tem- perature sensors are ineffective. The safety system also invokes a re- cator emergency drain to enhance containment if there is evidence that radicactivity is escaping from the primary fuel loop. These subsystems are covered subsequently in this section. ?mergency drainage is effected by the following actions (see Fig., 1.5.4): 1. The freeze valve in line 103, which comnects the reactor drain tanks, is thawed. Thawing is accomplished by closing valves HCV-919A and 919B, a redundant pair, to stop the flow of cooling air. The system is designed with a heat capacity sufficient to thaw the plug in less than 15 min. 2. The helium pressures in the fuel drain tank and the unfilled portion of the fuel salt loop are equalized by opening bypass valves HCV-544-A1, HCV-545-A1, and HCV-546-Al. 3. Vent valves HCV-573-Al1, HCV-575-A1, and HCV-577-Al, which re- lease pressurizing helium in the drain tank to the off-gas system, are opened. 4. Pressure regulating valve PCV-517-A1 in line 517, the inlet header that supplies pressurizing helium to all the drain tanks, is closed and shuts off the supply of pressurizing helium. 5. The drain tank pressurizing valves, HCV-572-Al, HCV-574-Al, and HCV-576-A1, in the helium supply lines are also closed to halt further addition of fuel salt. Actions 2 or 3 are immediately and independently effective in re- versing a fill, and hence the valves are redundant. Similarly, PCV-517- 21R. E. Thoma and H. A. Friedman, "Segregation of the MSRE Fuel Salt in Drain Tanks," MSR-65-15 (Mar. 17, 1965) (internal memorandum). 224, A, Friedman, "Segregation of IiF-BeF,-UF, Fuel Salt on Freez- ing in Drain Tanks," MSR-66-19 (July 12, 1966) (internal memorandum). 69 Al and the individual pressurizing valves, referred to in 4 and 5 above, form series pairs and provide redundancy. For example, it can he seen from Fig. 1.5.4 that, taking fuel drain tank No. 1 as typical, pressure equalization and venting are accomplished by opening HCV-544-Al and HCV- 573-Al respectively. Administrative control is used to ensure that when the reactor is filled with fuel salt, both drain tanks, FDT-1 and FDT-2, are empty and both of the freeze valves, FV-106 and FV-105, are thawed. The tank condition is monitored by reference to the weigh cell and level instrumentation on each tank. 1.5.2 Helium Pressure Measurements in the Fuel Salt Loop One channel of the instrumentation which measures helium pressure in the fuel pump bowl and the overflow tank is shown in Fig. 1.5.5. The components and their installation are designed to meet containment re- quirements. The pressure transmitters are installed just outside the main sec- ondary containment shell. From the standpoint of containment, the trans- mitter housings are "blisters" on the main containment cells. Contain- ment criteria would be satisfied by 1. venting the reference pressure side of the transmitter diaphragms to the inside of the containment cell, 2. sealing the vent port at the transmitter, 3. connecting the transmitter's vent port to a containment-grade volume which is maintained at a known and constant pressure. If the transmitter's reference pressure port is vented to the containment cell, the pressure measurement includes cell pressure. This pressure is controlled nominally at —2.0 psig during operation, is at atmospheric pressure during in-cell maintenance, and is well above atmospheric pres- sure during periodic checks to verify the containment capability of the cell, The normal and acceptable fluctuations around the nominal -2,0- psig value would reduce the accuracy of the transmitted measurement by an unacceptable amount. If the reference port of the transmitter is merely sealed shut, the reference pressure and hence the transmitted pressure would fluctuste with temperature changes in the sealed refer- ence volume in the transmitter. Evacuating the reference side of the transmitter was deemed unscceptable because these vital measurements would then rely entirely on the long-term reliability of the vacuum. The variable-volume reference chamber (see action 3 above) re- solves these conflicting demands of containment and measurement ac- curacy. Conceptually, it acts as a strong but extremely compliant bag which automatically adjusts its volume to maintain an internal pressure very nearly equal to the externally applied pressure. By connecting the reference ports of the transmitters to these reference chambers which are located outside the containment cells, the dual requirements of the containment and measurement accuracy are satisfied. At the MSRE the reference volume is housed, and the housing is vented to the off-gas duct near the blower inlet. During operation the ambient pressure in the off-gas duct is approximately —2.0 in. Hz0, the blower inlet pres- sure. This ~2.0-in. Hz0 offset is not significant. The reference 70 chamber is shown in diagrem in Fig. 1.5.5 and is described in detail in T Sect. 6.2. (ufi Two channels are used, one in the pump bowl and the other in the overflow tank. These normally operate at the same pressure. Any safety signal from either channel initiates the appropriate safety action. The system may be tested periodically during reactor operation by: (1) observing system response to small operator-induced pressure changes and (2) shunting the torque motor in the pressure transmitter. These tests will establish that, in the channel undergoing test, the lines from the pump bowl (or overflow tank) are clear and the electronic equip- ment and associated wiring are capable of operating the output relays. Since it takes from 10 to 15 min to thaw drain valve FV-103, this time can be used to observe the response of the thermocouples on the freeze valve as it heats up but before actual salt flow begins. The valve can then be refrozen before an actual drain is initiated. In such a test, valve HCV-533 (Fig. 1.5.4) will be opened, and the con- trolled pressure (5 psig) in the pump bowl will be lost for the dura- tion of the test. The response of HCV-533 can be noted by observing the actuation of the position switch on the valve stem. This test pro- cedure checks the entire safety channel, except the ability of the trans- mitter measuring bellows and the associated linkage to transmit the pres- sure. Monitoring of these channels is accomplished by indicating and alarming the pressure downstream from the hand throttling valves in each helium line serving the primary elements (the bubbler tubes) in the pump bowl and in the overflow tank. A downstream flow stoppage by a blocked line is indicated by a high-pressure alarm; low flow caused (;; by & loss of upstream (supply pressure, an upstream blockage by foreign matter, or a hand valve closure is indicated by a low-pressure alarm. The fuel level in the overflow tank is measured by the differential pressure across the helium bubbler probe which dips into the fuel salt in the tank. The design criteria for testing and monitoring these dif- ferential pressure measuring channels are the same as those which guided the design of the pressure channels described in the preceding paragraphs. The reference chanber is not required. Two channels are employed for safety, and either will initiate a reactor drain if the fuel salt level in the overflow tank exceeds 20% of full-scale level indication. 1.5.3 Afterheat Removal System The drain tank afterheat removal system, typlcally the same for both drain tanks, is shown in Fig. 1.5.6. Once placed In operation the evapo- rative cooling system is designed to be self-regulating and to operate without extermal control. Reliable operation of the afterheat removal systemn requires (1) that the feedwater tanks contein a supply of cooling water, (2) that an ample supply of cooling water is available to the condensers, (3) that the system includes reliable valves to admit feed- water to the steam drums, and (4) that reliable block valves be provided 71 in the drain lines®3 from the steam drums. Administrative control is relied on to ensure that the feedwater tanks contain water. Valve ESV- 806 opens to admit water automatically to the steam drum when the salt temperature in the drain tank exceeds 1300°F and recloses at approxi- mately 1200°F. This valve is in parallel with manual valve ICV-8064, and the pair are a redundant means of admitting water to the steam drum. Normally the condensers are cooled by tower cooling water, but diver- sion valve HCV-882-Cl provides an alternate supply of water. Loss of tower water pressure caused by a loss of water or pump shutdown is de- tected by pressure switch PS-851-Bl, which operates diversion valve HCV-882-CL. When this valve operates, the cooling water supply is shifted from the tower to the process water main. Since it takes over 12 hr for excessively high afterheat tempera- tures to develop after a drain, there is sufficient time to effect a transfer to the other drain tank in the event of & failure or malfunc- tion. This is also ample time to make connections from the cooling water system to a tank truck in the event that the normal water supply is inoperative. The drain lines, 806-2 and 807-2, are used to keep the tanks dry during normal operation. They are extensions of the secondary contain- ment and are provided with block valves. Reliable, safety-grade con- trol instrumentation closes valves ESV-806-2A and 806-2B, a redundant pair, when the reactor cell pressure exceeds +2.0 psig or when the radiation monitors, RM-565A and B, in the cell evacuation line indicate excessive radiocactivity in the cell atmosphere. 1.5.4 Containment System Instrumentation Containment requirements are met by providing at least two inde- pendent, reliable barrlers, in series, between the interior of the pri- mary system and the atmosphere. For example, the two-barrier concept is fulfilled by: l. two independent, reliable, controlled block valves with independent instrumentation, 2. one controlled block valve plus & restriction such as a charcoal bed which will 1limit the escape of activity to the stack to less than the maximum permissible concentration, 3. one controlled block valve plus two check valves, 4. two solid barriers (vessel or pipe walls), 5. one solid barrier and one controlled block valve, o 6. one solid barrier and one check valve. 23These drain lines, 806-2 and 807-2, shown in Fig. 1.5.6, were added after the MSRE was in operation. Development tests disclosed that par- tially filled steam drums tended to corrode at the water line. 72 The recommended design practices outlined previously in this section apply to the reliable instrumentation and control equipment used to op- erate the block valves. Block valves, generally, are not located at such a distance from the containment penetration that the lines become tenuous extensions of the containment vessel. Valves and other devices used in lieu of solid barriers will be routinely tested and demonstrated to be capable of maintaining leakage below the specified tolerance when closed. 1.5.4.1 Helium Supply Block Valves Figure 1.5.7 shows the helium supply lines to the primary contain- ment vessel and the associated valves used for control and blocking these supply lines against the escape of radiocactivity from the primary system as a result of reverse flow or back diffusion. This sketch does not show the fuel storage tank (FST) and line 530, which supplies pressurizing helium to this tank. This line is blocked by HCV-530-Al. Two types of input signals are used to initiate helium supply block valve closure. The first, a reduction in the supply pressure from its normal value of 40 psig to 28 psig, actuates pressure switches and closes all the inlet helium block valves. The second, excess radiation measured by RM-5964, B, and C in any of the helium lines supplying the level probes (bubblers) and pressure measuring instruments in the pump bowl and overflow tank, closes the block valves in these lines. A reduction in heliwn supply pressure in line 500 from its regulated value of 40 psig indicates s leaky rupture disk or leaky piping and, possibly, a loss of primary con- tainment. In-service testing of the loss-of-pressure channels is accomplished by opening the hand valves on the lines to the pressure switches on the main supply pipe (Line 500), one at a time, and observing the action of the relays in the two-out-of-three coincidence matrix in the control room. Actual block valve closure is not tested with this procedure. Low- and high-pressure alarms are provided on line 500; these will actuate before the safety system pressure switches close the block valves., Additional testing of the solenoid block valves in the helium bubbler lines is pro- vided by closing each valve individually and observing the pressure change downstream of the hand throttling valve. The three radiation monitoring safety input channels, RM-596A, B, and C, are tested by exposing each individual radiation element to a source and noting the response of the output relays which produce valve closure. Since two-out-of-three coincidence is used, this test will not perturb the system; neither does it provide a valve closure test. 1.5.4.2 0ff-Gas System Monitoring The off-gas system (Fig. 1.5.8) is monitored for excess radistion in four places: 1. Iine 557. — This line receives off-gas from the main and suxiliary charcoal beds, helium from the coolant salt pump, and helium from the salt pump lube o0il systems and the sampler-enricher. 2. Line 528. — This line carries helium from the coolant salt circu- lating pump. Its primary purpose is to detect an internal lesk in the fuel-to-coolant~-salt heat exchanger. Should such a leak occur, 73 fission product activity will be carried into line 560 by the purge- gas flow across the coolant salt pump bowl. This line is monitored by RM-528B and C. Note that RM-557A and B provide a redundant indi- cation of this activity level. 3. Line 565, — This line is used to pump the reactor and drain tank cells down to the operating pressure of 12.7 psia. A portion of this line continuously carries a small flow of cell air, via bypass line 566, across the component cooling pumps which circulate cell alr (see Fig. 1.5.8). This continuous flow is monitored by RM- 565A and B. 4, Off-Gas Stack. — Stack gas monitoring is not a part of the MSRE safety system but is noted here for completeness. Refer to Sect. 2.11 for a description of this monitor. Its only output function is to pro- vide alarms. The stack gas monitor, located on the off-gas stack, provides a final check on the off-gas just before it is discharged to the atmosphere and after it has been filtered. Excess radio- activity in the stack gas is alarmed in the MSRE control room, and an glarm signal is also transmitted to the ORNL Central Monitoring Facility. Tt can be seen from Figs. 1.5.8 and 1.5.2 that an excess radio- activity signal from either RM-557A or B produces three output actions, all intended to preserve contaimment; these are as follows: 1. Closes HCV-557-Cl in line 557. This line is, in effect, the main helium off-gas exhaust header leading to the off-gas stack filters and carries off-gas from several sources, namely: a) the fuel salt circulating pump, b) the fuel salt drain tanks, c) the coolant salt pump, d) the coolant salt drain tanks, e) the fuel salt sampler-enricher, f) +the fuel and coolant salt pump lube oil systems (Fig. 1.5.9). 2. Closes valve PCV-510-A2. 3. Closes valve_PCV-513qA2. Actions 2 and 3 block the helium off-gas lines from the lube oll sys- tems (Fig. 1.5.9). o Radiation monitors RM-528B and C in line 528, carrying helium from the coolant pump, are necessary because they will provide an indication if a leak exists in the salt-to-salt heat exchanger (from the fuel salt loop to the coolant salt loop), Such a leak could put fission products in the coolant salt; however, when the coolant salt circulating pump is running, the coolant salt pressure in the heat exchanger tubes is greater than the fuel salt pressure in the shell, - The fission product gases would be carried from the free surface in the coolant salt pump bowl into line 528, This activity will be read first by RM-528B and C and then by RM- 557A and B. The output actions produced by RM-528B or C (see also Fig. 1.5.2 and Teble 1.5.1) are the following: (1) drain the reactor vessel, 74 and (2) stop the fuel salt pum;p.24 This also produces a rod scram if the reactor is operating above heat loss power, 15 kw. The sequence \=J of control actions which scram the rods is described in Sect. 2.6. Excess radicactivity in either the reactor or the drain tank cells is detected by RM-565A or B. Either monitor will produce protective actions thus: 1. Closes HCV-565-A) in line 565. This line, the cell evacuation line (Fig. 1u5.8), is used to exhaust the reactor and drain tank cells when they are being pumped down to their operating pressure of 12.7 psia. 2. Closes the steam dome condensate drain valves ESV-806-2A and ESV- 806-2B (see Fig. 1.5.6). 3. Closes block valves HCV-566-A1, A2, A3, and A4 to and from the ana- lyzer which monitors the oxygen content of the in-cell atmosphere. This analyzer (Fig. 1.5.12), is located in the vent house. 4. Closes block valve HCV-915-Al, which carries exhaust cooling air to the)rod drives and the control rod thimbles (see Fig. 2.7.12 in Sect. 2.7 e 5. Drains the reactor vessel. The reactor drain system is described in Sect. 4.7. These systems may be tested by inserting a radiation source in the radiation monitor shields and observing (1) the radiation-monitor indi- cator, (2) the control circuit relays, and (3) the output actions of the control valves and other controlled elements which provide protection. (fi) The three pairs of radiation monitors, RM-528B and C, RM-557A and B, and RM-565A and B, all operate so that an excess radiation signsl from either channel in a pair will produce safety action. Since these are all one-out-of-two systems, on-line testing of any channel will produce protective control actions and, to an extent, perturdb the operating system. The system disturbances caused by on-line testing of RM-557A and B and RM-565A and B can be tolerated if the test is of short duration. It was necessary to provide jumpers for on-line testing of RM-528B and C. Without jumpering, a test of either channel will stop the fuel salt pump and, if the reactor is at power, scram the rods. This is unacceptable operationally. Jumpering is the preferred alternative to omitting in-service testing. Testing these safety channels is, there- fore, subject to very strict administrative control. The jumpers bypass contacts K-26C and K-27C in circult 147, which starts and stops the fuel salt pump. As has been pointed out in footnote 24, these contacts do not produce a safety-grade protective action. The MSRE off-gas sampler will (1) utilize on-line instruments to provide a semicontinuous indication of contaminant level and (2) iso- late samples which may he transferred to a hot cell for analysis. The off-gas sampler (Fig. 1.5.10) was designed and installed after the re- 24Stopping the pump is not required to ensure safety. It may tend t0 reduce the rate but will not eliminate leakage. C 75 actor was placed in operation. Reference 25 contains a brief, conceptual description of the sampler as originally proposed. In the current ver- sion the chromatograph cell has been cmitted: pending further development work. Figure 1.5.8 shows the location of the sampler with respect to the main off-gas system. ' The samples are obtained from line 522, which carries fuel punp bowl sweep gas to the off-gas system. Bypass lines with valves across the piping to and from the analyzer permit taking the sample either be- fore or after the gas has passed through the charcoal filter and the particle trap. The sampler is located in the trench immediately south of the vent house. The reactor off-gas is highly radiocactive, and since this equipment is an extension of the primary contaimment into an ares frequented by operating personnel, the use of block valves in the supply and return piping to the sampler is mandatory. The sampler is well shielded and, except perhaps for the thermal conductivity cells (these cells are tested at 20 psig), meets the general MSRE containment require- ments with respect to pressure rating and leak-tightness. The sampler is housed in a ventilated enclosure which is exhausted to the off-gas stack. Continuous circulation within the enclosure is maintained by two (for redundancy) blowers. This flow loop is monitored by two flow switches, FS~54-D and FS-54-~C, connected to a single alarm. Excess radiloactivity in this circulating air is detected by two separate, independent channels of radiation detection equipment, RM-54A and RM-54B. A high-radiation signal from either monitor will close block valves ESV-537A and B and ESV-538A and B, redundant palrs in the inlet and outlet lines to and from the sampler. The circuits which control these valves are shown in Fig. 1.5.11. These valves are also closed (see output XVI, Fig. 1.5.2) if the pressure in the reactor and drain tank secondary containment cells rises above +2.0 psig or 1f the fuel pump bowl pressure exceeds 10 psig. The cell pressure safety channels and the protective instrumentation used to measure pump bowl pressures were described earlier in this section. The atmosphere in the MSRE containment is kept at no more than 5% oxygen, with the remalnder being nitrogen. Oxygen content is continuously monitored by an on-line analyzer which measures the magnetic susceptibility of the cell atmosphere. The analyzer and its operation are described in detail in Sect. 6.4. - | Figure 1.5.12 shows the analyzer flowsheet and the final control circuitry which closes the block valves to and from the analyzer, The inlet gas to the analyzer is taken from the cell evacuation line, 565, and is discharged to line 566. These two lines form a low-flow bypass loop across the component coocling pumps which continuously circulate the air within the containment cells., The piping to and from the analyzer meets contailnment requirements; the analyzer, rated at 30 psig, does not. Block valves are required for containment and because the instrument is located in an accessible, frequently used aresa and is not entirely protected from mechanical damage. The block valves also permit main- tenance and routine operations such as changing the cylinders of ref- erence gas and purge nitrogen. 25MSRE Project Staff, Molten-Salt Reactor Program Semiann. Progr. Rept. Feb., 28, 1966, ORNL-3936. 76 Block valve operation is apparent from Fig. 1.5.12. The valves } are automatically closed if either channel, RM-565B or C, in the two- Q.J channel radiation monitor, signals excess radioactivity in the cell atmosphere or if the pressure in the secondary containment cell ex- ceeds +2.0 psig. These input channels have been described previously in this section. Complete on-line testing is possible, since block valve closure can be checked by observing the rotameters in the ana- lyzer. A complete test involving any two channels of the cell pres- sure input instrumentation is not conducted during reactor operation, since this same test, described earlier in this section, causes un- acceptable system changes elsewhere. The radiation channels are tested with & source, on-line, and the block valves and the control circuits are redundant. 1.5.4.3 In-Cell Liquid Waste and Instrument Air Block Valves The in-cell (secondary containment ) liquid waste lines are blocked if the reactor cell pressure exceeds 2 psig (see Fig. 1.5.13 and input XTII, Fig. 1.5.2). The normal operating pressure in the containment cells is 12.7 psia. Excess cell pressure is a symptom of system mal- function or, at worst, the maximum credible accident.! The protective instrumentation and control hardware and blockage of instrument air lines have been described earlier in this section. 1.5.4.4 In-Cell Cooling Water Block Valves A simplified flow diagram of the in-cell cooling water system, with instrumented block valves, is shown in Fig. 1.5.14. The signal to close L the block valves is provided by an excess radiation level in the pump (ij return header. Three independent sensors, RE-827A, B, and C, initiate block valve operation when any two of the input channels indicate excess radiation in line 827. Operation of the system is apparent from Fig. 1.5.14. Testing is accomplished during operation by manually inserting a radiation source in the monitor shield (refer also to Sect. 2.10) and observing that the indicated radiation level increases and that the proper relays operate. The construction of the sensor shield is such that each radiation monitoring channel can be tested individually. Since the monitor contacts are arranged in two-out-of-three coincidence, test- ing of individual channels does not close the valves. The valves may be tested individually by operating a hand switch and observing that flow stops in the line under test. The complete system is tested during shutdown. Valve ESV-DGT serves as a backup to FSV-837-Al1, FSV-841-Al, FSV~- 846-A1, FSV-847-Al and provides redundant blocking in the system. The thermal shield is protected from excess hydraulic pressure by the rupture disk in line 844. Pressure control velve PCV-844C and block valve FSV- 844-A1, actusted by either pressure switch PSS-844-Bl or valve position switch ZS-847-A2 on valve FSV-841-Al, prevent breaking the rupture disk with the transient pressure surge produced by closing FSV-847-Al., Valve FSV-844-A1 is also closed by the action of pressure switch PSS-855-Al when the pressure downstream from the rupture disk exceeds 5 psig. This action serves two purposes: (1) maintains some protection of the thermal shield if downstream pressure develops on the rupture disk, and _ (2) minimizes the loss of cooling water when the rupture disk does burst. tfi; 77 Any water discharged through a burst rupture disk passes into the vapor condensing system and is contained. 1.5.5 Underpressure Protection for the Secondary Containment Cells Failure or malfunction of the pressure control system for the com- ponent cooling pumps, if undetected, could lead to a dangerous subatmos- pheric pressure reduction, causing a buckling type of failure of the secondary containment structure. ZProtection against such an event is provided by a three-channel, reliable system, schematically identical to that used for cell overpressure protection deseribed above and earlier in this section. If cell pressure falls to less than 12.2 psia, a control-grade alarm sounds. The safety-grade instruments (pressflre switches) actuate at 10.7 psia (input XII, Fig. 1.5.2) and produce two protective actions: (1) shut off both component cooling pumps, and (2) close HCV-565-A1 in the cell evacuation line (Fig. 1.5.8), thereby preventing further outflow of cell air to the stack. 1.5.6 Tuel Salt Sampler-Enricher Containment Instrumentation The sampler-enricher is fully described in Sect. 3.12 and in refs. 2629, When in use it must penetrate the primary containment and, there- fore, is potentially capable of contaminating the area and exposing its operators to all the various types of radicactivity associated with nu- clear fuel. The material in this section is limited to a functional de- scription of the more important instrumentation and controls whose sole purpose is to prevent a loss of containment. Figure 1.5.15 is a simplified line drawing which illustrates the operation of the sampler-enricher. It can be seen that sampling or en- riching is accomplished by lowering and raising the cable-suspended cap- sule into and out of the fuel pump bowl. Throughout most of its travel the capsule is guided by and contained in the transfer tube, which pro- vides direct access to the molten salt in the pump bowl. The sampling- enriching operation may be likened to withdrawing or adding water to or from a well with the "old oaken bucket" powered by a motor-driven winch. Containment is effected during these operations by subdividing the region through which the capsule travels into compartments which are opened and 26R, . Robertson, MSRE Desisn and Operations Report, Part I, De- scription of Reactor Design, ORNL-TM-728 (to be published). 27Molten-Salt Reactor Program Semisnn, Progr. Rept. July 31, 1963, ORNL-3529, p. 35. . 28)Molten-Salt Reactor Program Semiann. Progr. Rept. Feb. 28, 1965, ORNL-3812, P 24 - 29Molten-Salt Reactor Program Semiann. Progr. Rept. Aug. 31, 1965, ORNL-3872, po 56. - 78 closed in sequence so that two contaimment barriers are maintained. The regions which are considered to be primary containment are: 1. area 1A, the transfer tube between the mailntenance valve and the punp bowl; 2. area 1B, the transfer tube between the maintenance valve and the operational valve; 3. area 1C and the short length of transfer tube which connects area 1C to the operational valve. Note that area 1C houses the motor- driven winch which raises and lowers the capsule. Compartmentalization and closure of these primary containment regions is obtained by the maintenance and operational valves and by the port which closes the access to area 1C. Since a complete sampling or enriching procedure requires that the material, either fresh salt or hot sample, pass through both the primary and the secondary containment barrier, the latter is also compartmented. These compartments are maintained by 1. The access port, which separates the primary and secondary contain- ment regions, 1C and 3C respectively. 2. The removal valve, which when closed, is the secondary containment barrier across the path traversed by the capsule. Note that area 3C contains the output side of the manually operated manipulator which the operator uses to unlatch the capsule from the cable, move it into area 3C, and thence to the transfer cask via the removal valve. Figure 1.5.16 is an austerity version of the sampler-enricher in- strument flowsheet and shows only the high-quality instrumentation whose sole purpose is to effect contaimment. Figure 1.5.17 diagrams the func- tions of these instruments and controls. Table 1.5.2 shows the normal aspects or status of the valves and the access door during use and when not in service. It is proper to point out that the sampler-enricher is used intermittently and by personnel well trained in its operation. In- termittent usage and functional requirements resulted in the arrangement of containment instruments in accordance with Figs., 1.5.16 and 1.5.17. Where redundancy is not obtained by duplicating individual instru- ment channels which produce the same specific output action, it is be- cause the desired protection is obtained by diversity (explained earlier in this section). There are additional instruments and alarms required by the device. These lend support to the high-grade interlocks discussed herein; the reader 1is referred to Sect. 3.12 for more information. 79 Table 1.5.2. Operating Situation Component Condition Maintenance Operational Access Removal Valve Valve Port Valve Capsule entering sampler-enricher Closed Closed -Closed Open (asbove removal valve) | Capsule in area 3A and being ma- Closed Closed Open Closed nipulated onto the latch Capsule latched to drive unit Closed Closed Closed Closed cable in area 1C Capsule in transfer tube and Open Open Closed Closed entering maintenance valve Capsule in transfer tube be- Open Open Closed Closed tween maintenance valve and pump bowl 80 EMERGENCY PRESSURE AC SWITCH-_ __ T CHANNEL NO.l\ —'“"tm ’;?:::;B 7> 7 CHANNEL NO.2 b - A GHANNEL NO.3\ 4 J——rfl-—}LZ ~— - 3 Q@ @ R - ’ ~ ] Q n ORNL-DWG 64-647TAR EMERGENCY T DC ~ s —ll 1F 0 w w A3, 2, A GAGE L L L L rd ¥ 7 ¥ PRESSURE SINTERED REAGTOR DISK SNUBBERS CELL Pl VOL = 18,000 i3 1a2 NORMAL OPERATING TVA PRESSURE l;:g}l ; —=2.0 psig PI 1A3 +0C BLOCK Esv &O)- : VALVE 1C1 (TYPICAL) Y AIR SUPPLY TO IN-CELL (TYPICAL) HEADER COMMON PORT / 45 GAGE (TYPICAL) M HAND o ¥ L A 75 VALVES ) VALVE k SOLENOIDS f ESV ESV ESV (? 3 ¥ 182 1CH icz ) # AG NEUTRAL 'PRESSURE |~ 7 DC NEGATIVE SOLENOID VALVE MATRIX. ‘ : ALL VALVES > SHOWN (N NORMAL OPERATING MODE WITH ALL SOLENQIDS ENERGIZED VALVE SOLENOID Fig. 1.5.1. MSRE-Redundant Instrumentation for Block Valves, *2°¢'T 31 Serq ndno-qndur A TISW SU3 JO Swel ‘woqsly £98Feg ORNL~DWG 67-4580 FSV 841-A1, F3Y 844-A1, FSY 848-Al, INPUT PRIMARY INPUT POTENTIALLY CIRCUIT NUMBER CORRECTIVE ACTION OQUTPUT ADDITIONAL REFERENCE INSTRUMENTS UNSAFE CONDITION. - . REFERENCE INFORMATION NO. : NO. * [ RE-NSCH Rx-NSCi1-A6 - 1 28 - i . I NSC2 NSC2 —-I REACTOR PERIOD LESS THAN +1.0 SECOND | NSC3 NSC3 i " REACTOR POWER (FLUX) GREATER THAN e 11.3 MEGAWATTS WHEN FUEL SALT PUMP 28 > # CONTROL ROD m . LOAD SCRAM J 1 SECTIONS [-5 MOTOR CURRENT EXCEEDS 35 AMP s ol (SEE OUTPUT NG XX) AND T1-8 RE-NSC{ Ry NSC1-A3 o S - 11 NSC2 NSC2 — ‘ RSS-NSCi-A4 NSC3 NSC3 REACTOR POWER {FLUX) GREATER THAN ' NSC2 11.3 XILOWATTS WHEN FUEL SALT PUMP / NSC3 MOTOR CURRENT IS LESS THAN 38 124 —#7, 118,49 TE-100-Al Tss- '00‘“’ FIJ'BLSA;.}’ TEMPERATURES AT REACTOR 5.2,3 28 : 30 :g 1 "i OUTLET GREATER THAN 130°F Ji 1,2,3—=18,19 —20,2 \ ——- 3 JI-A OPEN VENT VALVES; HCY 8§73, 20, 24 | HOV 575, HCV $T7, BETWEEN | ) o | DRAIN TANES AND AUXILIARY | CHARCOAL BEDS E_E 5998} LSS*SSQB} I FUEL PUMP OVERFLOW TANK LEVEL GREATER | 18,19 —20, 2 L———————w.*«u—uJ 6008 6008 THAN 20% f - ] Ir-—————-————v;;;’—-—-————' Y RAINS | FV-103 AND DRAIN TANK VALVES, : REACTOR Fl SECTION I-5 RM-528B } [RSS-52891 e ——_— 26, 27 —= 18,19, —= 20, 21 [ T¥-105 AND FV-108 {LF NOT ALREADY - - - ———————— e e e —— 11-C RM-557-A REFER TO INPUT NO. XVI {_ovm BY-PASS VALVES; HCV-544, 1 p— 557-B —pi | HCV-545, HCY-548, BETWEEN FUEL | PUMP BOWL AND DRAIN TANKS | P _d 20,21 —=131,132, - Z8S-NRRI-218A2 ANY CONTROL 10D BELOW ' R > ~ VI *FILL PERMIT" POSITION 20, 21 s [ L 127,115,116 | NCR3 [ [ 1. STOPE FUEL SALT PUMP ' > | 3. SCRAMS POPR TS REACTOR 1 SECTIONS _ Al HELIUM PRESSURE IN FUEL 22,23,—18,19—20, 21 L { POWER EXCEEDS 11.3 KW -5 AND [1-8 v {PSS 589 }—- BALT PUMP BOWL GREATER 22 23— 122 ( SEE INPUT BLOCK II. ? 592 & THAN 25 PIIG. 2 I ~ ~ HELIUM PRESSURE IN 20,21 —= 131,132, 133 [ [ [ BOWL. 70 AURDAARY CHARCOAL v SECTION I1-5 vt Pss-589 A2) | PUMP BOWL GREATER 20, 21 —=127, 115,116 [ BEDS BY GPENING HVC-532 AL 592 B2 THAN "FILL PERMIT" 20, 2| —=1{5 ( VALUE (2.0 PSIG) 2 BLOCK INLET HELIUM LINES TO 24,25—=18,19,20, 21 J’ FUEL DRAIN TANDS AND FLUSH TANK: 24,25, ~= 8t . N AN SUPPLY LNE IX {?M ~569 B}—’f?ss - 365 B'}—- HIGH RADIOACTIVITY IN 24,25-—=298 M B. CLOSE HCV 572-Al, HCV 5T4-Al AND v SECTION I-3 c 365C1 REACTOR CELL ATMOSPHERE 24,25 § - HCV 576-A1 IN INDIVIDUAL HELIUM SUPPLY 24, 25— 82 — LINES TO FUEL DRAIN TANKS 46,47,48 | _ L L L L CLOSE INLET HELIUM VALVE, PSS-500 N{ HELIUM SUPPLY PRESSURE | 127, 115,116 L, ( ( ( r . :cv “;A_:;;m TO FUEL Vi SECTION -5 X N2} —e IN LINE 500 LESS THAN 28 PSIG . ‘46,47.48—'—115 J: ( ( : | TORA N3 {HEADER PRESSURE} 46. 47,48 =y L >——3 CLOSE HCV 915-Al IN LINE 915 WHICH 1 . SUPPLIES COOLING AIR TO ROD VIi SECTIONS HIGH RATDIOACTIVITY IN HELIUM : f - DRIVE UNITS AND CONTROL 1I-5 AND [1-7 : ROD THIMBLES RM-596 A RSS-536A LINES NOS. 588, 509, 582, 593, - - . X1 { B}—{ B~ 59, 599, 600, WHICH SUPPLY HELIUM £0,6t, 62 6‘? Toes A4 : o C TO FUEL PUMP BOWL AND TO OVERFLOW INC'L i L & CLOSE STREAM DOME CONDENSATE DRAIN - TANK ¢ gy | vALVES NOS ESv-t06-24 VI SECTION I-5 AND EBV-800-2B : PSS-RC H PRESSURE IN SECONDARY | 84 %0 - A : . ) xi A CONTAINMENT LES3 THAN " | 84—=85—=312, 314 (315) _ l L L L L ' i CLOSE BLOCK VALVE IN ALL - : K 10.7 23 . . : - . | HELIUM LINES ENTERING : : 1X _ SECTIONI-5 e A e T e U e e e e - 30,31,32—=36,37. 1 bAoA CONTAINED REGIONS - - § e e . — "4 30,31, 32— 38, 37—=298 " PSS-RC B PRESSURE IN SECONDARY . CLOSE BLOCK VALVES X F}—» CONTAINMENT GREATER 30, 31,32 —=36,37 —~38,39 IN LINES SUPPLYING HELIUM T0 X i SECTION 1-8 THAN 2 PSIG . 30,31,32—=33,34 FUEL SALT PUMP BOWL AND GVERFLOW TANK |_30,31,32 —=36,37 L L4 _ _ —=318,319 (1 . . i CLOSE BLOCK VALVE HCV 585-Al XIV HIGR RADIATION ACTIVITY IN LINES 51 AND 54 : ( IN CELL EVACUATION LINE | X1 SECTION I-5 BETWEEN OFF-GAS SAMPLER AND STACK _ [ [ ’ : f SHUT OFF BOTH COMPONENT XV P55-589 A3 FUEL SALT PUMP BOWL PRESSURE l > > - ! COOLING BLOWERS ' X1 SECTION I-5 592 B3 GREATER THAN 10 PSIG 3IMASE—318,319 L L L L . - J ’ . 70,7 —=72 [ L [ : CLOSE BLOCK VALVES NOE. HCV 568-A1, RM-55T A RSS5-557 Af BIGH RADIATION ACTIVITY IN I r [ [ * HCV 566-43, HCV 566-A3 AND RM-5578 B OFF-GAS LINE NO. 587 70,71 —~73,74 [ l HOV 568-A¢ TO AND FROM Xt SECTION I-5 —— CONTAINMENT OXYGEN ANALYZER RM- 827A RS -827 A'l HIGH RADIATION ACTIVITY IN IN-CELL + ) 1 COOLING WATER SYSTEM S3TOSBINCL A A A/ . 8 B77-AL. BL. AND €1 | CLOSE BLOCK YALVES NOS. FCV 333-A1, L > FCV 333-A2, FCV $43-A1 AND XIV SECTION I-5 FCV 343-A2, IN LIQUID WASTE LINES TE-202 Aq TSS 202 A2 TEMPERATURE OF COOLANT 45,6 A Ak XVII! —e BALT AT RADIATOR OUTLET, l O Ao SO0 v ALVES TN DS TRUMENT 02 LINE NO. 302 L33 THAN S30° F ) LINES WHICH PENETRATE THE Xv SECTION I-5 SECONDARY CONTAINMENT T-201 FSS-201 A B :morcoomumrww. 7 TO 10 INC'L—= E-CPG! 5$55-CPG1 n' : mm[ o ; t:;mm umnmlum ! 1,12—=13TO ! ; CLOSE BLOCK VALVES NOB. ESV 537-A 2™ . UREMENT 16 INCL® ) AND B AND ESV 538-A AND B TO XVI SECTION 1-5 7§-1D- 339 r—_—__ AND FROM OFF-GAS SAMPLER 1D-B4B | EFTHER RADIATOR DOOR | ‘ 00-B3B K 255 AT FINAL UPPER LEMIT. | CLOSE BLOCK VALVE HCY 557-C2 0D-B4B > IN MADN OFF-GAS LINE TO STACK XVII SECTION I-5 - K 255 DOOR DRIVE MOTOR K 266 CURRENT AT OVERLOAD VALUE | CLOBE VALVES PCV 510-A2 AND sy PCV 513-A2 IN HELIUM VENT LINES XVIIT SECTION I-5 ' FROM BALT PUMPE TO OFF-GAS SYSTEM. : | CLOSE BLOCK VALVES NOS. FSV 837-A1, g | FROM FSV 847-A1, AND ESV-DGT IN THE X1x SECTION -5 OUTPUT | TREATED WATER COOLING SYSTEM s > IL:MKDSCRAH P XX SECTlOP:l 11-8 255, 256 — 568, 13, 15 {1) 5TOPS DOOR DRIVE MOTOR : 255, 256 —= 568, 13,15 ] (2) SXSENGAGES DAIVE CLUTCE XXI SECTION 11-8 o et A A e 151 0 | i ! e et oAt e e ot e A INPUT REFERENCE NO. I II I I H (R iy e — INITIATING CONDITION ROD SCRAM (a) SHORT PERIOD (b) HIGH FLUX (c) HIGH TEMP. - FUEL SALT TEMPERATURE AT REACTOR QUTLET GREATER THAN 1300°F FUEL PUMP OVERFLOW TANK LEVEL GREATER THAN 20% HIGH RADIOACTIVITY IN COOLANT PUMP OFFGAS HELIUM PRESSURE IN FUEL SALT PUMP BOWL GREATER THAN 25 PSIG HIGH RADIOACTIVITY IN - EITHER REACTOR CELL OR DRAIN TANK CELL ATMOSPHERE ANY CONTROL ROD BELOW 'FILL PERMIT' POSITION P HELIUM PRESSURE IN FUEL SALT PUMP BOWL GREATER THAN 2.0 PSIG | I RSS-NSC1-A4 nz RSS-NSC2.-A4 124 18 ‘ 1RSS-NSC3-M ne CORRECTIVE ACTION A OPEN VENT VALVES - HCVY.573, HCV-575 82 OPEN (THAW) FREEZE VALVE NO. 105 OPEN [THAW) FREEZE VALVE NO. 106 REACTOR DRAIN. DEMAND T OPEN (THAW) FREEZE VALVE NO. 103 OPEN BY-PASS VALVES HCV.544.A1, HCV-545-A1, NN . :ua.: — - 7‘5 ~— »N NS L/ \LS HCV-546-A1 CLOSE MAIN HELIUM SUPPLY doAvgov oy v VALVE, PCV.517-A1 AND BRANCH LINE SUPPLY VALVES, HCV.572-A1, HCV-574-A1, AND HCV-576-A1 ORNL DWG 67~4644 EFFECT REACTOR BLOCK INLET HELIUM LINES USED TO PRESSURIZE FUEL SALT DRAIN 1 1O FUEL SALT DRAIN TANKS LEGEND | ¢ o B CIRCUIT NUMBERS ——j 1 COINCIDENCE OF A AND B REQUIRED TO GET C Fig. 1.5.3. Input-Output Diagram of the MSRE FuTl Salt Fill and Drain Safety System. TANKS. DOES NOT INCLUDE HELIUM PURGE LINE VALVES ESV 519A AND ESV-5198 ] 83 System Conditisn e ORNL-DWG 63-8395R ESV 5198 ESV 519A CLOSED WHEN INLET HELIUM PRESS. IS LESS THAN 28 psig, (SAFETY SYSTEM INPUT NO. X} Fig. 1.5.4. PraeFill Cparate ! Velva Ne. Pra-rill Norm Drain Inte i with Circ. Nomat Fill brom Fils from Fill fram —— == Emerg. 1 Mellws He Operation FDT#1 FDT#2 FFT FOT#1 FDT#2 FFT Drain ; PCY 512, Fill prass o x x o ° o X X x X _ 1. roguiate L HCV 572, Fill, FOT #1 x % x 0 X x X X %X HCV 574, Fill, FDT #2 X x x x o x x x X X HCV 876, Fill, FET X x x x x o x X XX OFF-GAS TO HCV 544, By pusa 0 o o X Q o a £ E 0 HOLDUP AND CHARCOAL . o o Hev S4By pove o o £ v o6 x & £ o o INLET HELIUM GOOLER BEDS ) LINES 140 liters He §78; Vo X x ox ox oxox T ° r CHARCOAL HCV 877, Vent X x X H x o © : FILTER HEY $33 Al o x X o o 0 x x X X | ?l-; RATF:C LE HCV 119 AG B xox o x x x X X X X | g HCY SO0 Al o o o 0 x x o x X X I HCY 210 A o o o X o x X 0 X X t M 2l ey sty ase! o x X x x X x x x X R | OVERFLOW Hoy st e o o 0 0 0 o o o o & : t t ! ! TANK ey 52z a Hg fetdewn e ° o 0 0 ° o 0 o o SAFETY -— —= EMERGENCY DRAIN _[ :: :::,. Reel drsin valve : : < : o : g ‘),( : g g g SYSTEM | QPEN HCV-533-A M e | ey FY 106* X X 0w X* 0 X X o X x 0 1NPUT NO.V“ FY W7 x X x x x x % X X x : BYPASS LINE ‘ 0 AU v ior X F o X x x o x o xx —Gad 52l ; —GeD §6D—+ CHARCOAL K =—Chaed; O '-.mu; E - aither cpan ar closed. [* FUEL SALT 'Durlnl narmal operation both FY 105 and FY 106 are kept apen. . V‘ Tuev 519 AmB opened afrer sompleting fill and before cpamtion te satwe that drain line 103 Is clearsd. ‘! & EHCY 523 closed enly whan blowing selt aut of everflew tank. - i‘l ) - [ INITIAL i LOADING ‘ 1 REACTOR ~ CONNECTION 1)) VENT ‘; VESSEL E7)— 86 { | - HCv- HGV- LINE ! 577-Af HCV-544-Al - HCV & Y ore Cv-54 * \ 545-A1 | % N 546 G—;[* ° > Hev- o | * HCV-573-Af @ 575-At | * b @ ' FV103 Bion 6108 FREEZE FVi04 VALVE FV105 j : x X COOLING TO FUEL FV106 1 ? AIR i QO ysn TanK — TO FUEL S : - PR TANK | og) P07 FV 109 D € 3 FV107. b | 50 @ HcgJA X | @ ; i WASTE SALT Z 910 A1 SO9n > 1 ] DISPOSAL " 57 f‘—"\§77 L1~ ==~ @ foer————eee ‘;" ' @ | i srapH | " ' | SR nov T | o I FUEL TANK 908 A b I FUELl DRAIN | " JFLUSH CAPILLARY I TANK j No-2 A E TANK : NO.{ . i £ . , FLOW RESTRICTOR L H L Hov 4 ! | HELIUM pcy ST2:Al 574-A1 L 576-M- X SUPPLY 517-At x (—Yx | Ml 0 A HELIUM 35 peig * ) | FROM (547 - (578) . HEADER, N b T 1 LINE 500 CAPILLARY o NOTE: ‘ g FLOW RESTRICTOR _ VALVES MARKED WITH ASTERISK, (TYPICAL) : THUS { * | ARE SAFETY SYSTEM ‘ BLOCK VALVES X X 549 ] HCV B19A HCV519 ! i : FREEZE VALVE Diagram of Reactor Fill and Drain {f;System. COOLING AIR 84 ORNL-DWG 64-627R ALARM - FROM FUEL SALT OVERFLOW TANK PRESSURE TRANSMITTER ~METER NQTE : : OPERATION OF THE TEST SWITCH SIMULATES THE APPLICATION * TO SAFETY OF PRESSURE TO THE TRANSMITTER AND CHECKS ALL SYSTEM COMPONENTS IN THE SAFETY CHANNEL EXCEPT THE CONVERSIDN OF PRESSURE TO FORCE BY THE TRANSMITTER BELLOWS)| SINGLE ALARM SWITCH , DUAL ALARM SWITCH ' SWITCH CAPABLE OF VENT TO | PRODUCING TWO DIFFER- STACK NTAINED. ZERO | ENT SAFETY INPUT ] SIGNALS 8 psig REFERENCE N%‘”' oy &5 CHAMBER. RATED 50 psig | 2 psig TO DATA AND TESTED AT 100 psig 1 : LOGGER SLACK Cerdeeres e, DIAPHRAGM - T { ] TesT switck J [ fifl 6 & > Qume _A'A'A'l'_ H [=40 TO S5O0ma £ 4008 ° - r - 1=10 T0 50 mo S~ WELD SEALED PRESSURE \ISOLATION HCV TRANSMITTER WITH PRESSURE- AMPLIFIER 593|83 TO-CURRENT TRANSDUCER-AMPLIFIER. INLET (592) RATED AND TESTED AT 250 psig HELIUM * 27/ v TO PRESS TRANSMITTER USED FOR CONTROL REFERENCE LINE TO FUEL PUMP BOWL NLET TO OVERFLOW TANK, b TO FUEL PUMP HELIUM BOWL GAS SPACE SAME AS ABOVE Fig. 1.5.5. Typic?.l Chennel of Safety-Grade Pressure Instrumentation for Use in Primary Containment. e e e i e Voo »* 516 Al { m % u \/ A \/ A 3 < ¢ sieaz 85 TO FUEL PUMP a; B EOD——D—H< EED—td—< e e e e VENTED TO FILTERS AND THENCE TO OFF-GAS STACK EXCESS FLOW VALVE § _RUPTURE DISK : / 50 psig CEnm) TO FILTERS AND THENCE TO OFF-GAS STACK __igl RELIEF { “VALVE HELIUM SUPPLY peV ey R - 4 =<} HELIUM STORAGE RAD PCV MON. 2 6054 3000 -—-)4——-—-;LP-€EE}—>4L—- X *x K HCV 595 B1 i HCV Y 595 82 LOW PRESSURE ORNL-DWG 63-8398R2 HCV E 59583 TO COOLANT SALT PUMP BOWL BUBBLERS - PT A n n PRESSURE GAGE} AND PRESSURE SWITCHES WITH HIGH AND ALARM IS TYPICAL OF ALL BUBBLER LINES [ HC et *gsggss TO LEVEL PROBES, (BUBBLERS) IN FUEL SALT OVERFLOW | TANK. ) TO LEVEL PROBES {BUBBLERS) IN FUEL SALT PUMP BOWL. > Fig. 1.5.6. CAPILLARY RESTRICTORS &3 \ HELIUM PURGE LINE P\ LINE NO. 103 - ' SECONDARY CONTAINMENT SSIs . NOTES:! 1, AN EXCESS RADIATION SIGNAL FROM RE 596, (ANY 2 OF 3) CLOSES HELIUM SUPPLY VALVES , HCV 593 Bi, B2, B3, AND HGV 599 B1, 82, B3 TO BUBBLERS IN FUEL PUMP BOWL AND TO BUBBLERS IN}OVERFLOW TANK, RESPECTIVELY. i § | MSRE Drain Tank Afterheat Removal System. PURGE FLOW TO REACTOR DRAIN 2. A LOW HELIUM SUPPLY PR IN LINE 500, (ANY 2 OF 3 PRESS. SWITCHES) CLOSES BLOCK VALVES MARKED WIJH ASTERISK, THUS *i FSSURE HELIUM POV . = HCY . A G ' ¢ 1 G $10 'll; -} TO LUBE OIL § o D *gsggaz - X SYSTEMS FOR FUEL AND | o — » POV L COOLANT SALT PUMPS ! ' « & Hey ] C T 5134l St .@ ~y 59984 X . .l L_—_T— X PV OV % 10 COOLANT y i o5 NG DRAIN TANK L 5“ 1 rxfl o I FOV A* . . 5121 ] : (512 N T0 COOLANT PUMP f; | & E 201 (804~ [ CLOSES i BLOCK VALVES ' } 517 SEE NOTE 1 [ - o 2 OUT OF 3 el TO FUEL STORAGE COINCIDENCE e TANK AND CHEMICAL MATRIX %= “iNPUT | PROCESSING SYSTEM NO.X1 ! ' ‘ 2 OUT OF 3 CLOSES !- SNUBBER | — 3INDEPENDENT ____ [ ___ .| COINCIDENCE | — —=BLOCK VALVES SIGNAL, SAFETY MATRI SEE NOTE 2 | | Y SYSTEM INPUT NO.X ! X ! I} : '{J vl - w I | THREE CHANNELS A | | FOR INPUT SIGNAL. PRESSURE SWITGHES ! 1| ACTUATE AT 28 psig CAPILLARY FLOW | INDIVIDUAL TESTING OV .“ OF EACH CHANNEL pCV 572 Al ‘:’ AND ARE SECONDARY CONTAINMENT BARRIERS BY OPENING HAND 517 Al *i N I VALVES TR \ Qo= 574 At ' . / * . e ; 57 NN 574 T0 FDT-2 57641 } s C,, oy - ~GTO—— NN 79 = TO FF} 5194 * 1 3. LINE AND ASSOGIATED PXM'S ARE A ZERO psig REFERENCE SYSTEM WHICH MAINTAINS CONTAINMENT AND PRESERVES ACCURACY OF THE PRESSURE TRANSMITTERS DURING FLUCTUATIONS OF CELL PRESSURE COOLING TOWER PUMPS P3 B HCV-882 G NO.2 COOLING WATER TO OTHER COMPONENTS TO CONDENSATE (GO t-Ptt- STORAGE TANK ORNL-DWG 63-8388R o 7O OFF-GAS com_mg«—@ 2 TO COMPONENT O TACK FROM TOWER COOLING PUMPS PROCESS RUPTURE WATER MAIN #] oisks A ® — i 3 o ® —I* "~ 33 > 30-in. MOTOR OPERATED BUTTERFLY TO VAPOR CONDENSING : _@ @-. SYSTEM VALVES b (SEE NOTE 1) ) FEEDWATER TANK NO.A TC DRAIN TANK CONDENSER NO.2 FROM RUPTURE DISK IN COOLING WATER LINE 2 , FEEDWATER o ) @ r—-@ ESV-806 I —ple CONDENSATE TO REACTOR \@ * SUPPLY LINE THERMAL SHIELD STEAM | L L L LTl LCV-806A NOTES: . THESE VALVES ARE CLOSED DURING NORMAL REACTOR OPERATION. VALVES ARE OPENED ONLY DURING MAINTENANCE OPERATIONS WHEN THE REACTOR CELL 1S OPEN. 2. VALVES MARKED BY AN ASTERISK, THUS * ARE SAFETY SYSTEM BLOCK VALVES, Fig. 1.5.7. '~ im OSUONNN SN SNNNESNSSNSS SN ~ # - REACTOR CELL g RN TANK EXHAUST LINE A7 | . steam 30-in. DIAM A 1t DRUM A\ 1 i - DRAIN LINE FROM. STEAM DRUM ON FTD-2 SIGNAL TO CLOSE FOR EXCESS RADIOACTIVITY IN REACTOR CELL OR FOR HIGH PRESSURE - FUEL {>2.0psig } IN REACTOR Il pRAIN I CELL. REFER TO INPUT TANK t CONDITIONS NOS. IX AND (TYPICAL} | X1t " 77 Z 7777777 77777 STEAM DRUM Secondary Containment Regions. PUMP, CAPACITY -10 gpm X X ESV ESV 806-2A 806-28B CONDENSATE DRAIN TANK TO FLOOR DRAIN Diagram of System Supplying Helium to Primary and [ 'L' e VENT LINE OXYGEN _ ' , FROM FUEL DRAIN TANKS ANALYZER ORNL-DWG 63-8397R2 : AND FLUSH SALT TANK - 5D a. DRAINS REACTOR FROM ' T SAFETY SYSTEM b. BLOCKS STEAM DOME FONDENSATE DRAIN gfig&ifi § (342> INPUT NO. IX _’r“-"‘ c. (B)LOEKS LINES TG AND [FROM ] A e 2 ANALYZER — TO IN-CELL COMPONENT r 4 , o Bloc ) COOLING AIR HEADER & A | . BLOCKS COOLING AIR TO ROD DRIVES Q) OFF-0AS STRAINER % ! | . 8] SAMPLER - REACTOR CELL ALARM OFF-GAS HELIUM FROM ‘ #c HOV (BLOCK) EVAGUATION LINE FUEL SALT PUMP , 565A1 \VALVE { BOWL, LOWER LINE R ! PRESSURE BLOWERS rrrrrrrrbrrrr - : ' STACK ey - AUXILIARY [ - ) CHARCOAL BEDS [T V< >-GE2 MO(l;\l‘}?'OR OFF-GAS ; ACK—__ —22 o G5 CHARCOALL,-B_EDS"I DD ey J_NoS. 1aND2 [ 924 0 L ;o ) OFF-GAS STy = (?g HELIUM FROM FUEL HELIUM FROM @ } ] @-I\J—DQ—-— SALT PUMP, UPPER LINE PARTICLE CHARCOAL COOLANT SALT PUMP 25 RM SaFeTY ‘ TRAP FILTER 528 . . r : ‘ B SYSTEM SAFETYY | | SNt sysTEm |} R Al CAPILLARY POV %Iy e NO. V1 AT % FILTER R FLOW ELEMENT § MBA2 T e —— —7— === —1< Ino. xvI \ | & 53D——=piq : o - HELIUM FROM BLOCK VALVE L ' HCV i | -] COOLANT DRAIN TANK 534 Pr—e } (BLOCK s57c¢ XL AND LUBE OIL SYSTEMS POV | % .J o VALVE) 51042 " B, —GEe0 . — 1 /93"5\ SAMPLER- 4 | = ENRICHER CHARCOAL , - — ; TRAP H— ) - —@2D Fr B M 927 5 r 2 J MOTOR OPERATED 2 SPECIAL === ) G BUTTERFLY VALVES EQUIP ROOM ~_i i — ’\ 1 P 05 VENTILATION AIR RUPaRE , | P30 B FROM: ~ ] S | 3 1. LIQUID WASTE CELL pL L § ] o THIS 30-in. DIAM LINE 2. DECONTAMINATION CELL TT A1 ; R USED ONLY WHEN REACTOR 3. REMOTE MAINTENANCE CELL IS OPEN oumr;e PUMP CELL MAINTENANCE TO OBTAIN 4. HOT STORAGE CELL IN FLOW TO CELL 5. FUEL STORAGE TANK VENTILATION CELL - AIR FROM notes: IN-CELL COMPONENTS 6. SPARE CELL SERVICE TUNNEL ; RODS AND RODODRIVES o 1. COMPONENTS MARKED WITH ASTERISK, FREEZE VALVES, PUMP BOWL ETC ; THUS &« s Li—LL. i ———(E32) v , PERFORM INSTRUMENTED / | b A SAFETY FUNCTIONS / ].—.@5 COOLANT ereeze CELL d o 2. AIPES AND DUCTS LARGER THAN 2-in. DIAM qvawve | TS (PR EQUIV} ARE DENOTED THUS / ‘ B s 8 REACTOR CELL 4 VENT DRAIN . TANK CELL/ VAPOR i HousE PROCESS WATER CONDENSING ; TANK NO.2 ‘fi” FILTER. 250 CONDENSING cfm VT — [t ‘ FROM RUPTURE DISK ON ; THERMAL SHIELD COOLING WATER LINE i 4 Fig. 1.5.8. MSRE 0ff-Gas System. C f ) I b i l SIGNAL TO CLOSE - FROM RADIATION MONITORS RM-557A ORB, SAFETY SYSTEM INPUT XVI ORNL-DWG 63-8393 - I | 53 LOG COVER GAS OFF-GAS FROM 53 . e PrESs GonTRO ——|— SooranT - T0 OFF-AS. ALARM | SYSTEM | SALT PUMP ‘ < | STACK N QUICK ED BREATHER, CONNECTS SIGNAL TO CLOSE . | DiscONNECT TO FUEL SALT PUMP WHEN INLET HELIUM -———- o | A INTERCONNECTING OIL PRESSURE IN LINE 500 ¢ ==V 1 | RETURN LINE FROM IS LESS THAN 28 psig raoar |1 rov / [ COOLANT SALT PUMP (SAFETY SYSTEM INPUT X) 513-A1 L 593 A-2 . | HELIUM I ADDITION SUPPLY, 513 o | LINE O ey 35 psi Pl 510 A = I SALT PUMP ALARM 1A + ~ _N LOG OlL SUPPLY ~ — TANK FOR c—-——-l Ren FUEL SALT o PUMP —— (70— OT-1 OTI-B = ¢ (15— EXCESS FLOW \OT-2) ~ RETURN FROM PUMP OUTLET ALARM - — . TO OIL € (714) D<= | PUMPS ¢ - [~ —————————— e [ FOP-1 AND ‘ FOP-2 S % ; — g’) NOTES: oiL 1. BOTH LUBE OIL SYSTEMS DRAIN ARE SIMILAR. NUMBERS LINE ENCLOSED THUS () ARE EQUIVALENTS IN ¥ COOLANT SALT PUMP COOLING QUICK LUBE OiL SYSTEM WATER DISCONNECT Fig. 1.5.9. ASTERISK, 2.VALVES MARKED WITH THUS * ARE SAFETY SYSTEM BLOCK VALVES. Lube-0il System Off-Gas Monitors. HELIUM 2 39 SIGNAL. TO CLOSE =4— —— ——~ BLOCK VALVES ESV 537 A AND B ~— — ~* SIGNAL TO CLOSE BLOCK VALVES SAFETY ESV 338 A AND B SYSTEM INPUT NO. XIV — FLOW SWITCHES L —®- R RM 546 Dt V5228 LOSS OF @ ,> T FLOW ALARM ORNL-DWS 67-2519 TO AUXILIARY CHARCOAL. BED LEVEL s INDICATING 4 @ CONTROLLER 0 TO FILTERS = > LEv-50A i AND OFF-GAS ¥ STACK 1 . J‘:I ] I (fi g XVS0A XV508 ! PRESSURE RECORDER # . ‘ ; 2227 L L lr L A rd 2 L L 2 L . 11 4 ] LiQuip —u—@ LEVEL SWITCH NITROGEN ‘ 1 VIE Y CYLINDER . ‘/4_6\ / TTTITTT = SPARE / //////,/,4, /t-"TL " "A \2A /D|SCONNECT i1 4 VIOA VI0B — o — i Ty vizn ' D4 v J_¥vA _ __(conthoLLen . g L |— ¥4 1 POWER TO f 7 HEATERS wi2¢ g ¢ 1 wower o @ bme bbbl AR / 1 ft OF SMALL TR 7 2155 Y sramiess | __H _ _ _TorreEssurE ] DIAM Cu TUBING = ///f STEEL CEWAR | r {VACUUM) INDICATDR ] LeveL prose—"1 | Hifl RS E (___) ! / b % A [~LEAD SHIELDING A N i - S ~ (1o EQUIPMENT TO VOLUME HOLDUP: ] A S =i ENCLOSURE AND THENCE TO V - /, L= (75— MOLECULAR SIEVE : i CHARCOAL BEDS 4 7 )] MATERIAL IN 4 |- SAMPLE 4 PRESS _ SIGNALS TO { 7] weLDED STEEL e SaMPLE Fe-—ff ——— =R CLOSE FROM SAFETY 1 1 : | SYSTEM INPUT NOS SEAARRAEREINAAANANS 4 | BOTTLE SIGNALS TCL *nr XU XV XV A CLOSE FROM SAFE ‘ | : | @ P | e SYSTEM INPUTE NOS TEMPERATURE R _I Xl XIV | xv P yeiE Sy g’gfigfl:fiww INSTRUMENTATION: |—— — e — —= ‘ 4 4 } 4 ' L o. RECORDER v B CELL ——— e — + L —r— ] b. CONTROLLER - t“; : } vs80 ] ¢. TEMPERATURE HIGH ALARM T+ Tz /1 ] SWITCHES (5) i — - ) ‘ ] g i - £ 77 / £ (20)- 4 1 Cu0y V-20 i [ [ SCRUBBER ViK ‘ / : V30 1 _._’Q (M) ’ * G2 THERMAL = ] DG4 CONDUCTIVITY I A X X CELL 1 I esv- ESV- veon [ —"lo0o=- {75 & Y veer [ s3ma s37e ESV- H M1 xv808 xV73 } ] 538-d £ ‘ XVE0A b g / 11 f m : 4 ] Y / & o . “ VfflsG &L bl 2 » i / o / /] ] TO AUXILIARY % ’ 2Ll 2T MELIUM SUPPLY (CYLINDER) ; i1 USED TO PERIODICALLY [ cvsTev CHECK PERFORMANCE OF - = z T T L Z =z T TR E ST T Z TIFITITITT 77 7 Z TP L R RZZ) THE OFF-GAS SYSTEM 0 T0 PRESS @ @ ; RECORDER B __GD i b HIGH ALARM--35psig HIGH ALARM - 110 psig NOTE: . LOW ALARM-- 3 psid. LOW ALARM- 90 psig 1. VALVES MARKED WITH ASTERISK, ' } RELIEF t THUS: i vn £ | ] ‘;‘EI#%NT PRESSURE ! SYSTEM BLOCK VALVES PRESSUR . ) [ SWITCH I 125psig SWITCH I * —J —J 5 TO 30 100 psig VE4A STD SAMPLE psig\ H ELIUM CYLINDER 379 25 kVA PSS 589A3 . - OPENS WHEN FUEL PUMP BOWL PRESS. EXCEEDS 10 psig -/ ) o PSS 592 B3 o SAFETY SYSTEM INPUT XV e, | | - 90 E ORNL-DWG 67-1296 30 34 - 32 36 37 38 319 v - | 48V DC . ) L 48V DC N , _ R L 1vA DIESEL ) ; -F(Pseismssws) 1 L 25 kVA | D , N\ Ny \ A~ OPEN WHEN FUEL _I_ / _L T KA 379F - KB379F —~ 51648 51658 T K3QA ~—— K3{A T— K30C T K3iC ] PUMP BOWL 7 7T 7 PRESSURE EXCEEDS (TEST) (TEST) 10.0 psig ., T 4 4 d°K366 . OPEN WHEN REACTOR —— K376 —— KA3{BA Z" KB3BA CELL PRESSURE / _J EXCEEDS 2.0 psig PSS-RC-B | PSS-RC-F | PSS-RC-G _|_ A1 A1 - e . .y T K30F —K32A ——K30D ——k32C - OPEN ON HIGH 7“\(’% 71— /_ ACTIVITY IN OFF-GAS | <44 Rs-54- SAMPLER ENCLOSURE —— RS-54- OPEN WHEN REACTOR T RS-54-A2 A 2T, RS-54-B2 CELL PRESS. >2 psig : ' S162 A :l_ KABIBC 51634 I |KB 318C TTKMF " K32F T K3MD ——K32D (RESET) ]- (RESET) I+ :[— : (R I-3194 CR I-3198 KAZSB KB 3188 ESV ESV ESV ESV 537 538 537 538 A B . B A | = "l KB 318 } |l<325 K36B I K30 K3 | | | ING S S LSS k32 K37 2 . 0} ) L 319, 318 319, 318 318, 348, ) £ ) _ J J L l ) L 1 Y Y : \ ) OFF-GAS SAMPLER BLOCK VALVES CLOSED WHEN DE-ENERGIZED OFF-GAS SAMPLER BLOCK VALVES 1 3 . ‘ SAFETY SYSTEM ; ‘ INPUT XIII 38,3 38, 37 39, 298 39, 298 81, 81, 318 81, 81, 318 \ J Y BLOCK DEMAND FOR: 1. LIQUID WASTE SYSTEM 2. STEAM DOME DRAINS 3, OXYGEN ANALYZER * 4, OFF-GAS SAMPLER Fig. 1.5.11. Block Valve CircuitT for O0ff-Gas Sampler. ] 91 \ ! i . & 20 psig ) ! RELIEF VALVES NOTE: ?.f; VENTED TO VALVES MARKED ATMOSPHERE _ WITH ASTERISK, - 3I THUS * b 5 psig/ B { ARE SAFETY SYSTEM \ BLOCK VALVES | REFERENCE ‘ fi GAS 2 MEASURING 7 5% 0 100 20 CELL ! 95% NZ min i REFER TO INPUT IX FOR OTHER = SAFETY ACTIONS 2000 cm3/min - PRODUCED BY / RM 565 BOR C _ — 7. | SYSTEMSTSFEE NO. X111 —@ PRESSURE , | GAGE CELL PRESSURE >2.0 psig ROTAMETERS ¢ g CKTS' @ PCV-566-A 30,31, 32 S l T A ATMOSPHERE ‘ i 1 : i . ‘ ( CKTS - N = - - 36, 37 | - “\BLOWDOWN . - | VALVE > - - ; - = CKT 298 . | _CKT x HCV-566-A2 8 _ .. 298, R x HCV-566-A TWO-CHANNEL * ‘ RADIATION MONITOR, SAFETY SYSTEM INPUT IX RM l | (F o) 585 - — — — —— — >4 69 {CKTS} . - | | o 24,25 | | ; — | CKT | REFER TO SAFETY | —_ ——-—-i | ~ [ NO.80 ] SYSTEM QUTPUT XI CELL | | INST AIR LINE EvAcUATION LINE: | _|_ A FROM OUTLET OF §—<365) I COMPONENT COOLING PUMPS + 4 psig " = TO FILTERS AND FF-GAS STA HCV-565-At OFF-GAS STACK TO INLET -2 psig OF COMPONENT = s 566)- - COOLING PUMPS MANUAL SWITCHES FOR INDIVIDUAL CONTROL OF EACH VALVE; LOCATED ON JUNCTION BOX N VENT HOUSE 5_11 5V AC 2p8 ORNL-DWG 67-764 —11 d | — HS-566-A5A IN CELL § CONTAINM :@ HCV 566 - Al —— HS-566-A{ =~ HS-56 CONTACTS OPEN WHEN EITHER RM-565-B OR RM-565-C ~ K24G INDICATE EXCESS RADIQACTIVITY —— CONTACTS OPEN WHEN ~K36D PRESSURE% IN SECONDARY 4 ENT CELLS EXCEEDS T + 2.0 psig MANUAL SWITCHES ON INSTRUMENT PANEL IN VENT HOUSE —____ == VACUATION LINE NO. 5657 wh HS5-566-A58 K256 K37D B-A3 :E HS-566-A2 cv HCV 56 - 566~ A3 A2 ! o~ HS-566-A4 HCV 566- aq Sy~ E BLOCK VALVES ARE CLOSED V‘{HEN SOLENOIDS ARE DE-ENERGIZED Fig. 1.5.12. Block Valves to a.nd from Cell Oxygen Analyzer. FINAL CONTROL CIRCUIT CELL AIR OXYGEN ANALYZEiR BLOCK VALVES P, SERVICE AlR 100 psig AR Tl Ny PCV 3328 UNION SECONDARY / CONTAINM ENT\ REACTOR : NITROGEN et SUPPLY 50 psig MAX HAND VALVES PRESSURE INDICATOR SINTERED DISK SNUBBER ORNL-DWG 63-B396R PRESSURE SWITCHES o b I —— - (ACTUATE AT +2 psig) CELL, @ 2 ouT NOMINAL A3 SAFETY OF 3 OPERATING n @-—-'--— SYSTEM b==-e{ MATRIX OF [F—) ever | 4 PRES?;{D,,;Q / n | INPUT NO. SOLENOID | | TRANS. - DRAIN i t127pskl] I e @ 4 XN VALVES i TANK CELL ST 1 | ! : f RCFS™ ' | & T | PUMP SUMP A rev %L Fev : : ‘ @D 3 mar T 333z | | . =] = DT | i ] Dn ol L N, I "LEVEL J o P339 I | : | I E {BUBBLER) - SUMP SAMPLE [ — o —— l FCV ' | ' ’ BOMB * * NN GER L4 G K 0 INSTRUMENT | CLOSE BLOCK DRAIN LINES LINES WHICH | VALVES TO FROM AFTER- & - D LIOUID PENETRATE { AND FROM HEAT REMOVAL 2 WASTE SECONDARY | IN-CELL O, ggm;” STEAM TANK CONTAINMENT I ANALYZER NOTE: VALVES MARKED WITH 11,000 gol CELL I ASTERISK, THUS &% ; —i—— CLOSE BLOCK Fig. 1.5.13. ARE SAFETY SYSTEM BLOCK VALVES. VALVES IN VENT- ILATION LINES TO AND FROM OFF-GAS SAMPLER In-Cell Liquid Waste and Instrument Air Block Valving. 93 ORNL-DWG 64-638 A | TO VAPOR _ — CONDENSING fl DIESEL HOUSE MAIN SUPPLY SYSTEM : e~~~ HEADER T GAS ‘ psig L6 FILTER! : —.826) COOLER (573 l ! TO OIL VENT TO SURGE TANK -(829) f | TREATED | o COOLERS l__l | I WATER f G) FOR COM CENTRIFUGAL GAS . | COOLER | v COOLING PUMPS SEPARATOR ) ) UMPS Stpsig | | | FROM COOLING 3 TREATED WATER IGY TOWER PUMPS — T \877 ALARM ' i £ K S DX ! ESV @ ! i DT VENT PURGE AIR 1; o PRESSURE X & ] SWITCH B @ & 1 TANK ) SEE NOTE No.2-|” RUTTURE @ TO €7D 3 | ~. COOLANT _ ,4 FUEL PUMP ) SALT PUMP CHEMICAL TO FEEDWATER ; MOTOR T [3esig 4 MO ADDITION"S TANK o N ~J - JTOR ' o 7 7T T Tl AT T 1 PURF(?EO hflqm GG 874 ngOM SPECIAL \ f SuppLY | (876)— | EQUIP ROOM | ‘ ‘ 1 ; FROM N SURGE TANK COOLANT N J . j SALT PUMP ‘| 4— DRAIN A 8psig MOTOR 1 NUCLEAR | “ Tank - i INST 3 INDEPENDENT RADIATION Fsv 1! E PENETRA | CELL i v - MONITORS RE BAZ;DA,CB : 837 x A C % TION IR : 2 OUT OF 3 SN | v (1|1 U + COINCIDENCE | — ~ v e — - — — — ] SAFETY SYSTEM Ly * ] esv X 847 / ‘ yd \ f [ Marrix INPUT NO. XVII x L gae * / AIR N 9 | 3 RELIEF % a30)—U /] COOLERS |~ [ / | SAFETY SYSTEM ‘ VALVES Fsv | | ~ § L SUTPUT NOLXIX NOTES: 1. ON EXCESS RADIATION SIGNAL FROM ANY 100 psig 8at [*T— 625 | ~—T0 N p e TO BLOCK \;'ALVES, 2 OF 3 RADIATIOCN MONITORS ALL VALVES \ ‘||§l'—' ,/ THERMAL tflg_ THERMAL N 1/ SEE NOTE NO.{ MARKED WITH ASTERISK, THUS <% ARE CLOSED ZF] IF] ] SHIELD SHIELD SLIDES A 1 _ % — SECONDARY 2. RUPTURE DISK AND PRESSURE SWITCH PROTECT » &4 1 CONTAINMENT THERMAL SHIELD FROM RUPTURE IN THE EVENT : - @3 ~ q OF EXCESS WATER PRESSURE 0 : N ’ WASTE TANK ! Z 7 7 7 7 ZZ Z z 77 ] v o TRANSFER TUBE (PRIMARY CONTAINMENT LATCH STOP - PUM7 CAPSULE DRIVE UNIT— AREA {C {PRIMARY CONTAINMENT) -~ SAMPLE CAPSULE OPERATIONAL AND MAINTENANCE VALVES 4 ; Ll T 94 ORNL~-DWG 63-5848R > REMOVAL VALVE AND w7 SHAFT SEAL PERISCOPE LIGHT X LATCH-_| ACCESS PORT-_| CASTLE JOINT (SHIELDED WITH DEPLETED URANIUM) MANIPULATOR / - AREA 3A (SECONDARY / _ —I CONTAINMENT ) SAMPLE TRANSPORT %-L:l CONTAINER : LEAD SHIELDING AREA 2B (SECONDARY CONTAINMENT) 852' ELEVATION S o SPRING CLAMP DISCONNECT — CRITICAL CLOSURES REQUIRING A BUFFERED SEAL EXPANSION SECTION SAMPLER-ENRICHER SCHEMATIC MIST SHIELD CAPSULE GLIDE Fig. 1.5.15. Sampler-Enricher Schematic. J BUFFER HEADER 40 paig CKT, - 280 To . INSTRUMENT H3V AIR HEADER 678 B2 95 ————aeA37T REN/R . ‘ A& INST AIR HEADER \ I HCV HCY RV-AZ | Rv-A HSV CKT HCV 675 a2 383 6794 PUMP NQ.2 CKT 381 REMOVAL H5V €808 VALVE 2755\"111 PE PSS AIR CYLINDER - SAFETY CKT 393 ceT A294 FEEE9A CAPSULE AREA 44 CRIVE CKT. sy AREA ic . AREA 4A MANIPULATOR CAPSULE AREA {B HSV . 6598 CKT T“g3re [ 8382 «—CKT aA3re TYPICAL DOOR LATCHING ACTUATORS (AIR CYLINDERS) TOTAL NO. =8 . OPERATIONAL VALVE 220v moTop 3-PHASE KT 62~ { . L o CKT : ) ST o oot MOTOR ! VACUUM MAINTENANCE VALVE HSV 6688 CKT 265 : 220v i 3-PHASE HSY ; AREA 4A 6558 1 -———— : CKT 366 : B376 " SAFETY Fig. 1.5.16. Sampler-Enricher Simplified Flow Diagram. INSTRUMENT AIR HEADER 5048 EXCESS FLOW ORNL-DWG 676695 TO FILTERS AND OFF-~GAS STACK EXCESS FLOW VALVE ORNL-0WG 6T-6696 PRIMARY INPUT ‘ INITIATING CONDITIONS ‘ CORRECTIVE ACTIONS INSTRUMENTS PREVENT OPENING REMOVAL VALVE f\..t\l'\..—..1 PE PSS —(362) 670 }= == 670 }==—=(360)—-» REMOVAL VALVE OPEN (365) 8/ B — (368) _ — (366)— —s| MAINTENANCE VALVE OPEN |—(359) BUFFER PRESSURE <40 psia (368) — ‘ L] ' OPERATIONAL VALVE OPEN |—{359) — I _____(363)_______, , (359) . PREVENT PENING CAP! RT ' (LIMIT SWITCH) (368) . VENTS OPE SULE ACCESS PO _ —— — ——— ——— — . — . —— ————— —-—=————= ’ HSV-6784 NOT CLOSED [ o 1 . / ’ PREVENTS OPENING MAINTENANCE VALVE ’ ’ ' MAINTAINS CONTAINMENT: INSTRUMENTED CLOSURES TOGETHER WITH INTERLOCKED PE PSS —1(359) —————— T T e e e - OPERATION OF MAINTENANCE VALVE , 669 }-— —| €69 —{369)— -» ACCESS PORT IS OPEN (362) ‘ | OPERATIONAL VALVE, ACCESS PORT AND B 8 b (365) . _| CLOSE VALVE HSV-678-81 IN LINE BETWEEN | REMOVAL VALVE MAINTAINS A MINIMUM | SPCA ST PREVENT OPENING OPERATIONAL VALVE PSP L W W N e 7T PN == | ¥ S SPSa St VACUUM PUMP NO.1 AND CAPSULE CHAMBER {C OF TWO CONTAINMENT BARRIERS AND ’ PREVENTS DIRECT ESCAPE OF ACTIVITY | TO BUILDING OPERATIONAL AREAS OR = i TO SURROUNDING AREAS OR INDIRECT —(362) ESCAPE ViA THE HELIUM SUPPLY AND 680 - —(A394 )~ ~— ~ ~ —| MANIPULATOR COVER REMOVED (365) - CLOSE VALVE HSV-678A IN LINE BETWEEN VACUUM BUILDING CONTAINMENT AIR SYSTEM. ) PUMP NO.1 AND CAPSULE CHAMBER, AREA 1C L PSS 589 s wn cn[AFTY) e e == —(362) A3 (368) FUEL PUMP BOWL PRESSURE >10psig L e (365) > o] CLOSE VALVE HSV-677-A IN LINE 677 5 - ———e8r9) — — —— (381) BETWEEN AREA 3A AND VACUUM PUMP NO.i ’ Luuuu -(a380) l — —{A3TT )= (381) A HIGH RADIATION LEVEL IN ANY (D360) L ] cLoSE BLOCK VALVE AS FOLLOWS: BUFFERING HELIUM SUPPLY LINE [ (nag0) ‘ A HSV-657D IN HELIUM PURGE LINE TO AREA 1C (LINES Noo. 699, 837, 668) OR L ———-(B 382 B. HSV-6688 IN HELIUM BUFFER SUPPLY TO (c380) OPERATIONAL VALVE - = EITHER HELIUM OFF-GAS LINE (3934 NO. 675 OR NO. 684 C. HSV-655B IN HELIUM BUFFER SUPPLY TO 615 (B377 )ty MAINTENANCE VALVE D. HSV-680B IN SUCTION LINE FROM MANIPULATOR COVER AND MANIPULATOR BOOT TO VACUUM PUMP NO, 2 are) PRESSURE IN OF 542 [ (D380} \— N\ SURE IN OFF-GAS LINE NO. (9901 — GREATER THAN 7 psi @ {8378) ‘ P29 L (¢380) . CLOSE BLOCK VALVE HSV-675-Af CLOSE BLOCK VALVE HSV-659 IN LINE FROM AREA 2B TO VENT IN AREA 44A CLOSE BLOCK VALVE NQ. ESV-542A iN DISCHARGE LINE FROM VACUUM PUMP NO.1{ CLOSE BLOCK VALVE HCV-6T9A Fig. 1.5.17. Sampler+Enricher, Input-Output Diagram of Safety-Grade Control Actions. 2. SAFETY INSTRUMENTATION AND REACTOR CONTROL 2.1 NUCLEAR INSTRUMENTATION: INSTALLATION AND IOCATION All permanent neutron sensors are located in a single penetration. The penetration is a 3-ft-diam pipe installed at an angle of 42° to the horizontal so that its lower end is opposite the midplane of the reactor core and its upper end terminates on the main floor in the high-bay area. Figures 2.1.1 and 2.1.2 are plan and elevation views, respectively, of the installed penetration. The lower end of the penetration passes through the thermal shield, and the end closure plate is essentially flush with the inner periphery of the thermal shield. The penetration is, from a containment standpoint, an extension of the secondary contain- ment shell. The lower end of the tube is welded to the containment shell, and the upper end is embedded in the earth fill and the concrete floor. A bellows-type expansion Jjoint accommodates thermal expansion between these points. Since penetration was installed during modifications to the containment shell, it was stress-relieved and pressure-tested at the same time. The penetration is filled with water to within approximately 1 ft from its upper end. A float-type instrument monitors the water level and gives an alarm when the level changes more than 4 in. Water is added with a hand valve adjacent to the upper end of the penetration in the high-bay area. A 5-gpm pump circulates the water in the penetration to reduce temperature gradients and maintain a uniform concentration of cor- rosion inhibitor. The inhibitor, containing lithium nitrite (ILiNO,) and lithium borate (LiH,BO3), has 810 ppm of NO, and 57 ppm of boron. The solution is sampled periodically and tested to maintain the pH at 9.0 % 0.2. The penetration is designed to accommodate ten ion chambers. Each chamber is located in an individual guide tube; four tubes are 5 in. ID and six are 4 in. ID. The configuration of these tubes within the penetration and the types of chambers assigned to them are shown in Fig. 2.1.3. The guide tubes are not made of single lengths of 30-ft-long tubes; instead subassemblies, each approximately 10 ft long, were made by welding the tubes into end plates, or bulkheads, and the subassemblies were bolted together when installed in the penetration. The tubes were constructed this way (Fig. 2.1.4) because there was not enough headroom behind the upper end of the penetration to ease the handling problem at assembly. The tubes are open to the water in the penetration, and the upper, or last, bulkhead plate serves as the cover plate over the end of the penetration. Individual, smaller cover plates are used over the upper end of each tube. These contain the necessary gland-type fittings for signal leads and push rods for chamber positioning. Figure 2.1.5 shows the upper end of the penetration with the guide tubes and individual cover plates installed. One of two ORNL model Q-2545 wide-range counting channel drive units (see Sect. 2.3) is shown installed in the penetration. 97 98 The mounting flanges on these drive units fit the drilling for the cover plates, so that a complete drive unit is handled as a module which is in- serted in a tube and bolted in place. Farly critical tests disclosed that the curve of neutron flux in the penetration vs distance deviated grossly from the desired exponential type of curve. The deviation was beyond the capebilities of the compen- sating function generator (see Sect. 2.3) in the wide-range counting channel. Cadmium sleeves® were placed around guide tubes 6 and 9 to shield the fission counters from neutrons which entered from the side and distorted the curve of count rate vs distance. The design of the shields, their location, and their effect on the count rate as a function of distance in guide tube 6 are depicted in Fig. 2.1.6. Figure 2.1.7 is a diagram of the interconnection wiring layout. As much as possible the safety system wiring was separated from control and power wiring. It was not feasible to separate the first runs of cabling from the drive units to the Jjunction boxes on the reactor cell wall. These jumper cables (described in more detail in Sect. 2.7) contain all the electrical leads in a single well-protected bundle. The safety system interconnections, consisting of the wiring to the clutch coils and the potentiometers in the rod drive unit and the signal and chamber voltage leads to the safety chambers in the instrument pene- tration, are in individual and separate conduits to the control room. Except where absolutely necessary, these safety interconnections are unbroken by terminal blocks, comnectors, etc. All the in-cell wiring (excluding jumper cables) is entirely with mineral-insulated, copper- sheathed cables. Control-grade wiring, not subject to the restrictions imposed by separation, protection, and independence, is run in trays and conduits as dictated by cost and convenience. 1MSRE Project Staff, Molten-Salt Reactor Program Semiann. Progr. Rept. Feb. 28, 1966, ORNL-3936, Pert 1, p. 44. 99 ORNL-DWG 64-984R UPPER END OF NEUTRON INSTRUMENT PENETRATION / / REACTOR CELL / / ION CHAMBER IN GUIDE TUBE, NEUTRON INSTRUMENT PENETRATION BF3 CHAMBER” TUBE BF3 N CHAMBER TUBE REACTOR VESSEL THERMAL SHIELD *USED ONLY DURING INITIAL CRITICAL TESTS MSRE Plan View of Nuclear Instrument Penetration. Fig. 2.l.l. 100 ORNL-DWG 64-625R | 24t 2in. :‘.l ¢ FLANGE FACE NEUTRON INSTRUMENT JUNCTION BOX | HIGH BAY AREA I 41° 50’ / WATER-SANDC ANNULUS FACE OF INST. FINISHED FLOOR L~ SHELL FLANGE EL. 8521t °i"-\ EL.851ft Bin. 2 EARTH FILL &Y 3 WATER ® LEVEL 5 Q,\)’ 849t 8in. & ot S g W _ WATER LEVEL INSTRUMENT FARg p CHAMBER GUIDE TUBE (TYPICAL) REACLOR A ¢ END OF 4B-in. o% SLEEVE THERMAL - EL. 841t +3 in. SHIELD : Batft tg in CONCRETE SHIELDING ~ ELEV. : 837+t 7in. 48-in.0OD OUTER SLEEVE ASSEMBLY (WITH EXPANSION JOINT) ~~EXP JOINT Q SECONDARY ¢t CONTAINMENT 5 PENETRATION EL. 834f1 55z in MIDPLANE OF CORE 830 ft 8 in. - _ L EL.830 # 3in. SHELL ION 36 in. CHAMBER f._4" |- (rypicaL) ff 355 in 10, N INSULATION REACTOR CONTAINMENT CELL Fig. 2.1.2. MSRE Elevation View of Nuclear Instrument Penetration. 101 ORNL-DWG 66-10143 LINEAR CHANNEL LINEAR CHANNEL ‘||||||||l’ NoY Ne2 SPARE_GUIDE ' BFy COUNTING TUBE b CHANNEL WIDE RANGE ;| SPARE GUIDE_ COUNTING CHANNEL NO | TUBE WIDE RANGE SAFETY CHANNEL N2I COUNTING CHANNEL N9 2 SAFETY. SAFETY CHANNEL NO3 CHANNEL No 2 HOLES N2 3,4,5,6,9 610 — 47 DIA HOLES HOLES N2 1,2,7 & 8 5{D|A HOLES COVER PLATE DIA ~——wemmmmm39 1" DIA ' Fi.g. 2.1.3. Location of Neutron Sensors Within Instrument Pene- tration. ‘ 102 PHOTO 66306 to Imstallation 1lor Guide Tube on Shop Floor Pr Chamber 104. ion. 2 Fig. in Penetrat PHOTO 48571 b o w Fig. 2.1.5. Upper End of Penetration with Guide Tubes and Individual Cover Plates Installed. NORMALIZED COUNT RATE ORNL-DWG 66-2741 10° . MSRE GUIDE TUBE NO.9 N COUNT RATES IN GUIDE TUBE T a NO.6 BEFORE AND AFTER CONCRETE FILL ‘, _ oot L \ ADDING CADMIUM SHIELDING 9 oy - = / SECTION THROUGH — REACTOR SHIELD— NUCLEAR INSTRUMENT ~ \ /. PENETRATION — \ \\ GUIDE TUBE 102 = X ‘ A NO. & = VN ) : \ (LI REACTOR — ‘ \ ;o CONTAINMENT o0t \ MIDPLANE ’ Sin. = \ \ OFCORE | 4 S 10"5 =— CURVE "B" COUNT \ \ l = RATE WITH CADMIUM ) ' — SHIELD l m B ¢ 6 REACTOR 10 ° = CURVE "A" COUNT RATE — VESSEL = WITHOUT CADMIUM — SHIELD B 1 CADMIUM SHIELDING 107 SUBASSEMBLY — TYPICAL 0 20 40 60 80 IN GUIDE TUBES THIS LENGTH 100% x, DISTANCE WITHDRAWN (in.) 6 AND 9 (CADMIUM WRAP {0 ft-0in. A 10 t-Oin. SECTION A-A - ‘ LOCATION OF Fig. 2.1.6. T Y 8]1:3[1 @ GUIDE TUBES \OUTEF\‘ SHELL REMOVED FOR CLARITY—SHADED WEDGES ARE CADMIUM —UNSHADED WEDGES ARE ALUMINUM ' Cadmium Shielding of the Fission Chamber Guide Tubes. 105 ORNL-DWG 66- 4101 JB-t19 fi JB-115 (SPARE) ¢ CELL PENETRATION NO.XI ] MAIN MINERAL JB-112 (SPARE) 1 INSULATED sy ] g CONTROL | JB-109 ~ ¢ BOARDS {S)F (1 | —a INCLUDING | JB-110 D / CONSOLE &) SEPARATE JB-1t4 7CONDUITS [ Ly g CELL PENETRATION Ri / / - %comouws , 4 - 1 /1 || | _caBLE TRAYS 1 . [ - JB 1 JB-41 \20 / ] CONDUITS AND g AUXILIARY CABLE TRAYS FLEXIBLE i " g%%ggL JUMPER CABLES I’; ROD DRIVES J8-40 JB-67 fé\ H : o/ 3 JB-68 ~ % NUCLEAR S$)— 77 1 > INSTRUMENT ) PENETRATION JB-69 e 2 7~ SEPARATE NUCLEAR \ CONOU|TS SAFETY \TO SAFETY CHAMBERS CABINET TO LINEAR POWER CHAMBERS, REACTOR FISSION CHAMBERS AND BF, CHAMBERS CONTROL CELL 7 ROOM JB-JUNCTION BOX (S)- SAFETY SYSTEM WIRING Fig. 2.1.7. MSRE Interconnection Wiring for Nuclear Instrumentation. 106 2.2 BF; INSTRUMENTATION (o 2.2.1 General The MSRE is equipped with one channel of sensitive BF3 counting equipment. The counting chamber is located in guide tube 2 (Figs. 2.1.4 and 2.1.5). The electronic instruments used with these chambers follow typical practice (Fig. 2.2.1). This sensitive BF3 channel is required to get counting-rate '"con- fidence" at the neutron source level when the reactor is less than half filled or when it is being filled with flush salt. Except for the pre- amplifier, the electronic instruments shown in Fig. 2.2.1 are mounted in the nuclear instrument cabinet in the auxiliary control room. As soon as confidence is established by one or both wide-range counting channels, the BF3 chamber is withdrawn manually to prevent its being damaged. 2.2.2 BF3 Counter The neutron counter is & BF3 counter from Reuters-Stokes Company, No. RSN-28A, procured on UCNC purchase order No. 568-1724, May 11, 1964. The specifications and characteristics are as follows: Shell (shell is cathode) OQutside diameter 2 in. gfij Wall thickness (wall is the 0.55 in. cathode) Overall length 12 in. Active length g.13 in. Material Aluminum Anode 0.002-in.-diam wire in- sulated from the shell with ceramic insulation Filling Enriched BF3; (96% *°B) to a pressure of 40 cm Hg abs Performance Thermal-neutron sensitivity 15 counts sec™t (nv)™* Saturation curve See Fig. 2.2.2 107 For use in the MSRE, the counter is encased in a weighted water- proof can, described by Instrumentation and Controls Division drawings Q-2719-3 and -4. A jointed push rod is used as a handle to position the counter within the guide tube in the penetration. 2.2.,3 High-Voltage Power Supply The high-voltage power supply is manufactured by Electronic Research Associates, model 25/10UC. The output from the power supply is contin- uously adjustable from 500 to 2500 v dc, positive or negative, by six step-switch positions and a fine control. Maximumn load current is 10 ma for any voltage. The total amount of ripple, hum, and noise is less than 5 mv rms. ILine regulation is #0.005% for a +10% change of line voltage. Load regulation is a 60-mv change from no load to full load; recovery time is less than 10 msec. Front panel meters indicate from O to 10 ma and from O to 2500 v dc. The input is 115 # 10 v ac, 60-hertz, single-phase, l-amp. 2.2.4 Preamplifier, ORNL Model Q-1857 The preamplifier consists of a three-stage feedback loop, followed by a resistance-capacitance differentiator, and a second three-stage feedback loop. The third stage of the second loop is a power stage to drive a long, low-impedance transmission line. The gain of each loop is about 20. A 2.5:1 voltage loss occurs in the differentiator, so that the overall gain is about 150. Variable compensation is provided across the feedback resistor in each loop to produce satisfactory transient response. The preamplifier power supply is self-contained. 2.2.5 Pulse Amplifier, ORNL Model Q-1875 The output of the ORNL model Q-1857 preamplifier is developed across a 100-ohm resistor in the amplifier chassis. This resistor serves as the characteristic impedance termination for the transmission line from the preamplifier. The signal is coupled to & gain control,whose output supplies. the signal to the pulse amplifier.. The pulse amplifier has two separate three-stage ampllflers with feedback loops. The compensation on each feedback loop is adjustable: compensation is used in the first amplifier to adjust the rise time of the amplifier and in the second amplifier to make the transient response satisfactory. The gain of each loop is approximately 100, but, due to losses in the output cathode followers, the overall gain is about 5000. The output of the main amplifier is available at "low" and "high" output jacks. The low output is intended for driving long cables and has a maximum value of 5 v. The high output will deliver approximately 100 v. ' A pulse-height selector (PHS) is included on the amplifier chassis for measuring pulses between O and 100 v. The PHS is direct reading with 108 an accuracy of approximately 0.5 v. Two PHS outputs are provided: the first, a positive pulse with an amplitude of 3 v and a width of 0.4 usec, intended for driving a count rate meter, appears at CN6; the second, with an amplitude of about 20 v negative and of slightly longer duration, ap- pears at CN5. The second is intended for driving a scaler. The amplifier contains its own power supply and is designed to operate with 115-v, 60-Hz power. 2.2.6 Scaler, ORNL Model Q-1743 The scaler has & fast input decade consisting of a type 6700 beam switching tube, a Schmitt trigger, and slow decades which are Ericsson GC-10B glow transfer tubes. ZEach glow transfer tube is driven by & de- coupled 1AG4 tube. The glow tube stages are followed by & pulse shaper, register driver, and a six-digit mechanical register. The instrument contains a regulated power supply. The input resolving time is 1 usec, with a counting loss of less than 0.2% at 20,000 random counts per second. 2.2.7 Logarithmic Count Rate Meter, ORNL Model Q-751 This instrument measures the average rate of a series of electrical pulses. The input pulses are the output from the pulse-height selector (Sect. 2.2.5). The pulses are randomly spaced, positive 3 v amplitude and 0.4 psec long. The output of the instrument is logarithmic and spans four decades. The average counting rate, in counts per second, is dis- Played on a meter. In addition, provision is made for remote readout on either a remote meter or a 10-mv recorder, or both. The indicating meter is graduated from 1 to 10,000 counts/sec. 2.2.8 Confidence Trips This instrument is composed of two Control Data Corporation, Magsense level comparators. Each unit is designed to accept an input of O to 100 pa dc. The trip is continuously adjustable in this range. The trip level and hysteresis are adjustable by potentiometers mounted on the rear panel. The output consists of two SPDT relsy contacts. 109 ELECTRONIC RESEARCH ASSOCIATES 2.5/10UC CHAMBER POWER SUPPLY r ) BF3 COUNTER Pg]IT:vSE REUTERS-STOKES AMPLIFIER RSN -28A RC13-10-57 ORNL-DWG 66-2446 (= PULSE PREAMP RC13-10-56 Fig. 2.2.1. DECADE SCALER Q-1743-C + - RC13-10-59 LOG COUNT - + = ¥ RATE METER |— TRIP COMP TRIP cognp RC13-10-58 LCR>10cps LCR<10 cps} —HFTT< K1 CAL USE|+ cONSOLE O ((LO- —H:‘HWHKZ TO BF- CONFIDENCE CIRCUIT Diagram of BF3; Counting Channel. 110 ORNL-DWG 66 —10019 {0 nmn IO 8 /I P ¢+’ b — 0————./ b 1 o 1 x © L o w — 5 o 4 O 2 0.9 1.0 {11 {.2 1.3 14 1.5 ANODE (kilovolts) Fig. 2.2.2. Typical Plateau Curve for Reuters-Stokes BF3 Counter Type RSN-28A0 111 2.3 WIDE-RANGE COUNTING CHANNELS 2.3.1 Principle of Operation The wide-range counting chammel employs a 2-in,~diam, 6~1/2-in,- long fission chamber as the neutron sensor and is useful from startup (with a fully fueled core vessel) to full-power operation at 10 Mw. The principle of its operation, described elsewhere,l’2 is repeated here as a convenience to the reader. The design of this wide-range counting system is explained by ex- amining the behavior of a movable neutron sensor submerged in, or sur- rounded by, & neutron reflecting and absorbing medium in which the neu- tron attenuation with distance is approximately exponentiasl. For purposes of explanation it is sufficlent to consider the idealized case in which neutron attenuation as a function of distance from the neutron source is exactly exponential. For this idealized situation CR = Pe ¥ | (1) vhere CR is the count rate in counts per second, P is the reactor power (assumed proportional to flux), x is the distance from the reactor, and L is the attenuation coefficient of the medium surrounding the fission chamber., Rearrangement gives -~ log P = log CR + HX . (2) It is apparent from Eq. (2) that log P is the sum of two easily obtained numbers: the logarithm of the counting rate (log CR) and the distance, x, of the sensor from the neutron source multiplied by a constant, M. Inverse reactor period is obtained in the usual way by differentiating Eq. (2) with respect to time. Figure 2.3.1 is a simplified diagram of the arrangement of the in- struments that perform the operations of measuring the neutron flux and distance, obtaining a logarithm, adding, and differentiating. 1In the MSRE (or any other installation), neutron attenuation is not ideally ex- ponential,3 as assumed in the preceding paragraph; instead, u varies with x, and the form of this variation can only be established by exper- iments with the equipment installed for use at the reactor. An adjust- able position~-sensing device, the ORNL model Q-2616 function generator, produces a signal proportionsl to ux, The adjustment feature provides a means to compensate for variations in p with x and, further, permits these adjustments in situ. 1R. E. Wintenberg and J. L. Anderson, Trans. Am, Nucl. Soc. 3, 45455 (1960). 2J. L. Anderson and R. E. Wintenberg, Instrumentation and Controls Div. Ann. Progr. Rept. July 1, 1959, ORNL-2787, p. 1l45. 3MSRE Project Staff, Molten-Salt Reactor Program Semiann. Progr. Rept. Feb, 28, 1966, ORNL-3936. 112 The fission chamber is moved toward or away from the reactor by a servomechanism which attempts to maintain a constant output from the count rate meters. The value of this constant output (the count rate set point) is, within limits, arbitrary. It should be high enough to ensure a good signal-to-noise ratio in the input to the count rate meters, but it should not be so high that fission counter 1life is seri- ously reduced. A typical value for the count rate set point is 10,000 counts/sec. These wide-range channels can provide useful operating and control information as long as the counting rate is in the range from 1 to 100,000 counts/sec. Limiting values of count rate are used to pro- vide control system interlocks, discussed in detail in Sect. 2.6. The operation of a wide-range counting channel is explained in the discus- sion by tracing its response as the reactor goes from subcritical to full-power operation. Figure 2.3.2 shows curves of count rate and chamber position during a traverse of the reactor through its power range. The curves are based on the assumption that the count rate set point has been established at 10,000 counts/sec. In the source and very low power region, where the count rate is less than the set-point value of 10,000 counts/sec, the error signal, which is the algebraic difference between the actual count rate and the set point, is negative. This causes the servomechanism to drive the chamber toward the reactor until its lower limit is reached. The cham- ber will remain inserted at the lower limit until the reactor power is sufficiently large to produce a count rate of 10,000 counts/sec. While the chamber is at the lower limit, ux is constant, and (see Fig. 2.3.1) the rise in reactor power is followed by the output of the logarithmic count rate meter. When the reactor power is high enough to produce 10,000 counts/sec with the chamber at the lower limit, the error signal becomes positive and the servomechanism withdraws the fission chamber to maintain the count rate constant at 10,000 counts/sec. Changes in reactor power are now indicated by changes in the "compensated position,' ux, the output of the ORNL model Q-2616 function generator. If, for example, the count rate set point is changed arbitrarily from 10,000 to 12,000 counts/sec while the chamber is partially with- drawn and the reactor is in steady state, the servomechanism will insert the chamber a sufficient distance to satisfy the increased count rate request. The decreased value of px will exactly equal the increase in log CR, and the sum of the two, log P, will remain constant, as it should., Again, suppose that, with the reactor in steady state, the operator switches from servo control of position to manual control and arbitrarily withdraws the chamber a short distance, The decrease in log CR will be balanced by the increase in px, and their sum, log P, will remain constant., Now, suppose the operator continues to withdraw the chamber manually so that the counting rate approaches 2 counts/sec, which has heen established as the useful threshold operating value for the system., The count rate signal will contain s higher percentage of spurious electrical input "noise," and, also, the random variations in the neutron flux will become more apparent as the count rate is de- creased. In common with all counting instruments of this general type, the response of the count rate meter becomes progressively slower as the count rate decreases, The loss in response is such that when the count rate is reduced to about 500 counts/sec, the logarithmic count rate 1 113 meter is unable to follow the change in count rate produced by manual chamber withdrawal, Therefore, in such a case, the indicated power would lag and would be higher than actual power. This response lag would continue to produce an error, and the indicated power reading would be higher than actual power until the chamber had stopped moving and enough time had elapsed to attain steady state in the new position. This situation obtains regardless of whether the chamber is being in- serted or withdrawn manually. In manual insertion at count rates below 500 counts/sec, the indicated power will lag and appear lower than actual power. As the count rate is lowered, the output of the counting system, log P, may become erratic and fluctuate about the average value. At very low counting rates the ratio of useful signal to noise decreases and accuracy suffers. If chamber withdrawal continues until the count rate becomes less than 2 counts/sec, the confidence circuits will be actuated and the "no-confidence" interlocks governed by that channel will be established. If the reverse process takes place, the chamber may be inserted until the counting rate becomes 50,000 counts/sec, at which point the confidence circuits will also be actuated. This upper bound of system operation was established at this value to keep the instruments within their operating range. The confidence circuits and their functions are discussed in Sect. 2.6.6. From the foregoing it is evident that, if the count rate is 500 counts/sec or more, the servo need be fast enough to follow only normal maneuvers; any transients too fast for the servo to follow will change the count rate so that the chamnel will read correctly. This technique has several advantages: the operator need not switch range or take any other action, the system covers a very wide range of reactor pover, manual withdrawal of the chamber and the dead time induced when the chamber is withdrawn are eliminated, and the constant, optimum count rate of the amplifier is maintained when sufficient flux is available. Figure 2.3.3 is a detailed block diagram of a wide-range counting channel as used in the MSRE and includes the ORNL model Q-2609 fast-trip comparators (described in Sect. 2.5) which produce the trip signals re- gquired by the reactor control system. The increased number of operational amplifiers shown in Fig. 2.3.2 are required to obtain signal gain for impedance matching to output devices and for signal inversion (sign change). The detector, preamplifier, and radiation~resistant interconnecting cable are contained in an integral assembly, ORNL model Q-2617. This assembly, approximately 2 in. OD, is flexible so that a guide tube or thimble, curved if required, can be installed in the reactor shielding leading to the core. The assembly is waterproof and can operate con- tinuously in an ambient temperature of 100°C while surrounded by either air or water. ' . The detector is a fission chamber with concentric cylindrical elec- trodes coated with 1 mg/cm?® of 23°U over a total area of 860 cm®. The chamber is well saturated with 200 v applied; the operating polarizing potential is 270 v. The collection time is approximately 80 nsec. The pulse-height characteristics of the chamber, obtained by using the pre- amplifier described below, are shown in Fig. 2.3.4. It is evident that garma. pileup presents no problem, even in fields as high as 2 X 106 r. The chamber has ceramic insulation entirely, and the special cable con- 114 necting the chamber to the preamplifier is designed to withstand a . garma~-ray dose of 1010 r, o The output stage of the preamplifier drives one side of a balanced line, the other side of which is terminated symmetrically. This sym- metry and careful attention to shielding and grounding make the assembly, as demonstrated in many field tests, very insensitive to electrical noise pickup. The receiving end of the bhalanced line feeds a pulse transformer for common-mode rejection and clipping to give an approximately sym- metrical waveform. This avoids base-line shifts due to changes in counting rate and aids in keeping the discrimination level constant. Pulses from the pulse transformer are sent to the pulse amplifier and count rate meter, ORNL model Q-2614. Following a calibrated at- tenuator the pulses are amplified in two feedback stages, each with a gain of 10, and enter a biased amplifier whose variable bias level de- termines the discrimination level. Only pulses that exceed the dis- crimination level are counted. The output pulses from the biased-ampli- fier discriminator are shaped and applied to a conventional logarithmic count rate cirecuit of the Cooke-Yarborough type. The time constants are a compromise between the desire to have rapid response and the necessity to prevent excessive fluctuation in the period signal. The output of the log count rate circuit is applied to an ORNL model Q-2605 operational amplifier (1A in Fig. 2.3.3) whose gain is adjusted to give an output of 2 v/decade, or 10 v full scale. The function generator output is applied to amplifier 2B through the nor- mally closed contacts of Kl. The gain gives an output of 2 v/decade. Amplifier 2B is also used in a test mode and will be described later. Qij The outputs of amplifiers 1A and 2B are summed, with a gain of 1/2, in amplifier 2A, yielding an output signal proportional to reactor power. The span of the sumning amplifier 2A is 10 v, or 1 v/decade. The out- puts of the log count rate amplifier (1A), the summing amplifier (2A), and the gain amplifier (3B) are indicated on panel meters in drawer W-1. The generation of a period signal from the reactor flux signal is accomplished with operational amplifiers 3A and 3B. The output from amplifier 3A is the approximate derivative of the log P input with a dc gain of 4 (product of C 308 and R 331). To prevent excessive noise in the period signal a 250-kilohm input resistor and a l-uf feedback ca- pacitor are provided to limit the low- and high~frequency noise gain respectively. The output of amplifier 3A is amplified by amplifier 3B and is offset so that O to +10 v corresponds to a period of —~30 to +5 sec, An infinite period is +1.428 v provided by the offset network at the input of the amplifier., The amplifier gain is 24.6. The pulse amplifier and count rate meter module, ORNL model Q-2614, has, in ad- dition to the log count rate output, a simple diode pump circuit (linear count rate circuit) whose output is used as the signal for the chamber position servo. This circuit has an output of approximately 1.75 v at 10% counts/sec. This signal is compared with the demand potentiocmeter (servo level) in amplifier 1B. Amplifier 1B has a voltage gain of 50; further voltage and power gain are provided by a servo amplifier, ORNL model Q-2615, which has an approximate voltage gain of 3 and whose output drives the servo motor directly. In addition to the chamber, the motor drives a tachometer whose output is applied to the servo preamplifier Q;J 115 1B and with a polarity opposite that of the input signal; this negative feedback loop provides servo stability. To provide control interlocks, eight fast-trip comparators, ORNIL model Q-2609, are used. Two fast-trip comparators receive their input from the log count rate amplifier (1A). Comparator 1 trips if the comnting rate is less than 2 counts/sec, whereas comparator 2 trips if the counting rate is greater than 50,000 counts/sec., Their output (relay contacts), in series with the "calibrate-operate" relay contacts, provides counting channel confidence if all eight comparators are prop- erly plugged into the instrument cabinet drawer (see Sect. 2.5 for ad- ditional discussion of confidence). Summing amplifier 2A provides the input to three fast-trip comparators. The first comparator operates if the power "sags" below 200 kw while in the "Run" mode; the second oper- ates when the power is above 500 kw, thus giving permission to enter the "Run" mode; and the third initiates a control rod "reverse" if the pover exceeds 1.5 Mw in the "Start" mode. Several tests are provided to ensure that the system is operating properly. There is contained in the pulse amplifier module (Q-2614) a 10%- and 10-cps oscillator which may be applied to the input of the pulse amplifier by proper positioning of the gain switch on the front panel. In addition, with the gain switch on period test, the period test relay (KL) must be actuated by a push button in drawer W-1. This switches out the normal inputs and feedback resistors of the function generator amplifier and switches in a 10-pf feedback capacitor and a selectable input resistor. With an input of 25 v applied through the gain switch, this amplifier thus generates a voltage ramp which pro- duces a 5-, 25-, or 30-sec period indication as selected. An additional push button in drawer W-1 causes an adjustable voltage source to be ap- plied to amplifier 2A to test its fast-trip comparator. "In" and "out" push buttons on the same drawer provide normal override of the normal servo signal from the output of the Q-2615 module, The chamber drive mechanism is a ball-bearing lead screw with a linear speed of approximately 72 in./min and a total stroke of 90 in. The direct=-current, variable-speed drive motor has an integral tachom- eter and is protected from overload by a slip clutch. The position~ sensing components are connected directly to the lead screw shaft ahead of the slip clutch. - The position-sensing train contains a ten-turn potentiometer whose output is connected to a meter in drawer W-l. In addition, a one-turn data-logger potentiometer and synchro transmitter for driving a position indicator on the console is provided. Upper and lower limit switches restriet the overall travel of the unit. 2.3.2 Fission Chamber and Prégmplifier Assembly The‘following description has been excerpted from ORNL-3699 (ref. 4). The 3/4-in, fission chamber described in ORNL-3699 has been re- 4D, P, Roux et al., A Miniaturized Fission Chamber and Preamplifier Assembly (Q-2617) for High Flux Reactors, ORNL-3699 (October 1964). 116 placed with one of more typically standard dimensions (2 in. diam) with . greater sensitivity. The excerpted text has been altered accordingly. &,J 2e3.2,1 Introduction To meet the space and environmental requirements for high-perform- ance reactors, an articulated assembly (Fig. 2.3.5) consisting of a fission chamber, a preamplifier, and flexible cables has been developed. Because high-flux reactor cores are usually inaccessible, it becomes necessary to use a detector that is small and movable in a tube which can be bent to resolve the access problems at each reactor. The rel- atively low sensitivity of a small chamber is compatible with the large neutron source level encountered in such reactors. Locating the pre- amplifier close to the fission chamber drastically reduces the suscep- tibility of the counting channel to electrical noise pickup, so that the system responds predominantly to neutrons; comsequently, the reactor operator is assured of an adequate source. The assembly is particularly suitable as part of a wide-range counting channel,l but also can be used as part of a conventional counting channel. . The entire assembly is waterproof and can operate continuously at a temperature of 100°C ambient. The maximum outside diameter of the assembly is 2 in. (chamber diameter). The fission chamber and the cable connecting it to the greamplifier can withstaend a total integrated gamma radiation dose of 101Y rads; the preamplifier can withstand at least 108 rads. 2.3.2.2 Preamplifier ‘iJ Circuit The preamplifier circuit (Fig. 2.3.6) consists of two cascaded feedback amplifiers: a charge-sensitive input configuration (Vl and VZA)’ followed by a voltage-sensitive asmplifier (V2B’ V,, and V;) with symmetric output. The signal pulses are differentiated both at the in- put and at the output of the preamplifier, giving the pulse shape shown in Fig. 2.3.7. The gain of the preamplifier is 0.75 x 1012 v/coulomb. This corresponds to a system output pulse height of 150 mv for a nominal 50-Mev fission fragment. The counting loss for randomly spaced pulses is 10% at a counting rate of 10° counts/sec. The advantages of a charge-sensitive configuration are that, over a wide range of detector capacitance, (1) the output signal height de- pends only on the charge generated within the detector and is insensitive to the capacitance of the detector and connecting cable (variation of input capacitance from O to 200 pf produces a gain change of only 10%), and (2) the decay time of the detector pulse is also insensitive to the capacitance of the detector and cable (variation of input capacitance from O to 200 pf produces a decay time change of only 10%). The preamplifier output is connected to a balanced and shielded cable which is terminated at its receiving end by a pulse transformer. The common-mode electrical fluctuation signals picked up by the two signal leads are canceled in the pulse transformer., In one application at a reactor the common-mode rejection was greater than 95%. 117 The double differentiation reduces the effects of pulse pileup. With the first differentiator at the input to the preamplifier, the max- imum counting rate is limited by coincidence loss rather than by bias shifts. The pulse transformer serves as the second differentiator. The second differentiation time constant is determined by the ratio of the primary inductance of the transformer to its terminating resistance. The combined effect of both differentiators eliminates any duty-cycle shift in the main-amplifier discriminator threshold. Figure 2.3.7 is a photograph of the fission pulses at the main amplifier input. The in- tegrals of the individual pulse areas on either side of the reference are equal. Component Selection The operating temperature, the radiation requirements, and the per- missible overall diameter of the assenmbly demanded prudent selection of the components used in the preamplifier, Tubes. — Temperature and radiation conditions precluded the use of transistors; consequently, flying-lead subminiature tubes were selected. Nuvistors were considered but were rejected because their diameter is too large to mount components side by side with the tubes in the allotted space. Resistors. — Resistors were limited to those of wire-wound and de- posited-carbon types. The wire-wound resistors (miniature power ratings) were used in all critical circuit locations sensitive to the value of a resistor; deposited-carbon resistors were used in noneritical circuits. Capacitors. — Capacitors were limited to those of porcelain and solid tantalum electrolytic dielectrics. The particular ceramic capac- itors used (Vitramon type VK20) have maximal operating conditions of 150°C and 200 v. A 10%-rad gamma dose results in a capacitance variation of less than 1%. The tantalum capacitors (Texas Instrument type SCM) are used only for bypassing in circuits which can tolerate high leakage currents and considerable capacitance variations. The operating tem- perature of the tantelum capacitors is limited to 125°C. As a result, they are located in the preamplifier layout, where negligible heat power is dissipated (see the following section). Irradiation tests made at ORNL, on four type SCM tantslum capacitors to an accumulated dose of 108 rads showed an increase of less than 5% for the dissipation factor. Provisions for Operation at 100°C Ambient For continuous operation of the preamplifier in air or water at 100°C ambient, the following provisions were made: 1. The preamplifier was potted in a mixture of 70 wt % epoxy Helix P-430 and 30 wt % epoxy Dow Chemical DER 732 to which was added 6% of Helix hardener B. This particular potting compound improves the heat transfer and increases the mechanical rigidity of the preamplifier. The advantages of using this compound are that it is only slightly brit- tle at room temperature, it shrinks minimally during curing (the shrink- age of some epoxies during curing has caused tube and tantalum capacitor breakdowns), and its thermal expansion coefficient is compatible with that of the preamplifier components. 2. The tube filaments are heated with a voltage of only 5.5 v (6.3 v rating) to minimize the heat-power generation. 118 3. The tantalum capacitors (125°C max) are located at the ends of the preamplifier, whereas the subminiature tubes are positioned in the center of the preamplifier. The ceramic capacitors (150°C max) are also located at the ends, except for a group which is placed in a gap between the first and the second tubes as shown in Fig. 2.3.8. Two different tests were performed to establish that the capacitors operate below the manufacturers! specified maximum temperatures when the preamplifier is in a region with an ambient temperature of 100°C. In the first test the preamplifier was placed in still air at 100°C in an oven, In the second test the preamplifier was immersed in water at 98°C. In both tests five thermocouples were located inside the preamplifier close to the components of interest, and the time profiles of the tem- peratures were recorded. The results indicated that the equilibrium temperatures of all capacitors were at least 6°C below the manufacturers!? maximum specified temperatures in the first test and 14°C in the second test. The first test lasted ten days; during this time no change in the preamplifier gain or output pulse shape was observed. Separation Distance of Preamplifier to Chamber The separation distance between the preamplifier and the fission chamber should be short to satisfy the electrical noise pickup consid- eration, but must be long enough to limit the radiation damage to the preamplifier. (The preamplifier was designed to withstand an accumu~ lated dose of 108 rads over one year of continuous operation.) The evaluation of the effects of the accumulated dose should be separated into two parts: +the dose accumulated during operation of the reactor at power and the dose accumulated during reactor shutdown. In light- water-shielded reactors, the dose accumulated during reactor shutdown is considerably alleviated if the neutron counting rate is restricted to 10* counts/sec or less. The reason for this is that photoneutrons generated in the water by the residual fission product gammsa rays will give a neubtron counting rate that makes the insertion of the fission chamber and preamplifier assembly into a higher gamma flux unnecessary (see Sect. 2.3). For application in light-water-moderated reactors, a separation length of 4-1/2 ft between the fission chamber and the pre- amplifier is adequate, This distance is also sufficient to maintain the preamplifier in a gamma flux less than 10% r/hr (or 10% r/year) when the reactor is at full power. 2.3.2.3 Flexible Cables Cable Between Fission Chamber and Preamglifier The cable between the fission chamber and the preamplifier is a BIW 50-ohm coaxial cable enclosed in an external inorganic insulation sheath (spaghetti). The sheathed cable is inserted into a 1/4-in.-ID corrugated flexible metal tubing fitted with stainless steel braid and casing., The BIW ceble is a flexible, high-temperature (500°C max), radiation-resistant coaxial cable. It consists of a 24-gage stranded nickel-clad copper center conductor, an inorganic insulation, and a nickel-clad copper outer braid 0.200 in. in OD. Its capacitance is 35 pf/ft. The corrugated tubing provides watertightness and flexibility 119 with negligible elongation. The measured linear-expansion coefficients of the cable assembly are approximately 2 X 10™ per 1b and 1 X 107> per °C. Cable Between Preamplifier and Main Amplifier This cable is a Raychem No, 10023 cable. It has preirradisted polyethylene dielectrics and jackets, is radiation resistant, and is a multilead coaxial cable., The center member of this composite cable is a shielded and Jjacketed two-conductor coaxial cable for the signals; around the center member are wound three 26-gage and two 20-gage hookup wires for preamplifier supplies, and over all of these are a nickel-clad copper shield and a preirradiated polyethylene jacket. The maximum overall OD is 0.324 in. The cable will withstand a maximum temperature of 125°C and an sccumulsated dose of 5 x 10% rads. Following this ex- posure the cable can still be coiled on a form whose diameter is ten times the overall cable diameter. The Raychem cable is also enclosed within a watertight metallic envelope which may be varied for different reactor applications. The metallic envelope also serves as an electrical shield. For example, a stainless steel hose covered with polyvinyl chloride is used at the Oak Ridge Research Reactor (ORR). 2.3.2.4 Electrical Shielding Layout Multiple electrical shields are provided to prevent excessive elec- trical noise pickup in the fission chamber and preamplifier assembly. Figure 2.3.9 shows, schematically, the general shielding and grounding layout. A first (or inner) shield covers the entire path of the signal from the fission chamber to the main amplifier input. This shield in- cludes the cathode of the fission chamber, the outer braid of the BIW coaxial cable, a solid brass foil surrounding the preamplifier, and the two braids of the Raychem multilead coaxial cable. The preamplifier commonh mode, or ground, is electrically connected to the inmner shield, which is electrically insulated from an outer shield, or shell, of the assembly. This outer shield includes the fission chamber casing, the corrugated flexible metal tubing between the chamber and the preamplifier, the preamplifier casing (insulated from the brass foil shield), the me- tallic envelope surrounding the Raychem cable (described previously), and a shielding which forms an extension of the metallic envelope to the main amplifier in the reactor control room. The grounding of the inner and outer shields is discussed in Sect. 2.3.2.5. 2.3.2.5 Low Pickup-Noise Performance of the Assembly Extensive experimentation with different counting channels using this assenmbly was required to reduce its susceptibility to electrical noise pickup. The principal source of electrical noise pickup is elec- tromagnetic radiation from ac power lines which are shock excited where some piece of equipment is turned on or off. The sensitivity to noise pickup has been minimized by the short separation distance between the preamplifier and the chamber, the large output signal from the pream- plifier, the balanced configuration with common-mode noise rejection, and the multiple electrical shielding. 120 The lowest noise pickup is achieved with this assembly when the inner and outer shields are connected together in several places, for example, at the junction box and at the main amplifier, as shown in Fig. 2.3.9, This is contrary to the generally accepted precept of avoiding ground loops. Apparently, the capacitive coupling between shields de- feats any attempt at isolation of the system from the building ground. With the connections described herein and shown in the Fig. 2.3.9, the pulses from pickup are no larger at the main amplifier input than the pulses of the alpha particles produced in the fission chamber, even when the assembly is located in the noisiest reactor installations available at ORNL. 2.3.3 Preamplifier Power Supply 2.3.3.1 General The fission chamber and preamplifier dc power supply provides three regulated output voltages from an unregulated input supply of —32 + 4 v for use with the fission chamber and preamplifier assembly ORNL model Q~-2617-1. The three outputs are: +300 v for polarization of the fission chamber, +110 v for the preamplifier anode supply, and —22 v for the preamplifier vacuum tube heaters and for biasing. The -22 v is derived directly from the —32-v battery supply through a series regulator and a current-limiting eircuit. The other two volt- ages, +300 v and +110 v, are developed by a dc-to-dc converter with a series preregulator. 2.3.3.2 Construction The fission chamber and preamplifier dc power supply is contained in a module 4.25 in. wide, 4.72 in. high, and 11.90 in. deep. It is a standard "three-unit" plug-in module of the ORNL modular reactor in- strumentation series depicted on drawings Q-2600-1 through Q-2600-5. The circuits are on two printed circuit boards mounted parallel to each other and enclosed in a perforated metal shield to reduce electrical radiation and coupling to other modules. Adjustments and test points are accessible through the shield from the top of the module. 2.3.3.3 Application The module is intended to supply all required voltages to the fis- sion chamber and preamplifier assembly. Because the assembly is potted and unrepairable, the povwer supply is designed to limit currents and voltages to protect both the assembly and the power supply ageinst demage from almost any conceivable combination of crossed connections or short circuits. 2.3.3.4 Specifications Overall specifications for the preamplifier power supply are given in the following table. General Power required =32 * 4 v dc, 0.5 amp max Ambient temperature range 0 to 55°C 121 —22=V sSuUpply Output voltage range —20 to —24 v dec Output current range 200 to 400 ma Voltage regulation +19 Current limiting Adjustable to limit the output cur- rent to no more than 110% of nor- mal operating current from normal to short circuit +300-v supply Output voltage +300 £ 15 v dc Output current 0 to 100 pna Current limiting 3 ma max, any load Noise and ripple 100 mv max +110-v supply Output voltage +110 + 10 v de Output current 0 to 15 ma Current limiting 100 ma max, any load Noise and ripple 10 mv max 2.3.3.5 Circuit Description of the —22-v Supply The —22-v supply consists of a voltage regulator (Q8, Q9, Ql0) and a current-limiting circuit (Q7, D12, D13). The limiting circuit pro- tects the series heater string of the preamplifier from damage when any of several possible fault conditions occur. The action of the limiting circuit is similar to that of a con- stant-current circuit. The base voltage of Q7 is held constant at +2 v with respect to the —32-v supply by the two Zener diodes D12 and D13, The breakdown voltages of the diodes are 12 and 10 v, respectively, but they are connected in opposition so that the reference voltage is the difference in the two voltages. This arrangement yields a sharper knee and a stiffer reference voltage than a single low-voltage diode. The emitter voltage is different from the base voltage only by V be the base- emitter voltage drop of the tran51stor, vhich is fairly constant. Thus, the emitter voltage is constant across a fixed resistance R22 and R26, yielding a constant current in the emitter of Q7, provided that the collector-emitter voltage is large enough to keep the tran31stor out of saturation. When "normal" output current is flowing (less than the limit current),'the voltage at the collector of Q7 is less than 2 v more pos- itive than the —32-v supply, and Q7 is saturated. 1In this condition Q7 81mply acts like & series re31stor and does not control the output current. It is only when the output current tends to increase above normal that Q7 comes out of saturation and limits the output current to 1 _ vz'_ Vfie . . T ———————— , it pog 4 R22 122 where VZ is the difference in the breakdown voltages of D12 and D13 and ( v e 18 the forward base-emitter voltage drop of Q7. The voltage regulator consists of Q8, Q2, and Q10. The output voltage is sensed by the base of Q9 and is compared with the wvoltage of reference diode D14 in the emitter of Q9. The amplified difference on the collector of Q9 is applied to the base of Q8; Q8 provides current gain only to drive the base of the output transistor Ql0. The regulated output voltage appears between the emitter of Q10 and ground. Diode D15 is used to protect Q8 from turnon transients. The output voltage is adjusted with trimpot R30. The current at which the circuit limits is set with the "current limit" potentiometer R22. 2.3.3.6 Circuit Description of the +300-v and +110-v Supply The supply is designed to operate from a nominal 32-v station battery with a terminal voltage variation from 28 to 36 v de. This wide variation makes necessary a voltage preregulation, which consists of transistors Ql, Q2, Q3, and Q4. The preregulator output voltage is sensed by resistors R7, R8, and RO and applied to the base of amplifier stage Q3. A reference voltage (16.8 v) generated by Zener diode string D2, D3, and D4 is applied to the emitter of Q3. The amplified difference appears at the collector of Q3 and is applied to driver Q2 and pass transistor Q4. A constant collector current is provided for Q3 by transistor Ql, Zener diode DI, and the associated network. Qfi) The preregulator output (test point TPL) is filtered by Cl, C2, and R27 and is applied to the dec-to-dc converter. Q5, Q6, T1, and the associated circuitry comprise a free-running square-wave oscillator inverter. Networks Cl5-R32 and Cl6-R33 round the edges of the square wave somewhat to avoid the generation of sharp, high-frequency spikes, which may be coupled to other circuits. The 110-v output is obtained from a full-wave rectifier and filter, and the 300-v output from a voltage tripler. The supply can be short circuited without damage. Most transistor inverters will stop oscillating when overloaded. The oscillator transistors can be damaged unless their non- oscillating current is limited to a safe value. Current limiting by series resistance in a primary lead is undesirable because power will be wasted and the inverter will have poor load regulation., On the other hand, biasing so that the transistor current goes to zero in the non- oscillating condition will not allow oscillations to start when the short is removed. The current-limiting scheme used here consists of a combination of clamping and series-emitter resistance to set the current to a predetermined value. R1l and R12 bias the bases of Q5 and Q6 into conduction. R13 and Rl4 limit the transistor currents in the nonoscil- lating condition to a little less than the oscillating currents. The voltage drop across these resistors is less than the value that causes appreciable current flow through D5, D6, and D7 until oscillation begins., In the oscillating condition, the drops across R13 and Rl4, respectively, are limited by the diodes to 1.4 v. The low dynamic resistance of the diodes assures a stable, nonoscillating current value. 123 2.3.4 Pulse Amplifier 2.3.4.1 General The pulse amplifier and count rate meter amplifies and counts pulses from a fission chamber. The input sensitivity is such that some preamplification is required. The module consists of a pulse amplifier, a pulse-height discriminator (PHD), a logarithmic count rate meter of the Cooke-Yarborough type, a linear count rate meter, and two calibration oscillators (10 and 104 counts/sec) 2.3.4.,2 Construction The pulse amplifier and count rate meter is constructed in a module 5.6 in. wide, 4,72 in. high, and 11.9 in, deep. It is a standard "four- unit" plug-in module of the modular reactor instrumentation series de- picted on drawings Q-2600~1 through Q-2600-5. The pulse-height discriminator and the linear and log count rate circuits are constructed on one printed circuit board. The pulse am=- plifier and the two oscillators are constructed on separate boards. The pulse amplifier and discriminator count rate boards are housed in a cadmium~plated steel compartment which covers the entire top of the module. The two boards within this compartment are shielded from each other by a cadmium-plated partition. The oscillator printed circuit board is mounted horizontally at the back end of the module beneath the compartment. The front panel controls include a ten-turn potentiometer for the pulse~-height discriminator and an 18-position switch for amplifier gain control (13 positions) and module calibration control. A BNC connector is mounted on the front panel to provide a signal for a scaler. 2.3.4.3 Application The pulse amplifier and count rate meter is one element of a wide- range counting channell for monitoring neutron flux over a ten-decade span. It amplifies pulses from a fission chamber and preamplifier as- sembly%* and provides logarithmic and linear count rate output signals. An output pulse is also provided to operate a scaler. The pulses from the preamplifier assembly are bipolar in shape, vhich eliminates the problem of duty-cycle shifts in the pulse amplifier. The pulse amplifier, however, can be used with positive unipolar pulses. Count rates up to 10% counts/sec of unipolar pulses 1 psec wide can be accommodated, with a resulting shlft in effective pulse amplitude of less than 1%. The logarlthmlc output 51gnal is a current which drives an external, conventional operational amplifier, The output of the operational am- plifier is used to operate indicabtors and other circuits. The linear outpul signal is also a current which drives an external, conventional operational amplifier. The output of the operational am- plifier is used to operate other circuits. 1In the wide-range counting channel, this linear signal is used as the control signal for a servo system. 2.3.4.4 Specifications 124 Overall specifications for the pulse amplifier are as follows: Pulse amplifier Gain Rise time (10 to 90%) Linear pulse output (100-ohm load or greater) Saturated output Attenuator control Pulse-height discriminator Range Integral nonlinearity (including pulse amplifier) Output pulse for scaler Amplitude Rise time (10 to 90%) Fall time (10 to 90%) Pulse width Log count rate output Range Amplitude Accuracy (at 30°C) Temperature effects Linear count rate output Range Amplitude 90 % 5 Less than 0.07 psec 0 to +5 v Less than 7.5 v for pulse widths less than 0.5 pusec 13-position, 100-ohm ladder type at amplifier input in 1, 1.5, 2, 3, 5, and 7 sequence 0.25 to +5 v with ten-turn Helipot (500 divisions) Less than +0.2% of 5 v from 0.25 to 5 v at 30°C and varies less than 0.03%/°C of its 30°C value between 0 and 50°C +3.5 £ 0,25 v into load of 100 ohms or greater 0.05 psec 0.05 usec (no output cable) Varies with pulse amplitude in excess of PHD bias 1 to 10° counts/sec in five decades 0 at 1 count/sec and up to approx 40 pamp at 10° counts/sec Output deviates less than *3% from the true log reading at any point with regularly spaced input pulses Output deviates less than *1% from the 30°C value for any temperature from O to 30°C; from 30 to 50°C, output deviates less than +3% from the 30°C value at each point 0 to 2.5 X 10* counts/sec Approximately 170 pamp at 10% counts/sec Accuracy (at 30°C) Temperature effects Power reguirements Voltage Current drain Regulation Ripple 10 count/sec oscillator Stability Thermal error Output pulse Output pulse load Pover supply 10% count/sec oscillator Calibration accuracy at 70°C | Thermal error Output pulse Output pulse impedance Power supply ' Ambient temperature range (all'units)_ 125 Output deviates less than the equiv- alent of +25 counts/sec from the true counting rate from O to 10% counts/sec with regularly spaced input pulses The deviation of the 10* count/sec point from its 30°C value is less than 0.3%/°C from 0 to 30°C and less than 0.15%/°C from 30 to 50°C +25 + 0,01 v; =25 + 0.01 v 75 ma from +25 v supply; 25 ma from =25 v supply +0.04% or better against +10% line changes and with load changes from no load to full load Peak-to-peak ripple less than 0.01 v 30 ppm at 20°C with vertical ori- entation of spring balance wheel axis; 300 ppm at 20°C in any other orientation 11 ppm/°C from O to 30°C -11.7 v, 6 msec width, less than 20-psec rise time (10 to 90%) 50 kilohms minimum ~12 v £ 10% at 0.15 ma average; 3-ma peak per pulse Positive 0.000%; negative 0.004% —4 ppm/°C at 70°C 8-v peak-to-peak square wave; less than l-psec rise time (10 to 90%) 800 ohms | =12 v + 10% at 7 na 0 to 55°C 2.3.4.5 Theory of Operation General The following description of the module (Fig. 2.3.10) is divided into five main groups: (1) pulse amplifier and control switch; (2) pulse-height discriminator, which includes the shaper stage and emitter- follower; (3) pump driver, which includes the flip-flop, Q-25 as a 126 limiter-amplifier, and Q16 and Q17 as the complementary emitter-follower drive; (4) pump circuits, which include both the log and linear pumps; and (5) test oscillators. Pulse Amplifier and Control Switch The pulse amplifier consists of two fed-back groups which are cas- caded to achieve an overall gain of 100. Each group has a voltage gain of about 10, These two stages of amplification are preceded by a ladder- type attenuator, where the input impedance is a constant 100 ohms at all settings and the impedance, looking back from the amplifier input, is 50 ohms. The attenustor is part of an 1l8-position switch that (ls pro- vides attenuation of the input signel in 13 positions, (2) disconnects the amplifier input from the attenuator and grounds it through 100 ohms in two "off" positions, (3) disconnects the amplifier from the attenuator and applies 1.0% counts/sec to its input, (4) disconnects the amplifier from the attenuator and spplies 10 counts/sec to its input, and (5) dis- connects the amplifier from the attenuator and supplies a dc voltage for application to a 5~sec period generator circuit that is external to the module. Also, in all positions other than attenuator positions, the control switch provides a dc voltage which actuates a front panel light and can be used to actuate an external alarm. The pulse smplifier design is tailored to amplify pulses of the shape shown in Fig. 2.3.11A. This pulse shape is produced by a pre- amplifier which double differentiates the pulses from a fission chamber with a 0.125-pusec time constant. (The second differentiation is made at a pulse transformer which terminates the balanced transmission line driven by the preamplifier.) The preamplifier has a O.l-psec integrating time constant. The amplifier may also be used to amplify unipolar pulses clipped to 1 psec width or less, with the possibility that appreciable base-line shift may occur at counting rates grester than 5 X 10% counts/sec. Both fed-back groups are of identical design. Each fed-back group is a three-transistor configuration, with the first two transistors Ql and Q2 constituting a differential pair. The output from the second collector Q2 drives the third transistor Q3, which is an emitter-follower. Feedback is made from the emitter of Q3 to the base of Q2. The output signal is taken from the emitter-follower, and the input signal drives the first base QL of the differential pair. This results in a group with an output pulse of the same polarity as that of the input signal. The pulse gain of the stage is very nearly (R6 + R?)/R6, neglecting the shunting effect of R8 and R6. The measured”’ high-frequency feedback factor for the stage was 10. The fed-back group is dc-coupled &and has excellent de stability by nature of the differential input and a dc feedback factor in excess of 100, The bias in the amplifier has been selected so that both positive and negative portions of the bipolar input signal will be clipped pro- portionately under overload, thereby retaining its bipolar nature. 5The procedure for measurement is given by E. Fairstein, Pulse Amplifier Manual, ORNI~-3348, p. 20 (Oct. 26, 1962). 127 A closed~loop analysis, utilizing the hybrid-=n equlvalent circuit, shows that the predominant time constant is nearly C bR16 [(Rb + R15)/R151, where C,, 2nd Rb are the collector transition capacitance and base resistance of Q2 respectively. The output impedance of the stage was computed to be 12.6 ohms,.® The ac input impedance of the stage is very nearly equal to that of the base resistor Rl of the input transistor Ql, because the emitter impedance of QL is R2 (5.1 kilohms) in parallel with the looking-in impedance of Q2, which is nearly 300 ohms because of the feedback to the base of Q2. Thus, with an effective emitter impedance of about 300 ohms, the impedance looking into the base of Q1 is sbout 30 kilochms for an h_, of 100, fe Capacity coupling is used between the two fed-back stages and on the output to the pulse-height discriminator. These coupling time con- stants are in excess of 300 usec, which is adequate to eliminate the effects of any further differentiation. The bipolar nature of the input signal eliminates any possible duty-cycle shifts across these capacitors. Pulse-Height Discriminator The pulse-height discriminator (PHD) is based on a biased amplifier scheme which is very similar to that used in the pulse amplifier. The PHD control potentiometer R26 has ten turns, and the dial has 500 divi- sions. The position of R26 determines the differential bias that exists between the bases of Q7 and Q8. Since Q8 is conducting at any position of this potentiometer, any positive input signal applied to the base of Q7 must exceed this differential before Q7 is brought into conduction, and any portion in excess of this differential is amplified by a factor of 10. The voltage drop across the PHD potentiometer R26 must be 5 v to achieve the full~range control of 5 v for pulse-height discrimination. The voltage can be trimmed to this value by adjusting R32. The "zero" of the PHD can be trimmed by adjusting the values of R24 and R27. e, (a) 6 . _ V (open circuit) _ (é;) The output impedance R = T (short c1rcu1t) (A)/R ) s where A = open-loop gain, 100, A" = closed-~loop gain, 10, _R0 = open-loop output impedance. . _ base impedance of Q3 In this case, Ro = re h of O3 : fe 4 - 26 + 22 =126 , 100 128 An ac-coupled Schmitt trigger is used to shape the pulse from the biased amplifier., The trigger sensitivity is 2.5 v. A more sensitive trigger will create stability problems even though any sensitivity changes are reduced by a factor of 10 when referred to the pulse am- plitude, The sensitivity cannot be less than 0.5 v, because this is gbout the amplitude of "feed-through" pulses of the biased amplifier. Another consideration for keeping the Schmitt trigger sensitivity large is to relax the bandwidth requirements of the biased-off amplifier. The triangular-shaped character of the positive portion of the amplifier pulse places a bandwidth burden on the biased-off amplifier for the pulses which barely exceed the threshold level. The larger the pulse required to actuate the Schmitt trigger, the greater the output required from the biased amplifier. These larger pulses, because of their tri- angular shape, will be wider at the base line and will require less bandwidth from the amplifier. , The 2.5-v sensitivity of the Schmitt trigger results in PHD poten- tiometer control that is ineffective below a pulse amplitude of 0.25 v. This is only 5% of the 5-v full range and is considered to be only a minor limitation. Trigger sensitivities in excess of 2.5 v would result in even less usable portions of the PHD potentiometer and would not be desirable,. Transistor Q7 of the biased amplifier must have a base-to-emitter breakdown voltage greater than 5 v. The 2N2432 transistor designed for inverted chopper applications has a 15-v BVEBO rating. The pulse out of the Schmitt trigger is applied to emitter~follower Ql2. The magnitude of this pulse is +3.5 v, and its width depends on the amount that the pulse amplifier pulse exceeds the bias setting (of the PHD). The emitter-follower output drives the succeeding binary stage and an external scaler. The recovery of the pulse at the emitter- follower will be slow at the termination of each pulse if an untermi- nated cable is used to make connection to a scaler, because the charged cable will hold Q12 off and must be discharged through R47, a 6.2- kilohm resistor. Punp Driver The pulse from the Schmitt trigger and its emitter-follower does not have the proper amplitude or the width to drive the log and linear pumps. A binary stage (also called a flip-flop) is used to further shape the pulse. The output pulse of the flip-flop is rectangular, having a width equal to the time elapsed between two successive pulses., This method of shaping automatically provides the pump circuits with wide pulses without any increase in dead-time losses. The consequent division of the pulse rate by a factor of 2 must, of course, be con- sidered in the pump design. The flip-flop design composed of Q13 and Ql4 is a saturated type (i.e., the "on" transistor is driven into saturation) with resolution capabilities of 107 counts/sec. When either Q13 or Q14 is "on," the other is "off." The positive pulse from the emitter-follower acts to turn the "on" transistor off, and the regenerative nature of the circuit then switches the state of the flip-flop. Diodes D2 and D6 serve to steer or apply the pulse to the base of the "on" transistor. To under- stand how the steering is achieved, assume QL3 to be "on" and Q14 to be 129 "off." The collector of QL3 will be near +8.5 v, and the collector of Ql4 will be near ground. Diodes D6 and D5 are in series and are back biased by the difference in potential between the collector and base of Ql4 (about 8.5 v). The base of Q14 is clamped to a potential slightly more positive than +8.5 v by D4. (The only purpose for D3 and D4 is to limit the back bias applied to Q13 and Ql4 when they are turned off. With these diodes the back bias can never exceed about 0.5 v.) ‘In con- trast, diodes D1 and D2, which are also in series, are only back biased by a few tenths of a volt. Thus, a positive input pulse will take the route through D2 (and to the base of the "on" transistor) in preference to that through D6 because of the greater bias on D6. Diodes D1 and D5 aid in another menner. They help discharge ca- pacitors C19 and C20, respectively, by providing a low-impedance path to €21 (a 2.2-pf capacltor) through the collector of the "on" transistor between input pulses. These capacitors will acquire some charge as the input signal proceeds to turn off the "on" transistor and, if permitted to accumulate or to not sufficiently recover, can cause a malfunction of the flip-flop. The collector swing of Q13 and Ql4 is approximately 8 v. This value is marginal to provide reliable operation of a pump circuit. Also, the pump circuit input impedance is quite low and would drastically load the flip-flop and impair its speed. Thus, some further amplification is still required, and some impedance isolation is needed., It should be recoghized that any amplification process must also achieve high ampli- tude stability to achieve good pump performance. Transistors Ql5, Q17, and Ql6, along with diodes D13, D14, D15, D16, and D17, are used to perform this task. Diodes D13 and Dl4 are fast-recovery conventional diodes, and diodes D15, D16, and D17 are 5.2-v Zener diodes. The role of D7 will be explained below. Amplification with controlled amplitude is accomplished by Q15, the two fast diodes, and the three Zener diodes., The collector current of Ql4 forward-biases diode D7 and turns Q15 off "hard." The collector of Q15 is caught at approximately =17 v by the series string of the two fast diodes and the three 5.2-v Zener diodes. When Ql4 is turned off, D7 is released and QL5 is turned on "hard" by the base drive through R53. Thus, the collector swing of Ql5 is from —17 v to essentially O v, The two diodes in series with the Zener diodes isolate the large capac- itance of the Zener diodes from the collector of QL5, permitting fast rise and fall times. One diode is adequate for this isolation, but two diodes give better temperature compensation for diode effects on the diode pumps. = The Zener diodes have a specified rating of O, 005% per °C change, and the variation of the saturatlon voltage of QL5 is less than & few tenths of a millivolt per °C. It should be apparent that the scheme just descrlbed is one where the collector current of Ql4 is sampled rather than its collector voltage, so that ampliflcatlon is not achieved in the usual sense. Hov- ever, the method employed is one where no loading is placed on the flip- flop, permitting it to operate at maximum speed. Transistors Ql6 and Ql7 comprise a complementary emitter-follower driving stage which applies the 17-v pulses to the pump circuits. The necessity of a complementary design over that of a single emitter-fol- lower can be explained if we momentarily include the pump circuits in 130 the discussion. The following section will discuss these in greater detail. The negative-going step of the 17-v pulse proceeds to charge the feed capacitors of the pump circuits (C26 through C30 for the log pumps and €39 for the linear pump) through their respective diodes (D18, D20, D22, D26, D28, and D32) to the full 17 v. On the positive- going edge of the pulse {or the return to ground), these capacitors - must now be discharged quickly to O v to be prepared for the next pulse. This discharge path must proceed through the second diode of each pump into the smoothing capacitor or output capacitor of each pump for proper action of the pump., At this time Q17 is biased off and cannot provide this discharge. Q17 is off, since its base is at or near ground, and its emitter is at —17 v because the feed capacitor is behaving as a 17-v battery. With Q16 in the circuit as the NFN complement, it will be biased "on" and will permit the feed capacitor to discharge. Punp Circuits Logarithmic Pumps, — The log pump design is composed of six pumps and is based on the earlier work of Cook.e--Yarboroug‘h.7 The dec currents from each pump are summed at the common junction of R88, R90, R92, RY%, R96, and R98 and are delivered to the summing junction of an external op- erational amplifier. The composite response of six pumps is shown in Fig. 2.3.12. BSince the output voltage of each pump is positive, the conventional current flow will be out of these resistors. An additional current of opposite polarity is supplied through R113 and is adjustable by the "calibrate" control potentiometer R112. The gain of the externsal amplifier and hence the "span" of the log count rate meter are con- trolled by the parallel cambination of R115 and R116. For trimming purposes the value of R116 is adjusted. A 250-kilohm feedback resistor for the operational amplifier, in addition to a 1l-kilohm resistor which forms a voltage divider network with R115 and R116, is located at the operational amplifier. If these resistors were located in the pulse amplifier and count rate meter module and the module were unplugged, it would open-circuit the feedback loop on the operational amplifier and cause the operational amplifier to saturate. It is not advisable to leave these amplifiers in this state for extended periods of time. The operation of the pump circuit, discussed briefly in the pre- ceding section, will be described in more detail here. As charge from the feed capacitor is transferred to the smoothing capacitors C32 through C37, a voltage is developed across these capacitors which causes the current flow through any shunt resistance such as R88 and R87 of the first pump, R88 is essentially returned to ground since it is tied to the suming junction (a virtual ground) of the external operational amplifier. At a steady count rate, there is an equilibrium condition established where the rate of charge, or current inflow, is equal to the current outflow, and a steady dc voltage (with superimposed statise- tical variation) is established across each smoothing capacitor. "E. H. Cooke~Yarborough and E. W. Pulsford, "An Accurste Logarithmic Counting Rate Meter Covering a Wide Range," Proc. IEEE, Part II, 98, 196-203 (April 1951). 131 The voltage on each smoothing capacitor will bear the relationship8 V.nRC 1 v ='-_—__, © 1 & nRe where input pulse amplitude, detector count rate divided by 2, capacity of feed capacitor, b Q 53|—'-<: It total shunt resistance across smoothing capacitor, This response is shown graphically by any of the six curves in Fig., 2.3.12. For small values of n, where nRC is small compared with unity, the response is nearly linear as a function of n, the count rate. As n becomes larger, the response becomes nonlinear (appearing to be linear on a semilog plot) and ultimately reaches a saturation value of Vi when nRC is much greater than unity. As the count rate increases, each pump becomes successively saturated (pumps with the largest RC product saturate first), resulting in a constant output current from each pump. The Cooke-Yarborough principle will show end effects when a limited number of pumps are used to approximate the logarithmic response. To compensate for this, the two end pumps deliver about 10% more current than the four middle pumps. This is accomplished by making the value of the feed resistors R88 and R98 smaller than that of the other four feed resistors R90, R92, R9%, and R96. The values of the shunt re- sistors R87, R89, R91, R93, R95, and R97 are adjusted to keep the pump time constant RC at values which differ by a factor of 10. 8The derivation is as follows: Vo = ioR s where ._i‘ =& - (Vi— IV.O)C - (V - )Ilc o At l?n i o * Thus v = (Vi~— vo)nCR V,nRC =T ¥ nRC ° 132 The value of the total shunt resistance R across each smoothing capacitor was made as small as possible, but still permitting reasonable values of smoothing capacitors (i.e., values less than 100 uf). The product of the resistance and the smoothing capacitor values determines the statistical noise superimposed on the de current, The values shown were determined by experiment on the complete wide~range counting chan- nel, The first three time constants involving C32, R33, and C34 were selected to keep the period noise at reasonable values while the wide- range counting channel was behaving as a straight counting instrument. The remaining three time constants were selected to optimize the speed of response of the counting chammel. The leakage of the smoothing capacitors and diodes D19, D21, D23, D25, D27, and D29 behaves as an additional shumt resistance across the various pump outputs., The 1N914A is specified to have a maximum leakage of 0,025 pa at a reverse bias of 20 v at 20°C. This will have negligible effect on the performance of the pumps. The electrolytic capacitors C32, €33, and C34 were purchased with a specified leakage not to exceed 0.2 pa at 25°C at a working voltage of 20 v, which is equivalent to a dc leakage resistance of 100 megohms. A reduction in leakage resistance to 50 megohms would represent an error of 2.5% of reading over only a small range of the scale. Also, errors caused by leakage of the capac- itors will not accumulate, because as each pump goes into saturation, its output current is a function of only the pulse amplitude and the magnitude of the resistor feeding the summing junction of the opera- tional amplifier. In addition, any errors caused by the three electro- lytic capacitors, since they apply to the pumps at the low end of the scale, are negligible at the high end. The other critical components of the various pumps, such as the feed capacitor and output resistors, are high-quality, high-stability +1% components, or better. The effect of the variation of diode potentials in the pump is equivalent to a variation of the amplitude of the input pulse. The effect is such that, at higher temperatures, the input pulse appears bigger and there is greater output from the pump. More clearly, as the forward drop of D18 reduces with a temperature increase, the feed ca- pacitor will charge to a larger voltage. Also, the forward drop across D18 is less, and more charge is transferred. The two diodes D13 and D14 in series with the three 5,2-v Zener diodes have a tendency to com- pensate for this. As the temperature rises, the forward drop of these two diodes will be less and will result in a reduced pulse amplitude. Linear Pumps. — The linear pump circuit is designed to give a linear output current signal up to a value of about 170 pa for 104 counts/sec. This current is fed through R99, a 10-kilohm resistor, into the summing junction of an external operational amplifier. This smounts to a voltage of +1.7 v at the output of the pump. Without any attempt (such as bootstrapping) to improve linearity, the output signal would depart from linearity by nearly 9%. This can be computed from the general count rate expression given in the preceding 133 section with RC = (R99)(C39) = (10%)(0.0022)(107%¢) and n = 5 x 103 counts/sec. The bootstrapping circuit consisting of QL8 and Q19 serves to effectively increase the magnitude of the input pulse by an amount equal to the output dec voltage. Discounting the small drop in R117, any change in the output voltage appears at the anode of D32 and is in a direction to increase the voltage to which the feed capacitor is charged with each input pulse. Thus, the output current without boot- strapping is . (vi - vo)c i =e— 1/n This becomes [(vi + vo) — vo]C i = s 1/n which is independent of v_. Here all terms have the same meaning as in the preceding section. ' The cascaded emitter-follower arrangement (Darlington pair) is used to raise the looking-in impedance of the bootstrapping circuit, thereby reducing its loading effect on the output voltage. The voltage drop of the base-to~emitter voltages of Q18 and Q19 plus the drop across R117 is of sufficient magnitude to ensure that D31 is sufficiently back biased during the charging time of the feed capacitor to avoid a leakage of charge from the smoothing capacitor. Temperature effects in the linear diode pump are due primarily to changes in the two diodes D31 and D32. Variation in the forward volt- ages of these two dicdes is compensated for by changes in input pulse amplitude in a manner described in the preceding section. Diode leak- age currents and leakage in the electrolytic smoothing capacitors are negligible, particularly since the value of the output resistor is only 10 kilohms. - - - Temperature effects caused by the bootstrapping scheme are small, but are not negligible. Vbe changes of Q18 and Q19 will have a signif- icant effect on the output. Thesé changés will predominantly show up as a change in emitter potential of Q19 of about 4 mv/°C. Only slight changes of Vté due to temperature are seen at the base of Q18, because the 10-kilohm base impedance of QL8 is ‘so much smaller than the loocking- in impedance of Q18. The variations at the emitter of QL9 will change the magnitude of the bootstrapping voltage with temperature. At 50°C (assuming 4 mv/°C) the change in bootstrapping signal from the 30°C value is 120 mv, which is a chenge in output signal of [0.120/(17 x 20)]100, or 0.03%/°C, where 17 v is the amplitude of the input pulse, This change is in a direction to increase the output signal. If the output signal from the bootstrapped configuration had been taken from the emitter of Q19, the 0.03%/°C value will be increased by an addi- 134 tional [0.120/(1.7 x 20)]100, or 0.3%/°C, at 10* counts/sec. This oc- o curs because the pump output voltage (1.7 v at 10% counts/sec) receives the full effect of the Vfie changes. The actual temperature drift observed on the pump operating at 10% counts/sec is three times worse than 0,03%/°C. At 5000 counts/sec the measured drift is more nearly 0.03%/°C. The cause of the increased drift at the 10%-count/sec rate, which nearly amounts to an additional 2 mv/°C, is not definitely known. Ico and the base current of Q18 will flow through R99 into the suming junction of the external amplifier and sppear as signal currents. Ico effects will be negligible, because 0,001 pa is typical for Q18 and Q19 (NPN silicon). Temperature effects on hFE are also small, since the base current of Q18 is about 0.5 pa, or about 0.3% of the full-scale out- put (i.e., 170 pa at 10% counts/secs. The hFE value varies sbout O.4%/°C in the range O to 50°C. Test Oscillators lO—count/sec Oscillator. — This is a Swiss-made (Zenith model E59GJ) electromechanical oscillator with a spring balance wheel mounted in ruby bearings. The spring balance wheel is driven by an electronic circuit containing two transistors and two coils. The two coils are fixed and are located coaxially above and below a permanent magnet set in the rim of the balance wheel. The axis of the magnet is parallel to the axis of rotation of the spring balance wheel. As the magnet passes ‘sj through the region between the coils, a voltage induced in one coil (the pickup coil) turns on a transistor amplifier which has the second coil (the drive coil) as a collector load. The current in the drive coil imparts a force to the balance wheel in a direction to sustain its movement. The output pulse is taken from the collector of the amplifier transistor. The other transistor is connected as an emitter-follower and provides the necessary power amplification for the signal from the pickup coil. ' The oscillator produces an output pulse of the same polarity each time the magnet passes under the coils. This results in two pulses for each complete cycle., The time duration between successive pulses can differ by as much as 3 msec; however, the sum of the two intervals re- mains precisely at 0.1 sec (i.e., a 1lO-count/sec rate). The variation in time duration arises because the spring on the balance wheel is wound in one direction and is unwound in the other direction. 104-count[§ec Oscillator. — The lO‘-count/sec oscillator is crystal controlled by & 10%-count/sec quartz crystal. The oscillator consists of an Engineered Electronics Company. (EECO) plug-in unit T=-107, re- quiring a standard nine-pin miniature tube socket. The quartz crystal (EECO type H145-31) 1s mounted separately. The T-107 unit contains three transistors, two of which are used as a two-stage common emitter amplifier with feedback from the second collector to the first base through the impedance of the crystel. There is a full 360° phase shift, and the circuit will oscillate at a frequency which experiences neither phase shift nor apprecisble attenuation through the crystal., The third transistor serves as an emitter-follower output stage. Q,j 135 Oscillator Shaper. — Since the output waveforms of the 10- and the 10%-count/sec oscillators are widely different, preshaping is required if a uniform pulse is to be applied to the pulse amplifier. Q20 and Q21 form a conventional Schmitt trigger for this purpose. Q21 is nor- mally on and Q20 is off. The sensitivity is such that about 4 v is needed for triggering. The output pulse from the collector of Q21 is a positive pulse which is sharply differentiated by €38 and R86. The resultant pulse is about 0.1 v in amplitude. A negative pulse of about the same amplitude is obtained, but it is of the wrong polarity to trigger the pulse-height discriminator. 2.3.5 0,1-hp Servo Amplifier, ORNL Model Q-2615 2.3.5.1 @General The O.l-hp dc servo amplifier is a dc power amplifier that can supply & maximum of 75 w power at voltage and current limits of 25 v and 5 amp respectively. 2.3.5.2 Construction The servo amplifier is constructed in a module 4.22 in. wide, 4.72 in. high, and 11.9 in. deep. It is a standard "three-unit" plug-in module of the modular reactor instrumentation series depicted on drawings Q=-2600-1 through Q-2600-5. The four output transistors are mounted on separate heat 51nks; these are supported by four rods that connect the front and back plates of the module., The four intermediate transistors of the amplifier are mounted on smaller separate heat sinks; these are clustered on a metal plate supported by the four tie rods. The input transistor and most of the other components of the am- plifier are mounted on a printed circuit board near the front panel of the module. The series limiting resistors for the output transistors are mounted on the rear plate. All decoupling resistors and capacitors are mounted on a metal plate supported by the four tie rods and located near the rear of the module. This metal plate also shields the amplifier from the heat that is dissipated in the limiting resistors. 2.3.5. 3 Application The servo amplifier drives a Globe Industrles, Inc., type BD dc motor with a 27-v armature. It can drive this motor under all con- ditions from no load to blocked rotor. The motor is used as the servo motor to position a fission chamber in a wide-range counting channel. 2.3.5.4 Bpecifications Specifications for the O.l-hp dc servo amplifier are as follows: Voltage gain 3 v/v £ 10% noninverting Maximum linear output +28 v at no load; *25 v with 12-ohm (supply voltage * 32 v) resistive load; and %15 v with 3-ohm resistive load Nonlinearity (with 12-ohm resistive load) Maximum power output Output impedance Input impedance Input de offset 136 Less than 0,1 v deviation from straight line drawn between max- imum positive and negative outputs 75 w 30 milliochms 4700 ohms for signals not exceeding 10 v Negative 0.8 v (input voltage for zero output) Rise time (10 to 90%) less than 2 msec for input step Zero drift with tempera- Less than 9 mv/°C from O to 50°C; ture the output decreases as the tem~ perature rises Transient response Povwer supply requirements Voltage Current drain Positive and negative 32 v * 4 v 5 amp maximum Ambient tempersture range 0 to 55°C 2e3.5.5 Theory of Operation General The O,l-hp dc servo amplifier is a de-coupled amplifier with feed-~ back around two voltage-gain stages and two cascaded emitter-followers. The emitter-follower stages are complementary NPN and PNP pairs to per- mit the output to swing negative and positive with respect to ground. The last emitter-follower stage is a parallel combination of two transistors to increase its power handling capabilities. Circuit Description Reference is made to Instrumentation and Controls drawing Q-2615-1. The input signal is applied to the base of Ql, a PNP silicon transistor. A l-kilohm resistor R2 in series with the base limits the maximum load Placed on the input signal in the event of any failure in the servo amplifier. Diode D2 limits the base-to-emitter voltage on Ql when large negative input signals are applied under blocked rotor conditions. Negative feedback is applied to the emitter of QL through the re- sistive network R3 and R8. The feedback ratio is R3/(R3 + R8), which glves s closed-loop voltage gain of spproximately 3. The circuit shown produces a dc offset between input and output. With no input, the voltages will be as shown (+2.4 v on the output and O v on the input). For the output to be at a zero potential, the base of the input transistor must be at a negative 0.8 v to keep Q1. in a conducting state. 137 . Voltage gain in the loop is obtained from Q1 and Q2. Q3 is a cur- rent source which functions as a high-impedance collector load for Q2 while still providing adequate current to drive the emitter-follower stages under all design conditions. When the servo amplifier is driving positive with respect to ground; part of the collector current of Q3 is diverted into the base of Q5. When the servo amplifier is driving neg- ative with respect to ground, all the Q3 collector current flows through Q2, and Q2 must be capable of handling this current plus the required drive current into the base of Q4. Transistor Q4 and transistors Q6 and Q8 in parallel function as an emitter-follower chain; they operate when the servo amplifier ig driving negative with respect to ground. Transistor Q5 and transistors Q7 and Q9 in parallel operate when the servo amplifier is driving positive with respect to ground. The transistor not operating is held in a back- biased state by the base-to-emitter voltage of its complement. " Diode D1 in the emitter of Q2 permits Q2 to be turned off "hard" when the amplifier is delivering its full positive output. Any small collector current could create a large dissipation in Q2, since Q2 will have in excess of 60 v from collector to emitter. Capacitor Cl, connected from the base to the collector of Q2, along with the collector impedance of Ql, shapes the open-loop response to im- prove the high-frequency stability. The total capacitance at the col- lector of Q1 is increased in magnitude by the Miller effect. This re- sults in a smaller value of capacitance for the same shaping of the open-loop response. This internal time constant, coupled with the compensating effect of C2 across R8, stabilizes the amplifier over its entire range of operation with as much as 0.22 pf capacitance in shunt with the output. _ The behavior of the amplifier with a step input signal is different with positive and negative input signals. With a negative input step, Ql and Q2 are immediately driven into a higher conducting state, and the output rise time is exponential in character and is controlled primarily by the value of C2. With a positive step, QL and Q2 are both immediately turned off in the absence of a return signal from the feedback network. Thus, the current from Q3 flows into Cl, generating a ramp until there is sufficient signal from the feedback network to return QL to a con- ducting state and thereby restore the closed loop. Under these con- ditions the output wave shape will have a ramp-type leading edge. '~ Resistors R9 and R12 in the emitter of Q6 and Q8 tend to balance the current contribution of each transistor, even with large differences in transistor ‘parameters, such as current gain and transconductance. Resistors R10 and R13 are used for the same purpose with transistors Q7 and Q9. Resistor Rll, which is a series combination of three l-ohm resistors, protects transistors Q6 and Q8 under severe load conditions. With a blocked rotor condition the Globe Industries type BD motor will behave as a 3-ohm load, and the maximum dissipation possible in either parallel transistor is &bout 27 w. This is assuming supply voltages of *36 v. These potentials are possible when the batteries that normally pover this module are fully charged. Resistor Rl4 provides similar protection for transistors Q7 and Q9. 138 The collectors of Q4 and Q5 are connected to resistors R1l and Rl4 . respectively. This prevents damage to these transistors under overload conditions. 2.3.,6 YVernistat 2.3.,6.1 General The Vernistat adjustable function generator is composed of two separate, but integral, units: a function adjusting assembly and an interpolating Vernistat potentiometer. A function is set up simply by manually adjusting the positions of sliders on the function adjusting assembly panel. The panel is marked off in rectangular coordinates, with percent output as the ordinate and shaft position as the abscissa. The sliders provide a visual plot of the function that is set into the function generator. By rotation of the shaft of the interpolating Vernistat with an excitation voltage applied, the output voltage curve conforms to a series of straight-line interpolations hbetween voltages set up by the slider. Clockwise rotation scans the function from left to right (i.e., from slider 1 to slider 34). | 2.3,6.2 Construction Vernistat Function Adjusting Assembly The function adjusting assembly is approximately 1 by 7 by 8 in. and contains (1) a 10l-tap voltage divider; (2) a 34-pole, 10l-position t:j printed-circuit switch; and (3) a function adjusting panel. ' The voltage divider has a total of 10l equally spaced taps. These taps divide the input voltage into 100 equsal voltage increments. The 34-pole, 10l-position switch is a rectangular coordinate array. A printed-circuit grid consists of 101l parallel lines connected sequen- tially to the voltage-divider taps. Each of the 34 sliding contacts can be moved independently across the grid lines so that each slider may contact any of the 101 voltage divider taps. The voltage divider taps are spaced at 1% increments, and therefore any voltage may be selected to within *0,5%. A panel, marked off in rectangular coordinates, mounts directly over the printed circuit switch so that the 34 sliders protrude through slots in the panel and can be manually adjusted. The Y axis is pro- portional to voltage, and the X axis is proportional to the position of the interpolating Vernistat shaft. The X axis represents a range of approximately 11 shaft turns. Interpolating Vernistat Potentiometer The interpolating Vernistat consists of (1) a series of commutator bars which correspond to the sliders of the function adjusting assembly, (2) a switching mechanism, and (3) a 360° toroidal resistance element precisely tapped at 120° intervals. Connection of the function adjusting assembly to the commutator bars of the interpolating Vernistat is made through a multiconductor cable. This cable is an integral part of the 139 interpolating Vernistat and plugs into the function adjusting assembly. This is the only connection made to the function adjusting assembly. Rotation of the shaft of the interpolating Vernistat switches the taps of the interpolating resistance element one at a time along the commutator and simultaneously controls the potentiometer output wiper. There are approximately three interpolations per shaft turn of the interpolating Vernistat. 2.3.6.3 Application The Vernistat adjustable function generator provides a convenient means of generating mathematical and empirical nonlinear functions. The function generator is used in the wide-range counting instru- ment to modify a linear position signal so that it is equal to the logarithm of the neutron attenuation. 2.3.6.4 GSpecifications Overall specifications for the Vernistat function assembly are given below: Vernistat Function Adjusting Assembly Ad justable points on 34 rotation axis - Resolution of slider ad- 1% Justment Maximum input voltage 50 v Ambient temperature range 0 to 55°C Interpolating Vernistat Potentiometers (size 18, 1l-turn continuous rotation units) Linearity | +0,02% Maximum output impedance 540 ohms Minimum output-voltage 0.01% increment Ambient temperature range 0 to 55°C 2.3.6.,5 Applicable Drawings ~The Instrumentation and Controls Division drawing number and sub- title for the Vernistat adjustable function generator is Q-2616-1, Circuit. - ' o o : 2.3.6.6 Theory of Operation Figure 2.3.13 shows the electrical relation of the Vernistat in- terpolator commutator bars, interpolating resistance element, and out- put wiper. By synchronization of the switching of the interpolating resistance element taps along the commutator bars with the movement of the potentiometer wiper arm, the voltage output becomes a series of 140 linear voltage interpolations between adjacent commutator bars. The interpolating resistance element, used repetitively for each shaft turn, is a 360° toroidal potentiometer precisely tapped at 120° intervals. Switching of resistance element taps from one commutator bar to the next only requires about 30° of shaft rotation, whereas a complete interpolation requires approximately 120°, Therefore, the switching process of the interpolating resistance element is a noncritical oper- ation. No discontinuities of output occur, since in each instance as the output wiper approaches a new commutator bar, the next interpolating resistance element section is already in position. Switching of the taps of the interpolating resistance element along the commutator bars is accomplished with a planetary gear reduction. The output wiper is so synchronized with the switching operation that it is always on an energized section of the resistance element. This results in continuous, smooth interpolation throughout the output voltage range. The heart of the switching mechanism is a planetary gear reduction that consists of three elements: an intermal tooth gear with as many teeth as there are commutator bars, a planetary gear with one tooth less, and an eccentric on the shaft which keeps the two gears in mesh. These gears are shown schematically by the eccentric cirecles in Fig. 2.3.13. Because of the one-tooth difference, one shaft rotation results in a counterrotation of the planetary gear, which is equivalent to the angular spacing between commutator bars. The resistance element is mounted on the planetary gear and rotates with it at a reduced speed. The commutator wipers, connected to the resistance element taps, are also mounted on the planetary gear. The output wiper is attached to the Vernistat shaft. Because the resistance element rotates, the output wiper moves from one tap to the next in less than 120° of the shaft rotation. The 34 sliders of the function adjusting assembly equal the number of commutator bars in the interpolating Vernistat. Eleven shaft turns (3960°) are required to generate an entire 34-chord function. Each chord represents 116.47° (3960°/34) of shaft rotation. Sliders 34 and 1 are adjacent electrically; therefore, a repetitive function may be generated by continuous rotation of the input shaft. 2.3.7 Dual DC Amplifier 2.3.7.1 General The ORNL model Q-2605-1 dual dc smplifier is designed and manu- factured by Electronic Associates, Inc., as the EAT model 6.720. The unit consists of two independent high-gain amplifier circuits packaged on an etched-circuit board. The amplifiers are transistorized and de- signed for optimum stability and frequency response, Each amplifier can be used in conjunction with appropriate networks to perform linear com=- putations such as summation, integration, and multiplication by a con- stant. 141 2.3.7.2 Specifications Specifications for the dual dc amplifier are given below: Output voltage range +1.2 v min (no load); +10 v min (20 ma load) Offset (at the summing junction) +20 pv, max unity-gain inverter with 10~kilohm resistors Output current at *10 v 20 ma min Frequency response (=3 db) for a ' 200 ke min unity-gain inverter with 10-kilohm resistors (20 uv p-p input) Noise (p-p) from dec to 300 ke 400 uv rms max 2.3.7.3 Amplifier Balancing The amplifiers should be periodically balanced to assure accuracy. Under normal circumstances, the amplifier will remain balanced for periods of weeks., However, at intervals it is desirable to check this condition, and if an amplifier is found to be unbalanced, then an ad- justment should be made. The period bhetween balance checks depends to a large extent on the application of the amplifier., For uses which might be unusually sensitive to amplifier unbalance or integrator drift, the amplifier should be balanced at more frequent intervals. In any case, maintenance personnel should recognize the fact that many amplifier and network malfunctions can be detected by checking amplifier balance. Consequently, it is recommended that a check of amplifier balance be made biweekly. If the check indicates that the amplifier balance is within tolerance, no adjustment need be made. 2.3.7.4 Theory of Operation Basic Block Diagram The dual dc amplifier consists of an EAI model 6,715 dual dc ampli- fier card housed in a special package., The components for one channel are shown in Fig. 2.3.14. The major components consist of the stabi- lizer amplifier, the chopper, and the dc amplifier. The circuit is ar- ranged so that the drift-free characteristics of an ac amplifier are used to maintain constant de amplifier balance by providing a voltage to the input of the de¢ amplifier which tends to maintain the suming junction at virtual ground., The resulting circuit has excellent long- term stability and allows the use of a wide~bandwidth dc amplifier without the necessity of frequent manual balancing. Inputs to the amplifier are applied through an external input im- pedance Zin' " The dec and low-frequency components of the signal voltage at the summing'junction (SJ)_cannot pass diréctky to the input of the de amplifier section because of Cl. Instead, they are connected through R3 to contact 9 of chopper Dl. A chopper, or synchronous vibrator, con- 142 sists of a coil-driven vibrating reed 8 (Fig. 2.3.14) that alternates between contacts 9 and 7 on each half cycle of the coil excitation volt- age. The chopper alternately grounds contact 9, producing a 60~-cps square~wave input to the stabilizer amplifier. After amplification, the resulting signal is demodulated (or synchronously rectified) at the second contact 7 of the chopper. The resulting signal at contact 7 is a pulsating dc signal whose polarity is the same as the polarity of the signal at the summing junction. The dc signal is filtered by RE8 and C2 and applied through R7 to the input of the dc amplifier section. Thus dec and very low-frequency signals are amplified by the stabilizer am- plifier and by the dc amplifier. The circuit from contact 9 of D1 to contact 7 is a modulated carrier-type amplifier that provides high-gain de¢ amplification with no drift. The stabilizer is phase-sensitive; if the polarity of the suming junction signal changes, the phase of the modulated signal changes and the polarity of the pulsating dc output voltage changes. High-frequency components of the input signal are passed through Cl to the dc amplifier and are amplified by the gain of the dc amplifier only. The open-loop gain of the amplifier thus depends on the frequency of the input signal. At very low frequencies the gain is extremely high because the stabilizer amplifier is placed in series with the de am- plifier. At higher frequencies the gain is decreased but remains high enough to satisfy all expected operations when the feedback loop is closed. Any component of the amplifier output voltage due to drift in the dec amplifier section is fed back through the feedback impedance Zf to the summing Jjunction of the amplifier. Since any drift-produced voltage has a very low frequency, it will be amplified by the stabilizer section, filtered, and then applied as a drift-correction signal to the input of the de amplifier section. The drift-produced component in the output is reduced by a factor equal to the effective gain of the stabilizer sec~ tion., The amplifier would require balancing every few minutes without stabilization. The drift compensation produced by chopper stabilization allows the amplifier to be used for weeks without attention. The amplifier in the stabilizer section has a very high gain. Since it is connected to the summing junction, it serves as a monitor of the summing junction voltage. Under normal circumstances the input current of the operational amplifier is equal to the feedback current, and the suming Jjunction is at virtual ground. If the currents are not equal, the amplifier is not performing properly, and the summing junction de- parts from virtual ground. This rise in voltage is amplified by the stabilizer and results in an output signal which msy be connected through the appropriate push-button switch to the balance monitoring meter cir- cuit. DC Amplifier Section Refer to Fig. 2.3.1l5 for the following description. The summing Junction of the operational amplifier is connected to the input ter- minal. The ac components of the input signal are applied to the base of transistor QL through R2 and Cl. The input signal is also connected through R3 to the input of the stabilizer section., Two reverse-connected 143 diodes CRLI and CR2 are connected from the input to ground so that Cl cannot be charged to a high voltage should an overload occur. This feature allows the amplifier to recover rapidly following an overload condition. The voltage at this point is normally less than the diode conduction point. Transistors Ql and Q2 comprise the amplifier input stage. Tran- sistor Q2 is connected in a common-emitter configuration, with R7 (in etched~circuit resistor network NWl) and thermistor R15 providing self- bias. Transistor Ql is used in the emitter-follower configuration and uses the voltage drop (approximstely 0.3 v) across the base-emitter diode of Q2 as its operating voltage. The emitter-base resistance of Q2 provides a load for Ql. This configuration gives the amplifier a relatively high input impedance, The hase circuit of QL is completed through R8 (in NW1), R1l, and the balance potentiometer. These compo- nents form a voltage divider between —15, +15, and +25 v. The balance potentiometer sets the optimum operating point for Ql, as indicated by a zero output from the stabilizer section. The high-frequency rolloff of the input stage is controlled by C3 and R5. Temperature compensation is provided by thermistor RL5 and resistor R6, vwhich tend to keep the collector of Q2 at a constant potential re- gardless of temperature variations. The stabilizer output is connected through R8 and R7 to the input of Q1. The output of Q2 is coupled to the base of Q3 through NW1l-R5. Bias for Q3 is provided by NW1l-R4 and NW1l=-R5. The feedback network consisting of R10 and C5 provides the proper high-frequency rolloff for the Q3 stage. Capacitor C4 provides correct pha51ng for higher frequencies, The collector load for Q3 consists of resistors NWi-R3 and NW1l-Rl. Resistor NW1l-R3 provides direct coupling from the output of Q3 to the base of Q4, as well as forming a voltage divider with NW1-R1l to set the operating point for Q4. The Q4 stage is connected in the common- emitter configuration. The emitter is connected to +15 rather than ground, to establish the correct operating points for Q4, Q5, Q6, and Q7. The collector load for the stage consists of NWl-R2. Capacitor C7 provides high-frequency degenerative feedback for this stage, and the network consisting of C6 and R11l controls the high-frequency rolloff for Q4 and Q5. The collector of Q4 is connected to the base of Q5 through an in- candescent lamp DS1l. The filament of this lamp has a high positive temperature coefficient of resistance, providing an increase in resist- ance with an increase in current flow. This stabilizes the operation of Q5 by limiting base drive. The Q5 stage is connected as an emitter- follower, with resistor R12 providing the emitter load resistor. Diode CR3 provides a small forward bias for output tran51stor Q7, eliminating crossover distortion in the output stage. The output stage consists of transistors Q6 and Q7, connected in a complementary-symmetry configuration. ‘This circuit arrangement provides the advantages of push-puwll operation with a single-ended input. Both transistors are connected as emitter-followers. Since transistor Q6 (PNP) conducts with a negative input and transistor Q7 (NPN) conducts with a positive input, one of the transistors delivers current to the 144 load regardless of input polarity. With a zero input, both transistors g=J conduct equally, and the voltage drop across the load is zero. Incan- descent lamps DS2 and DS3 perform a function similar to that of DS1; by providing ean increase in resistance with an increase in current, they protect the output transistors from excessive current flow., Re- sistor R13 provides a dc feedback to the base of Q4 which tends to keep the output of the amplifier at zero volts with a zero input and compen- sates for minor transistor and temperature variations. Stabilizer Section The stabilizer section consists of a four-stage direct-coupled amplifier (Q8, Q9, Q10, and Qll), input and output coupling capacitors. (c8 and C12 respectively), and a 60-cps chopper (Dl1). The stabilizer preamplifies the dc and very low-frequency components of the signal appearing at the amplifier summing junction and applies the resulting signal as an input to the dc amplifier section. Stabilizer Amplifier. — The stabilizer amplifier receives its input from the suming junction through resistors R3 and R9. The chopper grounds the junction of R3 and R9 60 times each second, making the input appear as a series of pulses between ground and the input level. These pulses are coupled through C8 to the base of transistor Q8. The input stage of the stabilizer consists of transistors Q8 and Q9. Transistor Q8 is connected as an emitter-follower and uses the base~emitter voltage drop of Q9 to provide operating voltage. The cir- cuit arrangement of Q8 and Q9 is similar to the arrangement of QL and Q2 in the dc amplifier section and provides a relatively high input . impedance. Resistors NW2-RL and NW2-Rll provide bias for Q8. Capacitor ‘sJ C9 filters high-frequency transients from the input waveform. Resistor NW2-R2 provides the emitter load for Q8 and, together with NW2-R1Z2, pro- vides bias for Q9. Transistors Q9, Q10, and Qll are connected in the common-emitter configuration and are directly coupled through resistors NW2-R4 and NW2-R6. Capacitor CLO provides high-frequency degeneration for the Q11 stage, removing unwanted high-frequency components from the output waveform. Resistor NW2-R8 provides a feedback to the Jjunction of NW2-Rl and NW2-R1l, adjusting the bias on Q8 to maintain the stabi- lizer amplifier transistors at the correct operating point. The net- work consisting of R1l4 and Cll provides phase correction for very low frequencies and filters high frequencies from the NW2-R8 feedback loop. The stabilizer amplifier consists of an emitter-follower input stage vwhich is noninverting and three common-emitter stages which pro- vide an overall phase shift of 540°, This constitutes an apparent 180° phase shift, or an inversion from input to output. This cannot be tolerated by the overall amplifier, since the dc amplifier section pro- vides a 180° phase shift. Any feedback under these conditions would be regenerative, and the amplifier would not be usable. For this reason contacts 7 and 8 of the chopper demodulate the output of the stabilizer amplifier to provide a pulsed output to the filter network (R8 and C2) having the same polarity as the input. This is accomplished as described below. Chopper. — The chopper used in the EAT model 6.720 amplifier is a specially designed high-speed relay. It consists of a double=-pole 145 armature assembly which is driven by a 60-cps ac source and which al- ternates in position from one set of contacts to the other at this rate. Figure 2.3.14 shows how one pole of the chopper (pin 8) alternately grounds the stabilizer input (pin 9) and the stabilizer output (pin 7). The closing of contacts 8 and 9 at a 60-cycle rate causes the stabilizer input to appear as a series of pulses, This permits amplification of very low frequencies or de¢ levels while isolating the amplifier operating levels through the use of a coupling capacitor. The closing of contacts 8 and 7 effectively shifts the phase of the output by providing a short r-c charge or discharge time for Cl2 when closed and a longer time (through R8) when open. This operation is more easily understood with the use of examples, If the input to the summing Junction tends to go positive, the in- put to the stabilizer amplifier consists of a series of positive pulses. The output waveform at the collector of Qll then consists of g series of negative-going pulses, However, during the time that the input pulse is present (positive), the output (negative) at the junction of (12 and R8 is connected to ground through contacts 7 and 8 of the chopper. This allows Cl2 to charge rapidly to the level at the collector of Qll. The chopper arm then closes to contact 9, driving the stabilizer input to ground. The collector of Ql1l goes from its negative level toward ground at this time, and the positive change is coupled through C1l2 and R& to the input of the dc amplifier. The dc restoring action of contact 7 and the arm of the chopper thus makes the apparent output a series of positive pulses which are filtered by C2 and R8 and provide a dc input to the de amplifier through R7. If the input to the summing Jjunction tends to go negative, the stabilizer input is a series of negative pulses. The output at the collector of Q11 is a series of pulses from a negative level toward ground. In this case, the chopper provides a short-time-constant dis- charge path for Cl2 when the collector of Qll is close to ground. As contacts 8 and 9 of the chopper break and contacts 8 and 7 close, the collector of Qll goes negative and the change is coupled through Cl2 and R8 to filter capacitor C2. Stabilizer Filter., — The stabilizer output filter, con51sting of capacitor C2 and resistor R8, has a time constent of 3 sec., This is extremely long with respect to the stabilizer output waveform, conse- quently reduclng the ripple at the junction of R8 and R7 to a negllgible level. ‘Stabilizer Functions. — The stabilizer performs the apparently dual functions of preamplifying dc and very low-frequency input signals and malntalnlng the amplifier summing junction at a point very close to ground potential over wide variations in amplifier balance, When the amplifier feedback loop is closed (as it must be) and no input is ap- plied, the amplifier output should be zero volts. Any departure of the amplifier output from this point is coupled through the feedback resis- tor to the summing junction. This causes the stabilizer to generate a correction voltage which returns the amplifier output and, consequently, the suming junction to zero. If an inpubt signal is applied to the summing junetion, the stabilizer again generates a voltage. In this case, however, the output of the dc amplifier is shifted from ground 146 potential to produce an output with a polarity opposite to that of the input and a magnitude equal to the input voltage multiplied by the ratio of the feedback resistance to the input resistance. This output pro- duces a potential at the summing junction equal in magnitude and opposite in polarity to the input signal, returning the absolute potential at the suming junction to a point very close to grownd. It is in this way that the stabilizer attempts to keep the summing junction at ground regard- less of input voltage changes or variations within the dc¢ amplifier, 2.3.8 Fission Chamber Drive 2.3.8.1 Description The fission chamber drive, ORNL model Q-2545, is shown in Figs. 2.3.16 and 2.3.17. This unit contains a direct-current motor and as- sociated drive train for positioning the preamplifier and fission cham- ber assembly. In addition, there is a position-sensing train for pro- viding position signals to the servo power amplifier and to the data logger. Performance specifications are: Stroke 90 in. Chamber velocity 72 in./min Environment 150°F in water containing 2000 ppm sodium nitrite corrosion inhibitor A ball-bearing lead screw turning at 288 rpm provides the rota- tional-to-linear motion conversion with an efficiency rating of ap- proximately 90%. A water-resistant calcium-complex-base grease was selected as the lubricant for the lead screw. The ball-bearing nut is attached to a guide block which rides on nylon runners between two aluminum guide rails mounted within & 3-3/4-in.-OD stainless steel drive tube. A thrust tube connected to the guide block is attached to a cabling rig which is connected to the preamplifier and fission chamber assembly. The fission chamber signal cable, sheathed in Tygon tubing for water protection, and a piece of music wire are coiled into a helix. These are held together with nylon spiral wrapping to form a spring-loaded coiled cord. This helix provides the necessary cable takeup and is coiled loosely around the thrust tube between the cabling rig and the lover end of the drive tube. This cabling rig rides on nylon rollers inside the 4~in,-ID instrument penetration tube. (This tube is not a part of the positioner assen&flyu) The direct-current drive motor with Integral gear reducer and tachameter is protected from any torque overloads by a disk-type slip clutch. The position signsl system is directly connected to the lead- screw shaft ahead of the slip clutch by a pair of precision gears. The position signal system consists of a ten~turn auxiliary posi- ' tion-sensing potenticmeter driven by a 48:1 ratio reducer, to provide 7-1/2 revolutions for 90 in, of chamber travel. This, in turn, drives o 147 a 10:1 ratio reducer which is connected to a one-turn position-sensing, data-logger input potentiometer. On the same shaft there is a synchro transmitter for driving a position indicator on the console. A ten-turn Vernistat interpolating potentiometer, previously de- scribed, is gear-driven from the shaft of the ten-turn auxiliary position- sensing potentiometer to provide ten revolutions for 90 in. of chamber travel. This interpolating potenticmeter provides the position feed- back signal to the function generator amplifier (ORNL model Q-2616). Upper and lower limit switches are actuated by rods which are tripped by the guide block at each end of its travel. These rods are held captive in grooves between the guide rails and the drive tube. This permits mounting of the limit switches in the motor drive assembly where they are readily accessible, 2.3.8.2 Drive Motor The permanent magnet dc drive motor is a Globe Industries, Inc., type BL-7, 27 v, with a 30.7:1 ratio gear reduction and a 1-7/8-in.- square flange mounting. It has an integral permanent maghet dec gen- erator, type LL-1l, which produces a minimum of 1.8 v per 1000 rpm at no load. The motor has a 350-to0-450-rpm no-load speed range, rated at 137 in.-oz torque, part No. 102A276, purchase order No. 62X-20042 special; the output shaft is 5/16 in. in diameter by 3/4 in. long with a 1/8-in.-square key seat. 2.3.8.3 Lead Screw The actuator assembly is a commercial-quality ball-screw type, No. 1000-0250-C1l, by Saginaw Steering Gear. The screw is 8 £t 6 in. long. The screw threads have a 1-in. pitch diameter, a 0.250-in. lead, and a 0.820-in. root diameter, and are right-hand threads. The nut has a 1- 1/2-in.-square body with a 1.583-18NS thread. The screw and nut are heat-treated 17-4 PH stainless steel., The balls are heat-treated type 440C stainless steel, with every other ball 0.002 in. undersize, 2.3.8.4 Position-Sensing Potentiometer The position-sensing potentiometer, which provides the input to the data logger, is by Beckman Instruments, Inc., Helipot No. 5203R5KL.25RS. It is a single turn with servo mount, ball bearings, and double-ended shaft extensions. The characteristics are: 5000 ohms, +0,25% linearity tolerance, and 3 w. 2.3.8.5 Synchro The synchro is a Norden No. 121F1A torque transmitter, 115 v, sin- gle phase, 60 cps ac. Its characteristics are: three-phase stator, 0.38 in.-oz torque gradient, 0.50 in,-o0z frictional torque, and *8 min electrical error, The shaft is 0,2405 in. in diameter with ASA spline and threads. 148 2.3.8.6 Auxiliary Position-Sensing Potentiometer The auxiliary position-sensing potentiometer is by Beckman Instru- ments, Inc., Helipot No. 7603R1KL.15RS. It is a ten-turn potentiometer with servo mount, ball bearings, and double-ended shaft extensions. The characteristics are: 1000 ohms, *#0.15% linearity tolerance, and 5 w. 2.3.8.7 Vernistat Interpolating Potentiometer The Vernistat interpolating potentiometer is a Perkin-Elmer Cor- poration Vernistat No. 2X5. TIts characteristics are: interpolating, 3960°, electrical rotation (continuous), 34 chords, 470 ohms maximum output impedance, 0.004% approximate angular resolution, and size 18 servo mounting, part No. 124-0118. 2.3.8.8 Gear Reducers The two gear reducers are by Metron Instrument Co. One, Metron No. 9B48R, has a 48:1 ratio with a 15-min maximum backlash, servo moumt, and 3/16-in.-diam shafts. The other, Metron No. 9A10R, has a 10:1 ratio with a 15-min maximm backlash, servo mount, and 3/16-in.-diam shafts., 2.3.8.9 Slip Clutch The Sentinel Manufacturing Corporation makes the type 40, size 2000 single-disk slip clutch. It is a coupling type with a 6 in.-1b setting, a 5.16-in. bore-through disk hub, no bore in the housing hub, and a 1/2-in.-diam housing hub. 2.3.8,10 Limit Switches The snap-action limit switches are Micro Switch units, No. BZ- 2RW82255-A2, with a short roller lever, 6 oz operating force, and a rating of 15 amp at 125 v ac. ORNL~-Dwg .66-3994 TACHOMETER D.C. sSERVD MOTOR SERVO 22‘?356 TIONS , AMPLIFIER MODEL ©-26/¢ X COUNT RATE FUNCTION GEN. ol SET POINT € - LEADSCREW SEC NOTE | | vounr pars | _ METER ‘ LOG 4 LoG WATER FILLED ) 74 PULSE 105 | €& POWER PENETRATION | COUNT RATE - AMPLIFIER METER - ;\.’ DIFFERENTIATING A _ | | SomINe MBLIFIER 4 | AMPLIFIER o | REACTOR N /7 - o P T C bo-se Nore S . PRE-AMP /= THE FUNCTION GENERATOR IS AN ADJUSTABLE, MON~ LINEAR DC FOTENTIOMETER WHICH PRODUCES FISSION A MODIFIED CHAMBER FOSITION SIGNAL. THE REACTOR CHAMBER SIGNAL MOBIFICATION COMPENSATES FOR CHANGES IN THE NEUTRON ATTENUATION COEFFICIENT, i, SHIED WITH POSITION, X. TS e, ol X & KRR e 2y 3 . = QD Fig. 2.3.1. MSRE Wide-Range Fission Channel Block Diagram. 6v1 COUNT RATE (counts/sec) Fig. 2.3.2. 150 ORNL-DWG 66-7635 COUNT RATE SET POINT (10 k counts/sec) 7 ACTUAL COUNT RATE " ACTUAL CHAMBER POSITION (SEENOTE 1) “oeny ~ WITHDRAWAL / / CURVE, s = CONSTANT "2 cps LOG REACTOR POWER—> *NOTE 1: THIS SOLID LINE CURVE IS NOT NECESSARILY REPRESENTATIVE OF AN ACTUAL OR TYPICAL CURVE BUT ILLUSTRATES THAT THE ACTUAL CURVE WILL DEPART FROM THE IDEAL STRAIGHT LINE. 100 50 Actual and Ideal Curves of Count Rate vs Reactor Power. WITHDRAWAL DISTANCE ,-x Q-2617 ASSEMBLY L r A = | 1 FISSION | cHaMBER PREAMP | _______ T LINEAR = POTENTIOMETER FISSION CHAMBER POSITION SIGNAL FOR READOQUT FISSION CHAMBER POSITICN SIGNAL FOR READOUT AT CONSOLE SYNCHRO TORQUE TRANSMITTER LCG COUNT = RATE SIGNAL FOR READOUT LINEAR COUNT RATE METER COUNT RATE SET POINT. o TACHOMETER VERNISTAT INTERPOLATING FUNCTION POTENTIOMETER GENERATOR VERNISTAT FUNCTION Q-2616 ADJUSTING ASSEMBLY ‘ Fig. 2.3.3. je—- LOG COUNT RATE SIGNAL PRODUCES TRIP COUNTING SIGNAL WHEN COUNT CHANNEL RATE IS LESS THAN 2c¢ps | *CONFIDENCE" PRODUCES TRIP SIGNAL WHEN COUNT RATE EXCEEDS 50,000 cps NOTE: ’ : "Q" NUMBERS REFER TO OAK RIDGE NATIONAL LABORATORY INSTRUMENT AND CONTROL DIVISION DRAWING NUMBERS SUMMING AMPLIFIER LOG REACTOR POWER SIGNAL FOR READOUT GAIN AMPLIFIER DIFFERENTIATING AMPLIFIER ja— LOG REACTOR POWER SIGNAL PRODUCES TRIP SIGNAL WHEN REACTOR POWER 1S LESS THAN 200 kw ————————a= ELECTRICAL SIGNAL ————— == MECHANICAL DRIVE “RUN SIGNALS Q-2609 PERMIT" TO REACTOR ¢ CONTROL, PRODUCES TRIP " SYSTEM SIGNAL WHEN REACTOR POWER EXCEEDS 500 kw CONTROL ROD Q-2609 "REVERSE" WHEN IN START MODE Y PRODUCES TRIP SIGNAL WHEN REACTOR POWER EXCEEDS 1.5 Mw OPERATIONAL AMPLIFIER MSRE Wide-Range Counting Channel. ORNL-~DWG 66- 4102R REACTOR PERIOC SIGNAL FOR READOUT FAST TRIP COMPARATOR {TYPICAL) CONTROL ROD "REVERSE" AND ALARM PRODUCES TRIP SIGNAL WHEN REACTOR PERIQD IS LESS THAN 5 sec " INHIBIT ROD - -° 2608 = I THORAWAL" PRODUCES TRIP SIGNAL WHEN REACTOR PERIOD IS LESS THAN 25 sec "RUN PERMIT" PRODUCES TRIP SIGNAL WHEN REACTOR PERIOD IS LESS THAN 30 sec 1Ss1 counts/sec 152 ORNL—-DWG 67-11922 0 5 PULSE HEIGHT CHARACTERISTICS OF 2-in. FISSION CHAMBER FISSION CHAMBER WX—- 31095 CONNECT- ED TO ORNL MODEL Q-2647 PRE - AMPLIFIER AND A{ AMPLIFIER WITH 2 GAIN OF 64 10 COUNTS DUE TO NEUTRON 10 \ @ AND NOISE PILEUP 107 0 1 2 3 PULSE HEIGHT SELECTOR Fig. 2.3.4. MSRE Wide-Range Counting Channel. 153 PHOTO-87826 Fig. 2.3.5. "Snake" Assembly. 154 ORNL-LR-DWG 69732R +300v 3500 +110 RECEIVING END [ T 1oy OF PREAMPLIFIER - I_‘_-\ gma Ima k3 : ol -4 - - vi—o—] z TPUT EW oot i “ it 1008 It 3 1 0.1 ) L 3 53 220k 5 ] 30k = z 2 PIC H-TY . oot = . Vo % 602! ; L e ' £ 20k 7995 3 4 = 0001 ks OO 15k 3 o0 | z "3_‘&- oot - }‘— o ; N 30k 001 A \— o TR T ar I - INPUT oot | el9n Y TOME,., koaz T4t + 7995 z : L ot 82.5k 1 Z 10k s 2 o] 2500 £ *14.7 -22v +0v F-o, Fig. Fig. 2.3.7. 2.3.6. Preamplifier Circuit Diasgram. PHOTO P-55826 PULSE IHEIGHT Fission Pulses at the Main Amplifier Input. o r ) . 1 ’ \ . : ‘ 7 " ’ 155 N . fi : . - \ i - i ! . . X . T ’.I . . \ » . ~ ' . A . : ORNL-DWG 64-7741R S R C . C = AMPLIFIER s ’ PREAMPLIFIER JUNCTION BOX ) (IN CONTROL ROOM) i i - , — i e e — s ey . ‘ ) ' , — | | o | T e oz I i o . a - < | ! RMER FISSION o , > < L s ity CHAMBER il ‘ z /i\L"“ 1 T T ) FN"TTTTN 7\ = ‘ , o [ () L Je ] L Hi— T TN T 'z ) ‘, e i 4 7 : . } r— g Pruvras — .‘ I N - _ ¥ 1 - . . . 1 . : \ $ . . b | ——t . : . b e e e | : : BUILDING \ . _]_ BUILDING __|_ BUILDING . ' = GROUND - = GROUND = GROUND : L | T ' © . 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AMR INPYT " oUT WASED AMR OUT (bt frigpering) SCALER DRIVE (ke Frigperiog) A : | | "~ WP DEIVER OUT MOOULAR REACTOR T R STy T C (AXS@ 500, dmp Ot Avies 2 8.3V) (AvS @508, Amyp Owt Roks & £.87) (60 cps Count Lrde @t Amp. input) — T T OULAR REACTOR INSTRULENTATION > } — . - . - Sl A J gg%&-;g,;»?w s, e T - ] : A ) L A - 71 s lrd Jaciter? tA a; Lo Tia PULSE_AMPLIFIER 4ND S St T S | ua Lo et e | 10 ¥ H T rrod e Lo wmiin ] ke COUNTRATE METER TAT e ' ‘ T3 : eresfes Taug=io-sa 37| 708 .‘; % . _ 'l‘*l‘ "th'" *Lfi-l'- ' L ..l 1 e14r (03 |- 13- 14 €2 | Tea mf./RCU/T ’ .- . Poser|n] Iuca3oiz-ee | 3ea + INSTAUMENTATION ANO CONTROLS Divisien - - ‘r “"L "‘"’l"‘ F-evet| K |mpt-13-18 Kt | Ju# C . ‘ ' ¢ . 1-143| R0 Jacci3-13 -4 | 704 ‘ _ e Re j&C-41-18~14 *i.A . s fow - ! 3 SHHAD 56 17 -0m Q- 2418/ VOLTS VOLTS 157 ORNL-Dwg. OT-7512 ® InpuT OUTPUT VOLTS VOLTS c A } ] ? 1 ? ] c 1 - ] OUTPUT-NO OVERLOAD © - | (D) OUTPUT- X2 OVERLOAD 1 } 1 ? i ? i \\______////”fifisec' (E) OUTPUT - X10 OVERLOAD Fig. 2.3.11. Pulse Amplifier Waveforms. 158 ORNL=-DWG 67-7040 6 — 4!’: Rr -Q J;CI = PLJ“ t = - = =AW / W e — - — —AAAL / g b - e - —w~ - Y b = = — —AAA / % - -—f“ RE e o 6§ / s rIr Lo -2€ o %23 o 3 / S / " '§ 2 3 / I S / 1 . ur"" . No. - P pump 8| pymp 225 | pump 105 0.5 5 S0 So0 S000 Sx10* COUNTS PER SECOND Fig. 2.3.12. Pump Response Where Cn X Rn = 0.1%* Camposite Response of Six Diode Pumps with Individual Cl X Rl. 159 A ""'_'" A A AAADMA vITVYeSYYVW The output wiper has just passed commutator bar 2 and is interpolating between bars 2 and 3. Resistance element tap A is Jjust about to dis- engage from commutator bhar 1. As the output wiper moves in a clockwise direction, the output voltage changes linearly from the voltage on commutator bar 2 to that on com- mutator bar 3. Resistance element tap A has disengaged from commutator bar 1 and is switching to commutator bar 4. VYT VY Y-t AAAAAL NN The output wiper is approaching commutetor bar 3. Resistance element tap A has completed switching and is in contact with commutator bar 4. Continued clockwise rotation of the output wiper Wlll result in smooth interpolation past commutator bar 3. Fig. 2.3.13. Electrical Relation of Vernistat Interpolator Com- mutator Bars, Interpolating Resistance Element, and Output Wiper. 160 ORNL-DOWG 67-7036 r'—-—"——_———_—{z_'g"a ___________ ] R2 Ein-{ 3._,._3.—@—4 —AAN ' {( p—] DC AMPLIFIER E s CRI i—[jcnz ‘b $ ke = TO OUTPUT MONITORING cs c12 CKTS . snanuzan l" '—“R“g"fi AMPLIFIER H Y Fig. 2.3.14. Dual dc Amplifier Card Simplified Block Diagram, One Channel. TO BALANCE MONITORING CIRCUIITS ORNL-DWG 67-T7T038 - ———— i | | I | a3ve I Aemee = - | Waig | T o 5 sor e ——— lll.‘ "~ -av 2ws o wur EOrur — Lid Y Fo [T Lg d 00w - n 1 Z20N I | b =t P f f L 2 o£r he P ) o3 GO—d = 3 NOTE: PIN CONNECTIONS t 'Y SHOWN FOR CHANNEL 2. = s rPoA e $ BAL MOMTOMNG Fig. 2.3.15. 6.715 Amplifier Card. Simplified Schematic, One Channel. | i i i { f i | | | | | ; | ! i | i [ t £ i ! ¥ i DRIVE MOTOR, WITH INTEGRAL TACHOMETER AND GEAR REDUCER- UPPER AND LOWER LIMIT SWITCHES 161 oo PHOTO 67688A SYNCHRO TORQUE ~ TRANSMITTER DATA LOGGER POTENTIOMETER 10:1 GEAR REDUCER VERNISTAT INTERPOLATING POTENTIOMETER AUXILIARY POSITION SENSING POTENTIOMETER Fig. 2.3.16. Fission Chamber Drive-Motor Drive Assembly. ORNL-DWG 66-4234 THE VERNISTAT INTERPOLATING POTENTIOMETER : s IS PART OF MODEL Q-2616 FUNCTION GENERATOR. / 10 TURNS EQUALS 90 in. OF CHAMBER TRAVEL. - LT SWITCH 90 TEETH 7Y%, TURNS EQUAL 90 in. OF CAM 0 40 TEETH s CHAMBER TRAVEL (OR 1 TURN | VERNISTATLE EQUALS 12 In, CHAMBER TRAVEL) SIZE 3 4 ‘ = l SYNCHRO 1:1 RATIO ¥4:1 RATIO {08 TEETH POTENTIOMETER - SSoa REDUCER E—{ REDUCER . . 1070 1 /E 48 10 { 288-rpm RATED SPEED SAGINAW BALL BEARING . ‘ : , 1O-TURN UPPER AND LOWER LEAD SCREW, 4 threads/in. 270° ROTATION EQUALS - 120 TEETH—"" POTENTIOMETER {:1 RATIO T2 UM switches 90 in. OF CHAMBER TRAVEL GLOBE TYPE 90 in. TRAVEL PREAMPLIFIER FISSION SLIP CLUTCH wos teeTd L . (8in.~Ibs) - 22 In/min o CHAMBER ORNL MODEL Q-2617 RETRACTABLE CORD Fig. 2.3.17. MSRE Drive Unlt for Wide-Range Counting Channel, Block Diagram. [A*) 163 2.4 LINEAR POWER CHANNELS 2.4.1 Description These linear power channels (Fig. 2.4.l) comprise the instruments used for the most accurate determination of reactor power and for input to the rod control servo system. These compensated ion chambers and associated power supplies, ORNL models Q-1045 and Q-995, respectively, were removed from the HRT and reconditioned for use in the MSRE. The design of the chamber, testing and compensation procedures, and its high-current saturation characteristics have been described in two ORNL docum.ents,l’2 applicable portions of which are included later in this section. The MSRE chambers, unlike the illustration in ref. 1, are equipped with motor-driven remote compensation adJustment and do not use a continuous flow of nitrogen. The Q=995 power supply is a conventional regulated supply designed to provide the requisite positive and negative voltages to the two sec- tions of the chamber. The negative voltage adjustment is used to assist compensation in accordance with ref, 1. For the circuit diagram see Fig. 2.4.2. The picoammeter is a Keithley Instruments, Inc., model 418-20 (Sect. 2.4.3). It has an overall range from 10732 to 1072 amp, ac- complished by range switching. Range switching is described in Sect. 2.6; it may be done locally at the instrument or remotely at the con- sole., Detailed specifications and performance characteristics, ab- stracted from the manufacturer's instruction manual, are given in Sect. 2.4.3. Figure 2.4.1 shows only one channel of linear input instru- mentation. For a more complete diagram the reader is referred to Sect. 2.6, Either of the two channels may be used to supply input to the linear recorder on the main control board and to the regulating rod controller. The output channel not being recorded is read out on a console-mounted meter. The strip-chart recorder is a two-pen, self- balancing potentiometer type arranged in a somewhat unorthodox fashion in order to record both the output voltage of the picoammeter and the range switch setting unambiguously. _ This simultaneous record of picoammeter output and range setting is unambiguous because the range setting uses the left-hand 40% of the chart width and the picoammeter output is restricted to the remaining 60%. Therefore the chart traces do not overlap or cross over at any time, and there can be no question as to trace identification after the paper roll is removed. The above is 1llustrated by Fig. 2.4.3, the chart paper used for this power recorder. 1lH, E. Banta and S. H. Hansuer, Testing Procedures for Reactor Instrumentation, Section J, Compensated Chaflber Field Testing, ORNL~- CF-56-5-30 (Feb. 8, 1954). — 27. L. Kaufman, High Current Saturation Characteristics of the ORNL Compensated Ion Chamber (Q-1045), ORNL~CF-60-5-104 (May 25, 1960), 164 2.4.2 Visual Readout Device, Series 360 A visual readout device, mounted above the linear power recorder and legible to personnel in both the control room and the visitors' area, displays the range setting multiplier so that the reactor power can be read at a distance by simply noting the position of the indi- cating flag on the right-hand pen of the linear power recorder. This readout device (Fig. 2.4.4) consists of an assembly of optical pro- jection modules which display selected characters (numbers, letters, symbols, etc,) on a translucent screen located flush to the main board. In the MSRE the projection lamps in the modules are selected by the range selector switches on the console. 2.4.3 Keithley Model 418-20 Picoammeter: Specifications and Description RANGES: 10™1? to 10™2 amp full scale in twenty-one 1X and 3X overlapping ranges. Any range may be selected at the main chassis location or from a remote location, ACCURACY ¢ iEZ’ of full scale from 1072 to 108 amp; +3% of full scale from 3 X 10~ to 10°%? amp. ZERO DRIFT: With source voltages greater than 1 v and after a 30-min warmup, the drift is less than 1% per 8 hr on any range. RISE TIME, MAXIMUM (seconds, from 10 to 90% of final current): Range No External With 50 pf With 500 pf With 5000 pf (amp) Capacitance Across Input Across Input Across Input 10712 0.03 0.06 0.4 4.0 10711 0.005 0.01 0.035 0.4 1010 0.004 0.004 0.006 0.04 10™° 0.004 0.004 0.004 0.006 1078 0,004 0,004 0.00% 0.004 107 and <0.001 <0.00L <0,001 <0,001 RANGE SWITCHING TIME: 5 msec maximum, INPUT: Grid current is less than 3 X 10714 amp. Change in input voltage drop is less than 1 mv for full-scale deflection on any range. Input resistance increases from 0.1 ohm at 10™R-amp range to 1000 megohms at 10712%-amp range in decade steps. QUTPUT: A *3-v output at up to 1 ma is developed for full-scale meter deflection. Impedance is less than 1 ohm. Polarity is opposite to input polarity. Noise is less than 2% rms of full scale on 10732 amp range. Provision is made for lower voltage outputs. ZERO CHECK: Allows zeroing without disturbing the circuit. REMOTE CONTROL: Local or remote control selected by front-panel switch, Remote range switching requires a five~bit binary input with 165 binary "1" corresponding to the 10™2-amp range in numerical order to binary "21" corresponding to the 10™12?-amp range. Zero check requires a separate input signal. All inputs require closure to ground. CONNECTORS: Input: Teflon-insulated uhf-type receptacle. Output: Amphenol 80 PC2F receptacle. Remote: Cannon DA15S. Remote control: Winchester type XAC 34-S-F-2-A-016G. TUBE COMPLEMENT: One 5886. POWER: 105125 v or 210-250 v, 50-1.000 cps, 22 w. 2.4.4 Procedure for Field Testing and Compensating Compensated Chamber Q-10453 Re4e4el Description The compensated chamber (Fig. 2.4.5) really consists of two cham- bers, one of them boron-coated. The output current is the sum of the currents of the individual chambers; since the high-voltage electrodes of these individual chambers are at potentials opposite in sign (one is +600 v; the other, —300 v), the output current will be the difference of the two chamber currents. The current from the boron-lined chamber is proportional to the neutron flux and to the gamma flux, while the mcoated chamber responds to gammas only. By making the gamma responses equal, the output current is proportional to neutron flux alone, even in the presence of a high gamma flux. It would not do to make the coated and uncoated chambers identical; they would then have to be placed in the same location in the reactor. What is done is to build them very close together and then make one adjustable to accommodate differences in gamma flux at the two chamber locations. The process of finding the best adjustment is known as compensating the chamber. It must be done in the reactor at the exact location where the chamber is to be used. The reactor itself is used as a source of gamma radiation. 2e4o4.2 Testing Insulation Tests The purpose of these tests is to determine whether the leakage current of the chamber is negligible compared with the operating cur- rent., To do this, one applies a high direct voltage to the high-voltage electrodes and observes the leakage current with a sensitive device. Two high-voltage supplies are needed: +1000 v and +500 v. They need not be well regulated, but they must be well filtered and have a low noise and hum output. It is desirable to operate them from a sine-wave Sola constant-voltage transformer., Connect the +1000 v to the positive high-voltage receptacle on the chamber; the +500 to the negative high- voltage. Connect the output to a current-measuring device capable of 3This section (written by J. C. Gundlach and S. H. Hanauer) was excerpted from ref. 1 (Specification 126), 166 indicating a current of 10712 amp. This may be an electrometer; often it is convenient to use the log N amplifier, calibrated as per Q-915-6, The ground (or low) side of the log N or electrometer must be comnected to the ground side of the high-voltage supplies, since the receptacle shells are not comnected to the chamber., This may be done with a clip lead, but in view of the high voltage involved, a wire properly secured to a screv is safer. A leakage current greater than 1 X 1012 amp is excessive, and the chamber must be disassembled and cleaned by someone experienced in this job. Do not attempt this in the field. Compensation 1. The preferred method of compensation consists in varying pile povwer level and comparing the output of the chamber to be compensated with the pile level as read on another instrument, usually the fission chamber. The pile is run at a high level for half an hour or more (to build up gammas); the flux is then changed as quickly as possible to a lower level. The procedure is trial and error; increase the high-to- low flux ratio as the compensation gets nearer and nearer the correct value. The reference instrument will give the ratio of the two flux levels; compare this with the ratio as measured on the test chamber, If the ratio from the test chamber is too low, the chamber i1s under- compensated, and the compensation must be increased. If the ratio from the test chamber is too high, the chamber is overcompensated, and the compensation must be decreased. 2. The compensation may be varied by screwing in or out the com- pensating adjustment on the chamber and by varying the negative potential on the compensating electrode. Changing the adjustment of the chamber varies the relative volume of the uncoated chamber; this is how the compensation is usually changed. The adjusting screw is turned clock- wise to decrease the compensation of an overcompensated chamber; turning it counterclockwise increases the compensation. When the adjustment is nearly correct, turning the adjusting screw 30° will change the (nega- tive) gamma current by about 1%. The effect of this change on the total current will, of course, depend on how large the gamma current is with respect to the neutron current, and this will in turn depend on how large the gamma flux is compared with the neutron flux. Changes in negative potential on the high-voltage electrode of the uncoated cham- ber may also be used to adjust the compensation. Decreasing the voltage decreases the compensation; increasing the voltage (more negative volts) increases the compensation. The magnitude of the change in compensation depends on the gamma current and on the position of the negative high- voltage electrode, which is moved by turning the compenssating adjustment. The effect of a 30-v change may be equivalent to as little as 1/20 turn change in the compensating adjustment, or to as much as 1/2 turn., At newer installations, means are provided for turning the compen- sating adjustment remotely, so that it is not necessary to dismantle lead cables, shield plugs, and the like. Compensation of chambers so installed is far better carried out using the compensating adjustment exclusively, with negative high voltage set at its maximum value, since the uncoated chamber has better saturation characteristics at higher voltages, Where chambers are installed without means of remote ad- justment, it will, in some cases at least, require considerable time o 167 and effort to make each change in the compensating adjustment. One may, if access is difficult or time short, aim at slight overcompensation with full negative high voltage and then decrease the voltage as a final adjustment. It is especially necessary in this case to guard against leaving the chamber slightly overcompensated (see No., 6 below). A principal reason for avoilding this method lies in the variable effect of the voltage adjustment — it is quite possible that compensation can- not be achieved at any reasonable voltage and that the chamber adjust- ment will have to be turned again. DO NOT adjust a compensated chamber to operate with the negative high voltage less than —50 v. 3. The choice of flux level at which to perform this experiment is not easy, in some cases. Usually the only instrument one can believe as & reference is the fission chamber, because only that device permits rejecting all signals due to gammas. One must use flux levels such that the low level gives a sufficient counting rate to permit good statistics in a reasonable time and the high level gives a counting rate less than 10,000 counts/sec, at which rate the error due to resolving time in the A=l amplifier starts to be important. 4, One must take care that the control rod positions are as nearly alike as possible for the two flux levels; variations may cause "shading" effects which impair the validity of the experiment. 5. In reactors vhere the y-n contribution to the shutdown flux is negligible, the compensation may be checked, at least approximately, by leaving the log N recorder chart running during any shutdown of 6 hr or more., The flux will decrease on a period which approaches the 80-sec half-life of the longest-lived delayed neutrons. If, at some point, the flux deviates from this 80-sec-period straight line, and this is not explained by lattice or experiment changes or something similar, then one can usually sssume the chamber compensation is incorrect. Upward deviation (toward a constant level instead of a constant period) indicates undercompensation; downward deviation indicates overcompen- sation. 6. It is best in the period channel to err on the side of under- compensation. Overcompensating the chamber will result in a negative output current; as the current passes through zero during startup the period circuits will scram the reactor. Prolonged negative current will induce "sleeping sickness" in the 9004 diode in the log N. 7. It is not a foregone conclusion that every compensated chanmber can be exactly compensated in every reactor. In cases where the cham- ber cannot be compensated with the adjustment available, the dimensions of the cups will have to be changed. This is not a job for the field; the ORNL Instrument Department Counter Laboratory should be consulted. 168 2.4.5 The Use of a Colloidal Dispersion of Boron in 0Oil to Cbtain a Uniform and Easily Applied Coating of Boron* (This specification supersedes ORNL drawing Q-1045-11) The process of applying a boron coating to graphite,” as developed at ORNL, is to quickly heat the boron-painted graphite electrode in an inert atmosphere to a temperature sufficient to drive off the oil car- rier. The following specific steps are used here to obtain a known thickness of boron coating. l. Heat to a dull red color by means of an induction furnace, the graphite electrode which is to be coated, to drive out some of the collected gases and surface contamination. A flow of nitrogen® over the piece during heating and cooling prevents oxidation. 2. Weigh graphite electrode. 3. Apply the dispersion of boron in o0il with brush to the graphite electrode. A thick coat, but not sloppy, on fine-grained graphite results in a final coating thickness of approximately 0.8 mg/cm?. 4. Weigh the painted graphite electrode; 20% X weight of applied dis- persion + cm® of painted surface = desired coating thickness (20% by weight of the dispersion is boron). The desired coating thickness for a single-plate chamber is 0.8 mg/cm? (£0.4 mg/cm2 =~ 90% current). The desired coating thickness for s 4-plate chamber is 0.5 mg/cm?; the desired coating thickness for a l6-plate chamber is 0.3 mg/cm?. 5. Under a strong flow of nitrogen, heat the painted graphite electrode to a temperature at which no more oil is being driven off (dull red heat) and allow to cool quickly. It is important that the nitrogen® flow carry away the oil vapors quickly and that the flow is continued until the coated graphite electrode has cooled to near 100°C. Boron oxidizes quickly at temperatures above 200°C. 6. The coated electrode may be weighed again to check the thickness of coating. It is expected that some amount of the graphite will be lost by oxidation. 2.4.6 High Current Saturation Characteristics of the ORNL Compensated Tonization Chamber (Q-1045)7 The saturation voltage and current characteristics of the ORNL compensated ionization chamber (Q-1045) have been measured with special 4Excerpted from ref, 1l; this portion was written by J. C. Gundlach. °Magnesium, brass, aluminum, etc., may also be satisfactorily coated. SNitrogen with 10% hydrogen is perhaps better. "Excerpted from ref. 2. 169 regard to high voltage and current ranges. The chamber was sealed in an enclosure containing dry nitrogen at 15 to 20 psia. The chamber was secured at a position in the grid plate of the Bulk Shielding Reactor such that the sensitive volume was approximately 15 in. from the reactor core face on the horizontal center line of the reactor. This position was chosen so that the chamber current at full power would be of the order of 1 ma with only a small gamma background error (5%) at a reactor power three decades lower. The chamber was connected as shown in Fig. 2.4.6. The output of the regulated high-voltage power supplies was measured with a D'Arsonval microammeter (1/2% F.S. accuracy) with 1% precision resistors in series, High currents (107 amp and up) were measured with a D'Arsonval micro- ammeter and lower currents with a Leeds and Northrup micromicroammeter (model 9836A). The reactor was held at power levels between 1 kw and 1 Mw, and the chamber voltage was varied in 200-v increments. The data are shown in Fig. 2.4.7. The actuasl reactor power was 4% lower than the indicated power at 100 kw and 10% low at 1 Mw due to the decreased neutron at- tenuation in the shielding caused by decreased water density at higher temperatures. ‘ It can be seen from the curves in Fig. 2.4.7 that the neutron- sensitive volume is well sabturated for currents less than 100 pa at any voltage above 600 v. For high accuracy the chamber should therefore be operated only at currents of 100 pa and below with the standard power supply Q=995. The saturation voltage for 800 pa is approximately 2000 v. The inaccuracy at 400 pa at 600 v is about 20%. Since the chamber can easily withstand high potentials, there is no reason why it cannot be operated at 1 ma with a suitable power supply. _ Thanks are due K. M. Henry and the staff at the Bulk Shielding Facility for their help in making the measurements. POWER SUPPLY Q-998 170 ORNL-Dwg., 66-3912 RANGE CHANGER - RANGE SIGNAL = COMPENSATED ION CHAMBER Q-1043 PICOAMMETER REACTOR FLUX,LINEAR > SIGNAL FOR READOUT AND CONTROL.SEE FIGURE £.28, PO® TM-TBE. “Q" NUMBERS REFER TO OAK RIDGE NATIONAL LABORATORY INSTR. 8 CONTROL DIV. DWG.NUMBERS . Fig. 2.4.1. MSRE Linear Power Channel. Two installed. r,,_‘,_ e T g 3t me g s 171 ORNL DWG. 67-10700 o 7 T=rr. {J"s e €T Block /IPL-28 000 ;:,”-’ .o Jut put Gas Adapted 4 ST From {======:(e) 220 \chamber) RG-62/ AN A S /. Sutput; RG-62/t Cas Q8 reld P, - Pl gPJ JQC’O.JS‘I rel EXTERN AL to § ——== :Z;_é) gr,, S AlAaRWV ZIKT @/yano.— 2 Cre e, (Blaw—-Knox Ttem ¥ 854)only - Al resistors [ wetf except as nofed. E1-M-10 @ Negative connecter jo be gas adgpred aSper @-900-7 (1) - NOT CLASSIFIED Py b.Add | 1PC 27000 gas adapted as per A 75 llr ek S1F1/ 9-303 -7(1) latéled Oatput from Port of Blaw-Knox Item Na 650-4C ¢ 654-2C Chamber : REVISIONS Vs erucvee Sescieres OAK RIDGE NATIONAL 1. ABORATORY s & é “labeled " Output to Galvanometer I‘; /70| 1 |General rensiotms .4 '\f ' A Egnsfarr‘ner £ ipgr] rvr v POWE R SUPPLY 0 FOR MFORMATION OMLY e g chage 1 1. COMP ION, CHAMBER % |3 Vo C/ Lhrw o s J. Gonet /s * ., Q ”mm '” ” ‘ 3 '4 “'Maam/ C‘/PCU/T ,.‘,‘:‘v_~ r____H .".T!T”ANCI OR :e, < 73 w T A CONSTRUCTION L Do o feR0 seax Term, Dlock L aded o S | I Q- 9951 25| C : { | | Fig. 2.4.2. Circuit Diagram of ORNL Model Q=995 Pc’twer Supply. ". — 172 ORNL-DWG 67-€595 i A 3 Pl 12|18 (18| 18| 30 H NT 1 10 20 SO 40 50 60 [0 H#O Q0| ||| oo & .. 1 ‘ . ..... - L CHH 1 i * 3 : z | RANGE 2 2 D(i|14 1B | 1B ) L ':‘m q z ( 10 20 30 40 50 ¢0 0 80 90 100 3 ® : . < 5 Fig. 2.4.3. Chart Paper Used for Strip-Chart Recorder. F ig. 2ebrits. PHOTO 88131 The 1EE Series 360 readout meets human engineering require- ments for distance viewing by displaying characters up to 2" in height. The unit operates on a rear-projection principle. When one or more of the 12 lamps at the rear of the unit is lighted, it illuminates the corresponding film message, focuses it through a lens system, and projects it onto the viewing screen at the front of the unit. Visual Readout Device, Series 360, = ~J w ORNL-DWG 67-7039 174 oFf SAs Now i W X 59 : , E1i o1 o &5 3 3 : 85 8 g 3 o e bLE 23 P o s 2 9 % 3 88 y23k ¥g == E 82 0y . oy : 833 B aufY & . 25 Z, Jy 5 8 2 3§y £23 g3f, Speg LRl g3 3 g2 ¢ § ¢ ef3 338 w __________________ 7 T Fr-- - === = - ====3 D 9-2KV o O SUPPLY I NOTE: NEGATIVE TERMINAL - 1l DISCONNECTED | THROUGHOUT TEST _ || THROWOVER SW. I e et B v * i -JL i SiG T._ - 1 WESTON 0-50,100,500,1000 Ja METER ,1% F.S. ORNL COME ION CHAMBER (Q-1045) Fig. 2.4.6. Schematic Diagram of ORNIL. Compensated Ionization Chamber, 176 -3 ORNL~-LR-DWG 48162 5X10 SATURATION CURRENTS 822 ua 407 pa 82 pa 42.5 pa 10 8.5 ua 4.4 pc 170 10 0.88 ua NEUTRON IONIZATION CURRENT {gmp} SHUTDOWN -y BACKGROUND 19 0 400 800 1200 1600 2000 2400 COLLECTOR VOLTAGE Fig. 2.4.7. Saturation Charascteristics of ORNIL Compensated Ioni- zation Chamber (Q-1045). 177 2.5 ROD SCRAM SAFETY SYSTEM 2.5.1 Rod Scram Safety Channel — Input Instrumentation The control rods are scrammed by excessively high flux, short reac- tor period, and excessively high reactor outlet temperature. The safety system employs three independent channels for inputs to the safety sys- tem logic and requires that any two out of three indicate unsafe con- ditions in terms of either flux, period, outlet temperature, or circuit integrity to produce a scram. Table 2.6.1 in Sect. 2.6 lists control rod actions and the conditions which produce then. A typical channel of neutron flux input instrumentation is diagrammed in Fig. 2.5.1. It consists of a neutron-sensitive ion chamber, a period safety module, a f‘lux-amplifierl and ion chamber high-voltage supply, &a test module, and fast-trip com.parators.2 The outputs from the period safety module and the flux amplifier are the reactor period and power level signals which become the inputs to the fast-trip comparators. Flux amplifier sensitivity is adjusted by changing the size of a feed- back resistor. In the MSRE the flux level trip point has two settings, depending on whether or not fuel salt is being pumped around the loop. Current relays in the fuel salt pump motor three-phase supply are used to determine whether the pump is circulating salt or idling in helium. These relays provide the signals used to actuate switching relays which change the value of the flux amplifier feedback resistance by a factor of 1000 and thereby provide rod scram trip points of 15 kw or 15 Mw. Figure 2.5.2 diagrams the circuitry which shifts flux level trip point, and Fig. 2.5.3 is a block or signal flow diagram of this circuitry. The fast-trip comparator is a fast-acting electronic relay with sufficient power-handling capacity to operate small relays and similar logic and control devices external to.the instrument. It also contains two small, fast-acting electromechanical pilot relays which have greater power- handling capacity with somewhat reduced response time. The "on-off" outputs of the pilot relays in the comparators are the primary input signals to the safety system logic and to the control system. Detalled descriptions of these instruments are given in Sects. 2.5.3 to 2.5.8. The temperature input signal instruments are block diagrammed in Fig. 2.5.4. The measuring thermocouples (refer to Sect. 6.7) are com- posed of two individual thermocouple wires, Chromel and Alumel, welded adjacently but separately to the fuel salt outlet piping, thus forming a grounded junction. Each thermocouple wire is contained in an individual - Inconel sheath and is insulated from this sheath by magnesium oxide. This construction, using individual, separated wires for each leg of the thermocouple, is used in preference to a dual thermocouple assembly (both wires in a single sheath), so that if a thermocouple breaks or becomes 1Ronald Nutt, Instrumentation and Controls Div. Ann. Progr. Rept. Sept. 1, 1963, ORNL-3578, pp. 103—+%. 2J. F. Pierce and D. C. Shattuck, Instrumentation and Controls Div. Ann. Progr. Rept. Sept. 1, 1963, ORNI-3578, pp. 105-6. 178 detached from the pipe, an open circuit is created. An open-circuited g‘J thermocouple causes the emf-to-current converter to indicate a failure ' toward safety, that is, upscale. Thermocouple emf (in the 25-mv region) is amplified by a Foxboro Company type 693 emf-to-current converter which provides an output cur- rent, linear with input emf, of from 10 to 50 ma into an impedance of from 600 to 150 ohms for the selected input range of the thermocouple, in this case 0 to 1500°F. The type 693 converter uses magnetic amplifiers to obtain voltage and power amplification, contains no moving parts, and employs solid-state diodes where required in the circuitry. The 10- to 50-ma output from the type 693 converter is the input signal to the high-temperature trip switch. This switch, a Foxboro model 63 alarm, compares a set-point voltage with a voltage developed by the input current from the type 693 converter and actuates an alarm relay when the input signal voltage is greater3 than the set-point voltage. A contact on the alarm relay, closed during normal reactor operation, pro- vides the high-temperature input signal to one channel of the rod scram safety system, as will be pointed out subsequently. The emf-to-current converter also supplies a signal, the voltage drop across the 400-ohm resistor, to an isolation amplifier. This ampli- fier provides a barrier between the safety system instruments and the remaining nonsafety instruments which make up an input channel. The isolation amplifier transmits the input signal in the forward direction to the remaining current-actuated switches but decouples the safety instruments in the reverse direction. This virtually eliminates the possibility that the effects of malfunctions or misoperation, calibrations, etc., of the nonsafety instruments will be transmitted in the reverse QEJ direction to the safety system. The isolation amplifier is a Foxboro Company N111IF magnetic ampli- fier designed specifically to amplify the output of Foxboro type 630 pressure transducers and to be compatible with the other Foxboro compo- nents in Fig. 2.5.4. The amplifier has an input of 0.2 to 4.0 ma into 10,000 ohms impedance and an output of 10 to 50 ma into 600 ohms load. The remaining two current-actuated switches in Fig. 2.5.4, whose outputs are labeled "Alarm" and "Control Rod Reverse," are Foxboro dual type 63 alarms, both in a single case. The meter is a Foxboro model M65PV-OHT. This is a D'Arsonval cur- rent meter designed to operate over an input from 10 to 50 ma dc. 2.5.2 Rod Scram Safety Channel — Qutput Instrumentation The output section of a typical safety channel (channel A) is diagrammed in Fig. 2.5.5. From the left side of the figure, it can be seen that the four trip relay contacts in the input instruments are in series and are maintained closed during normal reactor operation. These contacts are located as follows: 3In other applications an alarm mey be produced when the input signal is less than set-point voltage. This mode of operation (low alarm) is accomplished by a simple wiring change. - 179 1. high-temperature trip (Toutlet greater than 1300°F) in the Foxboro model 63 alarm switch, Fig. 2.5.4; 2. channel integrity monitor trip in the Q-2634 MSRE test module, Fig. 2.5.1; 3. high'neutron flux trip in a Q-2609 fast-trip comparator, Fig. 2.5.1; 4. reactor period trip (v £ +1.0 sec) in a Q-2609 fast~trip comparator. A fifth set of normally closed contacts formed by a manual "Test" button is also included, followed by & seal contact in parallel with a "Reset" push button. During normal reactor operation relays KAl to KA5 are energized. These relays, push buttons, and associated indicating lamps make up the ORNL model Q-2623 relay safety element, which provides the contact multiplication needed to produce the safety actions required. The contacts of relays Khl to Kfi? are interconnected with similar con- tacts from corresponding relays in channels B and C to produce three two-out-of-three coincidence matrices in the power circuits to the rod drive clutches. A typical matrix appears on the right-hand side of Fig. 2.5.5. Relay KA4 provides one of the control rod "Reverse" signals and the "Seal" contact, and relay KA? is used to open the drain tank vent valves and close the radiator doors (load scram). Figure 2.5.6 shows & block diagram and the additional circuits which operate the vent valves, radiator door, etc. Each rod drive clutch (see Sect. 2.7) receives its power through its corresponding contact matrix, and it can be seen that a loss of clutch current (rod scram) requires that relays in at least two safety channels be deenergized. This permits testing of individual channels during operation without disturbing the reactor and also allows the disabling of any one channel for maintenance. Kach leg in the two-out-of-three matrix shown in Fig. 2.5.5 contains a 100-ohm resistor and a current meter in series with a pailr of relay contacts. These meters function as input channel monitors, as can be seen from the following example. Assume that channel A is being tested during operation. This may be done with either the test routine built into the Q-2634 test module (see Sect. 2.5.6) in channel A or, by using the thermocouple test assem‘bl;y.4 A less complete test is initiated by pushing the "Test" button in the Q-2623 relay safety element shown in Fig. 2.5.5. In any case, relays KAl to Kfi? will be deenergized and thereby produce open circuits in two of the three branch circuits in each of the Q-2623 coincidence matrix monitors. From Fig. 2.5.5, it can be seen that the meters labeled "A and C" and "A and B" will change to show zero current. The total clutch current will now be carried by the third leg in the matrix, and meter "B and C" will change upscale to reflect this change. The 100-ohm resistors are required to “Molten-Salt Reactor Program Semiann. Progr. Rept. Jan. 31, 1964, ORN1~3626, p. 44. 180 ensure equal current division among the three legs in the matrix. With- out these resistors very small differences in relay contact resistance would produce large inequalities in the currents normally carried by the three meters. This resistor is sized so that its resistance must be at least an order of magnitude larger than any anticipated value of total relay contact resistance in series with it. Also, it must not be so large that it reduces clutch current to the "Scram" point when it assumes the total current load of the clutch, as it must, when one channel is in "Scram" mode. Tests on the prototype rod drive show that a typical clutch will transmit 39 in.-1b torque at 22.6 v, whereas the scram torque produced by the weight of the rod and unbalanced drive mechanism compo- nents is approximately 12 in.-1lb. Thus, it can be seen that there is ample margin to prevent undesirable scrams during testing or in the event that a single channel be tripped as by removal for maintenance or mal- function. The 32-v Zener diode across the clutch coil prevents high peak re- verse voltages that would otherwise take place when the clutch coil cur- rent is interrupted. Figure 2.5.7 is a functional diagram of all three channels and consolidates the contents of Figs. 2.5.1 to 2.5.6. 2.5.3 Safety Chambers These are Reactor Control Inc.? ionization chambers type R.C. 16-(2-2.88k) (Fig. 2.5.8). Specifications are as follows: General Integral cable construction with redundancy on both signal and high voltage Cable volume separate from chamber volume No organic materials used in the chamber or cebles Construction: all welded, guard on signal Mechanical Maximum diemeter 2.5 in. Chamber length 7.25 in. Sensitive length 4,25 in. Integral cable length 45 £t PUCNC Purchase Order No. 56X-71207, Jan. 24, 1964. 181 Material Outer shell Inner electrodes Cable sheath and conductor Insulation Detector Cable end seals Cable Electrode coating Resistance at 25°C Electrode to ground without cables Electrode to ground with 45-ft cable Maximum ratings Applied potential Temperature Operating characteristics Thermal neutron sensitivity Gamma sensitivity Saturation 99.97% pure nickel 1100 aluminum Stainless steel Alumina ceramic Alumina ceramic Al203 Enriched 0B >101% ohms >1012 ohms 1000 v dec 200°¢ 1.6 x 10714 amp/nv 5 %x 10712 amp r~t hr See curve in Fig. 2.5.9 2.5.4 Period Safety Module,® ORNL Model Q-2635 2.5.4.1 Description General The input, or current-sensing element (logarithmic diode), of the period safety module (see Fig. 2.5.10) is connected in series with the flux amplifier input. The voltage across the logarithmic diode is differentially amplified with a very high input impedance amplifier so that the chamber current passes undisturbed into the flux amplifier module. This voltage is further amplified and differentiated to give outputs proportional to the logarithm of the current and its period 6This description of the Q-2635 Module is taken from the Instruction Manual, pp. 49, written by E. N. Fray, Instrumentation and Controls Division, Aug. 25, 1965. 182 (time required for the current to increase by one e factor) respectively. The input current range is from 1030 o 10°4 amp. In the usual appli- cation the period output serves as an input to a nuclear reactor safety system; hence the name "period safety." Construction The period safety module is 1.40 in. wide, 4.72 in. high, and 11.90 in. deep. It is a standard "one-unit" plug-in module of the ORNL modular reactor instrumentation series depicted on ORNL drawings Q-2600-1 to Q-2600-5. ' , The circuits are on a printed circuit board which is completely en- closed by a shield. The outputs are displayed on front-panel meters. Test points and access holes to trimming potentiometers are located along the top of the shield enclosure. Application The period safety module is primarily intended to continuously monitor the neutron flux and period of a nuclear reactor. Since the module is not intended to measure reactor power accurately, the panel meter on the output of the logarithmic amplifier is calibrated in "log current” from 10~° to 10~% amp. The output of the period emplifier is displayed on a panel meter which is calibrated in seconds from -30 to +1. Specifications Overall specifications for the period safety module are as follows: Period Output voltage range Output current Scale Zero drift Power required Ambient temperature range Log current Output voltage Output current Scale Zero drift Input leakage current Power required Ambient temperature range -0.033 to +10 v for =30~ to +0.1- sec period 0.1 ma into 100-kilohm load =30 to +1 sec Less than 20 mv/month +15 v dc with regulation *0.1% 0 to 55°C Approximately 1.67 v/decade with zero voltage point determined by "Hi Cal" setting 1 ma into 10-kilohm load 10~10 o 10~% amp less than 50 mv/month Less then 10~13 amp at 25°C +15 v dc with reguletion 0.1% 0 to 55°C Applicable Drawings 183 The following list gives the drawing numbers (ORNL Instrument Department drawing numbers) and subtitles for the period safety module: Q-2635-1 Q-2635-2 Q-2635-3 Q-2635-4 Q-2635-5 Q-2602-6 Circuit Details Metalphoto Panel Printed Circuit Board Assembly Parts List The following list gives the drawing numbers and subtitles for the plug-in chassis system: Q-2600-1 Q-2600-2 Q-2600-3 Q-2600-4 Q-2600-5 2.5.4.2 Theory of Operation Genersal Assembly Details Details Details Details The ionization chamber current passes through a thermionic diode in the period safety module and then into the flux amplifier (Q-2602) or equivalent. proportional to the logarithm of the current. The voltage drop across this "log" diode is approximately The diode voltage is applied to a very low leakage differential amplifier, whose output is further amplified with a second differential amplifier to give the “log 11 current” output. The "log current" output is differentiated with an operational amplifier to generate the "period" output. It is required that the leakage of the input difference amplifier be small compared with the flux amplifier input leakage. This leskage current must come from the ionization chamber current, and if the leak- age current is excessive, the current amplified by the flux amplifier will be in error. Circuit Description The input current flowing through the thermionic diode V1 develops a voltage across the diode that is essentially logarithmic over the cur- rent range of 10710 to 10™% amp., This voltage is applied to a difference amplifier which uses insulated-gate field-effect transistors (FET's) as active elements (Ql). The gate leakage current of the FET's is extremely small, so that essentially all the signal current flows through the diode and then into the flux amplifier. The gates are protected against over- voltage transients by neon tubes Il and I2. (Ordinary Zener diodes are not adequate to furnish this protection because of their high leakage current.) A constant-current circuit, comprised of transistor Q2 and resistors R7, R8, and R9, furnishes the bias current for the difference 184 emplifier and appears as & large source load impedsnce to improve the common-mode rejection ratio. The gain of the difference amplifier is approximately 2.5. Its output is applied to a Fairchild type ADO-3 differential amplifier whose gain is adjustable from 2.67 to 4 by the trimming potentiometer R11l ("Io Cal"). The particular gain required is determined by the characteristics of log diode V1, and it is adjusted to give approximately 1.67 v/decade at the output of the "log current” amplifier. Trimming potentiometer R18 ("Hi Cal") is required for proper scale adjustment of meter Ml. The "log current" output is differentiated by an additional ADO-3 eamplifier whose gain (product of C4 and R25) is such that a 1-v output corresponds to a l-sec period. Two significant smoothing time constants are associated with the "period" amplifier. They are determined by the product of R20 and C4 and R25 with C5, and each is approximately 100 msec. 2.5.4.,3 Operating Instructions Installation The period safety module is & module in the ORNL modular reactor instrumentation series. ILike the other modules in this series, it has standard connectors and dimensions and has a pin-and-hole code on the rear plate so that the module will not be inserted in a wrong location in a drawer. The module is installed by placing it in its proper lo- cation, inserting the module firmly, and tightening the thumbscrew. The module may be plugged in with power on without damage. Operating Controls Log Current Panel Meter. — The log current panel meter is calibrated to indicate current from 10—° to 10™% amp. This represents a voltage swing of =10 v; however, the output voltage measured with respect to ground at a particular current will vary from unit to unit. This is de- termined by the "Hi Cal" setting, which adjusts for variations of input diode characteristics. Period Panel Meter. — The period panel meter is calibrated to in- dicate reactor period from —30 to +1 sec. This is a voltage range from -0.033 to +1.0 v. The meter is mechanically zeroed to give an "w" in- dication with no voltage applied. Zero Adjustment. — "Bal 1" is for zeroing the output of the insulated- gate difference emplifier Ql with TPl and TP2 shorted together. "Bal 2" is for zeroing the output of the "log current"” amplifier with TP3 and TP4 shorted to ground. "Bal 3" is for zeroing the output of the "period” amplifier any time when the input is not changing. Test Points. — The test points are locaeted at the top of the front side of the shielding enclosure. These are used primerily when zeroing or balancing the instrument, as described sbove. Connections All connections are made through the rear connector P29 when the module is inserted. 185 Operating Procedures The balance of the insulated-gate difference amplifier, log current amplifier, and the period amplifier should be checked periodically for drift. If correction is required, the following procedure should be followed: l. Place a jumper between TPl and TPZ2 and measure the voltage between TP3 and TP4 with a Triplett meter (or equal). Adjust "Bal 1" until the voltage is zero. 2. Place the jumper across TP3 and TP4 and TP6 (ground). Adjust "Bal 2" until the voltage between TP5 and TP6 is zero. 3. The period amplifier may be zeroed at any time the input is not changing by adjusting "Bal 3" until the front-panel meter indicates "e'" or until the output is zero. 2.5.5 Flux Amplifier and Ion Chamber High-Voltage Supply, ORNL Model Q-26027 2.5.5.1 Description General The flux amplifier (Fig. 2.5.11) is a low-level dc amplifier that amplifies current in the range of 10™10 o 30™4 amp from an ionization chamber. The current from the ionization chamber is proportional to reactor neutron flux in the usual application; hence the name "flux amplifier.” . An ion chamber high-voltage supply, & de-to-dc converter, is con- tained in the same module with the flux amplifier to provide +250 v to polarize the ion chamber. The two sections are electrically independent. Construction The ion chamber high-voltage supply and the flux amplifier are in a single module 2.83 in. wide, 4.72 in. high, and 11.90 in. deep — a standard "two-unit" plug-in module of the modular reactor instrumentation series depicted on ORNL drawings Q-2600-1 to Q-2600-5. - The circuits are on two printed circuit boards mounted side by side. The output is displayed on a front-panel meter. A balance meter, mounted in the top front of the module, is visible when the module is plugged in and the drawer is withdrawn. Near the meter is a "zero" push button and a trimming potentiometer for balancing the flux amplifier. Application The ion chamber high-voltage supply and flux amplifier are intended primarily to continuously monitor neutron flux in a nuclear reactor. To ” _ Written by J. L. Anderson, Mar. 3, 1965. 186 this end the panel meter is calibrated in percent power from O to 200%. However, the amplifier may be used, with or without the ion chamber high-voltage supply, wherever it is desired to measure current in the range 10~8 to 10™% amp full scale. The amplifier has two internal feedback resistors and provisions for connecting an external feedback resistor to establish any desired scale calibration vs current within the capability of the instrument. A flux reset mechanism Q-2603, a companion unit, can be used with the flux amplifier to continuously adjust the feedback factor or gain over a 3 to 1 range. The flux reset mechanism is a small instrument servo that adjusts the feedback ratio of the flux amplifier so as to force the flux amplifier output to agree with another signal, typically computed heat power. Specifications Overall specifications for the flux amplifier and ion chamber high- voltage supply are given below. Flux Amplifier Output voltage range O to +12 v linear for positive current (flowing into ampli- fier); O to —~12 v for nega- tive current Output current 30 ma into 300-ohm load Scale 0 to 200% power Zero drift Iess than 1 mv/day at con- stant temperature; less than 10 mv for O to 55°C Input leakage current Iess than 10710 amp at 25°C Response time 10 to 90% rise time in less than 100 psec with a 200- kilohm feedback resistor and 0.002-uf capacitor on input Power required +25 + 0.25 v dec with regulation +0.1%; —25 + 0.25 v dc with regulation 0.1% Ambient temperature range 0 to 55°C Ion Chamber High-Voltage Supply Qutput voltage +250 * 25 v dc Input power required +32 t 4 v de and 200 ma maximum Output current Rated 5 ma continuous; will deliver ~50 ma into a 3- kilohm load or 1 ma minimum into a short circuit 187 Overload protection ILoad regulation Line regulation Output ripple and frequency Adjustments Starting Ambient temperature range Applicable Drawings Undamaged by any overload, in- cluding a short circuit less than 15%, O to 5 ma Iess than 10%, 28 to 36 v dc ILess than 50 mv at 5 ma load; ~8 ke None Self-starting, no load to full load 0 to 55°C The following list gives the drawing numbers (ORNL Instrument Department drawing numbers) and subtitles for the ion chamber high- voltage supply and the flux amplifier: Q-2602-1 Circuit Q-2602-2 Details Q=-2602-3 Metalphoto Panel Q-2602-4 Printed Circuit Board Q-2602-5 Assembly Q-2602-6 Parts List SF-239 Fabrication Specification The'following list gives the drawing numbers and subtitles for the plug-in chassis system: Q-2600-1 Assembly Q=2600~2 Details Q-2600-3 Details Q-2600-4 Details Q-2600-5 Details 2.5.5.,2 Theory of Operation Generalr The ion chamber high-voltage supply and flux amplifier consist of a stable, direct-coupled low-leakage emplifier and a self-contained high- voltage supply for ionization chamber polarization. The chanber voltage supply consists of a series preregulator, to regulate the battery input voltage, and an unregulated dc-to-dc converter. , Circuit Description of the Ion Chamber High-Voltage Supply The power supply is designed to operate from a nominal 32-v station " battery with a terminal voltage variation from 28 to 36 v dec. This wide variation makes necessary a voltage preregulator consisting of transistors Q9, Q:LO) Q,ll, and Q,l2. 188 The preregulator output voltage is sensed by resistors R24 and R26 and applied to the base of amplifier stage Ql1l. A reference voltage (16.8 v) generated by Zener diode string D4, D5, and D6 is applied to the emitter of Qll. The amplified difference appears at the collector of Q11 and is applied to driver Q10 and pass transistor Ql2. A constant col- lector current is provided for Qll by transistor Q9, Zener diode D3, and the associated network. The preregulator output (test point TPl) is filtered by C3, C4, and R27 and is applied to the de-to-dc converter. Q13, Ql4, T1, and the associated circuitry comprise a free-running square-wave oscillator; D7, D8, and D9 assure that the circuit will be both self-protecting and self-starting. Capacitors C6 and C7 round the edges of the square wave somewhat to avoid the generation of sharp, high- frequency spikes which may be coupled to other circuits. A square wave of approximately 250 v peak-to-peak amplitude and frequency of approximately & kc appears on winding 1-3 of transformer Tl. This voltage is rectified by diode bridge D10-D13 and is filtered by a pi-section RC filter composed of C8, C9, and R32. The output is approximately 250 v de with less than 50 mv of 8- or 16-kc ripple. The output voltage vs load current is shown in Fig. 2.5.12. When the output is short-circuited, the circuit continues to oscillate at a very low amplitude and supplies about 1 ma of current. The circuit will recover undamaged upon removal of the short circuit or overload. Circuit Description of the Flux Amplifier The flux amplifier converts a low-level current from an ionization chamber to a usable voltage. The current range is determined by feed- back resistor R33, which may be paralleled by R10 or an external re- sistor. The input current is converted to a full-scale voltage of 10 v at the output of the amplifier. The amplifier is an operational type with a high open-loop gain and a high open-loop impedance (Fig. 2.5.13). Only a small leakage current flows in the input of the amplifier; therefore, all the signal current flows through feedback resistor Rf. The voltage produced at the output is Eo (V’) = ISRf ) where I, is the signal current in amperes and Re is the resistance in ohms. The sensitivity of the flux emplifier can be adjusted by flux reset mechanism Q-2603. Instead of feedback resistor Rg being connected di- rectly to the output as shown in Fig. 2.5.13, it is connected through a voltage-dividing network to the output as shown in Fig. 2.5.14. Poten- tiometer R6 is motor driven to adjust the output voltage (with constant input current) until the flux amplifier output agrees with an independent signal as might be derived from & heat-power computer. The output volt- age is then R6é + R7 Bo = L Re (_0536 TR >’ where O is the potentiometer setting as indicated in Fig. 2.5.14. 189 The flux amplifier is composed of eight silicon transistors and a silicon diode. Input device Ql is a field-effect transistor which has low gate-leakage current. In the specified range of input current, the field-effect transistor is a satisfactory electrical replacement for an electrometer tube and is far more rugged. Some unusual characteristics of the field-effect transistor are used advantageously in this particular amplifier. The field-effect transistor drain-voltage drift with temperature is a function of the drain current. When the drain current is larger than approximately 30 pna, the temperature coefficient is positive. When the drain current is less than approximately 30 pa, the temperature coefficient is negative. The field-effect transistor is biased at approximately 45 pa so that its net current drift will be in a positive direction to cancel out drifts of opposite direction due to the remaining transistors and diodes. The voltage gain from gate to drain of the field-effect stage is about 20. The remaining transistors are operated in standard configurations. Transistor Q2, an emitter follower with near unity voltage gain, imped- ance matches field-effect transistor QL to the following gain stage. Q3 and Q4 comprise a differential high-voltage-gain stage. The gain from the base of Q3 to the collector of Q4 is about 500. Transistors Q5, Q6, Q7, and Q8 are complementary emitter-follower power-gain stages with unity voltage gain. The function of these four transistors is to allow the output to swing plus and minus 10 v and deliver up to about 30 ma of current to the load. 2.5.5.3 Operating Instructions Installation The chamber high-voltage supply and flux amplifier is a module in the ORNL modular reactor instrumentation series. ILike the other modules in this series, it has standard connectors and dimensions and has a pin- and-hole code on the rear plate so that the module will not be inserted in & wrong location in a drawer. The module is installed by placing it in its proper location, inserting the module firmly, and tightening the thumbscrew. The module may be plugged in with power on without damage. Operating Controls Panel Meter. — The panel meter is callbrated to indicate power from 0 to 200%; this corresponds to a voltage output of O to —10 v. If the amplifier is to be used with a- negatlve 1nput current the meter leads should be reversed. : Balance Meter. — A zero—center balance meter on the top of the module is visible with the module inserted and the drawer pulled out. The meter is used with the push button and zero adjustment located at the edge of the printed circuit board nearby to correct for drift periodically. ' Zero Adjustment. — The zero adjustment is used to balance the de amplifier to correct for drift. Zero Push Button. — This push-button switch short-circuits the in- put of the amplifier so that it may be balanced even when signal current is present. 190 Connections A1l connections are made through the rear connector P9 when the module is inserted. A Jjumper between pins 2 and 3 of P9 is provided so that if the module is removed from a drawer a warning signal is given. Opersting Procedures The balance of the flux amplifier should be checked periodically by depressing zero push button S1 and observing balance meter M2. If the meter reads anywhere on scale less than plus or minus full scale when the push button is depressed, the balance is satisfactory. With the push button released the meter should read upscale the same amount as the front-panel meter reading. If adjustment is necessary, turn zero- adjustment potentiometer R3 clockwise to move the indicator in a positive direction or counterclockwise to move the indicator in a negative di- rection. There are no adjustments on the chamber high-voltage supply. Precautions Since the output of the high-voltage supply can be lethal, care should be taken not to place fingers in the rear portion of this module. External connections to the ionization chamber should be made with the power off or the module unplugged to avoid possible damage to field- effect transistor Ql. 2.5.5.4 Maintenance Instructions General This module is designed to operate continuously with a minimum of maintenance and adjustment. Zero adjustment and voltage test points are accessible from the top of the drawer with the module inserted and the circuits energized. Periodic Maintenance The amplifier balance should be checked (see Operating Procedures, above) once every three or four weeks. The high-voltage output should be checked every three or four months by measuring with a voltmeter at the test points. The white point on the module is ground test point TP3; the red point is the high- voltage ocutput test point TP2; and the gray point is the preregulator output test point TPl. The voltages at the test points should read (with respect to TP3); TPl, +25 + 1 v; and TP2, +250 = 25 v. Calibration Procedures There are no calibration procedures. e 191 2.5.6 MSRE Test Module, ORNL Model Q-26348 2.5.6.1 Description General The MSRE test module (Fig. 2.5.15) is a special-purpose unit designed to supply calibration signals for testing the response of parts of the safety system of the MSRE. The module provides two calibrated current ramps at different rates to check the response and approximate calibration of the flux amplifier and associated fast-trip comparators. An adjustable steady-state current can be substituted for the ramps for more precise calibration. In addition, the module provides two steady-state currents for calibration of the "log current” portion of the period safety module and two voltage ramps for calibration of the "period" portion of the period safety module and associated fast-trip comparator. An ion chamber undervoltage monitoring circuit is provided in this module. All these are initiated by push buttons from the module front panel. Construction | The module is 2.83 in. wide, 4.72 in. high, and 11.90 in. deep. It is a standard "two-unit" plug-in module of the ORNL modular reactor in- strumentation series depicted on drawings Q-2600-1 to Q-2600-5, The circultry is constructed on two large printed circuit boards mounted within the module. Application The module is intended to supply signals for both preoperational and on-line testing of the nuclear safety system of the MSRE. Although the signal types and circuitry used are generally applicable to any re- actor safety system employing the ORNL modular reactor instrumentation series, the signal levels and rates for this module are tailored es- pecially for the MSRE. opecifications Output Ramps. — The basic ramp generator supplies a voltage ramp of 0 to +14 with a rate of +1 v/sec. This ramp voltage is applied to suitable multiplier resistors to obtain the required current ramp. The output currents are: high rate (300 kilohms), O to 46.7 x 10™% amp; and low rate (300 megohms), O to 46.7 X 10™2 amp. Output Currents, Steady State. — The output currents are adjustable with a ten-turn precision potentiometer on the front panel calibrated to be direct reading from O to 100. The output currents are: high current (200 kilohms), O to 100 x 10~° amp; and low current (200 megohms), O to 100 x 10™% amp. Log Current, Steady State. — Two calibration currents are derived from the ion chamber high-voltage supply by suitable multiplier resistors 8This material was taken from the Instruction Manual, pp. 514, written by E. N. Fray, July 28, 1965. 192 for current calibration of the period safety module. They are: high (25 megohms), 10™° amp; and low (250,000 megohms), 10~° amp. Period Calibration. — The +1-v/sec ramp is applied to the log cur- rent amplifier in the period safety module through a suitable input re- sistor. This produces a constant output at the period amplifier for calibration purposes. Two approximate calibration points are provided: +1 sec period (500 kilohms) and +2 sec period (1 megohm). Undervoltage Monitor. — The circuit continuously monitors the polarizing voltage of the ionization chamber on a return lead from the chamber. When the chamber voltage is greater than 200 * 10 v, a green light labeled "Normal" on the front panel is 1it. When the chamber voltage for any reason drops below 200 + 10 v, the circuit changes state and lights both a red "Low" indicator lemp and a yellow "latch" indicator lamp. When the voltage is restored, the "Low" indicator is extinguished, and the "Normal" light agein comes on. The "Latch" light remains on until the front-panel "Reset" push button is depressed. The relsy that actuates the indicator lamps has additional contacts (single pole, double throw) for use in external circuits. An additional front-panel push button labeled "Test" simulates a low-voltage condition to the monitor circuit without affecting actual chamber voltage. Power Requirements. — The module requires +32 * 4 v unregulated and +25 v * 0.1% regulated. Ambient Temperature Range. — The ambient temperature range is 10 to 55°C. Applicable Drawings The following list gives the drawing numbers (ORNL Instrument Department drawing numbers) and subtitles for the MSRE test module: Q-2634~1 Q-2634-2 Q-2634-3 Q-2634-4 Q-2634-5 Q-2634-6 Circuit Details Metalphoto Panel Printed Circuit Board Assembly Parts List The following list gives the drawing numbers and subtitles for the plug-in chassis system: Q-2600-1 Q-2600-2 Q-2600-3 Q-2600-4 Q-2600-5 2.5.6.2 Theory of Operation General Assembly Details Details Details Details The MSRE test module is & special-purpose module designed to pro- vide signals to test parts of the nuclear safety system of the MSRE. 193 Although it was originally intended to have a general-purpose test module which would be applicable to several reactors, and such a module Q-2601 was designed, it soon developed that a single test module would not suffice because of the different instrument sensitivities and varied functions of the several reactor systems under design. Consequently, a separate test module was designed for each reactor that uses this type of instrumentation. In spite of the unique project application of the module and because of the general applicability of the cirecuits used in the module, a "Q" number was assigned to the MSRE test module for the convenience of designers of future systems. Circuit Description Ramp Generator. — A linear voltage ramp is generated by charging a capacitor with a constant current. In circuit diagram Q-2634-1, it is seen that the base of transistor Q1 is held at a constant potential with respect to the +25-v supply by Zener diode D1. This in turn causes the emitter voltage of QL to be constant across a fixed resistor R2, estab- lishing constant emitter current. To a first approximation, transistor collector current is equal to emitter current, regardless of collector voltage, until saturation is reached, that is, until the collector volt- age equals the emitter voltage. Thus, the collector current of Q1 is constant and flows into capacitor Cl. In the standby condition, the capacitor is short-circuited by con- tacts of relays Kl and K2 and by contacts of push buttons S7 and S8. When any one of these contacts opens, the capacitor begins to charge. The rate of change of voltage across the capacitor is determined by the magnitude of the current and the size of the capacitor. In this case y_1 t " ¢ -6 _ 20 X 107" amp _ v/sec . 20 x 1076 r The voltage across Cl is sensed by a very high beta Darlington-pair emitter follower Q2 and Q3. The maximum amplitude of the ramp is limited by saturation of Ql and Zener diode D1 to about 15 v across Cl or 14 v at the emitter of Q3. : -Current Switching. — The MSRE test module is designed to provide test currents for both the flux amplifier and the period safety module. Since the input of the flux amplifier is in series with the log diode of the period safety module, any test current will be sensed and indicated by both instruments. Since the flux amplifier has 100% feedback to the input terminal, there is no input voltage offset. This means that a relatively low-voltage current source is adequate for generation of its test currents. For application to the period safety, a better current source is required, since the voltage across the log diode is not con- stant but changes with input current. To this end the calibration cur- rents for the period safety are produced by using the chamber high-voltage supply and suitable multiplier resistors. The "Rate" test currents and the "Adjustable" test currents are intended for use with the flux ampli- fier only; further, application of either of these currents causes the 194 period safety to indicate an incorrect current, which should be ignored. Since all test currents are applied by way of a second ionization chamber signal lead, which is separate all the way to the chamber plates, a test signal must travel to the chamber and back to the safety channel input. In this way a successful current test verifies that the chamber is connected. Flux Amplifier. — For steady-state calibration or checks, a voltage adjustable from O to 20 v by a front-panel Helipot may be applied through either a 200-kilohm or a 200-megohm resistor to the amplifier input by energizing relay K4 or K3 respectively. The corresponding currents are 0 to 100 pa and O to 100 na. The Helipot dial labeled "Current Adjust” is read directly from O to 100 units. The voltage ramp described sbove may be applied through a 300-kilohm or a 300-megohm resistor by energizing relay K1 or K2, respectively, re- sulting in current ramps ranging from O to 46.7 pa and O to 46.7 na. The ramp is initiated by a second contact of Kl or K2, which removes the short circuit from capacitor Cl. | Period Safety. — Fixed calibration currents for the period safety module are generated by applying the chamber high voltage (approximately 250 v) through either a 25- or a 250,000-megolm resistor, resulting in currents of 10™° or 10~? amp. These currents are initiated by energizing relays K5 and K6 respectively. To check the calibration of the period amplifier, the voltage ramp is applied to the input (terminal 6) of the log current amplifier. Sub- sequent differentiation in the period amplifier results in a constant- voltage output (constant indicated period) whose magnitude is determined by the generated ramp rate and the gain of the log current amplifier. Two calibration points are provided by applying the voltage ramp through either a 500-kilohm or a l-megohm resistor; the result is a period in- dication of about 1 and 2 sec respectively. Actually, the l-sec period test should always generate a period slightly less than 1 sec, so that the l-sec fast-trip comparator will trip. These tests are initiated by depressing push buttons S7 or S8 to generate the 1- or 2-sec period. Chamber Voltage Monitor. — In a manner similar to the signal lead, a separate high-voltage lead is returned from the plates of the ioniza- tion chamber. This voltage is continuously monitored by & circuit con- sisting of transistors Q4 through Q8. If the voltage, normally 250 v, is interrupted or reduced below approximately 200 v, an undervoltage alarm occurs. The sensed voltage is reduced from 250 to 100 v at R5 by two Zener diodes, D2 and D3. The voltage is further reduced to 20 v at the base of Q4 by the dividing action of R5 and R6. The emitter of Q4 is biased at 10 v, so that the transistor is reverse biased and not conducting under normal conditions. Since the collector of Q4 is near ground po- tential, the Darlington emitter follower Q5 and Q6 and the relay drivers Q7 and Q8, driven by the emitter-follower output, are also not conduct- ing. A normally closed contact of K7 energizes the green "Normal" lamp on the front panel. When the input voltage drops below 200 v, the Q4 base voltage is reduced to below 10 v, and Q4 conducts. The collector voltage of Q4 in- creases to 10 v, turning on Q5, @6, Q7, and Q8 and energizing both K7 and K8. The contacts of K7 extinguish the "Normel" lamp and light the 195 red "Low" chamber voltage lamp. A second set of K7 contacts controls external circuits. K8 seals itself in and will remain energized, light- ing the "Latch" lamp, until input voltage is restored and "Reset" button S2 is depressed. This enables the operators to identify a momentary chamber voltage fault. The voltage monitor circuit is tested by pressing "Test" push button S1 on the front panel. This reduces the voltage at the base of Q4, simu- lating & low input condition without causing significant reduction of the chamber voltage itself. 2.5.6.3 Operating Instructions Installation The MSRE test module is one of the ORNL modular reactor instrumenta- tion series. Iike the other modules in this series, it has standard connections and dimensions and has & pin-and-hole code on the rear pleate so that the module will not be inserted in & wrong location in a drawer. The module is installed by placing it in its proper location, inserting the module firmly, and tightening the thumbscrew. The module may be plugged in with power on without damage. Operating Controls on Panel Chamber Voltage Monitor. — Three pilot lamps indicate the state of chamber voltage. The green "Normal" light is on when the voltage is greater than 200 v. The red "Low" light is on when the voltage is less than 200 v. The amber "Latch" light comes on when the voltage drops below 200 v and remains on until the "Reset" button is pressed. When the "Test" button is depressed, it causes a simulated low voltage to test the monitor. High Rate. — When the "High Rate" button is depressed, a current ramp of 3.33 ua/sec is applied to the safety channel input. ~ Low Rate. — When the "Low Rate" button is depressed, a current ramp of 3.33 na/sec is applied to the safety channel input. High Current. — When the "High Current" button is depressed, a cur- rent, adjustable from O to 100 pa by the "Current Adjust" potentiometer, is applied to the safety channel input. Iow Current. — When the "Low Current" button is depressed, a cur- rent, adjustable from O to 100 na by the “Current Adjust" potentiometer, is applled to the safety channel input. 'High log Current. — When the "High Log Current"” button is depressed, a current of 107> amp is applied to the safety channel input. Low log Current. — When the "ILow Log Current" button is depressed, a current of 107° amp is applied to the safety channel input. l-sec Period. — When the "l-sec Period" button is depressed, a volt- age ramp is applied to the period safety module, resultlng in an output indication of approximately a l-sec period. . 2-sec Period. — When the "2-sec Period" button is depressed a volt- age ramp is applied to the period safety module, resulting in an output indication of approximately a 2-sec period. 196 Connections A1l connections are made through the rear connector P28 when the module is inserted. A jumper between pins 4 and 12 is provided so that if the module is removed from a drawer, a warning signal may be given. Operating Procedures All tests are initiated simply by depressing the proper push button on the front panel. 2.5.7 Fast-Trip Comparator, ORNL Model Q-2609° 2.5.7.1 Description General The fast-trip comparatorlo circuit (Fig. 2.5.16) compares the magni- tude of two input dc signals having opposite polarities and produces an output voltage having either of two possible values, depending upon which input voltage is larger. Two electronic outputs drive logic circuits ex- ternal to this unit, and there are also two relsy drivers within the unit. The change in voltage from one level to the other is completed in less than 200 psec after the trip signal occurs. The relays can change states in approximately 10 msec. Each relay has one set of contacts for external connections and one set to perform an indicating function on the front panel. One relay can be connected to hold a trip indication after the trip has cleared, and the other relasy indicates the immediate state of the circuit. Several external connections can be made that allow the circuit to trip for a variety of input conditions. With a reference serving as one signal, the circuit can trip on a positive or a negative input signal and on an increasing or a decreasing signal. For the case of two ex- ternal signals A and B, tripping action can take place when the magni- tude of A is greater than or less than that of B, provided A and B have opposite polarities. Construction The fast-trip comparator is constructed in & single module 1.40 in. wide, 4.72 in. high, and 11.90 in. deep. It is a standard "one-unit" plug-in module of the modular reactor instrumentation series depicted on drawings Q-2600-1 to Q-2600-5., The circuit is constructed on & printed circuit boasrd mounted within a shielding enclosure with removable sides. Token from Instruction Manuasl, written by J. L. Anderson, Instru- mentation and Controls Division, Apr. 13, 1965. 107, F. Pierce and D. C. Shattuck, Instrumentation and Controls Div. Ann. Progr. Rept. Sept. 1, 1963, ORNI-3578, pp. 105-6. 197 Application The fast-trip comparator is intended primarily to be used as a voltage level discriminator for safety and control functions in a nuclear reactor. For maximum flexibility the unit has two inputs, so that it may be used either to compare two signals or to compare one signal with an external reference. The circuit is bistable in nature; that is, there is no change in output indication until the predetermined trip level is exceeded, at which time the output suddenly changes from one state to the other. The trip level is nominally zero volts; that is, the two in- ruts must be of opposite polarity, so that when the magnitude of one in- put exceeds the magnitude of the other, the circuit changes state. By use of suitable external jumpers the circuilt can be arranged to trip on either net positive or net negative input. Two types of output are available. The logic output, intended for use in fast safety systems, is —10 v normally and O v when tripped. The switching time is less than 200 psec. Normally the logic level will revert to normal as soon as the input signal drops below the trip level. However, by use of external Jumpers, the circuit can be made to latch, or seal, the logic output in the trip state until manually reset, pro- vided the trip signal persists for 10 msec or more. The second type of output is provided by two relays. Both relays are driven by the logic signal described previously and respond ac- cordingly. Kl may be arranged to latch if the trip signal persists for more than 10 msec; the relay will go to the trip state and remain there until manually reset, regardless of whether or not the logic level signal is arranged to latch. This arrangement is sometimes called a "secram catcher," in that it allows a momentary trip to be located and identified after it has disappeared. K2 operates directly off the logilc signal and will be in the same state. Contacts of both relays are available for actuating external circuits. Specifications Specifications for the fast-trip comparator are as follows: Trip range The trip range shall be adjustable from +1 v to +10 v or from —1 v to -10 v Trip point accuracy - .Once.the trip point has been set, variations in temperature from 10°C to 55°C and aging of compo- nents should not cause the trip point to change more than 50 mv " referred to the trip circuit input signal : ‘ Trip point hysteresis When the signal falls 60 mv below the trip point, the circuit shall reset itself; the circuit shall not reset less than 40 mv below the trip point Input impedance Logic output Tripping time logic level Relay outputs Power required Ambient temperature range Indication Test and reset 198 150 kilohms, either input In the normal state the logic level output shall be =10 v = 1/2 v, 20 me meximum drain; in the trip state the logic level output shall be O v & 1/2 v The change from normal to @bnormal con- dition (~10 to O v) shall require less than 200 psec Type 1 is a DPDT relay having contacts rated at 2 amp at 32 v dc and 2 amp at 115 v ac; this relay must change state in less than 100 msec Type 2 is a fast-latching relay that will operate in less than 10 msec; the purpose of this relay is to in- dicate the location of a momentary trip signal +15 v £ 0.25 v de with regulation of 0.1%; =15 v * 0.1 v dc with regula- tion of 0.1%; +10 v + 0.1 v dc with regulation of 0.1%; —32 v = 4 v dec, unregulated 10 to 55°C Front-panel indicator lights shall show the immediate state of the trip, that is, "Trip" or "Normal," and elso "latch," which indicates that & momentary trip of 10 msec or more has occurred Front-panel push buttons shall cause the circult to trip regardless of the input signal ("Test") and to reset the latech indication ("Reset") Applicable Drawings and Specifications The following list gives the drawing numbers (ORNI, Instrument De- partment drawing numbers) and subtitles and fabrication specification number for the fast-trip comparator: 199 Q-2609-1 Circuit Q=2609-2 Details Q-2609-3 Metalphoto Panel Q-2609-4 Printed Circuit Board Q-2609-5 Assembly Q=-2609-6 Parts List SF-253 Fabrication Specification The following list gives the drawing numbers and subtitles for the plug-in chassis systems: Q-2600-1 Assembly Q-2600-2 Details Q-2600-3 Details Q-2600-4 Details Q-2600-5 Details 2.5.7.2 Theory of Operation General The fast-trip comparator is composed of three functional parts: a voltage comparator, logic switching circuits, and relay drivers. The input stage, consisting of Q1 and Q2, is a compound (Darlington) differential amplifier having & high degree of temperature stability and a high input impedance. This stage drives a simple differential ampli- fier Q3, which, in turn, drives a Schmitt trigger circuit Q4. These three stages make up the voltage comparator. All transistors after the Schmitt trigger circuit act as switches and are either off (open) or saturated (closed). Transistor Q5 acts as a buffer to prevent the Schmitt trigger circuit from being affected by variations in the load. Electronic output points are located at the collectors of Q6 and Q7. Two double-pole, double-throw relays Kl and K2 each provide one set of contacts for the operation of external circuits and one set for the operation of indicator lamps on the front panel of the trip circuit. Re- lay K1 may be connected to hold the "Iatch" indicator lamp Il from the time a trip has occurred until the manual reset switch S2 has been de- pressed, even if the signal level decreases below the trip point. Relay K2 energizes indicator lamp I2 ("Trip") or I3 ("Normal"), depending upon the existing state of the circuit. Either or both of the relay drivers Q8 and Q9 may be driven from either electronic output. For operational flexibility the connections to the electronic outputs and the relay drivers are made externally through plug P/. The following sections provide a detailled discussion of the design and operation of the various stages of the circuit. : The Voltage Comparator The 1nput stage Q1 and Q2 is a compound differential amplifier. The compounding Q1 provides high input impedance. The two inputs are applied to a single base, rather than differentially to the two bases, so that no shift in output will occur when the two inputs are of equal magnitude 200 at various levels from =10 to +10 v. The 2-kilohm trimming adjustment R2 is used to balance the input resistors Rl and R3. The output of the first stage appears at the collector of Q2A and is coupled to the second stage through R10 and R1Oa. The second stage Q3 is a simple differential amplifier that provides additional voltage gain to increase the sensitivity of the amplifier. Overall negative feedback is employed from the collector of Q3B to the base of QLA (R36) to adjust the sensitivity to the desired level and to improve the temperature-drift characteristics. The de level is adjusted by trimpot R10 to establish the correct trip point. The output of the second stage Q3 is directly coupled to the Schmitt trigger circuit Q4. The Schmitt trigger circuit is a regenerative bi- stable circuit that provides the actual voltage level discrimination. The output of the Schmitt trigger circuit and all succeeding stages have only two stable states, "Normal" and "Trip." Jogic Switching Circuits Loading effects on the Schmitt trigger circuit are buffered by an isolation stage Q5. The bistable signal is then coupled to Q6, where the logic levels are established. When the collector of Q5 (and the base of @) is in the "high," or more positive, state, Q6 is biased off, allowing Zener diode D1 to be fired through R25. The logic level output at pin A of P7 is then —-10 v, as determined by the breakdown voltage of Dl. In the "low" state, when the voltage at the base of Q6 is less positive (actually slightly negative), Q6 is saturated, shunting Zener diode D1, and the magnitude of the output at pin A is near zero (less than 0.2 v). The Q7 stage is nearly identical to Q6 and provides an in- verted logic level output for maximum flexibility; that is, when the level at pin A is =10 v, Q7 is saturated, producing "zero" level at pin J. Conversely, when the level at pin A is "zero," Q7 is cut off and the output at pin J is =10 v. The inherent speed of response of the entire electronic circuit, from a sufficient level change at the input pin T to a logic level change at either pin A or pin J, is about 10 psec. However, this speed of response has been intentionally lessened to about 120 usec by capacitors Cl to C4 to reduce the tendency to respond to sharp noise spikes. Relay Drivers Either logic output may be connected to either or both of the two relay drivers Q8 and Q9. Normelly KL is intended to pick up when a trip (abnormal) condition exists. To accomplish this, the base of Q8 is con- nected through R30 and pin X of P7 to a logic output that is at =10 v in the "Trip" state, namely, either pin A or pin J. Note that "Trip" and "Normal" are related to the character of the input signal and refer to = signal which may be either too large or too small and either positive or negative. The proper connections for a desired signal and function cen be determined by referring to the connection table on circult diagram Q-2609-1. One set of contacts of K1 is used to latch in the coill of Kl to keep it energized after a trip has occurred and cleared. This optional func- tion is accomplished by comnecting pin 4 of P7 to battery ground (pin W)e 201 Relay K2, driven by Q9, is normally connected so as to drop out in the trip state. This relay is intended to show the immediate state, and no provisions are made to latch it. One set of form C contacts is available from each relay to operate external circuits. | The logic level output may be latched in the trip state by using the cutput contacts of relay Kl. Pin b is connected to pin B, and either positive or negative 15 v is connected to pin F, depending upon the nature of the input signal. When this connection is used, K2 also latches, be- cause it is driven by the logic signals. 2.5.7.3 Operating Instructions Installation The fast trip comparator Q-2609 is a module in the ORNL modular reactor instrumentation series. Iike the other modules of the series, it has standard connectors and dimensions and has & pin-and-hole code on the rear plate so that the module will not be inserted in a wrong location in & drawer. The module is installed by placing it in its proper location, inserting the module firmly, and tightening the thumbscrew. The module may be plugged in with power on without damage. Operating Controls The only integral operating controls are the "Trip Test" and the "Reset" push buttons. The "Trip Test" push button causes the circuit to trip by overriding the input signal. The circuit will remain in the trip position if the screwdriver-actuated push button is rotated clockwise after being depressed. "Reset" is a momentary push button that releases relay K1 and the "Latch" indication. : In a good many applications of the fast-trip comparator, a single signal will be compared against a reference. The reference can be fixed by a simple external voltage divider, or it can be adjusted by means of 8 Helipot located in the drawer into which the trip circuit is plugged. This adjustment .is shown on the circuit diagram as R4 and is, in effect, an operating control of the trip circuit. Connections All connections to the fast-trip comparator are made through the rear connector P7 when the module is inserted. After initial calibration is completed, there are no adjustments or comnnections to be made within the module itself. However, a high degree of flexibility is provided through external connections. The various possible modes of operation and the connections required to achieve them are detailed in the con- nection table on circuit diagram Q-2609-1 and in the following section. Operating Procedures Input Signals. — The input signels to the trip circuit should be supplied from a low-impedance source (500 ohms or less). A single signal may be either positive or negative within the range of #10 v. The magni- 202 tude of two different signals may be compared, but they must be of oppo- site polarity. The input terminal for a single signal is pin T, and an external reference voltage of opposite polarity is required on pin M. If two signals are compared, the reference voltage is not required, and the second signal is connected to pin M. Reference Voltage. — The external reference voltage is required on pin M when the input is a single signal. This reference must be exactly equal in magnitude to the desired signal trip point and of opposite polarity. The source impedance should be 500 ohms or less. In applica- tions where the trip point is to be changed occasionally, the reference may be derived from a 500-ohm precision potentiometer connected to a 10-v supply. A potentiometer with 0.1% linearity will be sufficiently ac- curate to allow direct reading of the potentiometer dial as the trip voltage. Such a potentiometer is shown on the circuit diagram as Ré4. In applications where infrequent or no changes in trip point are anticipated, the reference should be derived from a 10-v supply and a fixed voltage divider with a total series resistance of approximately 500 ohms. It should be noted that, within the accuracy specifications of the trip comparator, the trip point is directly equal in magnitude to the reference voltage, and any drift or inaccuracy of the reference will re- sult in equal error of the trip point. The accuracy specifications do not apply in the range —1 to O to +1 v, and adjusting the reference to a trip point in this range should be avoided. Signal Polarity and Direction. — Since the comparator is designed for general-purpose use, it is capable of providing a trip signal for any of the following conditions: l. positive input signal increasing to a value greater than arbitrary pdsitive reference value; 2. positive input signal decreasing to a value less than arbitrary positive reference value; 3. negative input signal decreasing, becoming more negative than arbitrary negative reference value; 4. negative input signal increasing, becoming more positive than arbitrary negative reference value; 5. when input signal "A" is greater (more positive) than input signal "B," both "A" and "B" positive; 6. when input signal "A" is less (more negative) than input signal "B," both "A" and "B" negative. Different external connections are required for different types of input signals to achieve proper output sense. These connections are shown in the table on the circuit diagram (Fig. 2.5.16). The column headings refer to the nature of the signal; for example, the second column is headed "Pos. Signal, High Trip." This means that the input signal may range from O to +10 v, and trip will occur when the signal is greater in magnitude than the reference. The fifth column is headed "Neg. Signal, Low Trip," which means that the signal range is O to =10 v and that trip occurs when the signal is smaller in magnitude than the 203 reference. The column entries under the selected heading show the volt- age or destination for the pin or terminal in the same row of column 1 on the left. ' The preceding discussion of the second column, lsbeled "Pos. Signal, High Trip," is continued. The first row shows pin T as the signal in- put. Pin M connects to terminal 1, which is the wiper of the reference potentiometer. Pin M could go instead to the pickoff tap of a fixed divider if a fixed trip point is desired. Pin L connects to +10 v to provide the proper test voltage. Pin A is Jjumpered to pin K to provide proper drive to Q8. Pin J is Jjumpered to pin Z to provide proper drive to Q9 and is also the correct logic level output for driving externsal circuits. Iatching. — Latching instructions are not shown in the table in Fig. 2.5.16, but they are shown at the appropriate connector pins on the circuit disgram. With no latching, K1, K2, and the logic level outputs will all indicate the immediate state of the comparestor. Connecting pin d to battery ground causes only Kl to latch, that is, to remain in the trip state after a trip signal has cleared until the reset button is pressed. If it is desired to also latch the logic level ocutputs in the same manner, it is necessary to jumper pin b to pin B and connect an appropri- ate voltage to pin F, as shown in the table. In this condition all out- puts, Ki, K2, and both logic levels will latch and remain in the trip state after a trip-level signal occurs. Precautions Relay Contacts. — The contacts of the relays used in the fast-trip comparator circuit are rated for resistive loads only. If inductive loads are necessary, appropriate contact-arc suppression techniques should be employed. _ Transistors. — Some of the transistors used in the circuit un- avoidably have small reverse base-emitter voltage ratings. Most ordinary laboratory-type ohmmeters, such as the Triplett 630 or the Simpson 260, have sufficiently high voltage on some resistance scales to permanently damage these transistors. The common practice of using an ohmmeter to check transistors when trouble-shooting should be avoided in this unit. Trip Point near Zero Volts. — The trip-point accuracy specifications do not apply at trip voltages near zero. Owing to possible inaccuracy, trip points between —1 and +1 v should be avoided. 2.5.8 Coincidence Matrix Monitor, ORNL Model Q-26241% 2.5.8.1 Description The coincidence matrix monitor is designed to monitor and indicate on front-panel meters the current through each leg and the total current in a two-out-of-three relasy matrix. 1lmgken from Instruction Manual, written by E. N. Fray, Instru- mentation and Controls Division, July 23, 1965. 204 Construction The coincidence matrix monitor is constructed in a module 5.66 in. wide, 4.72 in. high, and 11.9 in. deep. It is a standard "four-unit” plug~-in module of the ORNL modular reactor instrumentation series depicted on drawings Q-2600-1 to Q-2600-5. Application The coincidence matrix monitor is intended to monitor and to regu- late the current supplied to a safety-rod scram clutch, or magnet, in a nuclear reactor. Figure 2.5.17 is a diagram of g typical application, where relay contacts A, B, and C come from separate safety channels. Appliceble Drawings The following list gives the drawing numbers (ORNL Instrument De- partment drawing numbers) and subtitles for the coincidence matrix monitor. Q-2625-1 Circuit Q=2624-2 Details Q~2624~-3 Metalphoto Panel Q-2624-5 Assembly Q-2624-6 Parts list 2.5.8.2 Theory of Operation As indicated in Fig. 2.5.17, the total current delivered to the clutch is adjusted by resistor Rl. If all the relay contacts are closed, and since resistors R2, R3, and R4 are equal, the current will divide equally in the three legs of the matrix. The total current goes through the clutch and returns to ground through the "clutch current" meter. The maximum voltage that can be applied to the clutch is limited by Zener diode D1 to +30 v. An external meter may be connected between pins 10 and 14. If a single channel trips, two legs of the matrix are opened and all the current flows through the remaining leg. Therefore, the tripping of either of the two remaining channels causes the third leg to open, which interrupts the clutch current. With two legs open, the resistance of the matrix is increased by & factor of 3; thus resistors R2, R3, and R4 must be small enough so that the current delivered to the clutch is not decreased to less than a reliable holding current. To ensure that the clutch coil can be deenergized, the monitor must be able to detect leakage paths around the relay contacts. If the leakage resistance is small enough, sufficient current can be supplied to keep the clutch energized with the contacts open. For example, suppose channel A has been tripped. However, one contact, instead of completely opening, can now be represented by resistance Rx. The minimum resistance value of interest can he found by the equation . E ‘em T R, +R_+R_’ ¢ X 205 minimum cluteh holding current, juy td i 1l clutch resistance, E = maximum supply voltage. The clutch current will divide between the branches B-C and A-B, where the current through A-B is given by the equation i=1 —2_ X “emRy +R_° X The requirement is that the current ix be easily detected on the meter A-Bo 2.5.8,3 Operating Instructions Installation The coincidence matrix monitor is a module in the ORNL modular re- actor instrumentation series. Iike the other modules of this series, it has standard connectors and dimensions and has a pin-and-hole code on the rear plate so that the module will not be inserted in a wrong lo- cation in a drawer. The module is installed by placing it in its proper location, inserting the module firmly, and tightening the thumb- screw. The module may be plugged in with the power on without damage. Operating Controls Current Adjustment. — A recessed screwdriver adjustment, labeled "Clutch Current Adjust," is located on the front panel. The proper operating clutch-coil current determines this adjustment. Panel Meters. — The panel meters are calibrated to indicate from O to 250 ma. These meters are in series with the clutch and indicate coil current directly. TO CHANNELS ] =% NB“ AND llcll la—- — La— RELAY MATRIX 3 INDEPENDENT SIGNALS FROM FUEL PUMP CURRENT SENSORS "TEST" {MANUAL) SIGNAL FROM REACTOR OUTLET TEMPERATURE INSTRUMENTATION PRODUCES RELAY MATRIX PROVIDES SWITCHING SIGNAL WHICH REDUCES FLUX AMP. GAIN TEST MOQULE Q-2634 PRODUCES TRIP SIGNAL WHEN: {. CHAMBER LOSES VOLTAGE TRIP WHEN REACTOR OUTLET TEMPERATURE EXCEEDS 1300°F 1 FOXBORO TYPE 63 CURRENT ACTUATED SWITCH CONTROL ROD “REVERSE" ON SCRAM CLUTCH CURRENT METER ORNL-DWG 66-5123R CONTROL "8"—e= COINCIDENCE FROM RELAY SAFETY ELEMENTS IN CHANNELS llBll AND Ilcll SEE NOTE 2 2. CIRCUIT CONTINUITY LOST I~ \ T 3. TEST" {MANUAL) PROVIDES . . l—| CURRENT TO FLUX AMPLIFIER ELAY | FEEDBACK TO SIMULATE HIGH FLUX *1 SAFETY GAIN ADJUST) | T ELEMENT NEUTRON | | wn SENSITIVE ION | A CHAMBER { TEST | q-2623 _’ — | PERIOD | ¢ FAST TRIP {— AMPLIFIER COMPARATOR RESET — Q-2635 __l i Q-2609 — | - | \Pnoouces SCRAM TRIP SIGNAL IF: | | 1. REACTOR FLUX, ¢, EXCEEDS 1.3 MW . CHAMBER HIGH | Yy AND FUEL SALT PUMP CURRENT . VOLTAGE POWER EXCEEDS 3% amp OR IF | SUPPLY | L _| 2. REACTOR FLUX EXCEEDS 14.3 MW AND FUEL SALT PUMP CURRENT LESS T T T T T T T e e — T | FAST TRIP THAN 35 amp € COMPARATOR Q-2609 PRODUCES SCRAM TRIP SIGNAL SAFETY CHANNEL "A", FLUX INPUT $ IF REACTOR PERIOD € +1.0 sec { TYPICAL, ONE OF THREE ) FAST TRIP u " COMPARATOR CONTROL ROD "REVERSE Q-2609 {GROUP INSERTION OF ALL RODS) NOTES: 4. Q-NOS. REFER TO ORNL INSTRUMENT AND CONTROL DIVISION DWG NOS, PRODUCES TRIP SIGNAL 2.ROD SCRAM REQUIRES THAT THE COINCIDENCE :zFxgEE:gsTogoFlian( MATRIX MONITOR RECEIVE AT LEAST TWO (2) . TRIP SIGNALS FROM ANY TWO OF THE THREE SEPARATE INPUT CHANNELS "a" "B" AND "C" $ PRODUCES TRIP SIGNAL IF REACTOR FLUX 3.REFER TO OWG RC-i3-9-53, ORNL INSTRUMENT EXCEEDS { MW AND CONTROL DIV, FOR DETAILS, ALL 3 CHANNELS FAST TRIP Fig. 2.5.1. ] COMPARATOR [—————= "SAG" BYPASS Q-2609 MSRE Safety System for Control Rods. C IIBH MATRIX MONITOR Q-2624 Wl Wm 8 C'—e1"a"AND "B IIBIIAND Ilcll ;‘ “c AND"A"Q) ROD CLUTCH ~CHANNEL MONITORS (METERS) ZERO READINGS ON ANY 2 METERS INDICATE THAT A SCRAM TRIP ORIGINATED IN THE INPUT CHANNEL COMMON TO BOTH METERS Block diagram of typical channel. 50C 292 A r N i P L CURRENT TRANSFORMERS, > 3 o’ ou t PH 2 FUEL SALT ‘E? PUMP MOTOR i | ER 3 BT 2 Ut 1 KA 292 K | ke 292 B 292 KE 292 293 3¢, 440V PHASE CURRENTS: {. FULL LOAD~-5C amp 2. NO LOAD-20 emp 3. ONE PHASE OPEN, NO LOAD-35amp CURRENT RELAYS SET TO TRiP AT 35amp KD 292 KF 292 ‘ 293 294 " ' 295 294 295 TVA-DIESEL -BUS . { 293 294 295 ‘ ¥ B ’ . — S12t A J _ S122A J S123A J b—l : K293B >_| l K 2948 ._| K 2958 (SEAL) , {SEAL) {SEAL) TIME DELAY TIME DELAY TIME DELAY TO OPEN TO OPEN TO OPEN o |LaKaze24 —KB292A KC 292A - :[/KE 2024 . o KF292A :l:,,xo 2924 THESE RELAYS ORNL-DWG 66-9125R WHEN THIS CONTACT IS CLOSED AMPLIFIER SENSITIVITY IS REDUCED BY A FACTOR OF 1000. { REFER TO CKT 275 276 277) 1.3 MW) 200k AN 200 meg L # k2934, TIME DELAY TO OPEN T (K294 A, K295A) INPUT SIGNAL OUTPUT SIGNAL TO FROM PERIOD — F U aoar = FAST TRIP SAFETY MODULE COMPARATORS RM-NSC1-A1 NOS. IN PARENTHESES igm::ggg:‘x; TYPICAL FLUX AMPLIFIER SWITCHING DESIGNATE FLUX WHICH CHANGES TRIP LEVEL BY A AMPLIFIERS IN FACTOR OF 1000 (FROM 1.3 kW TO CHANNELS 2 AND 3 426 A r ~ — ? _L K292D _L ' | K294C_I_ K 294D K292¢ WHEN AT LEAST 2 OF THESE RELAYS ARE ENERGIZED THE FLUX LEVEL TRIP POINT 1S AT 150% FULL POWER ARE TIME - K293 K294 K295 DELAYED TO' - 11.3 MW) DE-ENERGIZE ¢ 275, 293 276,294 277,295 426, 426 426,426 426,426 Fig., 2.5.2. K293C K 293D A FLUX SCRAM SETPOINT INDICATORS (LOCATED ON CONSOLE) MSRE Flux Level Scram Trip Point Switching. 0T CHANNEL NO.{ CURRENT IN PHASE NO.1{ TO FUEL SALT PUMP MOTOR ; RELAY KD 292 ENERGIZED WHEN RELAY KA 292 ENERGIZED WHEN CHANNEL NC.2 CURRENT IN PHASE NO.2 TO FUEL SALT PUMP MOTOR 1 l RELAY KB 292 ENERGIZED WHEN RELAY KE 292 ENERGIZED WHEN CHANNEL NO. 3 CURRENT IN PHASE NO. 3 TO FUEL SALT PUMP MOTOR 1 l ORNL-DWG 66~9124R PRIMARY INPUTS RELAY KC 292 ENERGIZED WHEN RELAY KF 292 ENERGIZED WHEN CURRENT GREATER| |CURRENT GREATER CURRENT GREATER CURRENT GREATER CURRENT GREATER CURRENT GREATER THAN 35amp THAN 35 amp THAN 35 omp THAN 35 amp To THAN 35amp THAN 35 amp I l____ __________ J { CHANNEL[ o _ 3 ] I e e e — e NO.2 ¥ e o e e e e e e e - ~|/‘ i conTacT | * | MANUAL MANUAL I MATRIX MANUAL | REQUEST REQUEST REQUEST SwiTCH |~ = = SEAL l CHANNEL CHANNEL swiTch |~ SEAL| | swiron |F——-= seac | | 5924 NO. 3 CONTACT NO. 4 5422 | S 123 I | MATRIX CONTACT I | MATRIX | ‘ | | | | CHANNEL NO.t ] CHANNEL NO.2 ] CHANNEL NO.3 ! RELAY KA 292 |— — — — — RELAY K292 |— ——= — — — RELAY KF 292 | —— — — — CONTACT CONTACT CONTACT CH:RP?IGAEL TANN c FEOME -~ =~ CHANNEL r~CHANNEL NO.2 ¥ nNoz I Y nNO CHANNEL NO.2 CHANNEL NO.3 CHANNEL NO.1 RELAY KE 292 RELAY K 292 RELAY KD 292 CONTACT CONTACT CONTACT . i RELAY WHEN ANY TWO OF THESE RELAY RELAY K 203 THREE RELAYS ARE ENERGIZED, K294 DIRECT ELECTRICAL K 285 I ROD SCRAM SETPOINT IS AT * CONNECTION * | REACTOR POWER (FLUX) = 11.2 MW | | | } ————— INDIRECT CONNECTION I ' ‘ {SWITCH OR RELAY CONTACT) I SENSITIVITY SENSITIVITY SENSITIVITY CONTROL CONTROL CONTROL FLUX AMP NO.t FLUX AMP NO.2 FLUX AMP NO.3 (CONTACT IN {CONTACT IN (CONTACT IN RELAY 293) RELAY 294) RELAY 295) Figo 2-5-3- CONTACT MATRICES PROVIDING INPUT CHANNEL REDUNDANCY TC ACTUATE QUTPUT QUTPUT Flow Diagram of Switching Signals that Change Reactor Power Set Point for Rod Scram. 80¢ " N/ MEASURING 2 o 09 ORNL-DWG 64-626A CURRENT ACTUATED SWITCHES INPUT III ) (¥ +THERMOCOUPLE TE-100-AI TE-100-A2 CHANNEL NO.2 TE-100-A3 CHANNEL NO.3 SPARE LINE NO. 100 TEST ASSEMBLY: . CONTROL ROD o. ELECTRICAL O ALARM REVERSE _ HEATER ( REFER TO 0 T_ b. TEST THERMO- SECTION I-5) DATA , COUPLE LOGGER (SEE NOTE {.) ' - — | = | R EH] (5] FOXBOR - | . oot Box TS0 SWITCH , FOXBORO | | Ts-100-a1 [ TSS-100 | EMF 1'0 o TYPE 63 o (r 1 ISOLATION | CURRENT AMPLIFIER - - —1- CONVERTER 100 Lo o -0 o 400 0 -0 o o : 3 : 10-50 ma 10 TO 50 mo METER SAME AS ABOVE NOTE: ~~————REACTOR OUTLET PIPE 1. POLARITY SHOWN FOR TEST THERMOCQUPLE IS THAT USED TO TEST SYSTEM RESPONSE TO A TEMPERATURE INCREASE Fig. 2.5.4. Diagram of Instruments Used to Measure Temperature in a Typical Safety System Input Channel. OUTPUT CONTACTS AND RELAYS FROM ONE CHANNEL OF SAFETY SYSTEM ( TYPICAL OF ALL THREE CHANNELS, CHANNEL"A" SHOWN) +32vDC ¢} RELAY CONTACT, PART OF Q-2609 FAST TRIP COMPARATOR RELAY CONTACT, PART OF Q-2601 MONITOR AND TEST UNIT RELAY CONTACT, PART OF Q-2609 FAST TRIP COMPARATOR TEST RESET P——I OPENS WHEN REACTOR OUTLET TEMPERATURE EXCEEDS 1300° F OPENS WHEN FLUX EXCEEDS IS MW{OR11.2 kW IF FUEL SALT PUMP CURRENT 15 LESS THAN 35 0mp) OPENS IF ION CHAMBER LOSES VOLTAGE, OR IF INPUT SYSTEM CIRCUIT CONTINUITY iS5 LOST OPENS IF REACTOR PERIOD IS 1.0sec OR LESS r +32 Vv OC 15-v AC 2—1——e 7 MANUAL SCRAM SWITCH CONTACTS QRNL-0WG 66-1002{R ROD DRIVE CLUTCH CONTROL CIRCUIT, ( TYPICAL OF ALL THREE DRIVES) LUTCH CURRENT ADJUST. @ 2624 COINCIDENCE MATRIX MONITOR (TYPICAL 1 OF 3) T0 SIMILAR CIRCULTS, OTHER RODS RELAY SAFETY ELEMENT Q-2623 TYPICAL (1 0F 3) Kad-1 "POWER" Ka4 27k "HOLD" LAMP; “ON" DURING NORMAL OPERATION "TRIP" LAMP: Kyt Kp2 Ka3 Ky4 KpS WITH ALL "ON" WHEN i RELAYS CHANNEL | ENERGIZED HAS BEEN TRIPPED 1 ) 1 J fom 14 { \ +0-v BATT -7 Q-2624 COINCIDENCE MATRIX MONITOR (TYPICAL 1 OF RELAYS K,1 TO K,5 {INCL) ENERGIZED DURING NORMAL OPERATION Fig. 2.5.5‘ NOTES: 1.Q-NUMBERS REFER TO ORNL INSTRUMENT AND CONTROL DIVISION DWG, NOS, 2. ALL RELAY CONTACTS AND SWITCHES SHOWN 3) ZENER DIOCE 32V CONTACTS IN RELAY SAFETY ELEMENTS, Q-2623, IN ! CHANNELS '| A,BANDC B AND C CHANNEL MONITORING METERS _,— ROD DRIVE CLUTCH, X _CEUTCH PART OF ROD DRIWVE, COIL-130 ohms DE-ENERGIZE TO DC RESISTANC SCRAM CLUTCH CURRENT METER VOLTAGE SIGNAL ~ CLUTCH CURRENT TO CONSOLE |METEF! EXCEPT AS NOTED, CIRCUIT ELEMENTS SHOWN ABOVE COMPRISE A TYPICAL COINCIDENCE MATRIX MONITOR, Q-2624. WITH SYSTEM ENERGIZED AND OPERATING NORMALLY. 3. THIS RELAY {K44) PROVIOES ONE OF THE “REVERSE" ON SCRAM CONTACTS; TYPICALLY CONTACT NO. RSS-NSC1-A4 iN CIRCUIT NO. 248 ON DWG D-HH-B 57327. Diagram of Safety System Rod Scram Circuits. 01¢ 77 o e st e bl st +32vDC 211 ORNL-DWGS 66~10020R 1 248 249 250 ¥ { —L SAFETY SYSTEM T~ | RELAY CONTACTS IN | FAST TRIP COMPARATORS : [ T oraet cnmersn | 1 1 SWITCHES ELEMENTS, TS, - - CHANNELS A,B CONTACTS TEST AND C. - - | £4-3 AND K4-4 POWER TRIP IN RELAY RESET TO SEAL CONTACT, Efgngu RELAY K4 = = CHANNEL "A" ' 248{ (TYPICAL) . TK 249 TKZSO Tk ? 3000 SEAL CONTACT : ' Ka-1L ACROSS RESET K5-1 . 48V DC MBVAC(TVA) {15V AC{TVA-DIESEL) —E_-. \ —E...— \ _E_. \ L PUSHBUTTON _T__. ¥ ’ ¥ ’ " T ' ) K2 K5 2 2 2 0 2 K3 - 2 K4 2 cowc:otnce ' COINCIDENCE COINCIDENCE MATRIX MONITOR MATRIX MONITOR MATRIX MONITOR K4-4 THESE CONTACTS KS5-4 " T CONTACTS RGD DRIVE NO! ROD DRIVE NO. 2 ROD DRIVE NO.3 OPERATE RELAY K5-1 IN Q-2623 o - K4-3 AND LAMP IN K5-3 RELAY SAFETY T . T T_. CKT NO.248 T v 1) "HOLD" ELEMENTS ZENERT DICDE - RELAY SAFETY ELEMENT (TYPICAL) Ka125 KB125 Ke12s ORNL MODEL Q-2623 ; ' . { L i ¥ 1 ¥ 1 T ¥ CHANNEL CHANNEL CHANNEL . A B . c . . 48V DC c 7 o T ¥ 1 1 1 L KAI25A 4 KB1254 "]_KCIZSA -L KA1250 L KB125D L KC1250 SAFETY TRIPS SAFETY TRIPS SAFETY TRIPS I I I I I I i FLUX, PERIOD FLUX, PERIOD FLUX, PERIOD KB125C " KC125C KA125C KB125B T KC125B KA125E AND AND | :| |______——_| ( TEMPERATURE TEMPERATURE TEMPERATURE 0-2623 [ 0-2623 . e Q-2623 TO Q-2624 RELAY SAFETY [—* |RELAY SAFETY ™™ |RELAY SAFETY}|—>} COINCIDENCE MATRIX < < ELEMENT [ ELEMENT [*J) | ELEMENT *] MONITORS, ROD DRIVES KA1248 KB1248B ‘ : NOS. 1,2, AND 3 RELAY RELAY RELAY 1 KA 125 KB 125 KC 125 KA124 KB124 RELAY RELAY RELAY ¢ ; K248 K 249 K 250 ; A~ : 3 > ¢ 1.' '.2 ¢ ! “7 4!8 1!9 ¢ { X 7 l l - 4av DC l l ’ > ) 3 ; L . [ 4 ’ i 4 l ’ b P r\ | I | I OTHER 2 TWO-OUT-OF THREE TWO -OUT~OF - THREE TWO-0UT-OF -THREE EONTACTS CONTACT MATRIX CONTACT MATRIX CONTACT MATRIX KAI24E KB124C KA124 A KA124C KA124D {CIRCUIT 186) {CIRCUIT 124) { CIRCUIT 124) I I 3 1_ ‘41" _J(' KB 124 A KA {24 F OTHER RELAY RELAT | | | CONTACTS KA124 KB 124 . " X [ i [ i ’ { | | | | 5} i PLOT LOAD VNE\:‘%'D HCV HCV CRAM 7 A 7 77 A2 VALVES s Kafl KB1| KA{2 KBi2 {7 PICAL) 5 342 575 A2 s L i Figl 2.5.6. v LCAD SCRAM WHEN EITHER KA11 OR KA 12 DE-ENERGIZED MSRE Nuclear Safety System Circuit Details. L J et —Lflwavmw F DRAIN TANK VENT VALVES, 575-Al AND 577-At OPEN WHEN THESE SOLENCIDS DE-ENERGIZED HCV'S 573-A1 : i i i. 212 — e — e e e e cwe BRVOGA— : ”e o 9 wosi vowr e —efotl | pwrome DRAWER S$-2A Fa | S pmen] e || 4w e 7 RAHICEAS & | o a"z""’" S | [ Ry ‘ cas-pos cv-s-sop < hagtintees AN I wrwscras] {owseran] amincras I — — — — — :95; — T T T T R T T YRS T wx !—‘ I Fe —I b S — l m I : . l 2 l cova Yot b — e VWA BN SSI-AT - 49-u3¢-AL RIS-MBC-M r | L Add 7RI o, CL/ TN BLAWER S-1A4 ; S npoa wir, SO0 iy 1 11 d}m' A3 RI8-daqe » I g _(hd.o.o' S L s ot Sl RANSBCN AL ¥ v “w M y 961812 ~TA -t e R RO < $ I.”.l le KIC. Ao, & Woloxe, sad x::.:r-.d e l B WLEL-AY 1%0% ; >110 % > 10 Te ifi“ FRRImT) o : I . 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WME dia] [ (MY 4V o0 el l - oo Car-t 808 Cug-ual J 8 Far Leds Aon. & & 3, connections ave iS4 “2.";’ w""'a' “: r m——-—u—_p— - - :——au—-—nfln—n-—_— 4~l— o, sa— -__“ T c “m/m‘ s nsct-hd ' ‘ : — ' = J— a,;_! £00 ssag —l ey _ | ) £00 il | €00 AR2Z]Cod No.3 ! “a VWV : ¢ EM-NSC-AT RYTUBCEAY ase-uske-At R3%-used-Al ‘d’ Cn-3-006 A\ CAr3 2054 | CHT-20¥4 LRAWER S-18 Wf‘z f‘l ems-aul e by, I wor 1 T d"’ wov oy I -2V s S DOED |cirS-2088 | cvr 32048 R NBHC2-AL 1 o sy, | a3 L0EC | cmstosc | cirsdove ( ATC, Mo L KLC Aot Q279 -————‘Wp—l f“é-l' —I p, fi L”]‘ I'“'l ELIE |sn"arm. v:::m Cah-F-308 | Cang-Sod | CinS-S08 Re yexion zoox gt | L F o83 0A pe 2¢13-9-1 RC/9- 9134 VAN AT SAFRTY 'Av.'__'."_ |5 Sty > 10% s Parmer) > To Comtrol Circur? I /3+43-41A covys B I T e L ; l % & WRT-A :t:.:‘- © ami e N o5, C-§-s08 I [E i oV e 2;5:‘3;‘ E "a PLeRbuset-pa e l Az o2 ce e e ey BRF4A =T ——— 1 . I I I | Fr.mee.0 RC/3-13-7A € ML s FLUX ANPLIPR il e Sk o5 Keid id /A PATH LOFSEA Ti-veRE-A —— s, s | s it | e e | e s | e (Rw-vaa s a) 1| 1] |—- ) £49 oIV gon 1 MEAY SA7ETY 2LEMENT (8) e, yasr ol p | 750 a » l i 32 voe { :E"’ #0}": 3 ) R—‘: ifi:—b: 4 4 ‘ &‘J,.:;‘c‘;‘:};w ; R — P ' . ’ e -1%6% >120 % >0 % ‘gm PamMT) " " Drower S-i O/ 3-9 56 CL3-/3-1iA ! I ) Zea- o w e " >3 o oY v/ % J } £ WeRB-A :‘s::i ST & gvol L Mtl—fl“‘ . ) " » ~ Sl -9 -384 4 4 SUsrLy | s as re08k - REFERENCE DRAWINGS DWaL NeL b L RCIS-9-7A CALE%%‘ET]QN 1 B s " | o sxzemnemantt EMNFRAY e — ——— — — i— — — —— Lmst & _[CHNGD, REF. DWG. Wo3. 700N @'s To RC 's. Vo667 igey) —T— = CREENT TEST ofi'm'é‘ AT aH '?‘u...... ! 113 5 MS.RE. 3 VAboen noTE S AT ", NIEN _ VOLTALE AN LUK AMPLITIER i\ ) | « (it Sley £ Goochs In Aoy Sy Somants :-':;'fl} t Oara’ cosean : wi l ad SAFETY SYSTEM Canascrery £ Mg o aotrel (m-nsc i) . 3 lappED PERiC LABZAT 885 k32 CIrRCUIT DIAGRAM ABDLY PARISD BARATY 4 SCRAW Sl N &) ? [ v T L6 | Zo | wores: A Sy | TR i SovTLE SR L 1ADDES NOTE S L eslenr Lo L Reiay circuit i3 completed when fuel st pump motor 3 currents are gredier mg’IDGE‘NAflONAL LABORATORY NQ. REVISIONS DATE APPD thon 35 amps. This reduces fiux amplifier gain = thus increasing scrém eI W‘ OV 8ot G / v e T - ] point by three decades, 3ee control stir. ® N1, 29% ¢ M4 on dwy. DN 8- 57395 . tery UNON mw"’“m"' COMPANY JCE Wawoowsn |250-6¢ |/ e ), H hnp frip open uM'll reactior esutlet Pemperature » rvoo k. - — ko —— e ':}w — - ; ? f:: oot :“."“" . L, 2,3 14,‘00 dage. O-H¥-B- n;::fl:fz’sn. /7’7;& /s Growsy m—q e ed % n_r‘ 3 » | ; A Arc sugoressing diodes md indjice mp dcross relay coils oWy 1) rawa, Conmaclor Y | | e | ] | é ot R s o et 'RC [/ 3-9-57 26 o A B 4 Fig. 2.5,7. Safety | ystem Circuit Diagram. Yo -in.-OD STAINLESS STEEL SHEATH Al,0q - | INSULATED COAXIAL e CABLES, 4 EACH-2 SIGNAL, 2 HIGH VOLTAGE 213 ORNL~-DWG 67-1104 THREADED RECEPTACLE FOR PUSH ROD ATTACHMENT, MAT'L ; HIGH PURITY Ni MHYV CONNECTORS HIGH PURITY Ni QUTER SIGNAL ~CABLE JACKS, 2 EACH CAN HIGH VOLTAGE-CABLE PLUGS, 2 EACH ] —— 1 LSENSITIVE __I LENGTH 4Y4 45 ft - 64 in. Fig. 2.5.8. MSRE Safety Chamber. 300 | ORNL-DWG 67-1103 250 | l l | I T T I 1 T /r 1.4x10'0 aV +~107 r/hr (GAMMA) 200 ‘ 150 (- / 100 SIGNAL CURRENT (pA) ~5x10? nV +~10% r/hr (GAMMA) 50./ / | o 50 Fig. 2.5.9. 100 150 200 250 300 350 400 450 500 POSITIVE VOLTS Saturation Curves — MSRE Safety Chamber. o ot i ek L, s e e 214 £33 7K s AN Poytin =&Y ol *¥7K - VA~ # ASY »VC%-'J" a1 4 fl/ov Of o 5 > LA Efi? 0003 S0 o K ..——.—-——1*—-—-———1 26 S J 2000 2 < ey wac g AMP 20/597-3 .y ) \ | . ¢ T TP3 H ARervoel 2 &ra. Koirchid 18 pse 3 SO0002 ' e {5 ' LO00uA Ul e e — e T\ 4 AERIOD 7 - V4 20 1o ¥/ pc !; Qs N3 paEV [ 3 < e | Log Current r ? E: Aersod [ .'u LIy [ I8V : S o Priafed Circuit Sowrd fe (T - =I5V 7 ® ;7 Choasie & Shiske Grownd . 70 xwre insirymeewd, batweerr TP annd TPL, messurs between 7y TRAE with Triplel? metar fa‘ oyval)y : gl *Bal 1 ”wn?i/ veltege /o xere. MW Hreom . ; 7PL and TR y TPZ and , easwre wiiige ! ram 705 to TPS, Adjust ‘hla'mfil'm- /s mero. Eameve . J’:wn’f. mh-zddmmrm: bt hm%mf i ! duw axgjussting ~ un n? pane! paried meler . indicates * ' » % e 7 -5 FOR INFORMATION OMLY i . - .y DO m UGI FOR | e . . WAINTENANCE OR l °2 COMSTRUCTION i DETAILS 2655-T i 42603 ADO-3 METAL PHOTO PANEL PRWNTED CIREU\Y BOARD l ASSEMBLN | PARTS \ REPERENCE DRMRINGS | owa wa. E Nore et £ N FRAY j ’ A resistors | Y Fgengiied corben excesy a¢ wolos! MODULAR BEACTOR TMSTRUMEN HTION PERIOD SAFETY - cirCcuIT f ~ Xy I ] 1 Pl ‘ SRR AN GRNNELE " REVSIONS DATE APTO , o ] ff .S wmmfi Cosammas T Wl — 1 e o ORI [ o iE - - a— [ S— - ! L34 | O |RUS =18 -11A - e EmFadr oaef ; DATE |QREV m APPD. BY | — _m—y - |= _—- , 1AS ISSUED FROM G- 2038 =/ L] 35/ eo ! Fig. 2.5.10. Period Safety Circuit. 2 DA ST/ s n o PERCENT POWER 7 P § ‘ TEIANWGE Shielded 38 "5V | %0 v ! L8 50 e 200k - O (Front Fonel) I 9 R P Imp. E0/597-3 2AI3) 200K _ __vey eta I —AA—={ :)—h 2 Swre Py ANME . - AAAA——— — " Spne/ trpu# A R2 28Oue Zero contered ¥ ZERO . ‘ | 1500 (lasidha F7ant fonal) C2ANE Shret. e//o Covovd Y Y | @J o | b FLUX AMP ' | INR's | wFERO " 4D Kow | ™ | 1 ne | f‘_’_z_i_ng Skl vg +25V | 1 e Sea Mote 5 L E5B asey % | I T '6023-4 7nt £40 “Vicloroen l | SOMeg B ' >, Flox l Gee Mote 2) BRI ; R nism e Sz B oo : S| Pusw 70 “zERO" g ' | Sr2ams Siotked| This connection used when ¥ is z(—L— - ' ‘ "“"‘% >/ red 1o frip 9 externsl circuiF | (See Mare 3) cé ] when Fhe module /s removed . C ZE0mF, 1OV 31 7oy . s OF thre D13, IN325S) | 4 l Grey) o ro0 £, | . 77 —d K -f;;':vgc: a8& l . r—=- r ISV : o 27 AOTES - =z ' ! ‘ . I AN resistors erc Y2 watt, ) Ve deposited corban o3 & ezs!; 1@ | £23 o k2e £28 o s unless. otherwise specified. ‘ NZBIEO P00 < Q0 Qi 2rooo g/ro00 . sé"va ‘; AN 2V 2NMHEI ‘ & The finel volve of the Ffeedback resisfors will be ' ! selected for the desired curren? range of the | i 7 4 ) - l 4;{3 2 a9 i 22015, 10V A | 3. Circuit board Las provision for externel selection 0K & anit07 ! Q13 r=—=n ) 4 of & diFferent feedback rasisfor for large. chenges ' . alals ,J c3 ¢ i wrsor | ' I i1 renge or sccess fo Hie summing jonction. 2413 < = = ' —@ ) . | l ] 2z "_(oaoo ;} < 4;3_&:’;-# E l 1 .0, | o, AFVer the exferns! wires ore sollered fo the ) sr6.8v ) = ae e d - 4 tronsformer ligs, & bead oF solder should ba ' l o¢ ;EEC r = tormed on Ihe end of the lws Ao asaurs good S R/8 3 % oz S 825 cs | w29y UP2-7015. connection fo fhe internal wiras. ‘ 23000 IN752A408 L 2400 g2/60 lnd = 50003 r . < I S6V eo. % asv | T ! [ 7P3 &, Grovrd bus of Flux Amplifier prinfed erircwif boerd i 227 Cer. : aoreE | 7/ (White J 73 saperors From the primary side of fha H.V. | w"ww eu1sot = Trind TY-88 supply wnd Is connacted exfernally Wrough pm S and 2ov Bl 15€ 3‘;\'_‘; . i (Sea tote 4) he shields of pins 1,7 £ /3. . AMETER FACE . -19-26'02"7 i ARTS L£/57 PEE5028) o ASSEMBLY : @-2EOS] LRINTED CXT. BCARD. PTEOL o APETALPHOTO RPANEL @-2602-3 - LDETALLS P-2502-2 bend up ' o REFERENCE DRAWINGS | DWG. NO. . cfcese) : " Goain S LN S5 alh E( o £ vl A ogoa-7 OrF ] [ . 4. ANDERSON Grre @ .g @ |58-6S| R& N miral rpcLedR JiA - . . 2 L : $-145 | R4 |ReB=-9 -7A- fl* TiA MODULAR REAC’UE /MS‘IRUMEMHT/OIV S _Ioale &8 chd R2.RT Add DIA BB |2.21c1| 714 Sesurce £ C C (case) : 4-4¢8 | REIRCH-TF-74 -0 | TLA < _Chel £70, tezed 727 smesd TU | - s fs et s T ra—| cHamMBER HIGH voLTaGE SUPPLY S e Bkt PR as QL Hhrw ot 12 o : Ler| Ry [Rensy oa Ry [ 7ea AND FLUX AMPLIFIER 2 |5, S e B T e T e (ro-se) (70-18) (vo-3) (ro-r0) | Tares| e Teoi-7 04 ek [ 77ea. | CIRCUIT Qels OF, Rav. #5485, CE WA EAMMICONDLUCTO ‘ >-214b | RE {RXH~F2A - R3 A - i Loltow notd &, A3 (isa 1) rovot TN vt m-Z6S| RI_(BCI3-9-TA-&) | Teh INSTRUMEIXATION 4D ol Ier3-LIVISION | owTE Jaero | wero | DT 7OM YV/iews .. it RERCI-T7ARE | Tid OAK RIDGE NATIONAL LABORATORY 723743] 5. A Rmmare | pav-es : *2301R0_IRe13- 9= 24] |7 4. UMON CARBIDE NUCLEAR COMPANY . Arreovee ar ) 7-23-¢3| RO | RCM:?A Tt A, Hewew [ T [P " e r_‘gm JRIV [ STFIA DRAWINLG MO, | AVPD. BY ' —_— v e ‘ | | | | | |t wumnon o 2cpz -1 [ |Q-2602-1 s Fig. 2.5.11. Chamber High-Voltage Supply and Flux Amplifier Circuit. i« k 216 ORNL-DWG &§7-6438 250 200 S~ T~ 150 ' \ OUTPUT VOLTAGE 100 v ) /,// L 0 10 20 30 40 50 LOAD CURRENT (ma) , Filg. 2.5.12. Output Voltage vs Load Current for Chamber High-Voltage Supply, Q-2602. ORNL-DWG 67-6437 Ag>10° TsionaL I,=0 —r INPUT o p—mom——0 OUTPUT —— Rin> 10'°0 I=1g6naL = A \N— R¢ Fig. 2.5.13, Amplifier Feedback Circuit. 217 ORNL-DWG 67-6436 FLUX AMPLIFIER Q-2602 F—————- _]l | FLUX I\ | | | RESET FLUX SIGNAL ° I/ | | ° OUTPUT | : : R6 | Re l : —— AN —7< | | / @, e v | 4 / | e l I | - /] | | HEAT | I R? | POWER 0———————#= : ‘ | [ |INSTRUMENT | SIGNAL ! SERVO 3-- | | P —— 1 = | | i___._._.__.._____.___.__l______’ | Q-2603 FLUX RESET | Fig. 2.5.14. Amplifier Gain-Adjusting Circuit. 218 P8 AP EO/5IT T - 12TV i L . r32y +22V 7 Al s : - v aq’gn'm:: ::..':": —, Sy ,.’:‘fii l ri ¥4 ;.«.A—n :.I:lm o ~8 :]:m P This comecrion vsex! wherr hd l i £ it is reguired to trip e G' @D L G axternw! cirevit whan | re I s Yeihar modv/e /s remo I Gpussmnns & /e i ser ‘,,5:’ oV I : e ‘ Q7 |fween) | (awe/ g€ Ao CrdE YT . Js7e L ‘ 2636 daw Cuocs rcx 2m “earen” | .'I"“ o1 as “aeIET " | Fres 225 24 g #.8.00d. s > > 2MEIF i . sodk SVA,L o ' s | | f:'-:' ' | wra. | | & ' ' ‘ :&m " Pl ; cw P —— T e e e e e T T T T T T I 5%« Vo A 2 2000 AW meeemeeed | & l | “-‘ . “;l =1 = | . z:ém [LA2A | eummasr, L T 1 | = P a8 v i 1L A by v Y = i i L B | ) [ ' | 26 | [ | 5 KéA P P | i |l wu i ‘ | l'—"‘—' /. All rasistors ara Ye W, /% depesited carbon, axcept 23 moted, v ~ 1 : ; : : : surrn] | I | 2 &.% " indicates freat pansl identitications. ) || L-—==—- J — - 500,000 Meg. . 8 K5 & K6 are Elgin VRS/2C/E7S0-24 and pick up on L-J L—d | i I 1 ' Hepe. KI & KE ara Clare CREM-1940 Reed lelags, I : K3 & kKo are Clare CRM-/913 Kaed Kelays. CHAMBER AND ARIPLIFTER ARECANSEMENT Jd | b — e e e e T | L < @Dmoh:h‘yfi.qwlflyyrwnd. l | W Dencbes 2OV battery ground. | o | | 5 0 s il r32Y : &7 - | “AIEN* i! /S, | ot RATE "y | vow= | N A I S& o8 | = ron Iteasarion, 53 ‘ NO I L | xs nmu:mg_e on —2 I\ CONSTRUCTIO | o 1 | CURRENT |/ Z8ze YWISH o | we rciietll) Qpmpmarrnce ' Se LV Abre e 4 <_-_J_ 7e L :' . NE RN EN.FRAY | Té%al L A% WMODULAR REACTOR INSTRUMENTAT SIE: we | SRE MOOULE K70 on M.S.RE. TEST i CURRENT . “9 ‘i facare 2% CIRCUIT ’ 6 7 1" ‘ 1 Tl 5570 106 CALIBRATE JWITCHE ) 5 l % L _ _— A — 4N e o TR 0GOS e - reamons ot w0 v 3 | \ YR 1 1QTHeit-d M prE | — OAK RIOGE NATION, LABORATORY — { i i 98/ L@‘-’,.‘_".‘Q‘.’.. LR . VOEON CARNDE CONe. EMmeosowin }I-12-68 - b _— . Chvasrs & Shinid . 348 o0 RQII-IT-s0A -RO - JiA o Sasr 345" ! . CBATTT N NPIATIIW S NG | ARD. BY ] [ i v SEPIAS 1SSUED FROM Q- 2634~/ Q-2634( »:¢ . | Fig. 2.5.15. MSRE Test Module Circuit. r | \ ! J - N R ——r—————— e - | i N ] 219 ; .‘ | li i : w7z T : AMP £O/359-3 fi. ‘% X} +/0v ) | | . | »(S5) sisv P 7 > L/2 ‘ /75 2/8 L2/ o 222 | £ SITE I oa"'flf oKk B FToe PN 3 pry ) 1508 £z AAA — | y, L0000 cnv‘. Zrimpot @ (7] PS l 4 f ; 4 “;."-T_ \a ——@ Vow22234 _2;"'@ 21279 | I , - @3 I Sok o1 2n2060 / | ~soe ‘T v INESPA . i » l ' oS | J S/ L2155 £/6 S 220 S £23 I .: FL7 4 -.faoa q: 2S5k 1; SFOx 1:25K | “TEIP TEST" | SL !S (Avwe! Becesred ) ' a | 26 ‘ ~ <00 J & . 2 £ D | 3 s VWA € € T ’ | (€} -wv Fr¥4 i | LoV Aers L ) { | >(N) M@ Ground I This connection: vied when (¥ ’é: 7# A5 required fo #rip s exherrs! I : 4 I cacan’? when Fhe module /s (e) : L} . removed. | . I l € ¢ == s i >(0) -32v ) eESET " mis79 Y £ I g L Sees 2275 s £28 (raar Aser) Spme SEMPICC | L2nf T :;gg'o::x S7L f $800 252 2294 v esm 2 e mrec dpgz | Z - »(Y) K2 Close on trip S . "m & - ‘e > | a7k $ ATew 7000 L5510 $¥7e |ni > (“V’j e Commen #3 P hos__ s sefer—oh d > e o0 rie | Shiakd £26 bfeos __Soe @9 T2 § 2300 , 5 SUIIZA| o TRIF | l 3300 Q8 o '!wgoazm v | ‘ X y, 02 Q7 fad | W w307 o 30208 ey sov 5332 234 _ 200457, -z2v | ’ I £ v, WV, b (2) Connecs (@xrernelly) Vo () € AAA | o &8 Fo fwrich elacrronc -~ -é\’.f 5 | { (¢) xs o I, ocsowr (Sea soYe &) SOR 20V Bert £302 ! L1 wes on rrp (onnrc!(exferna ) o . zwo‘r 2oV 8sers ¥ | (8) K/ Common pin b Fo % ; i (F) Kt Close on Frim Yronic o«#puf o I sca rore P < —— | (k) ‘@‘ ‘ 4 | () FOR INFORMATION OMLY Tod * o (4) DO NOT USE FOR ~¢ T MAINTENANCE OR G Mo Gd QS Meu Q9 ] Il CONSTRUCTION ) | ’ | ; W) 2oV Batt EXTERNAL JUMPERS AND CONMECTIONS FOR YARIOUS TRIP FUNCTIONS : NHOTES f;: 7564 ;-5'7' 29-6 A or |POS. SIGNAL \NEG. SIGNAL |POS. SIGNAL TNEG. SIGNAL |TWO SIGNALS | TWO .mmu‘ 20V oty | ASSEMBL 2-2¢09- 5] TERM NOAHIGH TRIP |Wi6K TRIP |LOW TRIP — [tow TRip ~ |70W A(e)> BL)| TRIP BC) > A aA fe-fl”-'f’ o fim.f” £/ % deposited carbon (emay) PRINTED €7, BO. @-2605-4 ~S/aWAL 3 oA '173»«. 1 excesl as e AMETALPHOTO PANEL 226035 A’ECT 7 & When pin b /8 comeched fo pin B for elecironic lafch, Mhe logic eas-2 M “remar 3 YERM, | TERM. L ZERLU. 1 ) ~Sie 8 -5i6 a outputs (pins A end ) will remain in tripped stote REFERENCE DRAWINGS oG, N0, i after & frip wnts/ the reset butfen is sctueted. L »oy -1ov -10v */0V +iov -rov e oy v L. ANDERSON 7 Pl & | A 7O P | SRS 75 i K | AR5 To P A | SR T8 P | A 5w s ~ow Rl Ao sstns OF T | e oo MODULAR REACTOR INSTRUMENTATION Term. 1 |G s D D } OINA | NN | AN AL | PN A LD CONN. | WO CoNM. [Fooge] 2 |G 3eo9-s | orz FAST TRIP COMPARATOR Torm, & -/0v - lov 4 s/0¥ NO Com, WO CONN. PMeS| 2 |WWTED Miied® | JiA CIRCLIT 3_[adt 05 Aweaviod O 1144 | 0% [ JAIPER TO | SRR T8 | JAMPER TO | JOMPTE 70 | JOMPER 70 | JORiPER T0 ;;-':-"I? 2 Teis-s-n1a &2 | 7i4 A7, Sow. £, O #B K s 499 N~ 20V 3 2 -4 % ¥ N _A e1-¢5] 2 laen-9-a-e2 104 / oI /- OF o, S, ot b4 ._n%IT Ty S . - ooy pri i K | pra oo ] A o 2t4eH] ! lecy-9-sa-R) | Tia INSTRUMENTATION AND COMTROLS DRVISION g |[ee A E| A in-oeeg| 1 [Rev-9-13a. @) | Tud OAK RIDGE NATIONAL LABORATORY . —a MO o POwieY A0V FESP| A0SR0 OV TEW LV MORY OF TRIP [0V MM W TN | 0-2-61] & [RC13-9-124-k0 | Ted oo = F I8V 14 -/5V r/8v »/ 5V ~/EV -— For MM Aodch only 23] O 8CY -9 -/3A Lo | Tia e . 6»0 é z; connected ":xkjmlly | DATE |QREV] A obehiTNO | W60 B = Jee no SPIAS ISSUED FAOM Q. 2609 - = [@-2609-1 s Fig. 2.5.16. Fast-Trip Comparator Circuit. ‘l ] 220 ORNL-DWG 66-11720 \-) +32 v Rl 500 Contacts in e -l ‘ -----2 Relay Safety I B _L C I. f 1_; o Elements in = . -, B_} S Channels A, B, L % and C < R2 R3 R4 N, 100 | | 100 100 330 ) \N 17 Meter /{ | - 0 - 250 na B A ) . ) . 11;{32 v R6 -= 8 k ~———— _ Console Meter Fig. 2.5.17. MSRE Coincidence Matrix Monitor. J e 221 2.6 SHIM AND REGULATING ROD CONTROL SYSTEM 2.6.1 Introduction This section is concerned with the circuitry and circuit components which are used routinely for operational control of the reactor. The rod control system should be considered as & separate system from the rod safety system described in Sect. 2.5. It is true that there is weak coupling between the systems, but only to the extent that certain inter- locks in the control system depend on information received from safety sys- tem channels. Reverse coupling is not designed into the system; that is, the rod control system circuits and components do not perform any safety functions, either as input or output elements. The design of the control rods and the drive units is described in Sect. 2.7. The location of the rods with respect to the core, their mounting and installation, rod worths, etc., are discussed in Sect. 2.7 and in refs. 1. 2.6.2 Rod Control Circuits Figures 2.6.1 to 2.6.4 are block and elementary diagrams that pro- vide the basic criteria for the design of the rod control system. Table 2.6.1 1ists the interlocks, safety actions, prohibitions, and permitted actions governing control rod action.ls : The reactor system is designed so that rod manipulation is either a 100% manual operation or, optionally, an automatic rod control servo- mechanism is used to maintain either constant flux or constant core out- let temperature, depending on the power being generated in the core. The rod servo is used to control one rod only; this rod is arbitrarily des-~ ignated Ycontrol rod 1" on MSRE design drawings and in the text and fig- ures in this report. The rod drive units (see Sect. 2.7) are inter- changesble, and individual rod worths (ref. 3, p. 58) do not differ widely from thimble to thimble., Therefore, the control system is de- signed so that any one of the three rods may be selected as the servo- controlled rod (rod 1). From this it can be seen that, without supple- mentary informgtion, the rod numbers used in design drawings, reports, etc., cannot be used as the only information required to designate thimble 1s. E. Beall et al., MSRE Design and Qperations Report, Part V, Reactor Safety Analysis, ORNL-TM-732 (August 1964). ?R. C. Robertson, MSRE Design and Operations Report, Part I, De- scription of Reactor Design, ORNL-TM-728 (to be published). 3P, N. Haubenreich et al., MSRE Design and Operations Report, Part IIT, Nuclear Analysis, ORNL-TM-730 (Feb. 3, 1964). “Servomechanism Fundamentals, Philco Corporation, Technical Center Staff, Library of Congress No. TJ2l4, p. 47. SMSRE Project Staff, Molten-Salt Reactor Program Semiann. Progr. Rept. Feb. 28, 1966, ORNL-3936. Table 2.6.1. Control Rod Operation Operational Mode Conditions of Operation -~ Interlocks, Permissive Actions, Prohibitions, Automatic Actions References and Notes 2. 5. Manual scram Automatic scram Individual insert (manual) Group insert manual "Reverse") Group insert No restrictions; at discretlon of operator at control console When any two of the three rod scram safety channels calle for "Scram." Each channel requests "Scram" for inputs as follows: a) Flux (reactor power) greater than 11.25 Mw; see b below b) Flux (reactor power) greater then 11.25 kw when fuel sslt pump motor three-phase currents are less than 35 amp c) Positive reactor period is less than 1.0 sec d) Reactor outlet temperature greater than 1300°F e) Channel integrity monltor shows a malfunction No restrictions other than lower limit No restrictions other than lower limit Automatically tekes place when: a) Any two of three fuel salt outlet temperature measurement channels indicates greater than 1275°F b) Fuel salt level in the pump bowl exceeds 75% ¢) Any two of three flux measurement channels indicate reactor power greater than 9.0 Mw a) Any two of three flux measurement channels indicate reactor power greater than 9.0 kw, and the fuel pump motor is drawing less than 35 amp e) Wnen reactor power (flux) exceeds 1.50 Mw and control system is in Operate-Start mode £) When positive reactor period is less than 5 sec and control system is in Operate-~Start mode g) Rod "Scram" takes place The manual switch contacts are not sealed See ref. 1, sect. 2.2.1, p. 58 Motor currents less than 35 amp imply that no fuel salt is being circulated See 2b, this table Power and period information used to initiate 5e and 5f comes from either of the two wide- range counting channels; see Sect. 2.3, ref. 1, Sect. 2.8, and Sect. 1.4 Applies motor torque in addition to gravity to inltiate scram. If a rod will not fall under action of gravity the motor will drive rod in e Teble 2.6.1. (continued) Operational Mode Conditions of Operation — Interlocks, Permissive Actions, Prohibitions, Automatic Actlons References and Notes 6. 7. Individual rod with- drawal Group withdrawal 6. a) b) c) Prohibited, with two exceptions, if the control gsystem calls for "Insert.” All manual switches and relasys are cross-interlocked so that "Insert" mode (see preceding Nos. 3, 4, 5, this table) takes precedence over "Withdraw" mode. The ex- ceptions are: 1. The servo can withdraw rod 1 within the span of the regulating rod limit switch, approxi- mately 6 in., while rods 2 and 3 are being inserted 2. By manually actuating two switches simulta- neously, two rods can be withdrawn while the third is being inserted Prohibited during Operate-~Start control system mode uniess one of the following conditions is met 1) "Confidence" is established in one or more wide-range counting chanmnels and the re- actor period in the chanmnel(s) providing "Confidence" is greater than +25 sec 2) Confidence is established in the BF3 count- ing channel and the reactor vessel is less than half full of fuel salt 3) Confidence is established in BF3; counting channel and the drain tank selector switch 86 (F111) is in the FFT position; i.e., when using flush salt in the reactor vessel, the "alf-full" requirement (see preceding Par. 2) is bypassed Permitted in Operate-Run mode without having "Confidence" (see bl above) providing no "n- sert" request exists. However, if "Confidence" exists In one, or both channels, the reactor period in channel(s) with "Confidence" must be greater than +25 sec Prohibited in Pre-Fill unless conditions per b above are met Prohibited if, for any reason, the control system calls for "Insert" as in 6a above —T. 2 8L e M sl a ™. d maea o . . . 2_ *_ N orouailplLuc WLLCEE COLLLUL sybLCill 1o LIl Dt mode a1t sub- Discussed in Sect. 2.6.2 and in ref. 5, P. 44 €Ce Table 2,6.1. (continued) Conditions of Operation — Interlocks, Permissive Operational Mode Actions, Prohibitions, Automatic Actions References and Notes 1) Control system must be in Operate-Start mode "Start" is a submode of the "Operate" mode (Sect. 1.4); Start and Run are mutuslly ex- clusive 2) Reactor drain valve (FV-103) must be frozen 3) Pump bowl must be filled NOTE: Group withdrawael is only intended for use during startup and at powers less than 500 kw. Power limitation is by means of a circuit interlock in the radiator door control circultry which requires that the reactor control system be in the "Operate- Run" mode in order to raise the doors and thus demand power levels above 500 kw. 1 {44 225 locations in the core. The selection of "eontrol rod 1" as the servo- operated regulating rod is administrative and is accomplished by making the appropriaste interconnections between the rod drive units and the control and servo system circuits. These interconnections are made in Junction box 120, locabed in the north electrical service area. Control rods 2 and 3, designated as shim rods, are always manually controlled. Figures 2.6.5 to 2.6.7 show the contacts and relays which directly govern control rod operation. Figures 2.6.5 and 2.6.6 are concerned only with the control of rod 1, the regulating rod. The dynamic brake (Fig. 2.6.6) is an addition to the design (see ref. 5, pp. 41—42), and while it does not appear on Fig. 2.6.5, it is always used in the circuit controlling rod 1. Because it is the servo-controlled rod, the circuitry is more com- plex than that required by the manually operated shim rods 2 and 3. The automatic rod control servo and the principles governing its design and operation are described in Sect. 2.6.3. Certain interlocks are common to all control rod "Withdraw' cir- cuits. The contact arrangement of these interlocks is shown in the upper left corner of Fig. 2.6.5. These interlocks are shown in block disgram form in Fig. 2.6.8. The "Confidence," "No Confidence," and "Reactor Period" interlocks originate in the BF3 counting channel and the wide-range counting channels described in Sects. 2.2 and 2.3 of this report. The "Automatic Reverse" (group insertion of all rods) has been oub- lined in detail in Table 2.6.l, and the circuitry is diagrammed in Fig. 2.6.9, The reactor operating modes are discussed in Sect. l.4. The interlocks diagrammed in Figs. 2.6.5 and 2.6.8 meet the follow- ing criteria: 1. Control rod withdrawal, during reactor start and at low powers ("Start" mode), is prevented unless at least one channel of the low- level flux instrumentation is complete, is operating correctly, and is on scale. This defines "Confidence." "Confidence" is established by a wide-range channel when all the following conditions are met: a) the indicated count rate is not less than 2 cps and not greater than 50,000 cps, b) +the selector switch on the model Q-2614 pulse amplifier and logarithmic count rate meter module is in the "Operate" posi- tion, ; ¢) all the Q-2609 fast-trip comparators (a total of eight — see Fig. 2.3.3, Sect. 2.3) are plugged into their cabinet drawers and the channel is selected by the operator. "Confidence" is established by the BF3 counting channel when these re- quirements are met: d) the indicated count rate is not less than 10 cps and not greater +than 10,000 cps, e) the "Use-Calibrate" switch on the count rate meter is in the - "Use" position. 2. Control rod withdrawal during the "Start" mode is prevented if the reactor period, meassured by elther or both of the wide-range count- ing channels in which there is "Confidence," is less than 25 sec. 226 3. Control rod withdrawal, either by the operator or by the servo con- : troller, is prevented if an automatic "Reverse" is in force. W 4. Simultaneous withdrawal (group'withdrawal) of all rods is desirable only during reactor start and at low powers and should be prohibited as a means of shimming when the reactor is in the power range (the Run mode). 5. Once the reactor is in the power region (the Run mode) and develop- ing more than 1 Mw, the wide-range counting chemnel "Confidence" interlocks in the Run mode circuitry (see Sect. 1.4) are bypassed so that a loss of "Confidence" will not require a return to the Start mode and consequent reduction in reactor power. This bypass- ing requires that two of the three safety channels be in operation. This bypassing is accomplished by control signals from the model Q-2609 fast-trip comparators in the control rod safety system (see Fig. 2.5.1, Sect. 2.5) and a seal contact on the Run mode relay. This is done to permit long, sustained runs at power uninterrupted by mal- functions in, or maintenance of, the wide-range counting channels. The block diagram in Fig. 2.6.8 may be difficult to interpret at first glance. It may be instructive to list and comment on the dif- ferent conditions which produce continuity to point A in the diagram. The conmbinations listed in Table 2.6.2 are consistent with the design criteria and the characteristics of the instruments involved. Note that if either one of the wide-range counting channel log count rate meters is functioning correctly as defined by "confidence," but if the reactor period is less than +25 sec, rod withdrawal is prevented re- o gardless of whether the reactor system is in Start or Run mode. This kfij may appear inconsistent with the criteria in paragraph 5 above and con- dition 4 in Table 2.6.2. This arrangement recognizes that it is highly desirable to have at least one wide-range channel in service at all levels of reactor power and that when they are in service the interlocks which they provide will be in force. For example, suppose that the MSRE was in the middle of a long, sustained power run at, say, 5 Mv and that wide-range counting channel 2 was out of service for routine maintenance, This is condition 2 in Table 2.6.2. Now, suppose that a malfunction de- velops in the ICRM in the remaining wide-range counting channel 1, re- sulting in a loss of "Confidence" in this remaining channel., This is condition 4; reactor operation may continue unaffected by the loss of the remaining wide-range channel as long as power is above 1 Mw. Again, suppose that a malfunction not in the ICRM develops which produces & spurious, short (1ess than 25 sec) reactor period signal. This inhibits rod withdrawsl, and the indication that a trip has taken place appears on the panel of the Q-2609 fast-trip comparator (see Fig. 2.3.3, Sect. 2.3). If & thorough check shows conclusively that the period indication is spurious, operation can be restored by manual selection of the other channel with the switch on the console or by putting the switch on the Q-2614 ICRM in the "Calibrate" position, thus going into "No Confidence" on the offending chammel and establishing a signal path per condition 4. Similarly, if it develops that, in this remaining channel, one of the Q=-2609 fast-trip comparators requires removal for servicing, the loss of "Confidence"” so produced will not inhibit reactor operation if power is above 1 Mw. gi#; Table 2.6.2 T = True; F = Falsge; NA = Not Applicahle Reactor Drain " 1 Situstion No "No " Reactor Reactor "oonfidence” "Confidence! Control Vessel "Confidence" Tank or Confidence Confidence Perlod Period 1n WRCC in WRCC System Less in BF Selector Not Condition in WRCC in WRCC >+25 Sec > +25 See Yo. 1 No. 2 in ‘than Chamei in FFT ® No. Fo. 1 _Fo. 2 (WRCC No. 1) (WRCC No. 2) ’ : “Run* Half o Position Full 1 F F T T T. T TorF F NA NA This is normal situation with the reactor filled with fuel salt above "BF; Con- fidence™ level and with both wide-range counting channels in operation 2 T F TorF T F T TorP¥F ¥ NA NA Reactor situation same as 1 but only one wide-range counting channel in opera- tion 3 F T T TorF T F TorF F NA NA Reactor situation same as 1 but only one wide-range counting channel in opera- tion 4 T T T or F T or F F F 7 F NA NA Reactor is operating st power (flux) greater than 1 Mw and neither wide- * range counting channel is operating; note that getting into "Run" mode can only be accomplished via condition 1 or 2 5 T T TorF T or F F F r T T F This gituation cbtains during esrly part : of a "Reactor Fili" with fuel salt and before flux is sufficiently high to pro- duce 2 cps in the wide-range counting channels 6 T T TorPF TorF F F F F T T Reactor beiu% filled from the flush salt tank FFT); selection of FFT eli- minates the requirements for "Confi- dence" in either the BF; or the wide- range counting chennels LTT 228 "Reverse" is the insertion, in group, of all control rods. It takes place when the instruments indicate that system conditions have ~ exceeded operating limits to the extent that rod insertion is the pru- dent sction to be taken. The conditions or situations producing "Re- verse" are listed in Table 2.6.1, and the circuitry which actuates the "Reverse' relay is depicted in Fig. 2.6.9. 2.6.3 The Autamatic Rod Controller The linear power channels (refer to Sect. 2.4) and automstic rod controller of the MSRE are shown in block diagram in Fig. 2.6.,10. The purpose of this system is to provide automatic control of the reactor by the movement of one of the three shim rods in either of two controller modes (refer to Sect. 1.4). There is also a provision for disabling, through the servo "on-off" switch, the autamatic controller in either mode to permit manusl operation of the rod by the operator. The other two shim rods are always operated manually, as pointed out above. One of the two automatic modes is called the flux mode and provides automatic control of neutron flux at a level selected by the operator when the reactor is in its "Start" mode of operation. The power range in which this mode is used extends fraom about 10 w to 1 M¢., The second mode is used to control the temperature of the fuel salt leaving the core and is called the temperature mode. This mode is used when the reactor is in the "Run" mode and is capsble of adjusting the neutron flux to maintain the reactor outlet temperature at a set point estab- lished by the operator. In this mode the steady-state reactor power 1is a function only of the thermal load, which may be varied from about 1 to 10 Mw. The instantaneous power levels depend upon the thermal load and any changes in system temperatures required to achieve the desired outlet temperature. Switching between these two modes of controller operation is automatically accomplished when the reactor operating mode is changed. Reference 1, pages 104 to 108, is suggested for additional reading to augment this paragraph. Significant features of the controller and its auxiliaries will be described below by referring to Fig. 2.6.10. The actual circuit dia- gram is shown in Fig. 2.6.11. 2.6.3.1 Basic Rod Control Circuit The output element of the rod controller (Fig. 2.6.10) is a pair of pilot relays which operate as simple “on-off" switches to actuate the "Insert" and "Withdrasw" relsys in the rod drive motor circuit of control rod 1. These "Insert" and "Withdrew" relays must always be actuated to produce controlled rod movement regardless of whether the reactor is being operated manuslly or automatically. The pilot relay contacts are identified in Fig. 2.6.5 as contacts R,SS-NARC-Al and A2 for "Withdrew" and "Insert" respectively. The power contactors which they comtrol are relays K183 and K176, whose contacts are in the power leads to the servo motor in the control rod drive selected as "control rod 1." Amplifier 8 acts as a comparator with three inputs: (1) meas- ured neutron flux, (2) flux demand, and (3) = sifinal proportional to rod speed. The model Q-2627 synchronous demodulator® is used to convert 229 the ac signal from the tachometer to a de voltage with an amplitude pro- portional to rod speed and a polarity that depends upon the direction of rotation of the rod drive motor. This dc signal provides negative feedback to optimize the response of the servo mechanism. When the conmtroller is in the "flux" mode of operation, the operator chooses the flux at which the reactor is to operate and at which the con- troller output is zero by adjusting the demand potentiometer and the range of the picoammeter in the channel selected as the control input channel, This demand signal is ldentified as "¢ demand" in Fig. 2.6.10 and originates with the operator at the console. The "¢ demsnd" setting determines the voltage from the picoammeter that is required to bring the output of the comparator to zero (assuming no tachometer signal) and, with the range selection, determines the value of neutron flux required to produce that voltsge. As indicated in Fig. 2.6.10, the range and the output voltage level of the picoammeters are recorded by the dats logger. In addition, the range setting and level of the selected channel are re- corded on a strip-chart power recorder located on the main control board. Although not shown in Fig. 2.6.,10, there is an illuminated indicator on the main board immediately above the recorder, which displays the range of the selected channel. In the "temperature control" mode the demand voltage is generated by the rod controller complex, and the range of the picoammeters is fixed., The way in which this is accomplished is described in the next section. 2.6.3.2 Temperature Control The control of reactor outlet temperature is achieved by continu- ously compubing a flux set point so that the temperature rise of the fuel salt through the core is just equal to the difference between the outlet temperature set point [To]SP and the measured reactor inlet tem- perature T;. Figure 2.6.12 is a diagram of the array of Q-2605 opera- tional amplifiers that accomplish this computation. The system is best explained by neglecting, for the moment, am- plifier 5 and its connection to amplifier 6. Considering the other two inputs to the summing amplifier 6, we note that, by proper choice of polarity, the algebraic sum of these two inputs is equal to the differ- ence between the desired outlet temperature [TOJSP'(selected by the operstor through the model Q-2628 temperature servo demand drive unit) and the measured inlet temperature'Ti. The output of amplifier 6 is (still neglecting the third input) proportional to the desired tempera- ture rise through the core and, at constant flow, is a measure of the nuclear power required to achieve the desired outlet temperature. This output, through a sign-changing amplifier 7 and limiting circuits not included on Fig. 2.6.12, becames the flux demand or set-point signal to amplifier 8. Because of the varying conditions, both in the relation- ship of neutron flux to total heat generastion and possible sensor errors, it is necessary to modify this set point if the measured outlet tempera- ture is to be truly equal to the desired set-point value. The modifica~ tion of the set point is accomplished by use of amplifier 5, the reset 230 amplifier, to generate a correction term. The reset amplifier is an in- tegrator which continuously compares the measured flux ¢, the measured core differential temperature (TO -T-), and a correction term whose value is a function of the sum of the other three inputs and slowly alters the value of the correction term until the sum of the four in- puts is zero, with the proper algebraic signs of the inputs considered. Since the correction term, the output of amplifier 5, is forced by this integration to be numerically equal to any discrepancy between measured flux and measured differential tempersture, applying this same correc- tion term with the proper polarity alters the flux demand as required to assure that the steady-state value of the measured outlet temperature is exactly equal to the set point. The response of the integrator is purposely adjusted to be considerably slower than the response of the other amplifiers on this computing system. Therefore, if either the reactor flux or inlet temperature, or both, experience a rapid change caused, for example, by & load transient or high rate of manual shimming, the error signal computation will initially proceed as if the integrator were not .present. The controller will respond immediately to the tran- sient, as explained in the first part of this paragraph. Because of the rapid response of flux demand, and therefore flux, to a change in inlet temperature or outlet temperature set point, it is desirable that neither of these be permitted to change rapidly under normal operating conditions. Inlet temperature changes, assuming con- trol of outlet temperature at a constant set point, are caused by load changes. These load changes are not normally permitted at a rate that exceeds the capability of the rod controller to hold the outlet tempera- ture constant. The rate of change of outlet temperature set point is limited by using a motor-driven potentiometer to determine the refer- ence voltage. This rate is necessarily very slow to prevent undesirable thermal gradients in the system when the controller is operating in the temperature mode, and, since it is desirable to match the outlet temper- ature set point to the actual outlet temperature prior to changing from manual to automatic control, a faster rate of altering the set point is avallable to the operator when the temperature is not being automatically controlied., 2.6.3.3 Flux Demand Limiting Because components and devices do occasionally fail or malfunction and may thereby cause an unscheduled lncrease or decresse in flux de- mand in the temperature mode, a limiting circuit, block diagrammed in Figs. 2.6.10 and 2.6.11, has been provided which prevents the flux de- mand signal from departing appreciably outside its normal range. This feature 1s also useful to mitigate the consequences of an operstor error such as turning on the controller when the outlet temperature set point is grossly different from the measured value. In addition, & Q-2609 fast-trip comparator, shown in Fig. 2.6.10, is used to provide an interlock (see Sect. 2.5, Fig. 2.5.8) to prevent initiation of the Run mode of reactor operation while under automatic control unless the computed flux demand is less than about 1 Mw. Since the transfer from Start to Run must be made (by circuits not related to the automatic rod controller) at a power level of about 1 Mw, this com- parator assures that no significant power excursion will occur. 231 2.6.4 Regulating Rod Limit Switch Assembly, Q-2586 It is good practice to limit the reactivity change that can be pro- duced by the autcmatic controller to an amount equal to or slightly less than the effective delayed neutron fraction B_ro.. Since each rod in the MSRE has a total full-stroke worth of approximately 2.2% in Ak/k (ref. 3, Sect. 4.3, Table 4.1, p. 58), the regulating rod limit switch as- sembly, hereinafter referred to as RRLSA, is provided to limit the stroke of No. 1 control rod to 6 in. when the automatic controller is in use. Figure 2.6.13 is a simplified functional diagram of the RRLSA., This disgram does not depict the actual configuration of the system. The rod drive unit does not actually contain any intermediste movable limit switches as implied by the diagram. The actual short stroke limit switching takes place in the control room, and the mechanism which accomplishes this is shown in Figs. 2.6.14 to 2.6.17. Figure 2.6.18 is a mechanical diagram of the drive train, and Fig. 2.6.19 is & detailed block diagram of the assembly. An ac servomechanism is used to position the limit switch cam when the automatic reactor controller is operating. This follows typical po- sitioning servo practice4 when a synchro control transformer is used as the position error sensor. The servo loop (Figs. 2.6.18 and 2.6.,19) consists of a size 15 control transformer whose output goes to an ac amplifier (Fig. 2.6.20), which drives the positioning servo motor. The control transformer is mechanically coupled to the positioning servo motor and is driven in a direction which reduces the error signal toward zero. When the rod controller is "on," the electromechanic clutch is engaged (the brake is off) and the cam is also commected, through speed changing gears and the differential gear set, to the ac servo motor. The shim-locating motor is also directly connected to the limit switch cam vy gears and through the other input of the mechanical differential. Be- cause the differential gear set is included in the drive train, both the ac servo motor and the shim-locating motor may be used independently and simultaneously to obtain cam motion. The net cam rotation is proportional to the algebraic sum of these two input rotations. The electromechanical clutch-brake in the output gear train hetween the shim-locating motor and the differential (see Figs. 2.6.18 and 2.6.19) is a design modification which does not appear in the photographs. It was added to eliminate the undesirable effects of coastdown of the shim-locating motor and of back- lash in the motort!s built-in gear reducer. Table 2.6.3 gives the rota- tional characteristics of the various components in the system when the reactor is in the sutomatically controlled mode and with the gear ratios in accordsnce with Fig. 2.6.18. When the reactor is in the "Manual Control" mode, the control cir- cuitry (Fig. 2.6.5) causes the electromechanical clutch-brake to become deenergized; the mechanical drive connection from the ac servo motor to the cam is broken and the brake is applied. Control eircuit interlocks also prevent applying power to the shim-locat motor. Because of the very high built-in reduction gearing (2400 to 1) in this motor, it is not susceptible to being driven by torque applied to the output shaft. The brake prevents rotation of the other input to the differential. Therefore, both inputs to the differential are locked, and the limit switch cam is not free to rotate when torqued externally. Table 2.6.3 RPM Outputs (Component Rotations in Q-2586, Input Conditions Regulating Rod Limit Switch Assembly) Limit Switch ReguJ(.;:;g.‘n% )ROd' Limi'g aSgitch giifirfi AC Servo Cam and Size Shim-Locating P T Motor 31 Position Motor ransformer Transmitter Withdrawing at 0.5 in./sec Stationary +0.42 +5.0 - +2.50 Zero 2. Inserting at 0.5 in./sec Stationary ~0.42 -5.0 —2.50 Zero 3. Stationary Withdrawing Zero Zero —2.25 -L.5 4. Stationary Inserting Zero Zero +2.25 +1.5 5. Withdrawing at 0.5 in./sec Withdrawing +0.42 +5.0 +0.25 -1.5 6. Withdrawing at 0.5 in./sec Inserting +0.42 +5.0 +4.75 +1.5 7. Inserting at 0.5 in./sec Withdrawing —0.42 5.0 —4.75 -1.5 8. Inserting at 0.5 in./sec Inserting —0.42 -5.0 -0.25 +1.5 A4 233 From Table 2.6.3 it is seen that the cam speed resulting from re- locating the span of the limit switches with the shim-relocating motor is slightly less than the cam speed produced by control rod motion. With the gear ratios shown in Fig. 2.6.18, these speeds are 2.25 and 2.50 rpm respectively (see Table 2.6.3). The cam is cut for a meximum of 180° rotation between limits, which is equivalent to 6 in. rod motion. The position of the 1imit switches is adjustable; hence, the effective span TAVE] (Fig. 2.6.13) of the regulating rod may be adjusted within this maxi- mum of 6 in. From Fig. 2.6.14, it can be seen that the gearing, clutch, -motors, etc., are supported on movable mounts and hearing hangers. There~ fore, it is simple and inexpensive to change the cam speeds and the span. A detailed description of the major components used in this unit is given in Sect. 2.6.5. : As noted sbove (see also Figs. 2.6.5 and 2.6.19), the net rotation of the limit switch cam is the resultant of two components: (1) the rotation produced by the balance motor and (2) the rotation of the shim-locating motor. When the reactor is in the servo control mode and if the operator is not relocating the position of the regulating rod span, the balance motor, driving through the clutch (the brake is disengaged) and the differential, rotates the limit switch cam through an angle that is directly proportional to the linear motion of the servo- controlled rod. Assume, for the sake of discussion, that the reactor is being operated in steady state and that no fuel is being added. Burnup and poisoning will cause slow withdrawal of rod 1, the servo-controlled rod, unless the reactor is manually shimmed by the other two rods. If no shimming takes place, the limit switch cam will continue to rotate clockwisen%see Fig. 2.6.5), and, unless the shim-locating motor is ac- tuated to produce counterclockwise cam rotation, the upper shim regulating rod limit switch will be opened, its associated relay K240 will drop out, and contact K240F will open. This will prevent the servo system "With- draw" relay contact R, SS-NARC-Al from transmitting power to the rod with- draw relay K176. Note that the servo system is not turned off and that it continues to exert comtrol in the "Rod Insert" direction; that is, if for any reason the servo calls for the insertion of negative reactivity with the servo rod at the upper limit of the regulating rod span, the rod insert requirement will be transmitted to relasy Ki83, which causes the rod drive motor to insert the rod. This rod 1 insert relay, K183, cross-interlocks the rod withdraw relay K176 so that an "Insert" request from any source overrides all "Withdraw" requests. This cross interlock is included in all rod drive circuits. The operator must now shim the reactor. If he chooses to shim by using rod 1, the servo-controlled rod, he does so by means of the individual rod control switch, S19, used for manual operation., This closes contact S19A and energizes K175, the re- lay which causes the shim-locating motor to turn the cam counterclock- wise. The limit switch closes, contact K240F closes, and the servo is in command of rod 1. The servo now withdraws rod 1 until the upper limit is again reached or until shimming requirements are met. The shim- relocating motor moves the cam at a slightly lower speed than does the balance motor, and the actual withdrawal of rod 1 in these circumstances is a series of start and stop movements until the span of the regulating rod is relocated. The alternate method of shimming is to withdraw either or both of the manually controlled rods 2 and 3 until the servo automati- cally returns rod 1 to a suitable place within the regulating rod span. 234 Should the servo controller malfunction and ask for a continuous out-of-control withdrawal of rod 1, the withdrawal will only persist until the upper regulating rod limit is reached. The "on-off" power amplifier relays in the servo controller do not exert direct control of the rod drive motors (see Fig. 2.6.5); instead they control the "Withdraw" and "Insert" relays K176 and K183, and a servo malfunction has to be accompanied by failure of other control-grade interlocks to become of consequence. Should the regulating rod limit switch mechanism misoperate in con- Junction with a servo controller malfunction so that the cam fails to rotate as the rod is being withdrawn by the servo, the control system interlocks may call for a "Reverse" (group insertion of all three rods) if the failure produces any of the situations listed in Table 2.6.1. "Reverse" by the control system is independent of the condition of the servo controller and may also be invoked should the operator inadvert- ently withdraw either shim rod so as to produce any of the listed con- ditions. ' ~ If one of the shim regulating rod limit switches remains actuated or if the cam fails to move off the mechanical stop, rod 1 is inhibited from further motion in one direction only. The operator can provide con- trol with rods 2 and 3 and can switch over to manual control until the trouble is cleared. A detailed step-by-step breakdown of the circuit and RRLSA responses to various situations is included in Sect. 2.6.6. 2.6.4.1 Range Switching The range switching circuits of the flux channels are extensive be=- cause of the large number of operating conditions possible. Figure 2.6.21 shows these circuits, as well as those assoclated with the various reactor and rod controller modes. The first two stages of the operator's range switches are used to connect the proper feedback resistors by energizing appropriate relays in the picoammeters. Contacts K204A and K204B (Fig. 2.6.21) are used to disconnect the range selector switches and to automatically connect a feedback resistor corresponding to a full-scale range of 15 Mv when a "range seal" condition exists. The "range seal" is described below. Stages 3 and 4 of the range switch are used for proper switching of the inputs to the range indicator light assembly. This range indi- cator displays, in exponential form, the nominal full-scale range of the selected channel in watts. The range switching is by alternate steps of factors of 3 and 3-1/3. Stage 3 monitors the position of the range switches and the console channel selector switch and causes one of two multiplying factors (1.5 and 0.5) to be illuminated. In the event that K205 (another "range seal" relay) is energized, the 1.5 light 1s operated regardless of the position of either range switch. Stage 4 causes illumination of the proper exponent in the range indi- cator, thereby completing the identification of the range. The range seal condition causes a 7 to appear in the exponent position, indie cating a range of 1.5 X 107, or 15 Mw, when the range seal condition exists. 235 Stage 5 is a voltage divider used to provide range information to the data logger and range recorder. K208B contacts are used to switch the range recorder input to the selected channel range switeh. Again K205 contacts disconnect the range selector switches and insert signals corresponding to the 15-Mw condition when the range seal is energized. Stage 6 is a permissive switch used to enforce the 1.5-Mw range required to switch the operating mode of the reactor from Start to Run. Stage 7 is used for the range seal function, which will now be de- scribed. 2.6.4.2 Range Seal The transfer from Start to Run or Run to Start in reactor operation involves a number of distinct, but related, operations. To assure that all these are performed and that no severe transients are introduced as a result of such transfer, the range seal circuits have been developed. The range seal, as the name may imply, is an electrical latching circuit which is energized whenever the reactor operating mode is switched by the operator from Start to Run. This transfer is restricted to power levels in the vicinity of 1 Mw. Energizing the range seal, represented in Fig. 2.6.21 by relays K203, K204, and K205, disconnects the range selector switches and causes the range of each picoammeter to become 15 Mw, as described above. Inasmuch as the range selector switches are now totally ineffective, it is reasonable to assume that they may be in any position during subsequent operations in the Run mode. It should be noted that the Run mode may be terminated automatically under certain conditions. Should this occur, the range seal circuits are used to auvtomatically force the rod controller flux set point to about 1 Mw. The operator can then assume control of flux set point by putting both range selector switches in the 1.5-Mw position, at which time the flux set point becomes 1.5 Mwv multiplied by the setting of the flux demand potentiometer. The above features are shown in Fig. 2.6.21 at the bottom of the sheet. Relays K203 through K208 are operated in the following manner: A contact from the Run relay in the rod control system operates K206, called a run auxiliary relay. This relay in turn energizes K203, K204, and 205. If either of the range selector switches is turned from its 1.5-Mw position, the relays are sealed in their energized condition through S1 or S2 and K203A. Relay K207 is the relay which defines, for the controller and for the reset of the control system, the temperature mode of operation. Although it is clear that K204 should always be en- ergized when K206 is energized, the interposition of K204C between K206 and K207 has a purpose. Inasmuch as the temperature control system cannot function properly unless the picoammeter range is 15 Mw, it was decided to initiate the temperature mode by the operation of the same re- lay, K204, that switches range. K208 is the relay which selects either channel 1 or ‘channel 2 signals to be the input to the controller at the request of the operator. At the bottom of Fig. 2.6.21 is also shown the switching circuit for the servo amplifier demand input. As described earlier, in the temperature mode the computed flux demand serves as a reference to be compared with the measured flux level. K207A, normally open, serves 236 this function. If K207 is deenergized, as it will be whenever the "run" . relay 1s deenergized, the controller will be in the flux mode, and a gui flux demand voltage is supplied through a K203, or range seal, contact. If K203 is energized, the picoammeters are on their 15-Mw ranges, and the setting of the operator's demand potentiometer is in terms of per- cent of full scale and could represent as much as 15 Mv if used as a reference to the controller. Therefore, K203 is used to introduce a demand of 1 Mw, based on a 15-Mw range, whenever the range seal is en- ergized and the run relay deenergized, as described earlier. The temperature reset amplifier, described earlier, compares flux and temperatures to compute a correction term so that the reactor out- let temperature is equal to its set point in steady state. Since the flux signal into the controller depends upon the range of the picoam- meter and the temperature signal does not, the reset mechanism would be saturated during most operations at low power. To provide a means for minimizing the error in the correction term at the time of transfer from Start to Run, a fictitious signal representing a 1-My flux level has been introduced whenever the range seal is deenerglzed. Since 1 Mw corresponds to a differential temperature of 5°, the correction term will at most be 5°, even if the power level is so low as to produce an unmeasurable differential temperature. As the reactor power approaches 1l Mw, prior to initiating the Run mode, the reset amplifier begins to operate properly. If the flux level is held actually at 1 Mw for a few minutes prior to transfer to the Run mode, there should be no appreciable change after transfer, since energizing K204 transfers the input to the reset amplifier from a fictitious 1-Mw signal to a real 1-Mw signal com- ing from the selected picoammeter. kiJ 2.6.5 Component Descriptions 2.6.5.1 BServo Motor This is a two-phase, 60-hertz ac motor primsrily designed to be the balancing pen drive motor in Minneapolis-Honeywell Company self- balancing potentiometer~type strip-chart recorders. It contains integral gear reduction such that it has a maximum no-locad speed of 27 rpm. It is capable of operating at stalled torque continuously without damage. Its electrical characteristics provide a good match to the amplifier de- scribed below. The motor is designated by Minneapolis-Honeywell as their part No. 76750-3. 2.6.5.2 Amplifier This is a general-purpose instrument servo emplifier designed to accept 60-hertz input signals in the millivolt range and to amplify them to a power level capeble of driving the servo motor described above. This amplifier (Fig. 2.6.20) is manufactured by Minneapolis-Honeywell and modified in accordance with ORNL Instrumentation and Controls Di=- vision Drawing No. RC-2-10-12. 237 2.6.5.3 Clutch-Brake The clutch-brake is manufactured by Autotronics, Inc., Florissant Missouri, and is identified as part No. MB-34-2. [Refer to UCNC (ORNL) Requisition No. R-7674, April 4, 1963, and Purchase Order 63X47734.] Its performance characteristics are outlined below. Operating voltage 24 to 28 v de Coil resistance, *10% 138 cohms Clutch torque, min 80.0 oz-in. Brake torque, min 100.0 oz-in. Response time to energize 0.020 sec at 28 v de Maximum no-load torque (drag) When energized 0.20 oz-in. When deenergized 0.50 oz-in. Operating mode With coil energized the input gear flange is free to rotate and the output is braked to the housing 2.6.5.4 Shim-Locating Motor The shim-locating motor is a synchronous capacitor type with in- tegral gear reducer. It is manufectured by Bodine Electric Company, 2504 West Bradley Place, Chicago, Illinois, and is identified by catalog No. B8122E-1200C, frame KYCC22RC with K-45 capacitor. (Refer to UCNC Purchase Order 63X-50673, June 10, 1963.) Its performance characteristics are outlined below. Input 115-v, 60-hertz, single-phase Output speed 1.5 rpm Output torque 105 oz-in. Capacitor 0.85 uf 2.6.5.5 Mechanical Differential The mechanical differential is a bevel gear type supplied by Reeves Instrument Corporation, Roosevelt Field, Garden City, New York. 2.6.5.6 Size 15 Control Transformer This transformer (U.S. Government type 15CT6b, Mil. Spec. S-20708) is manufactured by the Bendix Corporation, Montrose Division, South Montrose, Pennsylvania, and is identified by Bendix Catalog No. AY1501B- 11-B2, Dwg. 1501B-0, or equal. (Refer to UCNC Purchase Order 63X-47764, April 29, 1963.) Specifications are given below. . 238 Voltage, primary/secondary 90/57.3, 60 hertz i Current, mex (typical) 0.011 amp &si Power, primary (typical) 0.13 w Total voltage at null 90 mv Fundamental voltage at null 60 mv Electrical accuracy 6 min Phase shift 20° lead 2.6.5.7 Size 31 Torque Transmitter® The size 31 torque transmitter (U.S. Government type 31TX6b, Mil. Spec. S-20709) is manufactured by the Bendix Corporation, Montrose Di- vision, Montrose, Pennsylvania, and is identified by Bendix catalog No. AY-3101B-12-E2, Bendix Dwg. 3010B-O, or equal. (Refer to UCNC Purchase Order 63X-47764, April 29, 1963.) Specifications are given below. Voltage, primary/seconda 115/90, 60 hertz Current, primary (typical 0.395 amp Power, primary (typical) 4.5 w Electrical accuracy 10 min Max total signal at null 125 mv Max total signal, funda- 35 mv mental at null Phase shift 6.5° lead Torque gradient 0.40 oz-in./deg 2.6.6 Operational Situations Involving the Regulating Rod tsJ Limit Switch and the Regulating Rod Servo (Refer to Figs. 2.6.5, 2.6.7, and 2.6.9) I. Servo withdraws rod to upper limit of the RRLSA A. This moves cam clockwise to upper limit switch; this actuates (deenergizes) K240. B. The active contact chain during "Withdraw," in servo, is: 1. BRyxSS-NARC — Al — K240F — KA170D — K228A — KR220A — K183C — relay K176. 2. K240F opens and prevents further withdrawal by the servo. IT. Regulating rod at upper limit of the RRLSA; operator acts to let servo continue rod withdrawal A, This requires that the circuit to relay K176 be restored to en- ergize relay K240 (see A sbove). B. This is permitted if the RRLSA is withdrawn so that its upper limit switch 1s not actuated. This 1s accomplished by manual operation of S19A to energize reley Ki75. The contact chain in circuit 175 is: S19A — S20B — 8521B - KL70H — K241A — relay 175 energized. SThis synchro was also designed for use as a control transmitter. { - III. IV. c. 239 When relay 175 is energized, the RRLSA cam moves off the upper limit and these actions follow: 1. K240F closes. 2. X176 is energized since, by hypothesis, the servo error signal requesting withdraw rod 1 still exists and servo relay contact RXSS-NARC-Al is still closed. The RRLSA cam is now receiving motion from two sources: a) Clockwise rotation produced by the actual withdrawal of rod 1, which rotates the position synchro in the RRLSA, b) Counterclockw1se rotation produced by the operator's closure of the manual shim switch (S19), which operates the shim-locating motor in the RRLSA. c) Since the cam speed produced by withdrawing rod 1 is slightly faster than the speed in the opposite direction produced by the shim-locating motor, the net rotation of the cam tends to be clockwise. Therefore, the motion of rod 1 will tend to keep the cam at its upper limit, while at the same time the operator is continuing to re- verse the cam. Rod 1 will move up in steps as long as the servo requests withdrawal. d) When the servo error signal becomes zero: 1) R, SS-NARC-Al opens and relay K176 is deenergized. 2) If the operator continues to request withdrawal of rod 1 by actuating S19A and energizing relay K175, the cam continues to move counterclockwise. Pre- sumably the operator will stop the cam so that it is midway between limits. If the cam reaches the lower limit and energizes relay K241, rod 1 is pre- vented from responding to a servo error signal call- ing for rod insertion. Servo inserts regulating rod to lower limit of the RRISA Control system response is same as in I, but in opposite directions. Regulating rod at lower limit of the RRLSA; operator acts to let servo continue rod insertion Control system response is same as in 1T, bubt in opposite directions. Manual insert of rod 1 (regulatlng rod) or manual or automstic re- verse of all rods is requested A. B. C. Any one of contacts S22B, S19D, or K186F is closed. Assume that rod 1 is between limits of the RRISA; then the pertinent contact chain becomes: (S22B, S19D, or K186F) — KAL70E — K240A — relay K182. | The shim-locating motor rotates cam in the "Insert" direction. Note: Rod 1 does not move during this step as the cam approaches the upper limit switch in the RRLSA. The upper limit switch is actuated by the cam and relay K240 is deenergized. 1. Contact K240A opens and stops the shim-locating motor. 2. Contact K240C closes and the relevant contact chain be- comes: (S22B, SL9D, or KL86F) — KA170E — KA240C — K230A — K231A — relay K183, Relay contact KL83A closes, causing the drive motor for rod 1 to insert the rod. The cam will be rotated opposite in direc- 240 tion to its original rotation per VC above, and this action \.J will continue until it is backed away from the upper limit switch in the RRISA. Relay K240 is energized, and the cycle, starting with VB above, is repeated. The action is similar to that described above in IIB. F. Once rod 1 has reached either of the limit switches in the RRISA, its speed is limited by the speed with which the posi- tion of the RRLSA can be changed. This is approximately 10% less than that of rod 1. G. If, during a request for "insert" per VA above, the servo also requests rod 1 insert, the resulting action is to im- mediately insert rod 1 until the lower cam limit switch in RRISA is reached. During this time the rotational speed of the cam will be the absolute difference of two speeds; namely: 1. The speed, counterclockwise, of rod 1 reproduced by the rod position synchro which drives the cam. 2. The speed, clockwise, of the RRLSA produced by the shim- locating motor. The shim-locating motor moves the cam at a slightly lower rate (approxi- mately 10% less) than the position-transmitting synchro. The net speed is the algebraic sum (absolute difference) of the two, thus (refer also to Sect. 2.6.4 and Table 2.6.3): Cam speed. + (speed produced by shim-locating motor) - (speed produced by rod 1 motion) + 0.9 (rod speed) — (rod speed) Qfia — 0.1 rod speed. Therefore, in these circumstances, the cam will be turning, slowly in a counterclockwise direction until the lower 1limit switch in the RRLSA is actuated. As long as the servo is calling for rod 1 to insert, the rod will be nudging the lower limit switch in the same manner as de- scribed at the upper limit (see IIB). H. If, during a reverse, the servo is requesting withdrawal of rod 1, the reverse relay contact K186A (see Fig. 2.6.9) is open and prevents energizing relays K174, K175, and K176. This, in turn, prevents group withdraw of all rods, withdraw RRISA, and individual withdraw of rod 1. J. If the operator requests "insert rod 1" while the servo is re- questing "withdraw," the result is, in terms of pertinent con- tacts: 1. R, SS-NARC-Al — K240F — KA170D — D228A — K229A — K183C — energize relay K176 — (withdraw, rod 1). Rod 1 withdraws, and the position transmitter rotates the cam clockwise toward the upper limit of the RRLSA. : 2. 819D —» KA170E — K240A — energize relay K182. The shim- locating motor rotates the cam clockwise toward the upper limit RRIS. 3. The net result of 1 and 2 above is to make the RRLSA cam approach its upper limit switch at a rate nearly twice as fest as normal; that is, net speed, the absolute sum of the (;Q 241 two speed components, instead of the difference as described in VG, 4. When the upper limit switch of the RRLSA is actuated, the | closed circuit, per 2 above, is broken because contacts - K240A, K240F, and KA240C change their aspect. This ener- gizes relay K183 and deenergizes K176, thus: a) S19D — KAL70E — KA240C — K230A — K231A — ener- - gize K183, This calls for "insert rod 1." Note that K176 becomes deenergized for either of two reasons: 1) 2) Energizing K183 opens K183C (see J1 above) K240F opens. In addition, contacts Ki83A and K183D appear in both "insert" and ~ "withdraw" power leads to the motor in rod drive 1, so that "insert" ‘overrides "withdraw." Note that, when the servo is controlling, this overriding interlock is not in effect until the upper limit switch in the RRLSA has heen actuated. b) Rod 1 is inserted, and the RRLSA cam is rotated counter- ~ clockwise and away from the upper limit of the RRLSA. ¢) Insertion of rod 1 continues momentarily until the RRLSA ~ cam leaves its upper limit switch. | 1) 2) 3) ) 5) 6) KA240C opens. Relay K183 is deenergized. Rod 1 stops inserting. - K240A closes and the shim-locating motor drives. the “cam clockwise toward the RRLSA upper limit. K240F closes, K183 closes, and relay K176 is ener- gized, causing rod 1 to withdraw. | The RRLSA cam is also now being driven toward its upper limit by the position transmitter. d) This condition (4, 5, and 6 above) is the seme as that originally postulated, assuming that the servo is still requesting rod 1 withdraw and the operator is manually calling for "insert." ArmEE R meE T ' : MM, e Cote - C o . S et w i et e - e E o ames OPERATE WO RN G& AN | PCOANMEIER 2 » RANLE Yavicny asan saiecian nw:lu -h :!‘\“i"‘ ‘m* i / note*e \uore %% ,’ “evo o i sRAL | sERve uoDd | i SWITCh I NOLO" PaniTion ] [ [ ! UL Pt - i “wxmcrow | ) [ weacon ] T AT \ EAL Wet mor e mun | ] e mun ; vm \\ RATABAARED moom | | MO ] N l ‘ LRV MoDR ; Aite Rew VTCH el W | coutmoL w SHE* PatlieN | ; TEMP. MoDs o~ . - A0 N o7 coMTAn SN0 M / N R B “ | /By | = g - l - " ’ * v < . // soye®s N 4 I “F ; . N M vavien 4910w : i midwio i . ! j ' =| -y s o o v o o e . t curriean 2 P---—-fi—-——-——-—-- cnaMBAR, YE : i *AuTpmarie” ’ IFnonayic” o s A . 1 - - rE I g = . [ - 1 ACIOAL %1 wivnoeawl 02 iuseer | [v2 aveat . WIRPRAW [*1 aciunten 71 AcrAten EIT. SWITLH - SwhTen - TesT SwWiTcH TRT Bwire SIgNAL GMAL, PalitoH - Swita it - | AcTuATa L OpF " ACTUATED AcTuATRD AR cops” - { : ' X ‘ | 1 VNBARY | WITHDRAW " SieidAL, S BAL 2 F19sien T nevien U AMMER NoT G LR I e L R 4 SARLYY SYITEM BLOGK DIAGEAM oww-a 51835 . EREERE YALYE Wl.OLK DihGaERM CWH-E - 3734 NMOTES'S ; AUR, PROCESE GONTROL SYETEME BAOLK DIAGEANIRIAJDHWE: 518481 .—-I—é-'_ : AUL. PROCESS CONTEOL STSTEMS BLOGK TIAGEAM(SKLALDWIS- 3T840 3. THE RAMGER AL 14 UALE TO AMRULA SMOITUITRAMAITION BHATWLEY TREWPERATURL SELY0 MDY AUR, PROCESS LONTEOL AYAYEME BLOLK DINEAM{MAI ATONWE- 51D 39 PAUR . SARVO OPLEATION WWLMW TWE RLACIOR % TAREL OUT OB TWE RUN MOOK. ARTER TAR TEARSATION . TR FLUR DAMAND 15 MAVITRMLD ST . MROUT, 1 HRW et Twe OPLREMION CONTAINMENT SYSTEM BOLK TIMGEAM (SAZe$5) Jowms 315348 ALBUMES CONTEOL OR THE DLMAND HY SWATCHING . BOTH RANGE . SWATCWRS TO WA O-1. 3 MW CONTAINMENT SYSTEM ILOLK DIAGEAM (4.l o488 >. DHWS- 5718537 S POSIHION, Wir CAL TWEN BALELT RAMGE AN PR CENT DAWMAND. FOE LOW. LINEL TLRYO OPREATAONRS o oo SALT $YETEM WLOCK DIhGEAM owwer 57836, 2. TWR RESET MECHANIGM 18 TRE AUTOMATIL ROD CONTROLLER CAN OPERATE. ) MASTRE COMTROL WLOGHK TIAGEAM ($W. % «f T) [OnWS+ 519 ' | PROWERLY ONLY 1% THE WMICED MICED AMMEITER RAuGk 1S O-1F Mw. Wasw MASTAR, CONTREOL WLOLH DIAGRMACIN- a4 1) [OuwE- 51950 NOYT 1IN TRE RUN MODE A EIRED StavAl BLFLALES TWe VLUL S\GNAL YO Twe REBET MECHAMIGM, PROVIDING A RESET WITH A MARMMUNM BLEOR Ow A . [£OD couTeon BLDCK Dieeam {insey 2 aft) _ fOuw e F1W8Y rAW DEGRETS, ‘ REFERENCE DRAWINGS NO. A, TRAMPERATURE DRMAND CHAWGNE CAN IS MADE ONLY AT A EINED RATE WY OAK RIDGE NATIONAL LABORATORY MEANS OF A MOTORIGED POTENTIOMETER . OPERATED 8Y , ’ [ 4, REALTOR OPERATIG MODES ARL DERINED OW DEAWING * D -RW-the 51350 . UNioN CARBIDE NUCLEAR COMPANY ] DIVISION OF UNION CARBIDE CORPORATION i , 5 FIlaesiON CUAMEAR TEHT FWITOCALE AR LOLATED OW TWA . HULLLAR OAK KIDGE, PAVRL 1N THR AVKALIARY WOOW - MOLTEN SALT RRALTOR WAPLRIMLWMT "% |ved.¥ s0ey . v sv-esif{E Py . 4% E°0T ARE CAUBITRARY POMITIONS od RAMAR SELRGLOAE SiTel. RAMGE SWMACTOR UMITR ON DINCNZONS hLESS WALOCLK DI GRAM o 190% b | cHAN GR NeTicl WP BOSO Drresli{y T OITEN MAS 14 PiTient CevERING RANGRD FReM. G5 W . T0 LA MW I ATPREX: OTHERWISE $PECIFIED: - Vi DECADS. APy { £ MArs PR DICATL) . ARG DG, ReiB: 12-. 84 . RANMGE- SRSCTeR FRACTIONS + RO CONTROW RO, : REVISIONS | DATE |APFD] APFD SWITLH . DOWS HOT _MLWDR A 15 WW FosiTien (S8 udte 74 AUD THAGRAN ELIT. Y BLOCK UIAGRAM w77, hee-e BAT DATE: . ‘ DEGMALS £ . SHEET |\ o4 2 DESIGN DAT] APPROVED | DAT| ‘ ANOLES £ T""‘ W 5.3.9 A2 1, ke _ ’ : o mflru vy .W' -M mu APPROVED . | DATE | APPROVED | -DATE : ’ S . i . _ . . SCALE: NONE. . : O-HHIB 12079¢ Fig. 2.6.1. MSRE Rod Control Block Diagram. ! \ i i i ..... Rt " e o T T e A o ; T ol ¥ j i i } & ’ 1 } ¥ | : 4 § i \ 0 3 ' . ‘ ! ’ | , 179 . o S 1511 1 ‘ 5 " e : Y 1 st sy gvh. w0 " . . s e 9 ‘ 180 isi 209 d8VBe. 1P, l |f“ TN . o it - . A . KBISGD s e FEIOWN o KBI08A A CLOSR WwEw ‘ Nt PERIOD > 25 %%, : ; : ! O . : . i ‘ . e NCCT A i xatoh o K226A ‘.;'.".K\\N-h oe L~ OPBN WUEYS WRIGHT s i : T S Jyauw OR LALT (u RUALTOR 2 Y . : W N -l;q.v.‘ub.> 1% sec. ( o0l tan. :E_,.r‘f_f_ : ' Q ; : ; . - i . it I B4R ; : IR ’ J_ _ .\L'fi, - 'Lse? ' ¥ e . ‘ o ALY =K REIDN G P——]_ b I I ! : ! c KivGe ! ; S YBISE T-KBIaB ZOKBISSA KBI76A : f—— ' T L | T T T : : . ) Y ’ ' : : : . ::Z:'*A«-M?EKI'JEA xRN Frasen ; e : N - it . . 'm.::".'gw‘ - RO -1 —— : + : 250V. _‘*‘ G cel . NE ] 3 . . & 4 o e - isone . n.a%ro' /Q l _I- ) ™ o T v ’ : : - . < - - ok . > - > © TKISSA. TUKAIBGG oKIBeR fcLotE . ON SERVO. > 2 - : : [“unm:tuu SIaNAL 3 < ) N L cra 4 : K - ~Eraisse s . ) . : ! ) 1 1 : Fxassp Lo Zwnab. Awssp S RATTGCE. -’..X_AIT‘D ¢ 1B . . o SEKIAC | ITKAISBA Crarea SR _r\mn- S RAVEN — SR NOTE -1 /V'-‘-_—._—. t . <4 — K"‘.B‘bk KinSC L &rn_. 8-.11;. NS ZNY ; . ! . : \ ‘ : : 20— Looadlen A, e VVERLITE ARy A%, : { 10as, TN, o BT, T, MY o ToAB el S feM2, 483 116,16 - ANE,AAT. . AN, (987 199,099 N ) e NABINYY 188, £33, Sl : 188, 100 ABNL1BN. 184, . 404, %9, 148 o o S : _}l‘" G- S . LSONRNOTeN SERV0 1 FLUNL. EMERGITLI TS ENERGIE TO GROLE ERGULATING | ®1 2o0 : S W won : T @R ECD | DYNAMIC BEAKE . IORURT WITWORAW. L LvbRERT WMWORAW T AW MOTIE WIWEW. ' INCREASE DECREASE . WITHDRASAG:: gow AT Lo . — " . - WHLRGIND | DERMRRGAETT QUTLET TIMR SUTLKT TRMP, . CHWITLAL S S . : } ‘ R 4 RS1O . ST PONT SET POINY ) i . o o ’ L. OEREAIRED. . (DBMAND) {oemant) . ) . " T BeD . n . e T omr eom SLLVD 10 TR, : i ‘ — [ m———— - MODL. WINES . | . e ' ' . EWERMD : . S i -4 KWAID . . . ) \ ) . RERECINNG 5, ‘ — . s — : - e : - f o e T CONTROL RO WITHDRAIAL WHAEN WMNERGIEED COUTROL MO "DRIVES MOTORS, - " KOO SEEVO. A e it oR ' A IO DUTLEY " TEMPERATURE: DEMAN MY CH sHim mou vy AeTUarow swiyew SelELl ST s 5 : Wy : - . A1 . ‘ _ : . 200 SERND MODE SELECIOR SWITCH RERCIOR: DUTLETY EMAND SWITCH. SHUA L BDE T ACTVATL : PUALE IPLITTING CAPALITER To Ww A o - ORITION _(FTONT. View) - ] PORITION . { EEONY View ) B BOBRATION (FEONT VikEw) .. OI-FIALLD PAPR-K AWD EATED. AY R YR T U OFR]. . WoLty | JSERve- O] SOCMTIon | | ConNTACT I o ranen] .. orw . [mciumges] -OChTION S ROWTALT T TIMBERY ovr AITADERL | WOCRTIOR. 500 V.A.L.s CAPACITOR TO MumT : ‘ AN DU WS . a ] (ewt mae)] HAGDAGR BT e tery. mall [ wanDLke . Hwo —w— - {ext. wa). CRAVIEEMRLTS orcfo:fl.oo;_go:, TG, ELEM. CONTROL INTRELOLE CIRLLITE: M Lat T BUWB-5102Y sy Ity e . AN fatay ] oo oo Ve ALY G . : R L ovae i} ORive- Farve ™ AMB-FLATE .. LG, BLEM. BOD CORTROL CIRLOITS - 4W, To4l oww- 5. 51519 . Lletey | . Ana.. - w5 ] -~ =& ' . T s wt25] . o % . e ooovv REFERENCE DRAWINGS _ NO. - T : : , e (8l - w1 s . Che e T T e . . e . ——t e Oax RiDaE Nam“ummv : ICAS = e e st g . i : ‘ ‘ ‘ - i oLl ey e - — UNON CARBIDE NUCLEAR COMPANY -3 Al - VLl 1-&-6b) ) . el . 220 ' ot e R T ey ewiv & - ~ ATO wI\TC i . HiM ROD. =2 TACTOMOR, ' DIVISION Woaflbflm%mflflmm. TioN ‘ C locns sidn . . | % , POSITION (FEOMNT Vitwi) . - LPOBITION (FRONT View) , MOLTER SALT REMCTOR TAPLRIMWWT mpa n B8 lerANGE NOT. K] — v-scasilipn coONTALTS MLt orr . arinowiw | LOCATION CONTRCT I o lwer | onm_ |shinbeme | -oCRTIOW LIMITS ON DIMENSIONS Ungess | ™ ‘ ‘ A0S 50N, A ) WAK - e - enT M) WANOLE %ND Lewt. med OTHERWISE SPECIAED: - ‘ VAL | enAMGE uoTiCR® T 2917 4. 104/ d . RWOLE BN St 2y, Rt ) ) ’ - . et g B R, marefinsmsael). . . : REVISIONS ALY ® 11s .1 |7 aewvy |- . S R T hl FRACTIONS £ e ENGINGSERING LEMENMTARKY no, ! ‘ . | DATE. [APPD] APPD —— - - * ‘ " - CIMALS ' ROW " CORTROWL CQCIiRLUNIT= . - - =T : T P e T EETR Tt e Dec . O vy - \ ! . S S di biesees] - . c (3], % M 7 ) N R S s . : BT 1.3 Ly ] [ AFFrovED — | ota) x : TeE. ole | Al .1 .. . ANGLES & —1 <~ A - APPRONED - DA, o . _ scaLe: e 0 D e e —— . ‘ ; : 1 - - . 20 4T ED Fig. 2.6.2., MSRE Rod '.C_ontrol Circuits. ' b 244 s y NO LOUNT FENIOE LOUNT EATL METER LOMIIDEL e | ~uoyg ¥ ELALYOR | rcorm < ¥y POULL |flt R, & “N‘P‘IT L]m * !) 12 Mw -t ct\muu.‘\ REACTAL SWTART TUMS SR RTVAY >80 b Laanuts * ) [m.'s .mmm.'s. L Mw ‘)l! aw ®00 L1 ] semam BLRAM SCRAM ¢ HADLELS | HANUELESZ | uanaL®g . ROD e © ROD THCRAM . ".&IQM‘ " SCEAM . : AVOEL YR cnhneL ¥ 8 CHANREL®S o sug uo'ra.'gn J WGH LEVEL iy Hod et Bavi. — [ B i srany Moye *1 RVT-T-Y S e, o = REM T JOOT ... .. “"."“:l : fi(fi' a . . B | CHANGE wolrc& * 5::5:: A [EHANGE NOTICE NO. 2787 cealtimi| 4204 e SR DATE [APPD| APPD APPROVED | DATE: APPROVED | DATE PRLELL MOOE OPLEAT wWoR R ROD™TE wneve =00 “um;j I TN HOY W UPPRR LT ag xo ' wWOT W LowaR LimiT scnvo l AtTusoR EVER LA 'ws:.l“" t WITLH WITOR Ruvaxie numa uurcn REVERSE SN ‘waveER e ‘msclr.f ‘mevERSE S S ERY AMSEET .‘= xOOD NOTES 1 SIART § RUM MODES ARE MUTUALLY BXCLWISWE , 1.E, ReEACTOR CANNOL BE [H HIART ¢ BUN MODES AT THE BAWME TiWE, (Het DWG, D-HH-T-51331) 1. THE CONTROL HYSTEM DOED NOT REQUIRE TWAT WIDE RiGeE: COVNTING CHAMMELS Bt N OPERATIOM IN RUM KODE HOWEVER , |F ONE OR BOTH CHANNELS ARE OPERATING CORRECTLY (cou\'—mnuci ESTABLISHED) A PERIOD OF !o slcouos ar Lts': mmbfls RoD wlTuDfl.AwAu. wmw rFURL SALT IS cnzcumrmd » auve:se— OCLUKRS Ar 12MW AS SHOWA ., WHEN FuwiL SALT IS MOT CIRCULATING THE FLUX AMPLIFIER GAINS ARE JNCEEASED BY. A 1000 AUD *RBVERSE " OCCURS AT 12 kKw, Sk DHH E-5T73483 AND RC+IF-D-3-R} , FALTOR OB 4. EEFuR_ ro DEAWING . D:HH-B-57332 FOR. COMDITIONS Y ZRQuikeD TO ESTABLISH COMPDEMCE . [ COMTREOL OO HLOLK DIAGKAM -~ SHEEY | oF 2 [O-HeeB- JISB L. REFERENCE DRAWINGS NO. OAK RIDGE NATIONAL LABORATORY OPERATED BY UNION CARBIDE NUCLEAR COMPANY DIVISION OF UNION CARBIDE CORPORATION " OAK RIDGE, TENNESSEE . LIMITS ON DIMENSIONS UNLESS OTHERWISE SPECIFIED: FRACTIONS £ mtfl NGLES & e MOLTEN SALT RIATOR BAPLEIMENT. BLOCK A GRAM T L6 1303 SCALE: wmoww CONTROL ROD BLOCK DODiAGRAM SHEET __Z,_ o‘ Fig. 2.6.3. MSRE Cq ontrol Rod Block Diagram. g — s o — 245 e, (7= JISHS 184 : i o { aseva. '8 4uq 18D ~ 155 : 186 189 188 suq. J'st'l.b J--.‘nu ToNIsGE EuSS-HARC-AT 4— . -l' g}os‘.‘:‘u‘r:::& _ e e J o //—-.VWW__. - T ™ i - - D.c. Ao n *> 4 \ —=s1rcC g S X1 o KIBLG f:flzb ZIsnD ToKIBGD ;f‘.m.o'n-c 3_1:;&&5!05:. SRS e AL ::u‘c‘a-AsA ":R..s’umt-aa:'uzcz-nk pLYD < - BIPSA . . ‘ . CLOSE WueY [CLDTh PERWDILLOSE WHRELE [CLO%% P“lfl.m M e e ‘_\‘—- _I_ ' ’ ¥ o> nswmn | €10 o> .5 M | ¢ 10 suc. o kAOR . R TeE i CRMTY cRM b2 | o] H l ;:nm'\ot- t KBIOE L . . T KZAGK Huzene y l ‘ _ i oKl G Kine Gr Frronn 2 KBk ]:; N N ; g o b 3 W 7~ j:\ /:E J ‘ T : _ l . , . T=xamea . jfusu , ICRzRsA : (k@115 J=xis2n TN Ekamim ; : “-x2as5n N _I_nzssa __]- - _,rnmuc. P AN . :J.:K\un jf.!(lszc j : P e :‘ TR Akusa Fuwse Fowmae _ ’ . i i v -lL ‘4 J 4 L ‘ ] —~ K240 ~¥X150A K150 ¢ ; _ — el - 7 ¥ ; |_c.\.u1c|-i-..b!AKE-_ i;mm MoToR bn\;} ! | i I w | \, ~ s Nt N 1] Iesaoativg RoD | | REGULATING oD ’6:)1 &% | (— ,(D:—" , {;‘ | AT Switen || Lt swirek | ( ~ | B R | | Jol L MmeHARIsM || MackAuism 3“ Z &l& '&‘5 &‘ =D M BAYTT &\u 183 Y ~ s B Biaiay™ ZMG - 289 189, . . VYV L . n:. 179 180, wé, 118, la b . 179, 1 97,100 &) 1] 184, IAS 151,188 pE 2102 ne, e e ::gus‘._“m‘_u ‘ ) po *2 goo »npor ; WL ERY WHTHDRAM Ay oo Z » . . oy kB —tEoL —=re= - 1 ‘ ‘ ~ N s . ’ CONTEOL ROD IMSERTED WHEW EMEvRGILED LEONIROL ROD REVELSE WHEW ENELGILED. REGULATING _ROGH _SHIM MoTor Brars _ . ; LUMET _ Swsitowm OFEF_WHEWN ENERGIZRED. : POSITIONING MOTOR ‘ I T T ROD GROVTE ACTURATOR SWITOH LT * ’ PORITION (PRONT Views) ] COMTALTS L evekhw] HOLD |witnDrAw] -OCAtion CHAKNDLE BNt o S =) LanT. wa) AL L ' X 194 | B (22 X 185 ), ELEM . CONTROL WMREWLK CIRLITE. $W. T o4 T [OWWS- 51010 (%) S X 184 WG, BEM, ROD CONTEOL GIEGUNT:+ M. | ag T DAwE- SIBT4 4 x 18 R4 2 REFERENCE DRAWINGS NO. . OAX RIDGE NATIONAL LABORATORY : OPERATED BY . " L ‘ ] UNiON CARBIDE NUCLEAR COMPANY d Yocu =zrid . . . . lezreH il pwir DIVISION OF UNION CARBIDE CORPORATION 3 |ocw ¥ 5740 = Pé-as e . OAK MDGE TENNESSER : i OLTEN SALT REALTOR & APLR\MENT, 8 | cHANGE NoTicd NE_3047 _ |ssoesliin | oFly LTS O DIMENSIONS Uniess | ™ " 1son N | CHANGE Motie& * 1411 B-r-&4 L7 {nl @3 - . - - PRACTIONS & e EMGINEERING BLEMENTARY. NO. REVISIONS | DATE apPo| APPD | : ROD COMTROL CIRCUINTS AT O EWITTED | DATE DATE: DECMALS % e SHERT 2 of B AN W ' . — 4 ANGLES 2 =7 §UB N DATE - DATE | APFROVED 1~ DATE - }U Mmi!i' D TE DA APPROVED DATE SOME; rers et APPROVED Fig. 2.6.4. MSRE Rod Control Circuits. 246 f ! ORNL-DWG 64-6082R4 ' SEE NOTE 2 _ 74, 175 7 182, 183 o 240 244 . 115-v AC—2H I -t { ¢ L J_ Ki93A | RxS-NCC1-a4 A~ THESE CONTACTS LOCATED IN Q-2609 FAST TRIP COMPARATORS ‘ T\ IN WIDE RANGE COUNTING CHANNELS. CONTACTS OPEN IF REACTOR PERIOD IS LESS THAN 25 sec, ( INHIBIT ROD WITHDRAWAL ) J_ K194 A 4 RxS‘NCCZ'A" 7(— CLOSED IN THESE CONTACTS OPEN WHEN WIDE RANGE OPERATE-RUN COUNTING CHANNEL "CONFIDENCE * ESTABLISHED MOOE OPEN WHEN DRAIN TANKS FDT-1 AND/OR 2 —[//I_ SHOW LOSS OF 4550 Ib OF FUEL SALT WoS 1002 $65=CLOSED WHEN FLUSH SALT TANK KBI396G _ KI93H |/ KI94H 22 B4 'S SELECTED 7T K195C I “CLOSED WHEN "CONFIDENCE" / 0 ESTABLISHED IN BFy CHANNEL RELAY CONTACT THESE CONTACTS Py SS-NARC-A2 LIN Q-2615 CLOSED WHEN WIDE SERVO CONTROLLER RANGE COUNTING | T “INSERT" ROD NO.4 SHIM REG. ROD CHANNEL “CONFIDENCE"| Ki86A . \ $228 ~l. 5190 Ji86F - 1 ASSEMBLY LIMIT EsTABL]SHED _ffl OPENS ON AUTOMATIC REVERSE MANUAL - SHIM NO. § REVERSE , ' - UPPER SWITCHES LOWER - "REVERSE" ACTUATE _ L T N sl L Ki75A \ INSERT" kae3a L. kairea . 7 < L xis2a T 'WITHDRAW _ _lekeaie INSERT T WITHDRAW | “INSERT" Ri% I?gE‘ELS'M‘T TO "ROD WITHDRAW" 77" OPENS WHEN SHIM REG. ROD NO.1 ROD NO.4 REG. ROD LIMIT " _ CONTROL CONTACTS ROD LIMIT SWITCH SWITCHES Sf= K182C CLOSED IN E2E 'F10. Rea- ane 3 ' ASSEMBLY CAM AT KA1B3D ;é L I KI34E . RCS- ] LOWER LIMIT foPERATE™ 4 == goseom S CLoseD wirH OPEN T I ol KA136G LL™ Mo SERVO "ON" SERVO["ON" ° WITHDRAW INSERT e L kaz40c _l/ks170€ | ROD NO.t | ROD NO.14 R CLOSED WHEN SHIM-REG. 71" cLoseo wiTH ' s RELAY CONTACT ROD ASSEMBLY CAM AT "SERVO" ON son | IN Q-2615 UPPER LIMIT 2 k240 | KeH ° SHIM NO. 1 RySS-NARC-Al _| SERVO CONTROLLER I i f L Ki3eA 1 KiT4A : ACTUATE T~ WITHDRAW ROD NO.1 } : ; Z . CLOSED ONLY =T~ GROUP WITHDRAW wITHDRAW INSERT [ WITHDRAW ' // INSERT WITHDRAW IN"START 5208] SHIMS NO. 2 _|/ K240F _lek240a RIVE MOTOR | | | /s MODE AND NO.3 77— OPENS WHEN SHIM 71— OPENS WHEN SHIM o ;oo i y SHIM LOCATING MOTOR $218 | ACTUATE REG. ROD LIMIT SWITCH REG. ROD LIMIT . | ~ $22A CAM AT UPPER LIMIT SWITCH CAM AT L POSITION | C v =1~ GROUP ROD —L UPPER LIMIT TRANSMITTER WITHDRAW Lz kiron ‘_mg:&%lm _lz kar700 S \MECHANICAL DIFFERENTIAL (MANUAL) >f— CLOSED WITH SERVO "ON" 7T~ CLOSED WiTH SERVO “ON" SERVO "ON" CLUTCH-BRAKE CLOSED WHEN NOTES — Hi S#- k2284 | RoD DRIVE UNIT SHIM LOCATING 2l (a9 [ NOT AT uPPER CAM ROTATION ROD NO. { MOTION WL K241A T LMt | (cLockwisey | ™ | (witHDRAW) + | MOTOR ROTATION 71— OPENS WHEN SHIM REG. / kie3c (INSERT) ROD LIMIT SWITCH CAM = 6PENS FOR R AT LOWER LIMIT 7 SO_E,N ,NS%RT ob AND VICE VERSA FOR COUNTERCLOCKWISE CAM ROTATION 2. THIS DWG DOES NOT SHOW DYNAMIC BRAKE CIRCUITRY KI5 K(76 K182 K183 FOR ROD NO. IN CIRCUIT NO.179 THIS RELAY, WHEN ENERGIZED, THIS RELAY, WHEN THIS RELAY, WHEN ENERGIZED, THIS RELAY, WHEN ENERGIZED, < KiTa OPERATES SHIM LOCATING <, ENERGIZED, OPERATES OPERATES SHIM LOCATING OPERATES ROD DRIVE MOTOR 3. SWITCH AND RELAY CONTACT ASPECT (OPEN OR CLOSED) ON MOTOR IN REG. ROD LIMIT ROD DRIVE MOTOR IN MOTOR IN LIMIT SWITCH INSERT IN "INSERT" DIRECTION|CAM THIS SKETCH IS FOR FOLLOWING CONDITIONS : SWITCH. WITHDRAW DIRECTION ROD WITHDRAW DIRECTION, DIRECTION, CAM ROTATES ROTATES WITH SERVO 'JoN* O a. SERVO "ON", ZERO ERROR SIGNAL . CAM ROTATES CAM ROTATES WITH n b. REACTOR SYSTEM IN "OPERATE-RUN" MODES m SERVO “ON" O ¢. REGULATING ROD BETWEEN LIMITS d. REACTOR IN STEADY-STATE NEUTRAL ¢. "CONFIDENCE" ESTABLISHED IN BOTH WIDE : RANGE COUNTING CHANNELS GROUP ROD REG. ROD LIMIT ROD NO. 1 REG. ROD ROD NO. 1 WITHDRAW SWITCH ASSEMBLY WITHDRAW LIMIT SWITCH INSERT 4, ANY ONE OF THE THREE CONTROL RODS MAY BE DESIGNATED WITHDRAW INSERT "ROD NO.1", THIS NUMBER HAS BEEN ASSIGNED TO THE ROD WHICH IS INTERCONNECTED TO THE SERVO CONTROLLER MSRE Shim-Regulating Rog Control Circuits. Fig. 2.6.5. MSRE Shim Regulatihg Rod Control Circuits. -, N —— | 247 ORNL~-DWG 66-5716 15V AC = < —J: KA1B3A £ KA183D —HKAITE6A KBIS3B KBIB3A | KBI7T6A [: L L Ak AN [ KB!183C KAIT6C L 1y \ Al Al - 300uf l KB183D KA{76D I +_| " 280v ~ 2 I SERVO 508 500 MOTOR NEUTRAL 5 L F Fig. 2.6.6. Circuit Diagram for Regulating Rod Dynamic Brake. LIMIT SWITCH CIRCUIT, TYPICAL OF ALL LIMIT SWITCHING ORNL~ DWG 66-9430 CIRCUITS NO. 232 TO 239 CIRCUITS NO. 1uucn. , . 174 TO 178 INCL 184 185 C t ( ! _[ l MANUALJ— ——— —_— s522C "REVERSE"| 522D conFIDENCE" W —_ f— REACTOR PERIOD 'J."f»'«‘fl'fi’ A "REVERSE" AND MODE | 5200 s 21D INSERT INTERLOCK CONTACTS | —_— - TO ROD NO.1 T CIRCUITS K186 C Ki86 D e LmiT swiTch, - INSTRUMENT -4~ OPENS AT "REVERSE" LIMIT S21A INDIVIDUAL :[: I 1o L SHIM ROD ACTUATE 1840 | , K185D], S SWITCH CONTACTS, A~ 7 SEE BELOW _| K84A Ki85A s20C _— —_— KI7TA K178A KI74D K1i74C _— - GROUP WITHDRAW K234 A RELAY A K238A 1, CONTACT 77— LOWER LIMIT K 2354 SWITCH RELAY K239A Lz CONTACTS, K232A K236A | opep vl = PHASE PHASE | :[: LIMIT SWITCH SHIFTING SHIFTING RELAY CONTACTS CAPACITOR CAPACITOR K 233 A K 237 A | { X K 584 C K 185¢ OPENS FOR ENERGIZE RELAYS ROD "INSERT ENERGIZE RELAYS LIMIT SWITCH TO WITHDRAW TO INSERT RELAY ™~ / T ; K177 K178 K184 K 185 DRIVE DRIVE MOTOR MOTOR ¢ { ¢ 12N9 ROD NO.2 ROD NO. 3 ROD NO.2 ROD NO.3 INSERT WITHDRAW INSERT WITHDRAW . ' J L NO.2 NO.3 ' Y. v WITHDRAW INSERT CONTROL ROD SHIM RODS 2 AND 3 SHIM RODS 2 AND 3 DRIVE UNITS INDIVIDUAL SHIM ROD ACTUATOR SWITCHES NO. $19, S20 AND S21. 22 MANUAL , ON CONSOLE GROUP SHIM ROD ACTUATOR SWITCH S CONTACT POSITION CONTACT POSITION CIRCUIT NUMBERS INSERT | "OFF" | wiITHDRAW NO. REVERSE(INSERT) | HOLD { WITHDRAW | NO. S19A, S20A, S21A 0 o X S224 o o X S198, 5208, S2iB 0 X o s228 X 0 0 S19C, 520C, S2iC 0 X 0 s22¢ X 0 0 S19D, 520D, $21D X 0 0 $22D X 0 0 Fig. 2.6.7. MSRE Control Rods 2 and 3. Circuits. C 8¥C o O “CONFITENCE" REACTOR PERIOD WRC CEANNEL { OREATER THAN 25 SFC, . 1 (WRC CHANNEL MO. 1) N "CONFIDENCE" REACTOR PERIOD WRC CHANNEL JOREATER THAR 2 SEC. 2 (WRC CHAMMEL XO. 2) — [ eams A | sELECTOR 1n PFT FOSITION "CONFIDENCE" "co! " ESTABLISHED. 28 TARLIEHED IN WRC IN WRC CEANNEL #1 CHAKREL #2 A NO AUTOMATIC "REVERGE" REACTIOR SYSTEM IN EITHER "OFFRATE" OR "PREFILL" MOLES FEMAINING CIRCUTT GOVERNIIG INDIVIDUAL CONTROL ROD WITHIRAWAL INDIVIDUAL WITHIRAW FAST TRIF COMPARATORS IN ORNL-DWG 66-9074 48v-g¢ 193 194 195 L4 4h. » — . Llsi3A L sise L com SELECTOR "RILSE AN AND T CALIIRA WITe TI0N 8 H SWTICE RATE A on 100 - Q-261h "CALTHRATE-OFERATE " 1 RATE METFR TH SHTICH, HSS-NCC)-A, i WISE" POSTTION L_______J CICSED IN "OFERATE" 1 POSTTTON = 1 1 | 1 : CILOSED WHEN BF CHANMNEL COURT RATE THESE CONNECIORS USED TO FIDG THDIVITUAL Q- | ICEELS 10 cps UNITE INTO CONTROL SYSTEM i AND CARRY ALL POWER AND 1 SIGHAL CORNRECTIORS IN ™IS CIRCULIT ADDITION TO THE TIERTICAL 70 CONTINUITY LOOF SBOWH THAT OF WIDE RANGE COUNT- CLOSED IF COUNT RAYE [ — EXCEFIS 2 cps el | N\ —"(:l_ —- _‘.\_4 CLOSED IF COURT RATR LESS THAN 50,000 cps A WITE-RANGE COUNTING CHANNEL, 8 TOTAL. 2.6.8. ING CHANNEL M. L (#193) e - Ki93e KI94B KI95B Kig3 Ki94 K96 " vIE RAms WIIE RANGE momrTIVE S, COUNTING CHANNEL #1 COUNTING CEANNBL #2 COUNTING CHANREL — s CONFIDENCE CIRCUITS MSRE Control System Confidence Circuits. 6¥C 78% FULL SCALE - ORNL-DWS 88-3218 rempeRaTURE | 1557100A1-2 | THESE TEMPERATURE SWITCH CONTACTS SwiTCHES | TSS-100A2-2 ¢ LOCATED IN FOXBORO MODEL 63 S. CON TS5-100A3-2] DUAL SWITCHES RECEIPT OF A SCRAM SIGNAL. T % éKMOfiB % {KEO&B ¢ | A\ CONTACTS OPEN WHEN REACTOR OUTLET TEMPERATURE EXCEEDS 1275° F CONTACTS QPEN WHEN REACTOR 3 ) C 1 lfifi-NSCi lRSS-NSCZ J_RSS-NSC3 A4 A4 A4 POWER { FLUX) EXCEEDS SEE NOTE 2 K248 K249 K250 K202 (— REVERSE ROD "REVERSE" ON SCRAM 2 OUT OF 3 REACTOR FLUX AND TEMPERATURE INPUT DE-ENERGIZED WHEN ANY 2 OF 3 INPUT CIRCUT CIRCUITS FOR CONTROL ROD "REVERSE REACTOR OUTLET TEMPERATURE PUMP BOWL LEVEL INPUT INSTRUMENTS INDICATE CIRCUIT TEMPERATURES GREATER THAN 1275°F 5 1 KS108C K207C _L* “J‘R‘S‘NCCPAB l‘ “lRIS'NCCZ'B THIS CONTACT & CLOSED WHEN NeR NCEDe i CLOSED IF FUEL REACTOR OUTLET RyS-NCC1-A8 RyS-NCC2-28 " THESE RELAY CONTACTS, R,S-stc., K248A _[Kk248C _K24SC SALT LEVEL EXCEEDS TEMPERATURE IN Q-2609 FAST TRIP COMPARATORS IN WIDE RANGE I I I 8% FULL SCALE ON EXCEEDS 1275°F COUNTING CHANNELS, SEE NOTE 1 K294 | k2504 | K250C LEVEL INSTRUMENT Kig36 K 1940 NOTES : 1.{a) CONTACTS R,S-NCCi-A8 AND CONTACT MATRIX TO ANY 2 OF 3 CONTROL RODS ARE SCRAMMED PRODUCE "REVERSE" IF CLOSED WHEN _*" WIDE RANGE COUNTING CHANNEL "CONFIDENCE" EXISTS K203A, £ CLOSED WHEN REACTOR POWER {FLUX) EXCEEDS 12 MW (OR kW) N KB(3SC THIS CONTACT CLOSED IN "START" MODE OF REACTOR OPERATION K186 CONTROL ROD “REVERSE" QUTPUT CIRCUIT 2.6.9. MSRE Control Rod "Reverse" Circuits. ReS5-NCC2-A8 CLOSE WHEN REACTOR POWER (FLUX) EXCEEDS L5MwW {b) CONTACTS RxS-NCCI-A3 AND R.S-NCC2-A3 CLOSE WHEN REACTOR PERIOD 1S LESS THAN 5sec 2. WHEN FUEL SALT PUMP MOTOR CURRENT IS LESS THAN 55 AMPERES TRIP POINT 1$ REDUCED TO 9kw 0sT 251 ORNL-DWG 64-635 DATA LOGGER RANGE l CHANGER POWER SUPPLY Q-995 COMPENSATED ION CHAMBER Q-1045 TO INLET TEMPERATURE NOTE: Q-2605 IS OPERATIONAL SENSOR AMPLIFIER d TWO PEN ROER _/—' RECORDE FOXBORO i RANGE | LEVEL E/1 CONSOLE CHANNEL POWER Q-2605 SUPPLY SELECTOR SWITCH 2008 Q-995 AMPLIFIER =] S =N o ] S Q-2605 0-260 COMPENSATED ‘ NO RANGE —l/ ION CHAMBER M SEAL Q-1045 FLUX CLAMP FOXBORO ‘ £/1 TEMPERATURE SERVO DEMAND DRIVE UNIT o oy CONSOLE : . 10 QUTLET COMPUTED - TEMPERATURE FLUX OEMAND SENSOR J COMPARATOR |~ RUN PERMIT Q-2609 $ v AR 2 tos il X AIODE LISHTS xeaagn . f20/ L2803 Lot S ELY 2206 LES? arse SO— KSOS5D (Com. ) ST Sy TK 22e9 274 S e 74 2V Ti- WARC-AY n a ROOK wITNORA AMIERY AAN, ALUN. b Re _r - MARE- A208¢C (Com.) INCET 3 ourLer Feux wirnoraw rearr. TRACH, D& AeAwD nee’s uem-riee "k o-woe R »EV e v 2208 Ral-WARC-Ad cvtnss| cuue| SELE 242 pry INSGRT | /.4 Fr’ 4 7L 1 -32v 1)” ; g -E AL SEAL LroNy “""“_"T P Pry RANGE SWITCN ¢|‘ ‘ | i Tt | [~ ! E i oUN .s:wrr:#¢ w‘m——o—r v . }s:ur:rfp CNANMEL. LIGNT ‘ ‘ 2c l fc K#os : CAAINNEL SELECTOR SW. VOLTAGE ; rerrP. AOOE RELA S 1 DISTRIBUTION . _ CMP. A v 1 BUSES : I T PV o 4 .scat_ ; 7o ppud *2 1Suw SecélTon od s AR 2OF HANCE RELAY - g a8l 2 CAWCR R-2 ?4.0 - _I RK'NAQC—' Al To pud "L /S -22y ; LANEE RELAY L00 ¥ , - ' | MR 7 FOR INFORMATION ONLY e “:.:... P — "—... — —— mmfl DO NOT USE FOR r : | MAINTENANCE OR l [ l CONSTRUCTION I HEVAL/ OV & ~ov 45V E-Z5W wEY € WS 6.9 VAC WALT #66, VoL T, 65, VOLY. £€G. I Mo EE. UG, INITEUMENT APPLCATION DikGy. oA ded T TEANSF. RC[3-17-1 RCI3-16+1] RC/3-15/ .-mv: aul.u' yACH. 2 ) I R HALS- A RUARC- Y RuARY - A | [ EGEND Auto. Eod lontrodier Dwr. 28 l”nwy LLIAESH | ] .3 Ao, Lod Controlier Owr. £/ Wairig LTS A —_— -y — — —— .7_..__....__] 3 00 ORIV G Migh Qualify Ground Lo 2o Cow, Block D/ v e 1 REFERENCE DRAWINGS WA NO. ORAWER _R-1 5 W OV beg. Ground - NARC- A2 S Y EN.FRAY ”EC 232V W 2OV Batlery Grownd 4 [CrNGD. ATIYZAIA TeasTT 9% :n-; Py pe . ¢ Drower Conmecrtor AU T og;?ufrag/dcgg ; f(OL LER R2we fA0m 3000 TO Fo0 CA "¥7 - ; ‘ 3 |CcHNGD REF DG Nos. Ao &'s TD AC‘s)-27-47 i ¢, Extarnel! Connecler | & |etoles Computod Fiur Dovopad Woder Oniont ey | |_[2voo 220edzes acceo w288 kwvsleny |xeo | WNSTRUMENTATION ANO CONTHOLS DIVISION NO. REVISIONS DATE Em APPD = OAK RIDGE NATIONA& LABORATORY a— T P R — ] e ] m—— € £ Macoomn 10-5-68 |\ F I } 215 ¢ ‘ ‘M_“wou CARBIDE NUCLEAR COMPANY Wi [} ;'-'I .7.:-'. A it ) . St R amrnan L Fig. 2.6.11. MSRE Automatic Rod Controller Circuit Diagram. ] i | RESET AMPLIFIER - (INTEGRATOR) 253 ORNL- DWG 66-9304 SUMMING AMPLIFIERS: OUTPUTS ARE NEGATIVE SUM OF INPUTS FLUX DEMAND 8 SIGNAL TO SERVO PILOT RELAYS COMPUTED FLUX DEMAND ROD DRIVE MOTOR 7 =FUEL SALT TEMF‘ERATURE. CORE INLET L =FUEL SALT TEMPERATURE, CORE OUTLET ¢ =NEUTRON FLUX SPEED SIGNAL FROM TACHOMETER [7‘;]5 = SET POINT, FUEL SALT OUTLET TEMPERATURE 0 Fig. 2.6.12., Diagram of Regulating Rod Servo Controller. GEARBOX LOWER LIMIT SWITCH RCD DRIVE MOTOR, SERVO OR MANUALLY CONTROLLE CONTROL ROD—"] =Y o U T SHIM LOCATING MOTOR, OPERATOR CONTROLLED GEARBOX NOTE: AS REDUCED TO PRACTICE THE CONTROL ROD MOTION IS REPROOUCED IN THE CONTROL RCOM AND LIMIT SWITCHES ARE ACTUATED BY THE REGULATING ROD LIMIT SWITCH ASSEMBLY. SEE DIAGRAM. e REGULATING ROD SPAN,Ay, ¥ ~i ) —_— REGULATING ROD 0 LIMIT SWITCHES SYNCHRO POSITION TRANSMITTERS SCRAM CLUTCH GEAR REDUCER GEARBOX ROD DRIVE MOTOR: OPERATED BY ROD CONTROLLER ONLY WHEN IN SERVO OPERATION AND BY ROD ACTUATOR SWITCH IN MANUAL OPERATION ROD DRIVE UNIT i - g 2l A ORNL-DWG 64-622R2 REGULATING RCD LIMIT SWITCH ASSEMBLY IN INSTRUMENT CABINET ROD POSITION TRANSMITTER r————erwy, i e SYNCHRO CONTROL BALANCE TRANSFORMER MOTOR CLUTCH-BRAKE: 0. IN SERVO OPERATION THE CLUTCH 1S ENGAGED AND THE CAM IS COUPLED TO THE BALANCE MOTOR b. IN MANUAL OPERATION THE OUTPUT SHAFT IS LOCKED AND THE BALANCE MOTOR DECOUPLED UPPER REGULATING ROD LIMIT SWITCH WITH MECHANICAL STOP CALIBRATICN CAM AND LIMIT SWITCHE}, SHIM LOCATING MOTCR, OPERATOR CONTROLLED WITH CONTROL ROD ACTUATOR SWITCH. USED DURING SERVO OPERATION ONLY MECHANICAL OIFFERENTIAL SLIP CLUTCH GEAR BOX FOR SPAN CHANGE GEARS LOWER REGULATING ROD LIMIT SWITCH REGULATING ROD POSITION TRANSMITTER {SYNCHRO} | | { | | I | | | | | | | | | l | I I { ! i ] CLOCK CAM ROTATION EQUIV. TO: B4 0. WITHDRAW ROD NO.{ | =% AVAILABLE TO SERVO b. INSERT LIMIT SWITCH CONTROLLER WITH SPAN (DECREASE y,) | ROD REG. ROD SWITCHES ! / STROKE AT ¥, } /‘z_ Jd 9 (- A COARSE FINE Lz i _ REG. ROD POSITION /‘ A1 SHIM ROD INDICATOR {RELATIVE POSITION TO SPAN LIMIT INDICATORS SWITCHES) o - Bk CONTROL CONSOLE & Fig. 2.6.13. Regulating Rod Limit Switching = Operational Diagram. vST f | | i i ' i | 255 ' PHOTQ 62304A REGULATING ROD POSITION TRANSMITTER {SYNCHRO TR SLIP CLUTCH TORQUE ANSMITTER SIZE 31) SPAN CHANGE | SPIRAL BEVEL » CAM DRIVE GEARS SHIM LOCATING MOTOR ' MECHANICAL DIFFERENTIAL SERVO , - } il B . 48 || ELECTRO-MECHANICAL AMPLIFIER |~ | SEulmeuse) L TR B %4 CLUTCH-BRAKE SEE NOTE ' , , o L = ) | ' ; . CALIBRATION MOTOR DIAL ' BALANCE 256 Rod Limit Switch Assembly ~ Side View. Regulating 015. 6 2 Fig. PHOTO 62303 K wn ~J 258 PHOTO 62305A Fr LIMIT SWITCH (SEE NOTE 2) NOTES: {. REFER TO: MSRE DESIGN AND OPERATIONS REPORT, PART V, REACTOR SAFETY ANALYSIS REPORT, ORNL-TM-732, AUG 1964, PAGES 108 TO 113 INCLUSIVE FOR APPLICATION IN MSRE. 2. THIS ILLUSTRATION SHOWS FOUR (4) LIMIT SWITCHES SO THAT INTERMEDIATE SWITCH POINTS BETWEEN EXTREME LIMITS CAN BE PROVIDED. IN THE MSRE ONLY TWO (2) ARE USED Fig. 2.6.17. Regulating Rod Limit Switch Assembly — Underside View. 259 ORNL-DWG 66-4105R ELECTRO-MECHANICAL BRAKE TO REDUCE EFFECTS OF GEAR BACKLASH AND COASTING OF THE SYNCHRONOUS MOTOR, BRAKE RELEASES WHEN SYNCHRONOUS MOTCR IS "ON" CHANGE GEARS 961 B SYNCHRONOUS MOTOR [ 48 {1.5rpm} - SLIP 30+ mm} CLUTCH LIP CLUTCH | ° =~ 721 MECHANICAL (IDLER) 0 L = DIFFERENTIAL - - §4 AC SERVO MOTOR Ty swiTCH MAX SPEED 27 rpm ' [ T AR L T 1 40t 30° PER inch - OF ROD =3} 43 MOTION N2 | o 8~ —ELECTRO Q4 P MECHANICAL = CLUTCH- BRAKE \\\\\\\\\ 5° PER inch NSl OF ROD MOTION TN szt LIMIT SW|TCHES\® é 30° PER inch OF ROD MOTION gggcm:fim SYNCHRO TORQUE SYNCHRO . TRANSMITTER CONTROL SIZE 3t TRANSFORMER CALIBRATION DIAL SIZE 15 Fig. 2.6.18. MSRE Regulating Rod Limit Switch Assembly, Drive Train Diagram. 1.5-rpm SYNCHRONOQUS MOTOR ({DUMMY SHIM LOCATING MOTOR} TO MANUAL CONTROL SWITCH, SHEM ROD NO.1, ON CONSOLE —_—pm- MECHANICAL DRIVE CONNECTION ——wee——p= ELECTRICAL CONNECTION Q INPUT _ g CALIBRATION b —e=- SPEED CHANGE; oUTPUT - b DIAL SLIP 2 CLUTCH S —— <4 { ELECTRO-MECHANICAL CLUTCH-BRAKE { > - SIZE 15 CONTROL TRANSFORMER CLUTCH ENGAGED ERROR SIGNAL~——_ WHEN ROD SERVQ IS "ON" AC SERVO AMPLIFIER TO STATOR WINDINGS OF SIZE 31 SYNCHRO IN ROD DRIVE Fig. 2.6.19. MSRE Regulating Rod Limit Switch ELECTROMECHANICAL BRAKE, RELEASED WHEN DUMMY SHIM MOTOR 1$ "ON" / T0 SYNCHRO RECEIVER MECHANICAL DIFFERENTIAL CHANGE ORNL-DWG 66-4104R SLIP 2 . 1 1 / GEARS \ CLUTCH 2 _.U LIMIT SWITCH CAM SIZE 3 SYNCHRO TORQUE TRANSMITTER { REGULATING ROD POSITION) ON CONSOLE Assembly, Block Diagram. 09¢ 261 GO MHa Lnput Signal. omfl. DWG. 67-1584 o £, s v acd ‘ o~ 7o 788 I NOTE THAT FIRST STAGE IS BY-PASSED. Fig. 2.6.20. Modified Brown Amplifier (Unused Wiring not Shown] o O X2 ? 275V | 2285y p > 22Mep. 22Mep. f D;;:\:,—J b : T a—— i 922 . / o . - : -..-. :: 2 - :’-— 7 . 3 s 2 L / Meg. o ¢ X: Xz ¥ ¥ Y /500 'E, N J/Jf Servo - \ A7olor N /1 dz2pf ~ 262 /(MQ](; S| (we-mci-a) AND S2 (wwwica-a) ARE INPUT CHANMEL SELECTOD SWITCHES LOCATED ON COMNSOLE 6L CHWB 40068 41995 ¢ 41632 ' ‘ . @.B VA, ‘ . * Qv ) ' l ‘ l l.,_ J." 2.4 MODE PERMIT cuT. 4124 ROt SEAL CiRewT ' # T Fag - ‘ wion el . :iesu AL o MR- STMe { Doukh ATREL A B AW T T e A ne - Ko Al rl.‘l.o'. al ) K210% & Fnu.y ot E L vy et ; S . . i =S A e n i i o) | SiacE 142 52 | viAue 142 ‘bi-"‘fihc.! 3 S| PAGE 4 ’ o ° 1:0: e - o % " ° 3 "-6 '1.- gl TR countcTion 1 iNTREC OuslcTion . AL CRHATORS AR VK WIRIEG, WIRIN G & e - e = o . ° MOLTIPLIBR, |- = — jOF EXPOMENT ‘ | SeLector SELECTOR _ | T e e - - e RANGY . ‘ Ktos & 7] Tue:a B2 DiICATD “ WS : Y ¥ NPT ek 10 . 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GECWTET ST o] [eumeesran 3 ()} w “PARG ' GHAL: SLEM. ¢ ROD cHTRSL CRANITY: .1 ® 8 -t - 47924 ko othe 4 (v) n SPARG ‘ MUCLEAR WAVTEVMRUT APPLILATI®N DIAGRAM [0-488.4091% o oipo :t‘:; : ::., :::: L ' AVIOHMALIC B9 CHITEALAR - CIRGUT DIAGEAM (RE3-18-89 . REFERENCE DRAWINGS OWG. NO. oibo oqpo |1 X ne Kios TP CKT.* v To cxt. "\l O oxr, 183 & (W) X SP AN ; att sSeE Bee O-HW-B- §7D2S e — i Diuk-©-91324 D-Wi-B-37334 : MOLTEN BALT RPACTOR wXPGRIMENT -M. _ AUTOMATIC T € | 7 We e0* Y e LoD * 7 M 1' EOD COM QOLL R HIGK QUALITY GROUND . CANGE SWITCHING AND & RCI3-3-104 WiAS & -260, ail _I_|A0DED CowsolE NerirT el oml W 2 ov tte. atound RANGE SEAL ClRCuLITS . INSTRUMENTATION AND CONTROLS DIWMISION NQ, APPD ! A e e R W2 ov sATTERY GROUMD OAX RIDGE NATIONAL LABORATORY TWEIS (5-4-0d : ommrED Y X UNION CARBIDE NUCLEAR COMPANY T — | — r-—'_—'—fi‘“‘ ‘ r‘-T-—_t-_ : e T Fig. 2.6.21. Automatic Rod Controll|r Range Switching and Range Seal Circuits. 263 2.7 CONTROL RODS AND ROD DRIVES 2.7.1 General Arrangement The control rod drive unit and its housing are shown in Figs. 2.7.1 to 2.7.3. Figure 2.7.4 is a simplified electromechanical diagram which shows the functional location of the essential elements which comprise the drive train. The gearing and the clutches are inside a cast-alu- minum gear box. The drive motor, the two position-transmititing synchros, and the position-indicating potentiometer are mounted on and outside the gear box with thelr shafts carrying their drive gears projecting inside the box so as to mesh with the appropriate gears in the drive train (Fig. 2.7.2). The gear box subassembly, which includes the position transmitters and the clutches, is located at the upper end of the drive unit in an effort to keep the radiation-sensitive components (electrical insulation and lubricant) as far from the reactor as feasible. Figure 2.7.5 is a diagram of the gear train and the clutches. The worm and gear set is of somewhsat unorthodox design, if compared with typical standard prac- tice for this type of gearing (see Sect. 2.7.9.10). The other gears are conventional. The rod is scrammed by interrupting current to the electromechanical clutch. During scram, the driven element of the overrunning clutch is free to rotate and, except for a small amount of friction and inertia, does not interfere with rotation of the output sprocket in the "rod insert" direction. The electromechanical clutch and the overrunning clutch provide parallel power transmission paths between the motor and the output sprocket, The arrangement is such that the overrunning clutch transmits motor torque in the "rod insert" direction only and can be used to ap- ply motor torque to the drive sprocket in the event that a rod sticks or binds following a scram. If external torgue is applied to the output sprocket in the "rod withdraw" direction of rotation, the overrunning clutch provides a solid mechanical coupling between the drive sprocket and the input side of the drive train. The worm and gear set are in- herently self-locking with respect to torque in either direction origi- nating at the output sprocket. This combination of overrunning clutch and worm and gear set prevents rod withdrawals by upward forces applied to the control rod or by a torque applied to the drive sprocket. The drive unit housing, with the drive unit secured thereto, is atbached to the control rod thimble by means of a flange welded to the bottom of the housing. Figure 2.7.6 is a photograph of the rod thimble, vhich extends into the core wvessel, and shows the mating flange. The radial slots in the rim of the thimble flange mate with pins in the housing flange and are required to ease the problem of orientation dur- ing remote maintenance operations., The milled slot in the face of the flange accepts the T-shaped flange fitting, which is cap-screwed to the rod drive tow block (see Figs. 2.7.19, 2.7.20 and 2.7.14). It prevents the rod from twisting when it is being detached from the tow block dur- ing remote maintensnce. Figure 2.7.7 is a photograph of the subassenmbly formed by the thimbles and the graphite sampler taken before installation 264 on the reactor vessel. This illustration also affords a good view of the lower, stationary halves of typical thermocouple disconnects de- signed for remote handling., Figure 2.7.8 shows this subassembly mounted on the reactor vessel; Fig. 2.7.9 is a line drawing of the control rod drives and rod thimbles on the reactor vessel. The rod drives are off- set radially to make room for the graphite sampler tube (not shown on this sketch), which occupies space on the vertical center line through the core vessel., Flgure 2.7.10 shows the top of the control rod drives installed on the reactor. This picture was taken looking down through the access hole in the top of the secondary containment cell. The electrical jumper cables and cooling air hoses with their disconnects are visible in this picture. ZElectrical interconnections between drive units and junction boxes on the wall of the reactor cell are made with flexible jumper cables. Each drive unit has its individual cable as- sembly, which is designed for remote handling. The wires making up the cable are designed for high temperatures and use radiation-resistant insulation (see Sect. 2.7.9). The wires are tightly bundled by means of heat-shrinkable plastic tubing. This wire bundle is sheathed in a loose-fitting, spirally wound stainless steel hose to give mechanical protection. The fittings at each end use ceramic pin and socket inserts of standard pattern in shells and receptacles which have been designed to meet remote handling requirements. The interconnection cabling and junction boxes are described in Sect. 2.1. 2.7.2 Position Indication Continuous indication of rod position is provided by two synchro torque transmitter-receiver pairs, one "fine" and one "coarse." The location of the transmitters on the gear box is shown in Fig. 2.7.2. The "coarse" rod position transmitter rotates 5° per inch of rod travel., Since this is less than one full turn for the maximum rod travel of 60 in., the indication is unambiguous. The "coarse" position receivers, one for each rod, are located on the main control board. The "coarse" transmitter slso supplies the ac error signal to the synchro control transformer in the torque amplifying rod position follower. This unit (see Fig. 2.6.20) drives the potentiometer which provides the rod position input signal to the logger. On rod 1, the same ac signal is used as the input to the Honeywell servo amplifier in the Instru- mentation and Controls drawing Q-2586 shim regulating rod limit switch assembly. This device is discussed in Sect., 2.6, The "fine" trans- mitter rotates 60° per inch of rod travel and is expected to be capable of resolving incremental sprocket chain motions to within +0,050 in, Since both the "coarse" and "fine" synchro transmitters are geared to the sprocket shaft, they indicate sprocket shaft rotation and do not take into account changes in rod length caused by thermal expansion, stretching, etec. In order to locate the control rod as accurately as possible with respect to the reactor core, a single-point, pneumatically operated, position device is employed. The position sensor consists of an air nozzle at the bottom of the control rod which carries the flow of rod cooling air from the hollow inside of the rod to the thimble. When the rod is at the bottom of its normal stroke the nozzle is op- 265 posite a flow restrictor built into the thimble, The increase in pres- sure drop caused by the restriction is the position indication. The nozzle and restrictor are shown in Fig. 2.7.11l, and the schematic dia- gram of the pressure measuring instrumentation is shown in Fig. 2.7.12. This device is manually opersated and is used to check the zero readings of the position-indicating synchros and, inferentially, provides in- formation on how temperatures and stresses produce small changes in the relative position of the rod with respect to the thimble. 2.7.3 Shock Absorber The shock absorber is a development of the Vard Division of Royal Industries, who built the drive units. It uses the general principle of a typical hydraulic shock absorber but differs in that the working "fluid" consists of 3/32-in.-diam steel balls, Figure 2.7.13 is a vertical cross-section view of the shock absorber installed in the drive unit. Referring to this figure, the piston is the knob, which is an integral part of the plunger. The latter is a tubular rod which is threaded into the carriage and which commects the control rod tow block to the carriage. The closed cylinder, partially filled with steel balls, travels with the carriage and is positioned relative to the carriage (and the plunger) by the buffer return spring. At the end of a scram the bottom face of the cylinder strikes the stationary steel blocks which are bolted to the housing flange. The plunger continues to move downward and is decelerated by the forces developed by the springs and by the flow of the steel balls around the knob on the plunger. Shock=-absorbing characteristics are adjusted by changing either the spring constants or the preloading of the buffer return and ball reset springs, or both, by changing the quantity and size of the steel balls, and by sizing the knob on the plunger. A stroke of from 2.75 to 4,00 in. is considered satisfactory. During testsl of the prototype, the shock absorber performed consistently and provided a stroke of 3.4 * 0.2 in, following rod scrams from a height of 51 in. This produced an average deceleration of 6.2 g. 2.7.4 Cooling Air Flow and Temperature Monitoring The drive is provided with two separate flows of cooling air. The first is conducted into the thimble by means of a thin-walled tube that projects into the stainless steel hose which supports the poison ele- ments of the rod. This flow of air exits through the nozzle at the lower end of the rod (see Fig. 2.7.11) and returns up through the an- nilus formed by the outside of the rod and the inside of the thimble. The second air stream is admitted st the top of the rod drive housing and flows downward within the housing. ThlS air flow is counter to the first flow and prevents heated air from the thimble from rising into the drive unit. Both streams are dlscharged into the reactor cell at the upper end of the thimble, ~ Two bimetallic thermostatic switches are mounted on the support colum of the drive unit approximately 8 in. above the lower sprocket. AMSR-64-7, Feb. 10, 1964 (internal memorandum). 266 Their contacts are in series for redundancy and are set to open at 200°F. Switch actuation is annunciated in the control room; no control action results. These switches (Fig. 2.7.14) were added to the drive units after they had seen service during the initial critical tests and low=-power runs of the reactor; hence they do not appear in the photographs of the drive unit assembly. Their purpose is to signal the control room that the drive unit is in danger of being subjected to damaging temperatures, a condition which could result from loss of air flow into the housing, excessive thimble temperatures, stoppage of the exhaust line, or ex- cessively high ambient cell atmosphere temperature., The switches are described in Sect. 2.7.9.9. A second, or backup, method of checking temperatures within the rod drive is shown in Fig. 2.7.15. This method uses the temperature coefficient of resistance of the cooling fan motor windings (part of the rod drive motor assembly) to measure the temperature within the rod drive unit housings. The fan motor field windings typically have room- temperature resistances of 520 ohms. Copper has a temperature coef- ficient of resistance of 2.18 X 107> ohm/ohm-°F over the temperature range of interest. The slightly more than 10% change in resistance for a 50°F change in winding temperature provides more than ample sensitivity. Periodic measurements made during reactor operation showed that the de resistance of these windings gave a good linear correlation in following in-cell air temperature. The duty cycle of the rod drive motors is ex- ceedingly light; for example, the servo motor was "on" for a total of 51 sec in a 2-1/2-hr period with the reactor at an intermediate power level and in servo control of the outlet temperatures. Manual shimming is an infrequent operation and requires only a few seconds to accomplish. In addition, the servo motors operate at a fraction of their rated ca- pacity. The light load and duty cycle permit shutting off the fan long enough to measure the dc resistance of one of the fan motor field wind- ings. It is likely that the motor cooling fans are not needed in the MSRE. As can be seen from Fig. 2.7.1l5, the fan motor being checked for temperature is turned off temporarily by energizing the selector-switched relays, and the temperature is indicated on the meter in the output cir- cuit of the regulated voltage supply. The diodes across the motor wind- ings prevent insulation damage by preventing high-voltage switching transients caused by opening the highly inductive field winding. 2.7.5 Limit Switches Limit switches and their actuators are a frequent problem area in devices of this type. The MSRE rod drive unit was no exception; during the first critical tests, the actuator became stuck at the lower limit, This was caused by excessive wear and galling of soft steel sliding bearing surfaces in the switch actuator guide. The design was altered by providing hardened-steel, spring-loaded, floating bearing pads to replace the galled bearing surfaces. Tae revised design is shown in Fig. 2.7.16. The slide assembly is lubricated with Neolube (see Sect. 2.7.3.8). Figures 2.7.17 and 2.7.18 are photographs of the limit switches and actuators installed on the drive unit. 267 2.7.6 Control Rods Figure 2.7.19 is a photograph of the upper end of a display model of the MSRE control rod with the poison elements® removed. The poison elements? are shown in Fig. 2.7.11. There are three control rods, which are identical in construction, each weighing approximately 11.2 1b. The rod lengths are slightly different because of the required offset of the control rod thimbles. The rod lengths are: rod 1, 11 ft 9-7/16 in.; rod 2, 11 £t 9 in.; and rod 3, 11 ft 7-3/16 in. The control rod is attached to the control rod drive by means of a two=-bolt (3/8 in. X 16 thread) flange or tow block made of 304 stainless steel, The drive mechanism contains a matching flange containing the captive bolts, The assembly is designed to permit attachment of the control rod drive flange to the control rod flange through an access hatch in the drive unit case using a remote, manually operated extension wrench. The upper hose consists of a length (~6-1/2 ft) of 0.850-in.-0D by 1/2 in.-ID annularly corrugated, 321 stainless steel, flexible metal hose with a single exterior layer of wire braid. The corrugated hose provides a leaktight passage for the low-pressure (~8 psig, ~5 scfm) rod cooling air to reach the poison elements. The wire mesh serves the purpose of protecting the hose from abrasion, minimizes stretching of the hose, and acts as an emergency retainer in the event of hose failure. The 1/2-in. inside diameter of the hose permits passage of the 7/16-in.- OD stationary cooling ailr tube which is attached to the upper drive mechanism. When the rod is in motion, the corrugated hose and tow block move up and down over the air tube. The weld adapter serves to align the two types of metal hose used in the rod construction. It also serves as the upper anchor point for a 1/8-in.-0D INOR-8 retaining rod, which is located inside the lower hose. The lower hose is 5 ft 2 in. long, Inconel 600, fully interlocked, unpacked, strip-wound flexible metal hose 47/64 in. OD and 5/8 in. ID. The 38 Inconel-clad poison elements, detailed in Fig. 2.7.11, are beaded over the strip-wound hose, as shown in Fig. 2.7.20, The lower end of the strip-wound hose is welded to the air exhaust nozzle, which acts as the element retainer and lower anchor point for the 1/8-in. retaining rod. The rod supports a portion of the weight of the poison elements, contains the stretching of the strip-wound hose, and acts as safety retainer in the event of hose failure. During the two years of rod testing, there have been three inci- dents of rod failure, Two failures were due to misoperation of the equipment, and one incident was due to misslignment of 7/16-in.-OD air tube in the cCrrugatedfupper hose. The upper hose was worn by the air tube rubbing the inside surface of the hose so that when the rod was 23, E. Beall et al., MSRE Design and Operations Report, Part V, Reactor Safety Analysis, ORNL-TM-732 (August 1964); G. M. Tolson and A, Taboada, MSRE Control Elements: Manufacture, Inspection, Drawings, and Specifications, ORNL-4123 (July 1967). 268 released in scram, the hose broke away from the tow block when it hit the mechanical stop in the shock absorber mechanism. A bronze bushing was installed in the tow block to assure alignment of the air tube and hose. Subsequent examination revealed only minor wear at this point. , 2.7.7 Rod Drop Timer Routine operation of the MSRE®? requires that the drop time for each rod be checked each time before filling the reactor with fuel salt. Figure 2.7.21 diagrams the timing circuitry used to measure drop times. The timer consists of a continuously rumning synchronous motor connected, via gearing, to a fast-acting electromechanical clutch~brake whose out- put shaft drives an indicating pointer. The elapsed time indicated by the pointer, therefore, is the time during which the clutch is engaged. The drop time is easily measured. The rod is scrammed using the manual scram switch on the console. This closes relsy contact K29A, and the timer clutch is engaged and remains engaged until a lower rod limit switch is actuated by the rod at the end of the drop. 2.7.8 Performance Characteristics This list of performance characteristics is derived from prototype test data: 1. Rod speed with either 25- or 10-w motor running continuously at rated voltage (115 v ac, 60 cps), 0.53 in./sec. Note: The change in speed in going from "Up" to "Down" is approximately 1%. 2. Rod speed with the 25-w motor in "inching" mode (1/2 sec "On," 1/2 sec "Off," etc.), motor at rated voltage, 0.22 in./sec. 3. Motor speed as a function of applied voltage, see Fig. 2.7.22. Note: Rod speed (in./sec) = 1.53 X 10™ X rpm of motor. 4., Scram performancel a) Elapsed time to drop 51 in., 0.80 sec (see Fig. 2.7.23). b) Average acceleration during scram for a 51-in, drop, 13.2 ft/sec? = 0.4lg. c) Clutch release time, inferred from a curve of the square root of distance vs elapsed time (see Fig. 2.7.24), 0.012 sec. d) Figure 2.7.25 compares actual and required reactivity insertions during scram. These curves are calculated from curves "A" and "B" on Fig. 2.7.23 and the calculated percent of total rod worth vs distance curve, Fig. 1.19, p 59, ref. 2, and a total worth of 4.1% Ak/k. This value of total worth approximstes the total reactivity inserted by scramming any two of the three rods. The initial height prior to scram was taken as 51 in., 3S. E. Beall and R. H. Guymon, MSRE Design and Operations Report, Part VI, Operating Safety Limits for the Molten Salt Reactor Experiment, ORNL-TM-733 (Rev. 2) (Sept. 19, 1966). 269 2.7.9 Component Descriptions and Specifications 2.7.9.1 Rod Drive Motor Assembly General Description The drive motor is a 115-v ac, 60-hertz, two-pole, two-phase servo motor rated at 25 w maximum output.* As used in the MSRE, the input power is single-phase 115-v ac, and phase splitting is obtained with a 10- to 12~pf capacitor in series with one of the field windings. An ac tachometer is mounted integrally on the motor shaft. The tachometer output 1s used as a feedback signal to stabilize the servo controller, Tachometer output is 6 v per 1000 rpm. A small blower is included as part of the assembly. The blower is powered by a separate, capacitor- type two-phase motor and runs continuously whether the servo motor is on or off, These three units (motor, tachometer, and blower) are incorpo- rated into a single unit supplied by the Diehl Electrical Division of the Singer Manufacturing Company. The unit specified for the MSRE is sim- ilar in shape, size, and performance to a standard Diehl 25-w motor No. FPF 49-91-1. They are special in that they call for class H radiation=- resistant electrical insulation and use radistion-resistant grease. Performance data are given in Figs. 2.7.26 and 2.7.27. Procurement Information Procurement specifications are contained in Vard Specification No. 114096, modified by ORNL, and dated April 12, 1964, and in ORNL Purchase Order No. 63Y-76819. 2.7.9.2 Electromechanical Clutch This clutch is of the single-disk type with a stationary field coil. It is supplied by the Electroid Corporation, Union, New Jersey, their Drawing Z2EC-6CC-8-8. Characteristics and specifications are as follows: Rated static torque : 75 in.=1lb Rated coil voltage 32 de Coil current at 32 v dec 0.24 amp Nominal size (clutch disk diam) 2-5/8 in, Engagement time™ 0.0075 sec or less Release time Not available Electrical insulation - Class H - Friction torque (max) 0.5 in.-oz "This number from Electroid catalog for this size clutch with both 24- and 90-v de coils. A 10-w motor, identical in all respects but power rating, may be substituted for the 25-w motor. 270 Detailed procurement information is on Vard Corporation Drawing No. 114701. 2.7.9.3 Overrunning Clutch The overrunning clutch is a standard, commercially available device manufactured by the Formsprag Company, 23601 Hoover Road, Warren, Michi- gan. It is a Formsprag model. FS-05 in which the Oilite sintered bronze bushing normally used has been replaced with a bronze bushing and which has been packed with California Research Corporation type NRRG-159 or Shell type APL grease. The manufacturer states it meets performance requirements as follows: normal running torque, 3 1b-ft at 8 rpm; and stall torque, 20 1b-ft at 8 rpm., Additional specification-type infor- mation is contained in a letter dated February 1, 1963, from W. T. Cherry, Formsprag Company, 609 West Lincoln Avenue, Anaheim, California, to P. Butkys, Vard Division of Royal Industries. 2.7.9.4 Position-Indicating Synchros The synchro torque transmitters, both "Fine" (size 18) and "Coarse" (size 31), meet military standard (Mil. S-20708) design requirements with respect to size, shape, mounting dimensions, and performance characteristics. They are nonstandard in that the electrical insulation and lubricant are for a high-radiation environmment. The torque trans- mitters in the prototype rod drive unit were supplied by the Vernitron Corporation, 1742 Crenshaw Boulevard, Torrance, California. Additional specification data for these transmitters are as follows: Ttem size 31° Size 18° Primary winding Rotor Rotor Primary voltage, 115 115 nominal Frequency 60 cps 60 cps Input current, max 462 ma, 105 ma Input power, max 6.6 W 4,0 w Transformation ratio 0.783 = 24 0,783 £ 2% Phase shift, max 6.5° lead 18.0° Electrical error, max 10 min 6 min Torque gradient 0.40 oz-in./deg. 0.05 oz-in./deg. Null voltage 125 mv (total), max Null voltage 35 mv (fundamental), max ®Yernitron Corp. No. VIX31-6Rl, Vernitron Dwg, OD10581. bVernitron Corp. No. VIX18-6Rl, Vernitron Dwg. OD10582. 271 2.7.9.5 Position~Indicating Potentiometer The specifications for the position-indicating potentiometer, a Beckman Company type 6200 series potentiometer with ball bearings lub- ricated as described in Sect. 2.7.9.8, are as follows: Type Infinite resolution, cermet re- sistance element, continuous rotation with no stops, metal housing, 1-1/16 in. diam X 5/8 in, long with standard servo mounting dimensions, ball bear- ings Resistance 1000 ohms * 5% at 150°F Linearity 0.5% Electrical rotation 350 £ 5° Power rating 5 w at 185°F derated to zero at 300°F Refer to UCNC Purchase Order 5651446, Item 1 (Requisition 1.-8824), January 29, 1965, 2.7.9,6 ILimit Switches Limit switches are Micro Switch type V3-130l, a high-temperature nuclear-radiation-resistant design, manufactured by Micro Switch Di- vision, Minneapolis-Honeywell Regulator Company, Freeport, Illinois, Catalog information describing this switch is supplemented by two let- ters written by V. J. Brown, Los Angeles 22, California, to Povilas Butkys, Vard Corporation. The letters are dated December 20, 1962, and January 9, 1963, 2.7.9.7 ZElectrical Wiring Internal wiring within the rod drive wmit from the terminals on the disconnect to the various components is of high-temperature, radiation- resistant hookup wire., The prototype used Supertemp type MGT, manu- factured by American Super-Temperature Wires, Inc., 50 West Canal Street, Winooski, Vermont. Micatemp, & similar type of wire manufactured by Rockbestos Wire and Cable Company, Division of Aero Corporation, Nicoll and Conner Streets, New Haven, Connecticut, is equally acceptable. 2.7.9.8 Iubrication | | The gears, overrunning clutch, and the bearings in the gearbox, motor, synchros, etc., are lubricated with a nuclear-radistion-resistant grease: Shell Corporation type APL or California Research Corporation type NBRG-159. This latter grease®?® is composed of "Cp¢_jg-alkylbi- 3 James G. Carroll et al., "Field Tests on a Radiation Resistant Grease," Lubrication Engineering (February 1962). 6WADC-TR-57-299, Pt. II, p. 9 (report refers to NRRG-159). 272 phenyl fluid inhibited with didodecyl selenide and gelled with a sodium terephthalamate.”" The sprocket chain and the limit switch actuator are coated with Neolube, & film of colloidal graphite deposited as a dis- persion of graphite in a volatile carrier (isopropsnol). Neolube is manufactured by Huron Industries, Post Office Box 104, Port Huron, Michigan. 2.7.9.9 Thermostatic Switches The thermostats are small bimetal-type units with the bimetal mounted in a ceramic tube. Sample switches were tested well beyond destruction by heating to over 1200°F, and no release of solder or other low-temperature melting point material was observed. Technical data on these switches, based on the seller's catalog, are as follows: Electrical rating 50 w at 115 to 230 v ac, non- inductive load Qperatigg temperature Adjustable, by means of a screw, range to 300°F. Physical appearance 1/4 in. dism, 1-1/8 in. long; terminal at each end with a 2-56 tapped hole for making electrical connection Contact operation To open on rising temperature Yhe range specified for the MSRE was 150 to 200°F. The thermostats were purchased from the George Ulanet Company, 413415 Market Street, Newark, New Jersey, their model No. 17-L13. Refer to UCNC Purchase Order 59Y-17341, Requisition No. L-9682 dated August 10, 1965. 2.,7.9.10 Gears All gears are of carbon steel or stainless steel. The 24 diametral-~ pitch gears in the power train between the motor and the output sprocket are of steel and designed particularly for the drive unit. The 32 di- ametral-pitch gears which drive the synchros and the position potentiom- eter are commercially available components with minor modifications where required for mounting, etec. The worm and gear set is the end product of test stand experience with the prototype unit. The original design specified an aluminum bronze worm wheel mating with a steel worm. The worm had a hardness of 38 to 42 on the Rockwell C scale and a surface finish of 64 pin., maxi- mum roughness. These gears failed at a rapid rate by abrasive wear. The final design of this gear pair, based on additional test stand ex-~ perimentation and life testing with the prototype unit specified type 440C stainless steel, hardened to R, 55 or better, for both the worm and gear, The worm thread was ground and had a surface finish of ap- 273 proximately 20 pin. The gears were lapped to form selectively fitted pairs., Gear sets of other hardenable steels were tried in the proto- type, and it was concluded that the determining factor for the steels used in this service is probably surface hardness a.nd finish, not any particular type or alloy. : i i s e S v COARSE" AND "FINE" § SYNCHRO POSITION TRANSMITTERS GEARBOX i aanliad o SERVO MOTOR WITH INTEGRAL AC TACHOMETER AND COOLING FAN 3;& e e o LIMIT SWITCH ACTUATOR ROD gt SPROCKET CHAIN e TEMPERATURE SWITCHES (THERMOSTATS) g ETTR ing. and Hous MSRE Control Rod Drive Unit .ll 7 2 Fig. 275 PHOTO 62055 - Q w Z = Q Q ® o =z a. 1 M~ 0 a o = < Q o z ! z S = o o o & SYNCHROS DRIVE SPROCKET D GEAR REDUCTION AN CLUTCH UNIT CHAIN DRIVE LIMIT SWITCHES 25-w AC LOW INERTIA SERVO MOTOR SHOCK ABSORBER AND TOW BLOCK Unit — Upper End Showing Gear ive MSRE Control Rod Dr 2. Box and Servo Motor. 7 2 Fig. PHOTO 39975 UPPER AND LOWER LIMIT SWITCHES MSRE Control Rod Dr ion Locat ive Unit - Upper End Show Fig. 2.7.3. of Iimit Switches. 1ng Lo 277 ORNL-DOWG 63-8391R INPUT SIGNAL TO SIZE 18 SYNCHRO CONTROL TRANSFCORMER, PART OF TORQUE AMPLIFYING ROD POSITION | = —) TRANSMITTER IN SHIM REGULATING ROD LIMIT SWITCH ASSEMBLY INPUT SIGNAL TO Q-2560 TORQUE AMPLIFIED ROD POSITION POTEN- TIOMETER DRIVES IN LOGGER- COMPUTER ROOM ~-s—— FINE TO POSITION READOUTS SYNCRO NO.2 IN CONTROL ROOM -— COARSE 60° PER {NCH OF ROD MOTION POSITION POTENTIOMETER ROD POSITION INPUT TO SAFETY SYSTEM TO SAFETY SYSTEM REDUCTION GEARING FAN SYNCHRO NO.1 MOTOR 5° PER INCH OF ROD MOTICN TACH SERVO MOTOR DRIVE ELECTROMECHANICAL SPROCKET CLUTCH REDUCTION { ”’ Le— SPROCKET e~ 1-TO-1 GEARS GEARING CHAIN INCLUDES ! REVERSE T I LOCKING ) AIR FLOW VERR Nu\/ © EELLLJ;'II}JCH ¢ TO COOL ROD FLEXIBLE TUBULAR ROD SUPPORT——/ o — — - — » Yy V=0.5in./sec I POISON ELEMENTS ! [T [P HORIZONTAL GRAPHITE BARS — GRID PLATE CORE VESSEL — Fig. 2.7.4. Electromechanical Diagram of Control Rod Drive Train. SPROCKET CHAIN 41 PITCH SPROCKET, 69T PITCH CIRCUMFERENCE \ O ¢.00 /NCHES DIEHL €O, MOTOR BASIC ASSY. N FPF 49-9/-1 Fig. 2.7.5. 278 ORNL-Dwg. 66-3915 RATIOS: FINE SYNCHRO ROTATION _ 40° £OD TRAVEL N COARSE SYNCHRO ROTATION _ 5° ROD TRAVEL T IN POT. ROTATION _ 5° 527, 320P RoD TRAVEL = iN ( F-POTENTIOMETER 307, 82DP \ SINGLE TURN 4 jooon. 527, 320P .fe A 787, 32DP L COARSE " SYNCHRO Q(e\ S/ZE 31 267, 3EbP R 267, 320° ; ; V (@( e\. LEINE " SYNCHRO N e N 26T, 32DP S/ZE /8 ELECTROMAGNETIC CLUTCH, 32V.DC., 0:28 AMR, ELECTROID CO. NE 2EC-26CC-8-8 ] ] 1 ] ] WORM WHEEL 527 290P OVERRUNNING CLUTCH \\ FORMSPRAG TYPE FS/05~ WORM, 24DF, SINGLE THREAD QIT, 24DP 547, 24DF 147, 240P . qor, 240P (VB \# (4T, 249DP SERVD Momef_ 15V, o ¢Ps, 25 WATT, 2 # — ‘ AC TACNOMETER — BLOWER — "] MSRE Control Rod Drive Unit Power Transmission Diagram. PHOTO 39863 N ~J O Fig. 2.7.6. MSRE Control Rod Thimble. 280 PHOTO 71111 A FLANGE, MATES WITH LOWER END OF CONTROL ROD DRIVE HOUSING CONTROL ROD GUIDE ROLLER TYPICAL TYPICAL THERMOCOUPLE DISCONNECT LOWER ENDS OF CONTROL ROD THIMBLES NOTE: REFER TO FIGURES 5.4 AND 5.5, IN TM-728 FOR LR CONTROL ROD INSTALLATION OF i THIMBLES AND GRAPHITE THIS SUB-ASSEMBLY SAMPLE TUBE INTO CORE VESSEL. _- SUB-ASSEMBLY Fig. 2.7.7. Sample Tube. MSRE Subassembly of Control Rod Thimbles and Graphite 281 - - ~ o - Q X a. 7.7) Mounted on Reactor Vessel. 2 Subassembly (Fig. Fig. 2.7.8. 282 i ORNL-DWG 64-6083 \REACTOR GCELL ROOF PLUGS CONTROL ROD DRIVE MOTOR HOUSING ,—;CONTROL ROD DRIVE HOUSING CONTROL ROD L THIMBLE NO. 3 — CONTROL. ROD THIMBLE NC. 2 ~=——CONTROL ROD THIMBLE NO 1. REACTOR ACCESS PLUG FLANGE —=— SALT QUTLET TO CIRCULATING PUMP REACTOR ACCESS NOZZLE=~ C ) b CORE =—GRAPHITE LATTICE BARS REACTOR VESSEL = ~~—FILL AND DRAIN LINE Pig. 2.7.9. Diagram of Control Rods, as Installed. B PHOTO 81373A L AIR HOSE, INLET AlR TO ROD DRIVE HOUSING AIR HOSE DISCONNECT, TYPICAL - AIR HOSE, INLET AIR TO CONTROL ROD. HOSE SHOWN REMOVED FROM DISCONNECT. ROD DRIVE HOUSING FLANGE ON ACCESS OPENING TO CONTROL ROD DRIVES { i i i i ACCESS STANDPIPE TO GRAPHITE SAMPLES i { | | Fig. 2.7.10. MSRE View Looking Down Through Access Opening in Sec- ondary Contaimment Cell Showing Control Rod Drives as Installed. 284 ORNL-DWG 63~8394 R3 POISON SLUG 9% in. /\/ - LOCATION OF FIDUCIAL ZERO vw%u\/jl X, &-in. OIAM HASTELLOY N / SEE DETAIL {INOR-8) WIRE (TYPICAL) AIR FLOW ) ) AIR FLOW il L2 2 Ll L L L. 1-_\i“\\ \——_/ END FITTING WITH P I RESTRICTOR INTEGRAL AIR NOZZLE THIMBLE OUTER TUBE UPPER SEALING Gd, O3 - Al, O3 BUSHINGS RING LOWER SEALING -I \ ; - \ / 3 N N Y N Sl LN ] POISON SLUG INNER TUBE /TWICE SIZE 0.790-in, LD. 1.140-in. oD. AT 2Tl L NS G AALLLLGATKILLN 1.560 in, ———————— = 2.7.11. MSRE Lower End of Control Rod. DIFFERENTIAL PRESSURE INDICATOR DIFFERENTIAL PRESSURE SENSOR, RANGE 0-20in. Hy0 NOTE: MANUAL CONTROL STATION, HIC-915-A HAND VALVES OPENED (ONE AT o A TIME ) ONLY WHEN CHECKING ROD ZERO POSTION B X THROTTLING ‘{ VALVES — 7 TO etc. | REMOTELY OPERATED, MANUALLY — REACTOR CONTROLLED REACTOR 7 CELL WALL VALVE, HCV-915-At CELL WALL == % o SEE NOTE NOA _ \ _ b /A‘ ~ o U 7 20.7-psia / HEADER, R 989-A VALVE ASPECT IS THAT REQUIRED TO CHECK . ZERO POSITION OF ROD NO.4 L {1 g —BIFFERENTIAL PRESSURE INDICATING CONTROLLER, ADJUSTABL RESTRICTORS B # P L—"'5 ROD DRIVE THIMBLE HOUSING ® [+] a0, VENT TO CELL ROD 3 55-gal TANK Ps S Fig. 2.7‘12' A RIC-960A T T IiN DN ™ / v COMPONENT COOLING PUMPS ™~ SECONDARY CONTAINMENT PRESSURE -12.7 psio AN ORNL-DWG 84-4001R 2 RESTRICTOR, ADJUSTS FLOW TO CONTROL ROD THIMBLE DIFFERENTIAL PRESSURE . TRANSDUCER 989 A N COMPONENT R COOLING PUMP R NOZZLE - FLOW " RESTRICTOR; PARTS OF CONTROL ROD \‘ AND ROD THIMBLE ~ROD MOTION REACTOR CELL R - PRESSURE IN MAIN SUPPLY HEADER, APPROX 20.7 psio P, - PRESSURE IN SUPPLY LINE NO. 95 TO ROD DRIVES Py -~ PRESSURE AT INLET TO ROD DRIVES P, - ADJUST TO EQUAL Py WHEN NOZZLE |S NOT IN THROAT OF RESTRICTOR Fy - EXHAUST PRESSURE { REACTOR CELL PRESSURE}, APPROX . $2.7 psio NOTE: t. THIS VALVE 1S ALSO A SAFETY SYSTEM BLOCK VALVE. CLOSES IF RM 565 BOR C INDICATES EXCESS RADIOACTIVITY. Diagram of Instrumentation Used to Locate Rods at Fiducial Zero Position. 98¢ 286 ORNL-DWG 64-983 J T [ \ ] ] N | N N 7'"'\: M CARRIAGE ] N : SN I i N AR INLET TUBE-——____ ] R 1 N : . I N | \ N | N 7| — N \ 3 \ Ny e\ } ¥ I \ ] | BUFFER RETURN SPRING-—_ [ ) : . N I \ I | | | N | BALL RESET SPRING ——_N ! \ | CYUINDER——— | | » N PLUNGER - —————— | \ ¥, -in-DIAM \ /52 in-D ) | t STEEL BALLS———— ) | N E | | E \ | ' A \ ol CARRIAGE TRACK \ N | | \ T ] i ] N N R N b \ ROD DRIVE HOUSING ——__]] A ) H N ] N L] N \ N \ N \ N N N N M Tow BLOCK~—___ [} + N N N ‘\\ \ N RN N N N \ N \\\\\ §§§> \ - ) \ 2 \ \% / ; 7//////‘ N > / \‘ //< ! : /\ Y N N i ” 1 THIMBLE e POISON ELEMENT w Fig. 2.7.13. Cross Section of MSRE Control Rod Drive Shock Absorber. i i § i SHOCK ABSORBER! CAPTIVE CAP SCREW : USED TO ATTACH CONTROL ROD TO THE ROD DRIVE ASSEMBLY. NOTE THE CUP WELDED TO SOCKET HEAD TO GUIDE REMOTELY HANDLED WRENCH PHOTO- 73175A 'WO THERMOSTATIC EMPERATURE SWITCHES ENEATH COVER Flg 2.7.14. MSRE Shock Absorber and Thermostatic Temperature Switches. 115 V_AC Q@ { OF F o o OFF ' 3 AMMETER(/) AMMETER AMMETER P2 c: [ - BECMLATED KA KA KB KBI KC KC YoLTAGE |97AT |97e:[' usn:[' 1973'[ 197AT 1978T M? g : ”, o 09V kAl [ kBl ke 1 1970 1970 _ 1970 T FAN MOTOR T + FAN_MOTOR T T FAN MOTOR ROD N% | ROD N22 RODN23 KA LkB Lkec + L4 . + + KA 197 BIS7 KCI *) *) o7 'I‘mc 'rs?c. ‘[mc NOTE: REGULATED SUPPLY IS ZENER DIODE TYPE DESIGNED TO REPLACE STANDARD CELLS IN POTENTIOMETERS Fig. 2.7.15. MSRE Rod Drive Temperature Indicator. 88¢C ORML-Dwg. 86-4186 ) SPACERS, ADJUST TOTAL THICKNESS TO O8TAIN . SPRING RETAINER PROPER SPRING LOADING | ' ' LEAR SPRING (STERL) HARD (Re 58-60) sresL SPRING LOADED ) 'rwcé aPPeeAuu‘;;Tsmmas _ o A BEARING PAD, 2 RED'D, 5 SWITCH ADJUSTER SHOWN ACTUATED \ _ PIVOTAL AXIS : ) . _ _ 0O SWITCH - AU-TWO LOWER LIMIT SWITCHES _ OF SWITCN — i ) RETAINER : CSHOWN AOT ACWATED) MOUNTING PLATE ........... Ayt [ B2 N _ - s . N Swren e _ T Ny N i | o /Iflf-illl ot L , Keruor S T TN e \[7 g L= N 3 NI | ‘ % Sy oTIg 20T SWITCN ACTUATOR OPERATED BY CONTROL ROD " DE. i O / TOW BLOCK AT ENDS OF STROKE §UIDES (SOFT Y seerion A-A MSRE Rod Drive Unit, Switch Actuator—Guide Bearing Assembly. Fig. 2.7.16. 68¢ PHOTO 73176 A AIR TUBE TO S (i =~ UPPER AND LOWER LIMIT SWITCHES o e e LA g xR Showing Inlet Air Tube for Control Rod Cooling Air and Side View of Upper and Lower Position Limit Switches. 2 Upper End of Rod Drive Unit Fig. 2.7.17. 291 PHOTO 73177A LIMIT SWITCHES AND ACTUATOR ition ILimit Pos ing Show 2 t Uni ive Upper End of Rod Dri .18. 7 Fig. 2 Switches. BLED ELEMENT .- c6¢ ettt i T Ly AR ' AR R *“' 4 e ' y 3 3 LY, AR TIPS __ N b e e . 'i;H IRELES .'.‘?:fi\???}u? n.*_ e ¥, ; ! Y s ? ALY X g " & .4 3 P T e 4 e e 5 i SE Fig. 2.7.19. MSRE Control Rod with Poison Elements Shown Removed from Supporting Structure. Fig. 2.7.20. MSRE Control Rods, Assembled. €6C 294 ORNL-DWG 66-11377 SO kVA, 1SV AC ~~ SUPPLY 48v DC > - ' 2 THIS CONTACT IS CLOSED BY MANUAL ROD SCRAM K29A SWITCH, S-1. : ROD DRIVE ROD DRIVE ROD DRIVE S 120 ‘ NO. 1 | NO.2 NO.3 TOGGLE SWITCH o | ON CONSOLE ' | 1 A4 T Ke308 K234B -~ K238B ) 1iesE CONTACTS OPEN WHEN | CONTROL RODS AT == K231D K235D —= K239D LOWER LIMIT Vv V% JACKS MOUNTED ON CONSOLE PLUG CLUTCH NEUTRAL INDICATING DIAL 0.001-sec GRAD. r————_———————— [ ———— — | cLuTeH coil— GROUND , I T | = | L—_ | 3 | ,é,ps ELECTROMECHANICAL | | PORTABLE TIMER, |_ STD ELECTRICAL o -_———— = TIME CO, TYPE MSHOO'/_ Fig. 2.7.21L. MSRE Rod Drop Timer Circuitry. SERVO MOTOR (rpm) 295 ORNL-DWG 66—10180 g8 T L jour 1 — i I | T/ ) 5 SPROCKET m 60 cps g CONTROL ROD DIEHL NO. 49-91-1 / SERVO MOTOR,25 STROKE TOTAL SUSPENDED watts RATED OUTPUT n.. WEIGHT = 18.0 1bs 4000 3500 /DOWN r ————— 3 L ® __—-—-."t "’\kup 3000 FROM TESTS OF MARCH 9,1964 SYSTEM CONTINUOUSLY CYCLING 5500 FOR FULL STROKE.NOT IN "INCHING MODE. - — 0 50 60 70 80 90 100 1O Em (AC volts) Fig. 2.7.22. MSRE Control Rod Drive Motor Speed vs Voltage. DISTANCE (in.) CURVE A-REFERENCE CURVE OF SATISFACTORY SCRAM PERFORMANCE; BASED ON ACCELERATION OF 5 ft/sec® AND RELEASE TIME OF 0400 sec 10 20 30 40 50 60 296 ORNL—DWG €4—{4109R ™~ \ X NN \, \ \ \ \ \ X \ \, 0.25 0.50 0.75 1.00 1.25 ELAPSED TIME (sec) CURVE B-—SCRAM PERFORMANCE FROM TESTS OF JAN. 27-28,1964 Fig. 2.7.23. MSRE Control Rod Height vs Time During Scram. .50 297 ORNL-DWG 66—-1018!¢ @ / 6 ¥ | .,0 ’ 5 o 7| A S S - ./‘ £ L / . e THIS CURVE USED TO o2 ESTIMATE RELEASE | INTERCEPT AT &7 TIME. POINTS TAKEN > 1 ootz sec A L FROM CURVE B, MSR | /T MEMO 64 -27. CLUTCH ; - // 0 VOLTAGE -- 23 v dc. I I l / N | 0 010 020 030 040 050 060 070 080 - {ELAPSED TIME (sec) Fig. 2.7.24. MSRE Scrain Performance Tests (Jan. 2728, 1964). 0.01 O O N Ak/k INSERTED O @) (1 O o B 0.05 298 ORNL-DWG 64-2146 ™~ ADEQUATE PERFORMANCE —J REFERENCE CURVE PROVIDING KNug:eme SCRAM N \» % : ORNL DWG. 67-2414 ERFORMANCE DATA TACHOMETER ELECTRICAL DATA 60 cyc.t 25 WATTS OUTPUT. A YOLTS + 60 CYCLES. 2 POLES 2 PHASE : PHASE 1 POLES 2 EXCITATION | INPUT CURRENT (MA.) 50 PHASE (115v.) | INPUD POWER (WATTS) 5.0 *QUTPUT VOLTAGE /1000 RPM 6 OUTPUT LINEARTTY.% at 3000 RPM 1.0 PHASE RESIDUAL RMS (Mv.) 110 100 VOLTAGE VARIATION (Mv.) 55 1. 80 & g o0 & TOTAL WATTS INPUT . 5 EFF A ° 20 0 TOAQUE OZ N *May vary *10%. Based on tach. load of 0.l megohms. Fig. 2.7.26. Performance Curves, 25-w Servo Motor. 66C V=~ = 3 Lmoamol> 30 10 WATT MAX. OUTPUT « 115415 VOLTS » 60 CYCLES « 2 POLES - 2 PHASE 300 MOTOR PERFORMANCE DATA R. -3 M 3 ‘\\\\\ Y 3200 <,R.p.m 2000 N \\ AN , 2400 N / 2000 \\\\\\‘ )//, %00 VvV 200 TOTAL WATTS mu-r-7/ \ 6 / AMPERES #lpm Pm:szj/\ w % o Yo "/ ] L~ 1;4// — *”><:\\\ \ 30 4 ///7' ’/_”“ - §k \ 20 / // WATTS OUTPUT/ \\\ . 0 2 4 6 8 10 12 TORQUE-0Z. IN. Fig. 2.7.27. Performance Curves, 10-w Servo Motor. EFFICIENCY - PERCENT 301 2.8 LOAD CONTROL SYSTEM The reactor loading system in the MSRE has been described in detail in ORNL-TM-728.1 Some design changes to improve the effectiveness of the air seals and the annulus cooling air flow have been made since the publication of TM-728, but the basic design remains unaltered. Briefly, the nuclear power generated by the reactor is finally dissipated by a coolant-salt-to-air radiator and discharged to the atmosphere via a stack 70 ft high and 10 ft in diameter. Air flow through the radiator is supplied by two large, 250-hp (nominal), axial flow fans., The ra- diator consists of a bundle of 120 thin-walled tubes (0.750 in. diam, 0.072-in, wall, 30 ft long) bent in the shape of a zee (Fig. 2.8.1). The radistor 1s enclosed by two vertically sliding doors which act, to a degree, as air flow control elements. Additional control of air flow is obtained with a bypass damper and by selecting either one or both fans. When the doors are fully lowered, cams on the guide roller track force the gasketed door against a flat sealing surface to prevent the entry of air to the radlator. Figure 2.8.2 shows the radiator, the doors and their drive mechanism, and the coolant salt pump as they are installed in the duct. Figure 2.8.3 is a simplified drawing of the door drive mechanism, Note the flywheel which reduces the door ac- celeration during a load scram when the clutch and brake are released. The flywheel is connected to the shaft by an overrunning clutch so that it continues to coast after the door reaches the lower limit, The coolant salt experiences a calculated temperature drop (subject to small changes caused by slight variations in flow) in the radiator of 56°F at full power of 7.5 Mw. When ambient inlet air temperature is in the 40°F region, typical operating parameters at the radiator are as follows: Coolant salt inlet temperature 1015°F Coolant salt outlet temperature 1073°F Air inlet temperature 42°F Air outlet temperature 151°F Air flow 200,000 cfm Coolant salt freezes at 850°F, and the operating margin above the freez- ing point is therefore 165°F. This margin will be less on cold days, when the ambient temperature 1s reduced. The remainder of this section is concerned with the instrumentaticnm, control, and protection of the complex of equipment that is used to re- ject the reactor's energy output to the atmosphere. Tt has been pointed out in ref. 2 (pp. 107 and 140) that the MSRE is a load-following reactor and is inherently self-regulating when de- veloping any appreciable power. In any realistic power reactor system, 1R. C. Robertson, MSRE Design and Operations Report, Part I, De- scription of Reactor Design, ORNL-TM-728 (to be published), 2MSRE Project Staff, Molten-Salt Reactor Program Semiann. Progr. Rept. July 31, 1964, ORNL-3708, 302 the operators have little or no direct control over the public'!s demand for power. There was, therefore, no incentive to control closely the load on the reactor. The only requirement in the MSRE is that the op- erators he able to establish and adjust the load about a point in any region within the operating range, up to 7.5 Mw, of the reactor and to do so in an orderly fashion. It can be seen from Fig. 2.8.4 that the reactor load (the heat rejection at the radiator) is determined by five independently variable elements, namely: (1) inlet radiator door, (2) outlet radiator door, (3) main blower 1, (4) main blower 3, and (5) by- pass damper, Over a considerable portion of the range, the same value of load can he obtained by two or more different operating configurations of the above equipment. It follows that load changing and adjusting, if done strictly by manually manipulating these five different components, may add considerably to the duties of the operator at a time when he least needs such additional responsibility and, in addition, may produce unnecessarily high thermal shocks with accompanying high stresses. In view of the foregoing, the adjustment of the thermal load of the reactor has been designed for either manual or programmed control. With programmed control, load changes are accomplished by means of a single control at the console (Fig. 2.8.5) when the selector switch (8-23) is in the "Auto" position. 2.8.1 Blower Operation The main blowers, 1 and 3, are axial flow propeller-type fans. They are driven by direct-comnected, 250-hp, 1750-rpm, three-phase, 440-v ac wound rotor induction motors. High rotor resistance starting is incorporated in the power circuits to limit starting currents to ac- ceptable values. During start, the motor windings are connected in series to external resistances. As the motor accelerates, the external resistance in each winding is successively reduced by timer-controlled switching. This requires approximately 30 sec., After attaining full speed, when all external resistances have been disconnected, the motors operate as typical squirrel-cage induction motors. This startup cir- cuitry operates automatically when a motor circuit bresker is closed to start a blower and, in the following discussion, is not included as a part of the reactor control system. The control system relays control the blowers by operating the "Close®” and "Trip" coils in these circuit breakers. 2.8.2 Door Operation Figure 2.8.6 is a diagram of the door drives. A single gear-reduced motor provides power to raise both doors; individusl door control is ob- tained by means of clutches and brakes located on the separate sheave drive shafts. Operating conditions of the elements governing door move- ment in different situations are shown in Table 2.8.1. 303 Table 2.8.1 ‘ Brake Brake . . Clutch, o Clutch, ? Situation Motor Inlet Door Inlet Outlet Door Outlet Door Door 1. Normal, raise On Engaged off Engaged off or lower both doors simul- taneously 2. Normal, raise On Engaged Off Disengaged On or lower in- let door only 3. Normel, raise On Disengaged On Engaged Off or lower out- let door only 4. Load scram On or Disengaged off Disengaged Off Off Door position is indicated on the control console (Fig. 2.8.5) by synchro position receivers driven by synchro transmitters. The trans- mitters are mechanically connected, through gear reducers, to the sheave drive shafts, The intermediate 11m1t switches (Fig. 2.8. 7) used as control interlocks, are actuated by cams on the transmlttlng synchro drives., The position of these switches is adjustable over a wide range. The upper and lower limit switches are in redundant pairs and are ac- tuated directly by the doors. These limit switches are an integral part of the control system used during normal operation., Additional switches used solely to protect the doors and the drive mechanism from overtravel and overload are provided. These are described in Sect. 2.8.6. The bypass damper is positioned by an air cylinder with a built-in positioner, as diagrammed in Fig. 2.8.6. Cylinder position, directly proportional to cylinder pressure, is controlled either directly and manually or with a pneumatic servo, The servo positions the bypass damper to maintain the differential pressure drop AP across the damper equal to the set-point value AP Direct manual control of damper position may be obtained by man- ually adjusting the inlet pressure to the air cylinder with a pressure regulator in the manual control station mounted on the main control board., A three-way valve transfers cylinder alr supply from the servo to the pressure regulator. ~ Assuming that one or both blowers are on, servo control of AP across the damper is accomplished from the console by operator adjust- ment of OP sp with the switch labeled DP Demand (see Figs. 2.8.5 and 2.8, 6) - This switch operates an electric-motor-driven pressure regu- lator, PdX-ADZ-Al, whose output APSP goes to the pneumatic servo. If the condition of other elements in the system (doors and blowers) is not 304 altered, a request for an increase (decrease) in APSP will cause the bypass damper to close (open). If, however, the doors are moved or blowers are turned on or off, the damper will also respond to maintain AP equal to APSP. When load control is being automatically programmed, the adjust- ment of APSP is included in the program and is not directly manipulated by the operator. In either control mode the values of AP and AP and the damper position are indicated on the console. 2.8.3 Automatic Load Programming As the reactor system is brought from zeroc to full power, the various elements (as stated previously) governing reactor load are pro- grammed in accordance with Fig. 2.8.8. This diagram is based on tests conducted on January 31, 1967. The dashed portion of the door position curve merely connects the end-point values of power obtained by moving the doors from the fully closed to fully open positions. The curves will shift slightly with changes in ambient temperature. The programmed control system was designed with these fairly ob- vious assumptions: 1. When the radiator is presenting a constant frontal area to the air stream, heat transfer therefrdm is closely related to static pres- gure drop across the radiator.? 2. Heat transfer from the radiator increases as the doors are raised as long as the operating condition of the other flow elements (blowers and bypass damper) remains unaltered. The tests referred to above and in Fig. 2.8.8 indicate that the last 2 or 3 ft of door travel exerts little influence on the load; that is, the doors are most effective during the early stages of thelr movement. 3. The static pressure drop measured across the bypass damper (see Fig. 2.8.6) differs only slightly from the static pressure across the radiator; that is, the pressure drop in the branching ducts to and from the radistor doors and the bypass damper, respectively, is small compared with the pressure drop across the radiator tubes. The programming control system diagrammed in Fig. 2.8.6 uses the air flow differential pressure AP across the bypass damper and the limit switches (Fig. 2.8.7) to program the sequence in which the doors are raised, the blowers are turned on, and the bypass damper is opened or closed. Control system pressure and limit switches also provide re=- strictive and permissive interlock signals. Figures 2.8.9 to 2.8.11 are, respectively, the block diagram and the relsy circuits which im- Plement the block diagram. The operation of the load control system when the programmed load control ("Auto" control) is in use is best ex- Plained by tracing the sequence of events and operations which take place as a particular pover level is established following a reactor start. 3W. M. Kays and A. L. London, Compact Heat Exchangers, McGraw-Hill, New York, 1958, 305 Suppose that operation at 7.5 Mw is required and the operator will establish this value of reactor load using the programmed or automatic load control mode of operation. Procedure and system actions are out- lined below (refer to Figs. 2.8.5 to 2.8.11 in following the discussion): Actuate the load control selector S23 to the "Auto" position. This switch 1s spring-returned to the "Hold," or center, position; but, if the conditions required to establish automatic operation have been met, automatic load control is in force. These conditions are (see circuit 150, Fig. 2.8.10):4 1. reagtor system in "Operate" mode, contact KAL36F closed (see Sect. 1.4); 2. salt level in the fuel-pump bowl above 43% of full-scale level, contact K97C closed; . fuel-salt pump speed greater than 1000 rpm, contact K96D closed; . drain valve FV-103 frozen, contact K659D closed; . static air pressure drop AP across the radiator equal to the oper- ator-established set point APSP in the bypass damper controller (Fig. 2.8.6), contact K211A closed. 3 4. coolant-salt pump speed greater than 1400 rpm, contact KLOE closed; 5 6 Alternate conditions to 6 above are: 7. system not in Run, contact KA139C closed; 8. bypass damper 100% "Open," contact K214A closed; 9. operator-established set-point signal AP _ to the bypass damper controller set at zero. Sp With the automatic load control mode established and, in the case under discussion, the conditions listed above obtaining, reactor power is increased from near zero to approximately 1.0 Mw by the operator turning on main blower 1 or 3 and requesting the load increase with the load demand switch S24. Assume that it is decided to begin the ascent to 100% power (7.5 Mw) using main blower 1. The operator will actuate the main blower 1 Start switch S29, and, if system conditions are not producing preventive interlocks, the following conditions prevail (refer to the)block diagram in Fig. 2.8.9 and the circuits in Figs. 2.8.10 and 2.8.11): L 1. The bypass damper is being held 100% open (APSP = Q), 2. both radiator doors are closed, 3. main blower 1 is "On," 4, main blower 3 is “Off," “Conditions 1 to 5 must be met at all times to maintain automatic load control; that is, they are not sealed. The remaining conditions are required only to enter automatic load control but are not required to stay in this mode. 306 5. main blower 3 has been selected to turn on gutomatically when the load demand cannot be met by a single blower. Had the operator elected to start with main blower 3, he would then have selected main blower 1 to turn on automatically when the load demand requires both blowers. After main blower 1 is turned "On," the operator starts to load the re- actor by actuating load demand switch S24. This causes the radiator doors to start opening and, as long as S24 is actuated, they will con- tinue to do so without restriction until the lower intermediate limit is reached. The operator follows the course of reactor power by ob- serving either the linear power recorder on the main control board or the two indicators, RI-~NLC1-Al and RI-NLC2-A2, on the console. The doors will continue to rise until the lower intermediate limit is reached and the system power level is approximately 1 Mw. The doors may be stopped at any point before this if it is desired to operate at povwers less than 1 Mw. When the doors have been raised to the lower intermediate limit, system conditions are: 1. main blower 1 is "On," 2. bypass damper is being held 100% open (APSP = 0), 3. reactor power is approximately 1 Mw, The 1-Mw level is the transition point from "Operate-Start™ mode to "Operate-Run," and further increases in power level require that the Run mode of system operation be established. This has been discussed in Sects. 1.4 and 4.2. Once the system is in "Run" mode the operator can again request additional load, using S24 as before. This can be seen by referring to circuits 162 and 164, in which "Run" relay contacts KA139G and KB139D bypass the intermediate limit relay contacts K219A and K223A respectively. Note that if the automatic rod controller has been used during the pre- ceding operations, it has been in the "Flux" control mode during "Start.” Going from "Start" to "Run" automatically puts the automatic controller into the "Outlet Temperature” mode (see Sects. 1.4 and 2.6). As the operator continues to request more load, the doors continue to rise until fully open. As the doors are going from the partially raised, intermediate limit, position to the upper limit position, the bypass damper remains fully open since the control system, by means of contact S24A in circuit 151, Fig. 2.8.10, is keeping APSP = 0. The load is in- creasing because of the increasing exposure of the radiator to the flow- ing air stream. Once both doors reach their upper limits, the bypass damper must start closing to divert more air through the radiator and thus increase heat rejection. This is accomplished in circuit 153, Fig. 2.8.10, by switch contact S24C. Closure of this contact turns on the motor which drives the APSP device, PdX-ADZ-Al, in Fig. 2.8.6; APSP is increased, and the bypass damper controller PdC-ADZ-A closes the damper to satisfy the requirement for increased AP; more air is diverted 307 through the fully exposed radiator and more heat is exbtracted from the system. Reactor power rises to meet this increased load., As before, the operator continues to request increased load with 824 and to follow the power by watching the linear channel instruments on the console and the main board. Any power level in this region can be established by the operator. This type of system response continues until the bypass damper is fully closed and the entire output of main blower 1 is flow- ing through the radiator. A sumary of system conditions is: 1. main blower 1 "On," 2. main blower 3 "Off," 3. bypass damper 100% closed, o APSP at intermediate value, 5. power level at approximately 5 Mw. The only way now remaining to increase heat rejection (load) by the radistor is to turn on the second blower, main blower 3 in this discussion. Note, in Fig. 2.8.10, circuits 153 and 154, that when the bypass damper is fully closed, the following circuit actions tske place: (1) contact K215A in circuit 153 opens, preventing further increases in APSP, and (2) contact KR215F in circuit 154 closes and permits energizing of relay 154, which will turn on the second main blower. At this point, the value of APSP is established and is equal to or greater than the actual AP across the radiator. With the radiator presenting a constant frontal area to the air stream, as it will when the doors are fixed at their upper limits, the heat rejection is related to the AP across the radiator. Now, when the operator asks for more load via the ILoad Demand switch, S24, the circuitry (see action 2 above) is such that relay Ki54 is energized; this initiates the start of main blower 3. As this blower picks up speed, it delivers additional air through the radiator, thus raising AP above APSP, and the bypass desmper will open an amount sufficient to bypass some or all of the additional air flow produced by main blower 3, depending on whether or not AP and APSP were or were not exactly equal when main blower 3 was turned on. The load may change slightly when main blower 3 1s turned on. This is attributed to the large duct and the nonuniform shape of the radiator, which permits slight changes in air flow which are not measured by the single probe in the center of the duct. - After the second main blower (3) is turned on, the bypass demper is open, and the control circuit configuration (circuits 153 and 154) is as it was Jjust before the damper was completely closed with only one blower running; that is, (1) contact K215A in circuit 153 (Fig. 2.8.10) is closed, permitting changes in.APsp‘by energizing relay 153, and (2) contact K215F is open, and main blower 3, once "on," is sealed and is no longer controlled by relay 154. ' With both blowers "On" and with the bypass damper partially open, the heat rejection (load) is increased, as before, by actuating Load 308 Demand switch S24. This causes AP to increase, and the automatic damper controller (Fig. 2.8.6) closes the bypass damper to divert more air through the radiator. This mode of operation continues until the bypass damper is from 75 to 100% closed® and the load, somevwhat de- pendent on ambient temperature, is in the 7- to 8-Mw region. Reduction in load under automatic load control proceeds in the reverse direction. 2.8.4 Msanual Control When the reactor load is in the Manual Control mode, the separate components governing heat rejection (see earlier part of this section) are treated as independent units and are controlled separately. Refer- ring to Figs. 2.8.5, 2.8.10, and 2.8.11, it can be noted that each door, Inlet and Outlet, has its own "Raise" and "Lower" switch and that bypass damper position is controlled by a AP demand switch. The blowers are not cross-interlocked with each other or controlled by door position as they are during Automatic Load Control. The selection of a partic- wlar operating configuration of these components and the operational path required to arrive at the desired configuration are entirely at the operator's discretion. : 2.8.5 Interlocks In either control mode the reactor loading system is subject to a nunber of interlocks and control actions whose primary purpose is to prevent or reduce the possibility that the coolant salt will freeze in the radiator. These interlocks and control actions and their purpose are listed and described in Table 2.8.2 and, in some cases, amplified in subsequent paragraphs of this section. 2.8.6 Load Scram Load scram (or emergency closure of the radiator doors) is pro- vided to prevent freezing of coolant salt in the radiator tubes. A pessimistic, worst case, calculation® showed that salt freezing can take place is less than a minute. Operating experience tends to con- firm this calculation. Figure 2.8.12 is a diagram of the instrument system used to provide load scram, and Figs. 2.8.13 and 2.8.14 are elementary diagrams of the as- sociated control circuits. The primary input information is coolant salt temperature at the radiator outlet. Three independent temperature measuring channels are used so that if any two of the three indicate an asbnormally low temperature, the clutches and brakes in the door drive mechanism are automatically deenergized and the doors drop to the closed position. 5finel damper position is adjusted to keep system temperatures at reasonable values, 63, J. Ball, “"Freezing Times for Stagnsnt Salt in MSRE Radiator Tubes, " private commmication (Apr. 9, 1963). Table 2.8.2. Load Control System Protective Interlocks Initiating Condition(s) or Interlock or Control Action System Response Situstion(s) Supplemental and Explanatory Notes I. Load scram 1, Radiator doors are dropped 1. Abnormally low (980°F)a' coolant 1. Low salt temperature is the primary indi- to closed position salt temperature in radiator cation that freezing is imminent outlet pipe, line 202 2. Both main blowers, MB-1 2. Abnormally low {less than 700 2 and 3, A loss or substén’qial reduction of and MB-3, are shut down gpm) flow rate of coolant salt salt flow through the radiator is the pre- lude to a freeze; particularly true when 1 3. Abnormally low speed of coolant system is developing full pover salt pump 4, Control rod scram 4, Power generation ceases with a rod scram. Unless heat rejection Wy the radiator is reduced, a freeze 1s inevitable, Note (refer to Sect. 2.5) that when the reactor is developing power, a rod scram will be produced by an electrical power system failure, a loss of fuel salt level in the punp bowl, or any other condition which reduces input current to the fuel salt pump motor These are safety-grade interlocks with addi- tional deseription in Sect. 2.8.6. II. First upper limits Prevents doors from being Door(s) at normal, fully open, 1. These are typical limit-switching controls raised - position actuate limit switches, of the type ususlly associated with mech- two each per door anisms having limited motion. They are not the final limits whose sole purpose is to prevent demage to the system (see inter- lock No. III) ' 2. Redundsancy: a) Two switches per door. Actuation of either switch is capable of releasing the door drive clutch and applying the brake b) When doors are being raised one at a time (manual control), limit switch actuation opens the "Raise" circuit in the door drive motor starter 60¢ Table 2.8.2. (continued) III. Final (maximum) upper limits Shuts off door drive motor Door(s) raised sbove normal fully Disengages door drive clutches Applies brakes in door drive mechanism open position by epproximately 8 in. For detalls refer to: a) Limit switch circults 216, 220, 224, and 225, Fig. 2.8.7 b) "Raise" circuits 162 snd 164, Fig. 2.8'11 ¢) Clutch and breke circuits 13 to 16, Figl 2.8.13 d) Motor starter circuit 568, Fig. 2.8.16 These switches also used in the automatic load control clrcults Actuation of these limit switches indi- cates an sbnormel situation which, if continued, will demage the drive mech- anism or the doors. If the damage in- cludes a jammed door or snarled cable, it may prevent lowering the doors, elther normally or by a load scram, and hence cause a radiator freeze Reliability: a) Two switches per door b) Two independent relay circults with both releys actuated if either door at the final limit c¢) Either chammel (relay circuit) will produce the actions tabulated in the "System Response" column 1] §3 d) Interconnection wiring carried in separate, individual conduits to control room In genersal, safety system criteria (Sect. 1.55 were used wherever possible in design of this interlock For detalls, refer to: a) Limit switch circults 255 and 256, Fign 2.8.7 b) Clutch and brake circuits 13 to 16, Fig. 2.8.13 c) Motor starter circult 568, Fig. 2.8.16 Table 2.8.2. (continued) VI. Motor overload Manual emergency bypass of coolant punmp control circult Lower limits Same as IITI above Maintains forced circu- lation of coolant salt Drops door(s) Motor current in one phase indicates 1. that docr drive motor is overloaded Variable and at discretion of re- 1. actor operator 2. 3. 1. Door(s) being lowered and 1. 2. At Mower 1imit" position {see Fig. 2.8.7) 2. 3. Thie augments III above. Except that only one excess current relay is used, it has same degree of reliability and redundancy. The excess current relay has its contacts in series with the final upper limit switches and hence the output actions are identical This consists of a manually operated switch with contacts in the control power circuits of bresker K, This circult bresker controls ac power to the coolant salt pump This switch bypasses all the interlocks in elrcuit 142, which controls the coolant salt pump (refer to Sects, 3.3 and 4.2.3). It is used only for short periods, when it is absolutely mandatory, regardless of other considerations, that the coolant pump be operated to prevent a radiator freeze.® This switch does not bypass the overcurrent protection which is built into the circuit bresker. Coolant pump cpera- tion by this switch is annuneisted Refer to Fig. 2.8.17 for circuit details | §£3 This is not & true lower limit (Sect. VII, this table). These switches are actuated approximstely 8 in. above the fully closed, or sealed, position. The doors then fall freely as in losd scram and acquire suf- ficient veloecity to ensure an effective seal against leakage air flow across the radiator (door sealing is described in ref. 1, p. 298) Redundancy: Two switches for each door ‘with contacts in series connected to cne relay For details refer to: 8) Limit switch circuits 217 and 221, Fig. 2.8.7 b) "Lower" door(s) circuits 163 and 165, Fig. 2.8.11 ¢} Door clutch and brake circuits 13 to 16, Fig. 2.8.13 e e e TECTT—— Table 2.8.2. (continued) VII. "Seal” limits 1. Stops doors at fully sealed (fully closed) position a) Disengages clutch(es) if not disengaged by VI b) Applies brake(s) providing door(ss are belng lowered ¢) Shuts off door drive motor 1. Door(s) at fully closed position actuate 1imit swltches The seal limit is the true lower limit door position. At this location the door(s) has been self-cammed by its own weight agasinst the sealing gaskets which prevent excesslve air leakage across the radiator Reliability: a) Two switches per door b) Any one of following outpute based on switch actuation will stop door{s): 1} 2) 3) 4) 5) 6) Clutch disengagement via elther of limit switch contacts in each clutch circuit; refer to eireuits 13 and 15, Fig. 2.8.13 Clutch disengagement by either of two 1limit switch contacts which de- energize "lower door™ relay(s). Refer to circuits 163 and 165, Fig. 2.8.11 Drive motor shutdown by either of two limit switch contacts which de- energize "lower" contactor in the motor starter. Refer to circult 568, Fig. 2.8.13 Drive motor shutdown by contact on "lower door" relay, which de- energizes the "lower" contactor in the motor starter. Refer to circuit 568, Fig. 2.8.,16 Brake actuation by elther of two limit switch contactz in circuits 14 and 16 (refer to Fig. 2.8.13) If, because of malfunction, drive motor is "On" when a door (or doors) 1s sealed and brake is engaged, the excess motor current relsy (see IV, this table) will shut motor off c1e 313 Figure 2,8.15 depicts a typical temperature input signal channel. Note that this is virtually identical to the temperature instrumentation used to provide rod scram (Sect. 2 5) except that the polarity of the thermocouple in the test assembly’ is reversed; therefore, the appli- cation of heat and the resulting temperature increase of this test thermocouple appear as a reduction in temperature to the rest of the instruments. Each temperature input chasnnel can be tested by turning on the heater in the test assembly and dbserving the response of the relays, which are controlled by the Foxboro temperature switches. The equivalent drop in temperature produced during the test procedure can be observed on a meter by the person conducting the test. A Joss of coolant salt flow will inevitably produce freez1ng if the doors are open and there is any appreciable air flow through the radiator. Therefore, the doors are also closed automatically by com- binations of signals from the flowmeters on the radiastor outlet line and from the coolant salt pump speed monitors. These signal combina~ tions are tabulated in Fig. 2.8.12. The pump speed measuring instrumentation is discussed in Sect. 6. A "loss of speed" input signal to one of the speed monitors is simulated, for testing purposes, by means of the calibration switch built into the speed monitor. Output relay action indicates whether or not the sys- tem is responding properly. The instrumentation used to measure coolant salt flow rate is de- scribed in Sect. 6. For test purposes, a simulated loss of flow signal may be produced in each channel by shunting a leg of the resistance bridge in the differential pressure cell, Observation of the output relays gives an indication of input channel response. Redundant door travel limit switches (Fig. 2.8.16) are employed to protect the ability of the doors to drop when the safety system calls for a load scram., Door limit switching has been described in Table 2.8.2, but it is worth while to emphasize here that the primary purpose of this redundancy is to prevent jamming of the doors or the drive mechanism which, in turn, is likely to compromise their ability to drop. An excess current relay in the motor circuit (Fig. 2.8.16) is used to detect an overload caused by a jammed door, snarled cable, or similar malfunction if it occurs either in the normal motion span of the doors or at the limits. The action of both of these limiting cir- cuits is to stop the drive motor by deenergizing the relays in the motor starter. Manual reset (refer to circuits 255 and 256, Fig. 2.8.16) is required before restarting the drive motor. Insofar as possible the limit switch design and installation follow the recommended safety-system practices outlined in Sect. 1.5. The predominant requirement in controlling and operating the load control system is to prevent a frozen radiator., To this end the cir- cuitry diagrammed in Fig. 2.8.17 was added. The time required to freeze the salt in the radiator is extended if circulation is maintained with "Molten-Salt Reactor Program Semiann. Progr. Rept. Jan. 31, 1964, ORNL-3626, p. 44. 314 the coolant pump. The coolant pump control circuit (see Sect. 4) con- tains interlocks which stop the pump if it experiences a loss of motor- cooling water or lube oil. The salt pumps cannot run for any appreciable length of time without oil or cooling water, but no harm will come to either pump or motor during the first minute or so following a loss of either. The manual switch, S127, located on the main control board, overrides these interlocks which are capable of stopping the coolant pump. It does not bypass the overload protection in the coolant pump circuit breaker. Use of this overriding switch is controlled adminis- tratively and is only permitted if the pump stops and a frozen radisator is imminent. 315 ORNL DWG 64-8826 9" 0.D. INLET 5" SCHD. 40, HEADER LINE 201 L 2-7/16" 1.D. MANIFOLDS (10) 120 S-SHAPED 3/4" 0.D. TUBES T 1 9" 0.0. OUTLET HEADER vl Y S" SCHD. 40, LINE 202 l._—_fi,'gg" Fig. 2.8.1. Rediator Coil Configuration. ORNL-LR-DWG 55841R2 PENTHOUSE MAGNETIC CLUTCH ' AIR OUTLET DUCT 316 FIRST FLOOR (ELEV. 852 ft-0in) SUPPORTING STEEL BLDG. 7503, - R / / AIR INLET DUCT / i | \} /" AR DUCT FLANGE | | MAIN A / / / Radiator Coil and Enclosure. Fig. 2.8.2. 317 ORNL-DWG 63-8390R ELECTRO- ELECTRO- MECHANICAL BRAKE MECHANICAL OVER-RUNNING CLUTCH I I I I CLUTCH _ / « SHEAVES — FLYWHEEL VL T - )| == = I ORIVE MOTOR WITH ‘ GEAR REDUCER. SINGLE MOTOR USED TO DRIVE BOTH DOORS— 0 SPRING SHOCK ABSORBERS A ¥yl NOTE: THIS ARRANGEMENT IS TYPICAL AND IS USED FOR RADIATOR DOOR BOTH DOORS ' ' Fig. 2.8.3. Diagram of Radiator Door Drive. ORNL-DWG 66-10633 5| MAIN BLOWERS & ] Conlle ) Fig. 2.8.4. Diagram of Radiator Air Flow System. 318 PHOTO 68582 Fig. 2.8.5. Load Controls Located on Operator's Console. 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Pyis Pyss: 8 &% B 1!'- s RS ADL ADT ‘Dl 1D 10- 10 10- 00 '|‘\ AL Al A at < ot T\ai L an, RADIATOR RAD IATOR RADIATOR RapiareR L ! R AT AITAT R AY Doo, oseR FiINAL yPrPre IMIT - i u’v.v:c .\‘\'mv ::u L un.’n woweR Fa-10-33% B b D i TR MADIATS ¢ b wnr | POSITION NoRMAL LPPER LlMlT_h =pp" | : M xuz xus w4 Ky 26 KAty %218 a8 KN 20 8 k2t B-10-ul b2 t | o) ord) ' ' TN 3 ] , o < - - o & g * > > . 1 1590, 130, 158, 139,13 199,470 15, 148, 188,79 ;::.1 190, &;. ‘o | | 2481 58 182,164 &b "W » & s ihige gt ub e 2t ’ UPPER INTER MEDIATE - $ 820 re2 ;14 168 LM " ~ . . PR » —” ES-10D-A2 € AP__SITPQ!NT LIMITS aY- n:’“ DAMPLR RADIAYOW DOOR LMY SWITCHES : Ifl’ gc;osz'I:NQEAL e S 'POMITION ) LowetR MTERMEDIATE 0 S 222 123 114 213 246 47 LINMIT 1 o L] _ _ " wn 29 _ . - A | < sy 4 Z2S-1D AL | 'G’ 9 1 | KA. _j_ KVA . I 13- Laws2 LT ) p oo my i o1 £5-10-c1 je-2 : 1l 7773 i 7 > A e - 17 oD - 10 T8 - . . -y Doar Ssalso L _ . 4__Luy ! . L-nbt - o zs-lo,; ol Qb-e} h= o y _ng oreN wuaw wusy | orsu wians oPaN WHEM | ofEl wien - - OO JuLey ouTLuY INL 7 \bt ::.:.n :QI. :;:;::::fl unm‘:f:‘:.r RADIATOR rRADIATOR THESE QWITCHES OPERATER opan wasl L uPFER LT | UFFRR LIMIT UPPER urePRR By CaM3I ON SYNCHRO OUT\EY INTSRMEDIATE INYERMEDIATE | INTOEMADIATE TRANSWMITTER DRWE AND RAGIATOR Limir d :;"‘;?N Po";’:wou ARE CAPARBLE OF W\DER ' 1 DOOR SEARD | POSITION ‘ » n ADJUSTMENT 212 K228 2223 Kitle K249 on ) P L] . oINS < 4 & m- & * 2 2 - 5 199,19 . 181 162 156 104 168, I8, 468,18 a3, 6 488, s 368, a3, i s 2 RADIATOR DOOR LIMIT SWITCHES Fig. 2.8.7. Radiator Door Control System Limit Switches. 321 -MSRE- RADIATOR SYSTEM PERFORMANCE BOTH BLOWERS o_.._u/ ORNL DWG 674645 INLET AIR TEMP 40°F ONE BLOWER ON " BOTH BLOWERS NN Dy > o < o o n (= DAMPER POSITION - % CLOSED 100 80 60 40 DOOR POSITION=- o OPEN 20 A 0 2 NOTE: 4 Lt Program of Reactor Power ILoading. Fig. 2.8.8. PRESSURE DROP ACROSS RADIATOR, AP-INCHES H20 6 8 * HEAT BALANCE POWER - MW DASHED PART OF AP CURVE. “A* TO"B" TO “C" IS ESTIMATED. . | l | | 322 | gf2 L7 ALY e o bl O fumnn -l-ut\.r ST ‘b N.uulc. "4 . uu C e - I- LA !tfluu.v ] znul-. TD— ow l-m. b it =1 p DooORY " yrEiR vt RARLTOR, Hnor N RADATOR b - Aty WeRALS BYPTALS WO AR C!.Ult‘l‘ AL STRLT ARY ¥ BLOWER [®3 sn. D) & WA [ MO RAQURLT comysoL | Dauns g LOwAR raure Al ou_LP 1wk DooR I weao F“uo -ouu'r eut olo‘g 1 WITRO! ———— m‘s"'c' tore An- PR S NLEY DOOR BELOW PINAL VEPER LUMT - — - . e e - = - More W - N o o = = ——— - S e e e e o A v o e AT LONTROL AMUTOMAT G tawrsalt i PCLITI0N 2 WAL YA FOR INFORMATION ONLY e . DO NOT USE FOR ‘ oromanE. vy Soou] e MAINTENANCE OR roipead seg goi CONSTRUCTION “LEY DOBR AT DeRN S o . » ] :::::' :.I:‘:L ::’w:; :::\-.-: AvE 1.;* S fi-. ..cn-n ol VIB4L | | 1! u gqune. ., n-- [ PRI T YT TS ORI SR LI LT ,'-m ‘.“';5: qu:‘. :::,':;::" aut, tnc.\n. LonIRn ‘u-n-nl B Ginwr ‘qu t i [Cmam 9-\.0 i L_”P‘ } LMY L1y LOWBE LW T LomTeAL BYITIAL GUDLK LaAwAY .= i ) |Tewe ""\.'\__ < AMEY ‘ wLOCK DiaERAL g T a13) °~§‘-'-"?5 t,nu\mu-\un FERIMM BALCM S mtaithm L § e B Teal SRR ‘-m coCLANT tacy ’v;f‘m _BAOLN TramuEas L e . | \ SRRErY B¥ETAV ;.ev.n Ok kst josun ‘-“.'_.. BT L WTLYE WOl TiALERWA (WL TY) TuNE l‘\}, ‘!-'IJ CAMTE . RLOLW TIBGRAM {gum | 41D Cavl U831 i ‘Middle Limit Position will be preset to correspond to L M power with ona blower O, pover. Full power (10 J8f operation) will be resched vhen the bypass damper is fully. DAL GONTIO. WOLR Siaemam tweroc) prme I 2 uuo Comrol loonm in a8 follows: i ) closed . ARLTRE COMTRS. BLOLW D imdasbm (1w 3 ad L] punl. 1420 Start reactor and take power to approximste . . K1} 'T™e above s stopped st any point by returning the Losd Demand switch Place Bypass Damper Coutrol im Autamatic Poeitiom to 1ts noutral (lou) pouuon and way te reverssd (decressing pover) by turning losd REFERENCE DRAMVINGS NO. Lower AP sstpoint to(uro dewand svitch to 1ts "Decromse” positiom. Start either blower ¢ damper will sutcmatically move t0 full opon position and bnce Automatic ioed comtrol oparation is atteined, the reactor pover can be 1ad betvesn the other blower wiil sutomtioslly be selscted for sutomstic operstica) ) 1 and 10 M by operstion of the losd dsmand switoh. var v OAX RIDGE NATIONAL LABORATORY . Switch Losd Control Mode switch to "Automstic™ positica {loed cootrol vill seal in ) rae both bloyers ars ON" the selectica of the "Autcmatic” blover may be changed by OPERATED &Y to sutcmatic positioa) pushing the "ON" button of the dasired blowar. UnNiON CARBIDE NUCLEAR COMPANY b - 1 - P s m e (f) Turn Losd Demand switch to “Increase Losd” position. Doors will raise until stopped (5) [he load may be increased manually and then evitched to mutomstic control by edjusting 4 |0csn = 1270 e by mg-linis. {Pouer should incresse (o spproximtely 1 W) P setpoint 1o Mtch the wxisting o2 aad svitahing loud costrol mcde svitch to Sreatier ) DIVISION OF UNION CARBIDE CORPORATION 8 [ oen = 5067 AETIYIPR LR (g} Push "Pun Node CB” run mode elrcuits Eel Load 3ot back produces same Sction &é decrease losd, OAX RIDGE, TENNESSER - 7Y ‘ M’,“e T ETEs s 47as |, 0 will ';1:::1:’:“1..1': conu-ol from flux t.o ulwut.m servo nnl permitting Load screm drops rediator doors and stops fane. TS Oh D MOLTEN SALT REAGIOR GEAPERIMELNT — A I CHANGE NOTICE NO. 2'757 - "; '!a"x"].m (b) Turn Losd Demand switch to "Increase Load” position, Doors will ralse and po\nr wiil OTHERWSE SPECIFIED: Bl DK OV A GaR A N0 | . -_'(Ah. increase. Iypass damper will remain opes since AP setpoint is gzero. Whon door € Rewmoved Rev 4 N REVISIONS DATE [aPrp| APPD rouch Ugper Liait, the aF setpoime vill Biicasticully incresse (ribe). Vhem the o7 ¢ A FRACTIONS & oo |RADIATOR LOAD CONTROL SYSTEM - oquals setpoint the bypass demper will start to closs. Continmued request for load BLOLK D AGRAM APPROVED e inerense vill cause further Lacresse 1o AP setpoint. The dasper vill be positioned to DECMALS + [ R A snintain AF at setpoint and will closs as the setpoint incressss. Reactor pover will . ————— oD T ATl increase 48 the AP incremdes. When the dANper redches its closed positicm, the sscond (9) |Sam D-wu-6: ST/ ROR OPANATIN OF BLowaR BACK ALow DAMPEES . ANGLES £ e e iy v "A_’I . blower will start sutomstioal 1;. hthbla-r-udlmmu,thow-d-p-ruu ! T —— b e encioce antomatically open to maistain the AP at set d request far losd increass e : APPROVED | DA APPROVED | DA : will roswlt in further l.lu-u in AP setpolnt with & Tesultant increass in rosctor SCALE: NONE ¢ Vyrig 3 Fig. 2.8.9. BRadiator|Load Control System, Block Diagram. 323 L s el B 17171 2% LA tua-"" 152 % 9 o 154 158 N 11 197 158 2 lkmlb - 5246 ls'nn B TAW [nq'u. = KAWE ;'—'KI!‘C - xAiSON ;tKI‘?A Ktidc ;fimnc ;"_‘ KeisoH FKIe6A ..l-nzmn "D 24 Frmsoc ;_‘:nmson- [ . - wow O O [ Lgaa Hazien EeaTTe® > J_ Y ‘ SSRGS T KAl A gy X T 1 ! E 4 ’ _ = KAVZE. KAI2Gy wn.tsA raTzoA Al Eyazrom _,_ntlilr ;"nm“v. I NG C\ . J SEBA . [SY.18 : I wew srom RAISON ST ;"\u\#h :d - d Q .“,.~ s - —31rac ';“ .29 Fxrn L 4 T RGASOM g N1 1 - I ]: :d 234 . ' 1 ngd Ku STHM b —————— —— e e - = - —— fudod 3on . ~ -il- AN “‘d—+‘ . oW [ g L K . Sawln KiG70 %FK'“D Catat . . .‘ Zrkie Lwmson Friset Fxaisom -—’(/\ o 1. [ KiSBA ;[-.\ssc fomRIS4A TKisec r- \®'_.4; s ,.__33): ,__‘d : 7~ N oran ‘:L.—’ % {5 ’ ‘:‘( A WP g ‘ T orgu oy S s ~, , AT . 4 ") ‘@ TRWEL LT ,& rtf _@\ /C:j\ 4 b= { N1 %18 E‘: TKEISSL ®Asy nisy, Kiss <-|\tmss i. 8535 2&!5« 8&\9‘! ;[v.msa KIS i 2S5 i 2N & 180, 150,151 150, ", . TSN, 53, CONTACT 18 JuLs. } CONTRGY \h WWGE. 136 , {onthcr 1 twak. COWTALT 1% Rt . LeF A58 131,053 162,002 —22 xpve Lowaw 22 Be. oS e ext. : TRIP COIL CRY., i35 . e, {u?q.'u‘a‘a“:;'u. ey roor per e Y., 48T, 450 15).133 164, 16e TR T TO L ‘ s . an : 16D, 158 155,158 1o%, &S sseraie 16 =t B Rt Yo wugnoie 1O k nl.l.n:!l.!".l- vo m. LoD ‘:s‘l; tuAcTan rox fpuozoaw To nu.u:‘.gl“ Te - : . ~ - — - e - AR GRS AR - o, " & AP SLTPOIWY COMTROL, ENARG\LE: _‘L__ MEh-1 BLOWER CONTROL, AUTOMATIC % SLECTO ME-8 BLOWER COMTEDL AUTOMATIC ZRGVEST SIART : ! WHREN ERERGIALD AIOMATIC ! i BLOWER, 3 FOR MPORBXTTON UMY i 89 NOT USE POR Sk el ; MAWITENANCE OR LOAD COMIROL MOBE, SSLECTOR. SwWITCW ALOAD OEMAND RELECTOR, SWiYoW | TAYCTION PORITION (ErouT viEw) - PO ITION (weowy Vikw) LOGATION ’ COMNTACTS LOCATION CONTMET o T Een e HANELE D [IANOAL MOLE |ATOMATIC (CKT. wa) MABLE Bun (orcRRRL Sus2 < Cewy. vad e %, Rt} Qe 5 R = fe—— ) ‘ e ~ 1) - S0 Ta ) Ty T feramusts O, u w.vd{@m Ao Loh“.ol- TRLAY & [oNnC-4iN e &:2) * T T 150 s (2) * r 15 WKW Dikathwm TYA wob t,pgg o MK c- a1V c (™) . ) (5% W, ELAM. CONTROL INTREAD LK, CIRLUITS - 4W. 2 e d oW B 51N o(a) n b 159 MG, AL, TADIATOR LOAD CORTROL BYRTEM - 0. Lo 0-MA- - 51321 * (5) n % 138 REFERENCE DRAWINGS NO. - (o) R a2 PYTT T Ton mmnatlu\m"umm T T T |l OPERATED 221 MBI L R e , RBIDE NUCLEAR COMPANY - gADIAID POINT RDUURTING SWITLW s R T ies | m%‘ e, CLEAR LOMPANY gi:’: - 3!7:'? CONTACT % POLITION _(rmont vitw) LOCATION - { OAX RO JEMENNeL ST 31BL MR OLE *WD _ltowex H::D RAVWE (CKT. WR) R _DENOILES CLOSED GONTALTS ‘-'. LIWITS ON DIMENSIONS UNLESS MOLITRW SALT ERALTOR EIPQ.—HME!JT%“_"os G B t CHANGE Belicw ¥ 2411 O x = 4 OTHERWISE SFECIPED: ot L et e . FRACTIONS + NG I\NEETRING SLEMERTARY REVISIONS a0 e 4 * 33 { . RADIATOR LOAD CONTROL SYSTEM ' ' DECMALS [ SHEET 1 o4 2 3.8, Iee P - o [ e o Y] = | i - O Au|[Bis1822| D] ] Fig. 2.8.10. Radiator Load Control System. ] J 1 | i 1 i 5 e s, 324 TS WAA. 159 248 led Gl 1 6% 164 165 1 Caln 16" o8 a9 218 [ R T LFEa wums -} l l -]_ BEWAKE-K SEEAAL \ STA- TESISA KCISD G STNG Flln ;:nusm. orau | . oren |, (mealorn) S8 (wni-essm 2 | P SR ., KTisD smp| TS Smen H U{ AUR LONBLY AUk, CONTALT, ‘ K50 ‘ ‘ R RiISOe w ‘W HWaw, W WA et 'P,N{'}_n!- - L. . | I oyt s ) 43 - = ’ f""b B e - Wik conTaty | Aun ConTAst CLOSED WHEW [CLOSED WMWY ~ N Skl - Swat BRETAKEE BRUATIE TREAKST BehAgin ard ooy ’ ~ mose | ovem == (MBI ORE) MOJ ORR) [ ' . TKieew KiaTE LR KiGTIR K&i5oM sas | wienvar : ! . T Zwnisen T Zunisor ] cuottn | caten , Df 1T T I L ~ ;-KZMF SLL ) | i 1 : 1 ‘ Q—' - e - — L@ ==xtia KA @ = Ki23A SKEI ReIA N f‘ : N LI_I S RETAM ‘ KATIBA s KAZZZA I I - ; KB 2/8A KB2ZZA i | . i ] #KIe3D vd | : :(I [ , ' Exieso S | | :(}‘__",_____-L Yy | | = KB224A b ———— - ";?.:'o’.')h (re.0> z21-0D- i~ N, s i 1 (:E—-» £ ~ ~ /@ Ly -y %‘.‘: :2' : KAIGT N&i1et Kish Kibt KALT 1 25 5 ZNB OPRLATES OPRRATRYL S8 , 13 s68, 13 368, o 0, 198, 189 1GA, 189 WO “MReih - WLO- MDA i 14,19 i, 18 1%, ek 16, 6] i;’i.nb ighy , LB Lk% , 1% o8 % 168, il 1T, "4 W TNAE G ki TR G TRt R ENARGiE LT oLTILET M-l mMe-B TO Whih~ TO LOWEW TG WAlS S o LOWER \ w) = 13 CHA IASIN ) = LOMNTED DUTLEY WOOR COMIROL RADIATOR DUOR, POSiTION SHINCHROS FOR MFORMATION ONLY *25 Tt 00 NOT UGE FOR TADIATOR IMAEYT DOOR DRIWE SBuwWiTw RADIATOR] OUTLEY HOOR VRIVE Switiw MAINTENANCE OR PORITION (FEonT vigw ) PORITION {(MMONT view) COMTALT W Lowan WOLD Rapa | LOLATION COMTALT B LOWRR HOLD ®ague | LOCATION ConsTRUCTION HAMDLL BND {ewr, oa) HANDLE ¥uD CLMT. wa) msmmnoengns. %, R, v s . [~ e L A ) A L) X &1 wn (1) n L od R G BLAM, CONTROL 'MTERLOCK CILLITH - 4W. 24T Pwrn-ST3LY wi{l) A B L 1w B (1) x 1S G RLM, CONIRGL WMTEELRLW CIRLNITS - 34, § o4 T [DMHE- 37T d o e e — — REFERENCE DRAWINGS NO. A TRWOTRS CLORRD CORTALY OaK RIDGE NATIONAL LABORATORY OPERATED BY S |ocu. #3240 3/768 ; UNioN CARBIDE NUCLEAR COMPANY © [oen. * 297 i % 5738 57739 DIVGION OF UNION CARBIOE CORPORATION T [Cuavaw Wericw = 8734 ) ‘L"'fi" BLOWER OISCHARGE DANFEE SWITCH MB-3 BLONER DISCHARGE DAMPER SWITCH T T T T e e e e s CHAN, L 50 - POSINOG _(FEOUT VIEW) POSITION (FIONT VIEW) LIATS ON DIMENSIONS UMEIS | o o »ALT RRALY FPARIMENT A g 08, A [CHANGE MOTICE ® T4 Fred CoNTMLTS o <0380 LOCATION CoONTALTS —on cloSmD ;OCATIO*; OTWERWISE SPECLRIED: MO, v N KT, Ne, HANDLE mwp) V. NOy - e aTe o I‘“‘“’" B8O ¢ ) FANCTIONS & ENGIMEBERING %TLEMENTARY | A SPARE A SPALE DECIMALS & RATDTIATOR LOAD LONTROL SYSTEW 3.3, J1r-a-g Py = SPARS . Sraza me— DHEET T o4 2 " APPROVED i ¢ X isg | T X /S8 ANGLES o NPROVED o x 59 D X 160 ; 4 AL “HH [BIS132%IB ]| Fig. 2.8.11. R pdiator Load Control System. SAFETY CIRCUITRY ORNL~ DWG 63-8389 COOLANT PUMP MOTOR MAGNETIC PICKUPS PUMP SPEED| S4 5y OR Sz Sy OR Sz INSTALLED )7 | " MeNITOR SPARE. (el 3 INDEPENDENT COINCIDENCE ] oyl P ; Srow ]| ey . {o}2 FLOW — MATRIX PUMP SPEED | Sp ks (b) SPEED F MONITOR — —_— > MOTOR TO PUMP SHAFT GOUPLING VENTURI | e ooy HEAT DIFFERENTIAL PUMP BOWL EXCHANGER PRESSURE TRANSMITTERS TI AT~ | 3 INCGEPENDENT [ —F, " fzo'OUNCT”:)":F"g)E Y '\ TEMPERATURE —_—— SIGNALS T3 __| ReLAv RADIATOR MATRIX THERMOCOUPLE CIRCUITRY NOTE: EMERGENCY CLOSURE PRODUGED BY INPUT SIGNAL COMBINATIONS AS FOLLOWS: {a) §, OR S, +F, {b) S, OR S+ Fp CURRENT {e} Fy+ Fp THERMOCOUPLES ACTUATED —_ SWITCHES (d) ANY TWO OF THE THREE TEMPERATURE INPUT SIGNALS LINE 202 Fig. 2.8.12. EMF TO CURRENT ALARM o I—‘ TO READOUTS LOGGER ETC. CONVERTERS Diagram of Load Scram System. CLUTCH UPSTREAM DOOR GLUTCH E ’ BRAKE v BRAKE DOWNSTREAM DOOR ste —_ ORNL-DWG 67-913 13 14 1", 12 48V 0C § ) {15) (16) , OPEN IN "RAISE" OTHER DOOR I } MANUAL ROD SCRAM CLOSED iN KAI64B l "RAISE DOOR" {KA162B) I REQUEST -~— _ . KAI62C L KBI62C L az ’T{(KAIS‘!C) f"’(KB|54C) I MANUAL LOAD SCRAM KA162D _Tkaazgg) — (Kmsm):: KB'64233 ,OPEN ™ KA2{8D (KB162B) "RAISE AT {KA2228) DOOR"REQUEST CLOSED CLOSED IN L N , | MAXIMUM UPPER " ; A ~~————I—OPEN IN "LOWER" | LIMIT OR FOR RESET K AA RAISE DOOR KI65B OTHER EXCESSIVE METER S REQUEST {Ki1638B) DOOR CURRENT KBHA | K120 sio08 SEALS T (KB164D) K255C “A'ZA 4 Kmva Je(K2258) " KBiZA K|65F “‘22‘3) A " (Hres F, (K256G) CLOSED IN OPEN A ’CLOSED WHEN "LOWER LOWER DOOR 1S SEALED DOOR" REQUEST LimiT SHUT KA4 K5C TWO-0UT-OF THREE K4 K&C 42 CONTACT MATRIX. H OPEN AT MAXIMUM 558 - k2604 KAGA CONTACTS OPEN WHEN KAEC - k2624 KAZlBD COOLANT SALT TEMP s 262 UPPER LIMIT OR FOR k2568 2(KA222D) 2 k82160 LESS THAN 980°F EXCESSIVE MOTOR T = (XB2220) KAGG K5D KABD CURRENT / K2170 r OPEN AT (K221D) . LOWER KIG3C e L OPEN IN LIMIT (K185C) "LOWER DOOR" w SAFETY GRADE KAl24E OPEN FOR A CONTROL KBi2ac REQUEST ~ JUMPERS ROD SCRAM SAFETY GRADE o KB{124A KA{24F JUMPERS = KA{IH KAIIC I(KAHD) OPEN I(KAHE) L kaszn Ff‘)n LOAD SCR::: KA12C (kat2D) | (AND ROD SCRAM) (KA1Z E) K 2614 LOSS OF FLOW K7C K8C - K263A CL%TEH BRAKE COIL: AND PUMP SPEED = CONTACTS. K7 AND KB ks = I CONTACTS OPEN WHEN K7D I T0 REVERSING COOLANT SALT FLOW KioC STARTER, CKT 568 2 1S LESS THAN 700 gpm; K9 AND K10 CONTACTS K9D OPEN WHEN PUMP k8o | SPEED IS LESS THAN 1400 rpm GND } KBiiB DOQR DRIVE MOTOR Tt KB12 14,11,13,14,15 16,155,158 ", g 499, 1082 1,12 ,13,14 45,16, 155,158 Y’ LOAD SCRAM WHEN DE-ENERGIZED Fig. 2.8.13. 12,12 499, 1082 COLS DE-ENERGIZED TO RELEASE BRAKE AND DISENGAGE CLUTCH NOTE: INLET AND OUTLET DOOR CiRCUITS ARE IDENTICAL. NOS. IN PARENTHESES REFER TO OUTLET DCOR CONTROL CIRCUITS _/ Load Scram Output Circuits. C ) T ORNL-DWG 67-912 tsvac 24 5 8 , TVA-DIESEL’ — 115V AC . 50 kVA SUPPLY ! 48v 0C — 5 1 ssscpet | sss-cpe2 TEMPERATURE SWITCHES, l T T | Tss-202-02 CONTACTS OPEN WHEN RADIATOR FSS201-A | FSS-2018 - | Tss02-82 QUTLET TEMPERATURE IS LESS - FLOW SWITCHES SPEED SWITCHES, o TSS-202-C2 THAN 9B0O°F ' CONTACTS OPEN WHEN CONTACTS OPEN WHEN COOLANT PUMP SPEED COOLANT SALT FLOW 1S LESS THAN 700 rom IS LESS THAN 700gpm P 2 K4 (\' K5 KT K8 NEUT $d—uo KAS KB6 S K9 K10 NEUT piiod — 4 NEUT GND } - 50kVA SUPPLY 115V AC ' 5 TVA DIESEL Lo HsvaC ! 5 8 48V DC F— 5 5 — CONTACT K5-1 CONTACT K5-1 CONTACT K5-1 - IN RELAY —= IN RELAY = IN RELAY [KA125 | KBI125 | [ka1260 | KB125D | kci2s50 SAFETY ELEMENT, | SAFETY ELEMENT,! SAFETY ELEMENT, A A KC125A RSS-NSCI-A4, - RSS-NSC2-A4, RSS-NSC3-A4 IKE‘C*Zf’ Tketes T KA125C Ixerese Jxatess kawse CHANNEL NO.1 CHANNEL NO.2 CHANNEL NO.3 T - € T T \TWO-OUT-OF-THREE CONTACT MATRICES (ROD SCRAM) = KB1258 ‘g KA1248 KB t24 B KA (25 KB125 KC 125 KAf24 KB 124 GND &— 1,12, 147,148 11,12, 124 NEUT 119, 124 NEUT - J e J Y Y THESE RELAYS DE-ENERGIZED WHEN NUCLEAR SAFETY SYSTEM PRODUCES A CONTROL ROD SCRAM Fig. 2.8.14. Load RADIATOR DOORS SCRAM WHEN EITHER OF THESE RELAYS IS DE-ENERGIZED Scram Input Circuits. 328 ORNL-DWG 66-11424 CURRENT ACTUATED SWITCH Y2 OF TEST ASSEMBLY: FOXBORO DUAL a. ELECTRICAL TO SAFETY SWITCH, TYPE 63 ALARM r " HEATER SYSTEM INPUT NO. 10 | b. TEST THERMO- I:sl; 2'(")'2 :;”” o, COUPLE -202- LOGOER | v | I+ CURRENT | ! FOXBORO CO. I_I FI ACTUATED | I“J l— | —|——1J TvpPE 693 SWITCH, FOXBORO \ 3 9 TYPE 63 : MEASURING e o 11’ ISOLATION L3 | THERMOCOUPLE CONVERTER AMPLIFIER | 150 0 o > FOXBORO CO + O . = o ° 4008 | MODEL 63 PV OR ° o 3 [ 10-50 ma MODEL 65 PH - 10 TO 50 ma FOXBORO CO. METER PART N111 LF « CHANNEL NO.2 SAME AS ABOVE CHANNEL NO.3 < C SPARE D\J\\ RADIATOR OUTLET PIPE, LINE 202 Fig. 2.8.15. Temperature Measuring Equipment Used to Provide Load Scram. RADIATOR DOOR DRIVE MQTCR 34 48y DC 480V el — q-2 0 CURRENT SEAL BREAK CONTACTS TRANSFORMER IN DOOR DRIVE MOTOR . STARTER RELAYS CLOSED IN "RAISE DOORS" f l CCA ccB -[ S6BE T 568E "CLOSED IN "LOWER DOORS" r__ ——— & e ——— | SEAL | I [ | u‘L’ | [ 1 : | . ] | /l_ _________ o - OVERCURRENT RELAY, GE NO.1AC K5638 GROUND 255,256 RELAY ENERGIZED WHEN MOTOR IS OVERLOADED . 255 256 3 E;S-DDt-At |, _—OPEN WHEN MOTOR - 1; E;S-D01-A2 {(K569A) 71 CURRENT INDICATES DOOR DRIVE - (K569C) MOTOR IS OVERLOADED OR STALLED in. L a—OPEN WHEN INLET DOOR AT FINAL . Z5-1D-B38 UPPER LIMIT—— o A~ Z5-1D-B4B ke s —OPEN WHEN OUTLET DCOR AT an- Z5-00-B38 FINAL UPPER LIMIT ——— - £5-00-84B MANUAL . RESET . 51264 SWITCH MANUAL K-2554 RESET >—| K-256 A 51254 SWITCH K-255 . K-256 — - —f 255,13,44,15 256,13 ,14,15 1097,16, 568 097,16, 568 / Y FINAL MAXIMUM TRAVEL LIMIT SWITCHES Fig. 2.8.16. 568 T2X 480V flg 120 1 1 K255H K 256H ORNL=-DWG 67-91) OPEN WHEN EITHER OUTLET OR INLET DOOR AT MAXIMUM UPPER LIMIT OR WHEN DRIVE MOTOR CURRENT AT QVERLOAD VALUE THESE CONTACTS OPEN WHEN QUTLET DOOR IS SEALED SHUT THESE CONTACTS N ..;k?:g.?lmfl KA(62A KA164 A OPEN WHEN KAz'BE\ KazzzE INLET DOOR IS DOOR SEALED SHUT KB218E I KB 222E KBI62A KBI64A K163A KIE5A ——fl [ ] cLosep In \\ "LOWER" CLOSED IN "RAISE" OUTLET DOOR OUTLET DOOR 'JCCB ROS ~—~< CCA Z 5680‘____1 s lNTERLO(iK’S R cca = 568 - . \__\\2 ccB 52.@?'&%@ ~_TRESE RELAYS PART OF 3 PHASE g:?ERGEZE 10 REVERSING MOTOR STARTER WHICH COWER DOORS CONTROLS DOOR DRIVE MOTOR I THERMAL MOTOR \ 7= OVERLOAD cowmc1‘s/‘£ { } \T/ Radiator Door Drive Motor Control Overtravel and Overload Interlocks. 6C€ ORNL-DWG 67-685 240V AC 250 v DC — > z b < 30 amp iSamp _— MOTOR STOPS IN NORMAL CONTROL WHEN CLOSED. | KA 142 A l S127 A KB142A ~ s127¢ l___ ~——CLOSED, MOMENTARILY, TO START MOTOR L. X | X IN NORMAL CONTROL ]l i III -~ S1298B TRIP COIL IN CKT BK'R "K". STOPS MOTOR WHEN ENERGIZED CLOSING, " {START), COIL "%" RELAY a" THIS CONTACT IN CKT BK'R IN CKT BK'R ‘ CLOSED WHEN ne" " BREAKER IS K CLOSED € £ ¥ REFER TO IV-9,7 FOR TYPICAL MOTOR S127, EMERGENCY START SWITCH,LOCATED CONTROL CIRCUITS ON MAIN CONTROL BOARD CONTACT POSITION NO. STOP | NORM | RUN [ START S127A X CONTACT S1276 X % DEVELOPMENT $127C X S$270 X S127E* X S127F*® X *ANNUNCIATOR o-——0 CONTACTS SPRING RETURN Fig. 2.8.17. Normsl and Emergency Control of Circuit Breaker "K" Which Operates Coolant Pump Motor. ¢ C C oce 331 2.9 HEAITH PHYSICS MONITORING 2.2.1 Introduction The purpose of the Health Physics Monitoring Systeml is to provide personnel protection at the reactor site from radiation hazards due to airborne and fixed source activity. The monitors composing this system are placed at strategically located points throughout the reactor build- ing. Those monitors which measure area activity and airborne activity make up the Facility Radiation and Contamination Systeml'3 and produce signals which are transmitted to a central annunciator panel located in the reactor auxiliary control room and to the laboratory Emergency Con- trol Center in Building 2500. The Facility Radiation and Contamination System also produces a building evacuation signal based upon finding a coincidence of at least two monitors in an alarmed state. The other monitors composing the general system are mainly for personal survey and include such items as beta-gamma survey meters, & hand-and-foot counter, and smear counters for use by Health Physics personnel. 2.9.2 Facility Radiation and Cohtamination System 2.9.2.1 Introduction A Facility Radiation and Contamination System was installed in the Molten-Salt Reactor Experiment Building 7503 to continuously and auto- matically monitor gamma radiation (by seven gamms monitrons) and air contamination (by seven beta-gamme air monitors) in the entire facility. These instruments and other components in the network provide health physics monitoring information, sound local alarms when abnormal con- ditions occur, and indicate the abnormal conditions on a central panel- board and at the laboratory Emergency Control Center in Building 2500. Operating personnel are first given warning when a "caution level” of 7.5 mr/hr or 1000 counts/min is detected by a monitron or beta-gamma air monitor respectively. A second warning is given when a "high level" is detected, that is, 23 mr/hr by & monitron or 4000 counts/min by & beta-gamma air monitor. The building evacuation system operates automatlcally when two or more monitrons or two or more air monitors from a specific group of instruments detect a "high level" of radiation or air contamination. An lThe system is further described in ORNL-TM-1127, Description of Facility Radiation Contamination System Installed in the Molten-Salt Reactor Experiment Building 7503, May 13, 1965, by J. A. Russell and D. J. Knowles. Parts of this report have been extracted verbatim from T™-1127« 2D, J. Knowles et al., Instrumentation and Controls Div. Ann. Progr. Rept. Sept. 1, 1963, ORNI-3578, pp. 37—40. 3L. F. lLieber, "Radiation-Monitoring and Warning System at ORNL," Nucl. Safety 6(4), 414-20 (Summer 1965). 332 audible alarm in the building will be actuated, warning lights outside the building will flash, and an alarm signal will be transmitted to the Laboratory Emergency Control Center, Building 2500. 2.9.2.2 System Description The gamma radiation level is monitored by seven monitrons located throughout the building (Table 2.9.1). Air is monitored for beta-gamma- emitting particles by seven constent air monitors located throughout the building. ©See Figs. 2.9.1 and 2.9.2 for the location of all the instru- ments. Table 2.9.1. Radiation and Contamination Monitors Installed in Building 7503 Location Monitor No. 1. Facility radiation monitors®’P Control room 1 RE-7011 High bay, south 2 RE-7012 High bay, west 3 RE-7013 Basement, north 4 RE-7014 Transmitter room 5 RE-7015 Basement center 6 RE-7016 2. Radiation monitors with control room alarm only® Service tunnel 7 RE-7017 3. Facility contaminationm.onitorsb’c Offices 3 RE-7002 Basement, north 4 RE-7003 Transmitter room 5 RE-7004 Service tunnel 6 RE-7005 4. Contamination monitors with control room alarm only® High bay, west 1 RE-7000 High bay, south 2 RE-7001 5. Mobile air monitor 7 RE-7006 gAll monitrons are Q-1154B-13. bCoincidence of any two high-level alarms in the group causes automatic evacuation. cORNI.model Q-2240B«4 constant air monitor. 333 Since none of the health physics functions originally designed into the monitrons and air monitors were altered, each instrument is an in- dependent unit that retains all its local alarm features. FEach instru- ment, however, is connected to an individual indicator module on the monitoring panel located in the Auxiliary Control Room, Nuclear Board 3. By means of three colored lamps, which normally give a dim light, an indicator module indicates the condition of the instrument to which 1t is connected; that is, a white lamp burns at full intensity if the in- strument is inoperative, an amber lamp burns at full intensity if the "eaution alarm level" (7.5 mr/hr for a monitron and 1000 counts/min for a beta-gamma air monitor) is reached, and a red lamp burns at full in- tensity if the "high level" (23 mr/hr for a monitron and 4000 counts/min for a beta-gamma air monitor) is reached (Table 2.9.2). Any change in the intensity of any lamp, that is, from dim to bright, is announced by the sounding of a buzzer at the monitoring panel and by annunciation cn the main board. The high-level alarm outputs of six selected monitron indicator modules are connected to a coincidence module, and the high-level alarm outputs of four selected constant air monitors are connected to & coinci- dence module. If a coincidence module receives a high-level alarm signal from any two or more constant air monitors or monitrons in a group, the building evacuation system is actuated (see Teble 2.9.1). See Fig. 2.9.3 for a block diagram of the system and Fig. 2.9.4 for the control schematic. Table 2.9.2. Central Control Panel Alarm Indications for Monitrons and Air Monitors Lamp Intensity Instrument Condition Red Amber White Normal operation Dim Dim : Dim Caution level® Dim | Bright Dim High levelP o Bright Bright Dim Instrument inoperative Dim Dim Bright Instrument removed® , 'Bright Bright Bright aCautipn level for a beta-gamma air monitor is 1000 counts/min and for a monitron is 7.5 mr/hr. No caution level alarms are available on constant alpha air monitors. bHigh level for a beta-gamma air monitor is 4000 counts/min and for s monitron is 23 mr/hr. c - - s - - - - . - Lamp intensities remain bright until a maintenance connection is made giving "inoperative” indication. 334 2.9.2.3 Components Panelboard The central panelboard for the entire system, located in the Auxil- iary Control Room on Nuclear Panel 5, consists of two l2-module racks, one central control chassis, and one dc power supply (Fig. 2.9.2). The 12-module racks contain one indicating module for each instrument, coin- cidence modules for the beta-gamma radiation alarm system and the con- tamination alarm system, a remote alarm module, a buzzer module, and a manual evacuation module. The remote alarm module transmits a signal to a single annunciator on the main control panel. The racks and modules are made of anodized aluminum. The modules have anodized Metalphoto front panels. A Metalphoto text strip is provided at the top of each rack for instrument identification. The central control chassis contains menual switches, timers, relsys, and monitoring equipment which are parts of the system but not located in modules. For circuit details on the central control chassis, see Fig. 2.9.5. Monitron The remote monitron (ORNL model Q-1154B) is an ac-powered, null-type radiation detection instrument for monitoring gamma radiation. The monitron consists of two basic units: (1) a control chassis, which con- tains the power supply, the main amplifier, a radiation-level indicating meter, and the controls; and (2) a preamplifier and lon-chamber detector assembly. The detector assenbly can be located remotely 50 ft or more from the control chassis. A 0O-to-10-mv recorder or a O-to-1l-ma meter Qul can be connected to the monitron. The range of the meter is O to 25 mr/hr, and the calibrated accuracy of the meter is within 3% for gamma radiation. The zero setting may be checked by means of a push button. When the set point of an alarm circuit in the main chassis is exceeded, a bell is rung and a red lamp on the instrument is lighted. A connection on the instrument for an external alarm is used to operate the caution-level alarm for the system. In addition to these standard features, the monitrons installed in Building 7503 have two other features: (1) warmup time delay relays installed on the main chassis and (2) a high-level alerm meter relay installed on an accessory chassis. The instrument and alarms operate as follows: 1. A power failure or a disconnected power cord will cause the white lamp on the central control panel to burn brightly. After power is restored and a l-min delay for warmup, the white lamp resets itself. During this l-min delay, caution and high-level alarms at the instru- ment might sound, but the same alarms on the central pasnel are locked out and will not sound. 2. If the caution level of 7.5 mr/hr is exceeded, an electronic alarm circuit causes the yellow lamp on the central psnel to burn brightly and the bell at the instrument to ring. The alarms are automatically reset at the instrument when the radiation level decreases below 7.5 mr/hr, but they must be reset manually at the central panel. 3. The O-to-l-ma meter output terminals are connected to the accessory meter relay, which is set to operate when the 23 mr/hr (high-level) C 335 alarm set point is exceeded. At 23 mr/hr the bell at the instrument will be ringing, since it started at 7.5 mr/hr and the red lamp on the central panel will burn brightly. When the radiation level de- creases to less than 23 mr/hr, the high-level alarm at the instrument is automatically reset by a signal interrupter. (allows a reset every 30 sec) from the central panel. The central panel alarm is reset manually. Beta-Gamma Constant Air Monitor This monitor consists of &n aspirating system, a paper-tape filter, a halogen-type Geiger-Mueller tube detector, a linear count-rate meter, a recorder, and visible and audible alarms. Air is drawn through the filter by a Roots blower. A sample containing beta-gamma-emitting parti- cles is collected on the paper-tape filter (collected sample size of 11X 2- 1/2 in.). The sample tape is advanced automatically every 24 hr. The tape may be advanced manually at any time by the operator. The de- tector counts the sample as it is being collected. The count-rate meter is a linear duty-cycle type utilizing a single range and having an in- ternal high-voltage supply. The normal range is O to 5000 counts/min, and ranges of 0 to 250, O to 1000, O to 10,000, and O to 25,000 counts/min at full scale may be obtalned by various 1nterconnect10ns of two Jjumper wires under the chassis. The input voltage sensitivity of the rate meter is 200 mv. The overall accuracy of the rate meter, including the effect of long-term drift, is within 5%. The corona-regulated high-voltage supply is nominally 900 v with +150 v adjustment. The maximum load cur- rent is 20 pa. The rate meter has adjustable high-level and caution alarms and puts out a l-ma full-scale signal to drive an integrally mounted Rustrack recorder. The caution alarm is adjustable over the range of approximately 2 to 58% of full scale, and the high-level alarm is adjustable from the caution-alarm set point to full scale. The caution alarm is an electronic circuit which employs a dual triode and plate relay with potentiometer adjustment. The relay is energized below the trip point and is deenergized by current transfer from one triode to the other by a diode that couples the cathode circuits. Hysteresis is approximately 4% of full scale. The high-level trip is accomplished by the high contact on a contact-making meter which energizes the high-level trip relay. When the set point is reached, the meter contacts and relay are locked in; these are released by depressing the reset push button. A low-level pointer on the panel meter has no contacts and is used only as a visual indicator. The pointer should be set at the level corresponding to the caution-alarm set point. The instrument has an alarm panel with four lights, a bell and a buzzer. When the caution set point is reached, an amber lamp is 11ghted and the buzzer is energized. There is no switch to silence the buzzer, and the operator is expected to advance the tape when this point is reached. When the high-level trip point is reached, a red lamp is lighted and the bell rings. The bell can be silenced by a toggle switch, and when this is done, an amber neon indicator is lighted. When the filter tape breaks, a red neon indicator is energized and the caution circuit is energized through a flasher. The amber neon bulb 336 burns continuously, and the caution light and the buzzer come on inter- mittently. If a tape breaks and, the caution alarm sounds at this same time, the tape-break neon light, the caution light, and the buzzer will be on continuously. A test push button permits checking the alarm panel by simultaneously simulating tape break and high-level alarm signals. In addition to these standard festures, all air monitors at Building 7503 have an accessory "instrument-inoperative' chassis containing a meter relay. The instrument and alarms operate as follows: 1. An accessory meter relay connected to the O-to-l-ma output of the count-rate meter will cause the white "inoperative" light on the central panel to burn brightly whenever the meter pointer drops to zero, indicating no signal from the instrument. After power is restored and a 60-sec delay, this alarm clears itself. During the 60-sec delay, local caution and high-level alarms do not sound since they are locked out. 2. At the caution level of 1000 counts/min, an electronic alarm circuit will cause the yellow lamp in the control room to burn brightly. With an ORNL model Q-2240 air monitor, a buzzer will sound at the instru- ment. The alarm is automatically reset when the filter is changed. 3. At the high level of 4000 counts/min, the panel meter relay on the instrument causes the red lamp in the control room to burn brightly. Also, the bell sounds. These alarms are reset by advancing the filter and by pressing the manual reset button on the monitor. Indicator Module The indicator module (ORNL model Q-2563-1) consists of three inde- pendent transistorized channels, each operating an indicator lemp and providing a dec voltage shift signal for alarm or control purposes and a voltage pulse signal for operating the buzzer module. The three lamps and a push button are on the front panel. Each module is 35.8 mm wide, 120 mm high, and 125.8 mm deep. All connections are made on printed strip connections at the rear edge of the plug-in module. When the instrument connected to an indicator module is operating normally, all lamps on that module are dim (Table 2.9.2). When the module receives a signal that the primary instrument is operating ab- normally or that the caution or the high-level alarm values have been exceeded, the lamps burn at full intensity: white for inoperative in- strument, yellow for caution level, and red for high level. A signal is also generated by the module which causes a buzzer to sound. The white lamp indication will remain until the condition causing the salarm is cleared, at which time the lamp will return to the dim condition. The red and amber lights will remain bright until they are manually reset by a push button on the indicator module. If the indicator module is reset when the alarm or abnormal condition still exists, the lamps will momentarily become dim when the reset button is depressed and then will become bright and the buzzer will sound again when the reset button is released. Al]l indicator modules are identical and can be interchanged or re- placed without alteration (see Fig. 2.9.6 for circuit details). 337 Coincidence Module The coincidence module (ORNL model Q-2563~2) consists of one tran- sistorized circuit which accepts a dc shift voltage alarm signal from as many as sixX indicator modules. The circuit can be adjusted by in- ternal Jjumper connections to operate a relay for alarm or control pur- poses on any combination of one to six input signals. All coincidence modules at Building 7503 are arranged to operate the relay when there is a coincidence of any two alarms from & selected group of instruments. Each module is 35.8 mm wide, 120 mm high, and 125.8 mm deep. All con- nections are made on printed strip connections at the rear edge of the plug-in module. Four selected air-monitor indlcator modules are connected to a coincidence module. Six selected monitron indicator modules are con- nected to a separate coincidence module. When two or more monitron indicator modules or two or more air-monitor indicator modules receive high-level alarm signals, the associated coincidence module will actuate the building warning and evacuation equipment and will transmit a signal to the Emergency Control Center, Building 2500. A red lemp on the af- fected coincidence module will indicate which set of instruments has de- tected an abnormal condition. When the indicator modules showing an abnormal condition are reset manually, the coincidence module will also be reset. All coincidence modules are identical and can be interchanged or replaced without alteration, except for an internal jumper connection which determines the number of coincidental input signals required for an output signal (see Fig. 2.9.7 for the circuit schematic). Relay Module To alert the reactor operator, a relay in the relay module operates an annunciator at the main control panel whenever the buzzer module operates; that is, any alarm at the auxiliary panel also annunciates at the operating position. The annunciator at the main control panel op- erates in the same manner as all other Tigerman annunciators at that point. To reset the annunciator, the operator must first silence the buzzer at the auxiliary control panel. Buzzer Mbdule z The buzzer module (ORNI,model Q—2563 4) consists of a transistorized trigger circuit that operates a silicon controlled rectifier to actuate a buzzer when a voltage shift pulse is received from an indicator module. The buzzer module is the same size as all other modules and is interchange- able with other buzzer modules (see Fig. 2.9.8 for the circuit schematic). The buzzer module gives audible notice that an indicator module has received any one of" three input signals. The buzzer module, which serves all indicator modules, is reset by a push.button at the front of the module. After belng reset, the buzzer will sound again whenever an input signal is received by one of the indlcator modules. For example, a change from a normal condition to a "caution alarm level" at some location will start the buzzer. After it is reset, a change to "high alarm level" or to "inoperative instrument" will start the buzzer again. 338 Air Whistle and Beacon lLights When a coincidence module has heen energized by two or more monitrons or air monitors, four air whistles are activated by nitrogen gas bottles (one for each whistle) to notify the building occupents to leave the building. The air whistle, a "Clarion whistle" by Westinghouse Air Brake Company, will sound from 2 to 4 min on one filled gas bottle. A control box for each whistle contains a pressure valve, pressure switches which monitor tank and regulated pressures, and a solenoid valve that is opened by an electrical signal from the coincidence module. A momentary signal will open the solenoid valve, and the valve will remain open until it is closed manually by pressing the mushroom head of the valve stem inward. See Fig. 2.9.1 for the location of the whistles and Fig. 2.9.9 for the control circuit schematic. The normal gas pressures for proper operation of the whistles are not less than 1000 psig tank pressure and 80 to 120 psig line pressure to the solenoid valve. Abnormal pressures are indicated by red lamps (labeled "horn trouble") on the central control panelboard, one lamp for each whistle. A dim lamp indicates normal pressures, and a bright lamp indicates abnormal pressures. Inspection of the gages will indicate whether the tank pressure or the line pressure is abnormal. Federal Sign and Signal Corporation model 27S 110-v beacons with magenta-colored lenses are installed at 15 locations (Fig. 2.9.2) in and around the reactor building complex and the office building to warn personnel to evacuate the building. These beacons are actuated simul- taneously with the air whistles by a signal from a coincidence module, and they are automatically stopped when the coincidence module has re- turned to a normal condition. A key-operated switch, labeled "normal-disable," on the central control panelboard may be used to disconnect the air whistles and beacons during maintenance or abnormal operation periods. Since the Emergency Control Center receives an alarm signal when the switch is moved to the "disable" position, the Control Center should be notified before the switch is set at this position. A large red push button located on a module in the central control panel, labeled "manual evacuate," actuates the air whistles and beacons and transmits an alarm signal to the Emergency Control Center (if the Center has not already received an alarm). Remote manual evacuation switches are provided on the reactor control console and in the mainte- nance control room. If one of the manual evacuation push buttons has been used, the system may be restored to the normal condition by pressing the "reset" push button on the "manual evacuate" module. Power Supplies The main power for the system is 120 v, 60 hertz, supplied from instrument power panel 5 in Building 7503 to the 24-v dc power supply and the monitoring instruments. The 24-v dc transistorized power supply is a regulated voltage and current unit. A green "power on" lamp on the control chassis and a neon lamp on the power supply panel will be brightly lighted to indicate that the power supplies are operating. Also a "dec failure relay" is used which triggers an annunciator on the main control panel should the dc power supply fail. - 339 Drawings The Facility Radlation and Contamination System is described in the following ORNL Instrumentation and Controls and Reactor Division drawings. 1. Q-2354-1 to -7, instrumentation location and wiring diasgrams. 2. Q-2563-1 to -4, and Q-2563-16B, -17, and -19B, plug-in modules. 3. Q-2358-7, horn control box. 4. Q-1154B-1 to -14, monitron. 5. Q-2359-12, monitron high-level alarm. 6. Q-2240-1 to -23, constant air monitor. 7. @Q-2311B, constant air monitor instrument failure box. g. D-HH-Z-40641, instrument placement plot. Operating Manual See ORNL-TM-1127 (Revised)! for operating and checkout procedures. 2.9.3 General System 2:.92.3.1 Introduction This part of the Health Physics Monitoring System consists of all the instruments used for health physics purposes which are not included in the Facility Radiation and Contamination System. In general, these instruments are for use by the area health physicists and for operating personnel in conducting personal surveys of their bodies and clothes. Inciuded in this system are seven beta-gamma survey-type monitors, a beta-gamma sample counter, an alpha sample counter, and a hand-and-foot monitor. See Fig. 2.9.1 for location of these instruments. 2.9.3.2 Beta-Gamma Monitors, Q-2091 The beta-gamma monitors are mostly placed in contamingtion-free areas to provide a means of personal survey of clothing and body. How- ever, when not used for this purpose, they are left operatlng and serve as backup monitors for the monitrons. In four places (the cooling-water equipment room, the hallway between. Buildings 7503 and 7509, the instru- ment shop, and the venthouse) their primary purpose is area monltorlng. They are used instead of the monitron because of the lower unit cost and low ares background expected. They provide a local aural alarm only and are not tied to any central alarm systen. The Q-2091 monitor consists of a G-M tube and a count-rate meter with integral power supply. The G-M tube has an adjustable beta shield and is attached to the rate meter by a 3- £t length of coax cable. 340 The count rate meter (Q-2091) is of the duty-cycle, linear-scale type. It includes an amplifier designed to accept the G-M beta-gamma tube input. A high-voltage power supply, a high-level alarm circuit, an aural monitor with volume control, and a l-ma full-scale output for recorder or telemeter are included features. The unit weighs 19 1b and is enclosed in a cabinet approximately 8 in. wide, 9 in. high, and 12 in. deep. It operates from 115 v, 60 hertz ac. Performance Specifications Performance specifications are given below. Input sensitivity 200 mv Circuit linearity 2.5%; overall accuracy, in- cluding drift, 5% Amplifier gain control None High voltage 900 + 150 v, corona-regulated, 20 pa Range selector 250, 1000, 2500, 10,000, and 25,000 counts/min Integrator time constants 1, 11, and 21 sec Alarm Adjustable, zero to full scale on any range for high level only, manual reset Recorder output O to 1 ma output, 50,000-ohm impedance Aural monitor Gated relaxation oscillator and power amplifier with volume control 2.9.3.3 Hand-and-Foot Beta-Gamma Monitor, Q-1939-B The hand-and-foot monitor is located in an area which serves as the main entrance and exit from the reactor building (7503). This instrument is an ac-powered four-channel monitor for beta-gamma radiation with a channel for each hand, a channel for the shoes (feet), and a channel with & movable probe. The probe is mounted approximately waist high in order to monitor the front of clothes when not used for special monitoring. Three channels are identical modular-constructed units, actuated by a halogen-quenched stainless-wall G-M tube. The count- ing rate is indicated by glow transfer scaler tubes and electrical reset registers. The fourth channel, the survey probe, is an aural channel. The count in this channel is not totalized. Maximum counting rate in the probe channel is approximetely 5000 counts/sec. To start the instrument, a manual push button is depressed which energizes a timer, after which the operation is automatic. The instrument resets itself, and there is a S5-sec walting period before the counting cycle starts, to give the user 341 time to get both hands in position for monitoring. The actual counting period is 23 sec. The total cycle is 30 sec. The maximum count rate per channel is approximetely 250 counts/sec, and the input resolving time per channel is approximately 200 usec. The instrument is contained in a rack cebinet 68-3/8 in. high, 21-1/16 in. wide, and 220 in. deep. A detachable base, 4 In. high, 18 in. long, and 21 in. wide, contains the foot-monitoring assembly. The power requirements are 115 * 10 v, 60 hertz, 75 w, 0.7 amp. Operating temperature limits are 0 to 135°F. - 2.9.3.4 Beta and Alpha Sémple Counters The beta and alpha sample counters are located in the health physics counting room at the north end of the reactor building. Beta Sample Counting System, Q-2344-1 The Q-2344 beta counting system includes a Tracerlsb end-window G-M tube mounted in a vertical lead shield (ORNI-Q-2089). The lead shield also contains a card sample holder. Attached to the shield is a pre- amplifier and cable. The preamplifier signal is transmitted via this cdble to a decade scaler containing the high-voltage power supply (ORNL- Q-2188-1), A timer is also included in this unit. The complete assembly is usually mounted on a table or a laboratory bench. Alpha Scintillation Counting System, Q-2345-1 This system uses a scintillation detector composed of a 2 x 2 Nal crystal and a 2-in. photomultiplier tube (ORNL-Q-2287). The tube and crystal are mounted in & housing which is attached to a2 smear or slide sample holder. The system uses a preamplifier and the combined power supply unit used for the beta sample counter (Q-2188). This system, ‘like the beta system, is mounted on a table or a laboratory bench. S T T T T S AT L s s e e+ 342 - r__’(l') 0 RI-TOZIAS o @ ? RI-02IA1L Q R 1302347 le Hegay ‘QQE RE=TOZY - G- ©- RACIAFION MONITORING NSTRUMENTS WO 1703 3 o a EH ~ : g 3 3 o & | S5a O " 8 o . x9 ~ = = 4 § l‘.“ X . A .. g 3 mnl ) o 8 | Contro/ Room " MSRE INS TEUMENTLOCAT}OMS 28 ,wg’ . ;-wg:a-u Yo I4 6-29-¢4 SYMBOL DESCRIPTION : Hish Bay - Sout 18 L Ada RITO2IAY fo 41O 22245 » Herm High Bay - west & CENTRAL PA NEL TET AT B M. Pailare Medude A | % Basement- North - FRONTV’EW Yo PATORIA3 £- 8, ade RTRO2IATH M43 A | 8/co. Central Panel (Nucicar Boarg’s) | © Basemant - Center INSTRUMENTATION AND =t =L Counf Kafe Mefer, (Bets & Gamms) Transmit ter Room % e e [ Constanr Al menifor - @228~ | | OAK RIDGE NATIONAL LA mm N Ierae T ° 1 Signal light : ‘ v L Remots Monitron - G-1158, : i - il Mobria Unit - a-2240 i B - | Hand & oot Counter — ¢ 0‘/33.9 . Fig. 2.9.2. Instrument Panel and Health Physics Instruments Locations. Controf Room Wigh Bay-Sowth Hgh & 344 ORNL-DWG 67-7830 Constant AlF Mopiters Q@-2290 with Inst. Failure Bones Q-23:/8 A anr; rom 2 Basement-Mer’h Troasmitier Am. Sasement-Conter Service-Tontl "yt Koy -West Wi Bay- Soulk oFfices 2asemeant- North Transmitier Moom* Service Timmwel! Modiie Uni? 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Fig. 2.9.5. 3 ~ 347 ORNL DWG. 67-7842 M/-LEVEL MPUT " pip I > Fin /5 o8 —»—> P /4 e o—> Lin 13 o7 —»—> Ln s2 I? 3z7 RED - LEVEL I EATOR Y Note . 2 #4 CAUTION WNPUT - Pin 6 Prrr 8 Prry 7 CH_rinn JALOICATOR L > n 1 Notes 14 [ >— > FPrn 9 # Prp 10 211 &80 Yew e 2Naé3 IN::!;ATIVF NPy Prrn & o¢ “‘”—') Ay 5 o5 I E > »W—> ~re Dé = J > 2 3 o lf"t? _IT FOR NON-LATCHING OPERATION <~ USE A CONDENSER INSTEAD OF A JUMPER FROM A2 TO B2 j Lz ICT WarTE NOFERATIVE INDICAYOR Nore < 2¢ 4 Fig. 2.9.6., Indicator Module. 348 ORNL -DWG &7-7834 reev 5 £y 15 THIS JUMPER PROVIDES I T > 2, 20 2, 12 £73 T ! TWO-OUT-OF -SIX ACTUATION éa.%a éz?: Tix Ssico Skévo SEice g 342260 OF RELAY K-1 i 1 P & I & & e o - H’g"”‘ i Priz 7 s | F ] Pir & P I € AAN—— fi" P & ) «— -’W\p———lfiz Q2 P 3 Pra 18 &——AN—1e ar Loce e 1 P4 €6 - o3 Forr [ €E—— N—d \ SNEIE £ P S . — £E 27 £9 ALre "~ Prr .9 € Vv 300 o s8¢ 'gzaw Godd P f ~ Fig. 2.9.7. Coincidence Module Circuit Diagram. ORNL DWG. 67-7832 1 ey —> Lo S5 Prry 13 C€——— L7 coo Pin @ FPn 18 K&—————— ISV A, VI sxolafion Crarrsforrrer Frr W E— ¢ Sercre " “on 1O E&——m—y 5 Pin i4 To operate remofe &larm reldy (@ 25e3-17 ) D7 Pn 9 % Jplrcorn geo Sfecs oy o, P 8 &——rdy | Sl 57a iy € . ) £ Porn 7 & &2oo 1000 Pn & e———;——. Fl Porn & e} YO n. S o z BUZTEL lr d @ e———y LE€S€7 o Pn 3 g %e; oL P I <« Fig. 2.9.8. Buzzer Module Circuit Diagram. 6ve 350 ORNL IWG. 67-7836 WESTING HOUSE CLARION WHISTLE N\ - - ( 7 ) H—- — &, i O-z C;/ 3 Test Pecept- \ M E-q-:n IO~ ! 4 19 =¢ m_““tp'; i 3 7 ] —0— o— 4 1 9:} } o ) J::i—g g S o—! o t o—a ;’ B 2§ o83 i — 4 —AF—1_ 9 Hpt— & s 10— RA 7023A] % i H-t V2 ’g IN3253 HORN BOX-|¥ Froor # = @2358-7 2\ T $ Ne Na Fig. 2.9.9. Air Whistle Schematic Diagram. 351 2.10 PROCESS RADIATION MONITORS 2.10.1 Introduction The process radiation monitoring system monitors radiocactivity levels in process pipelines, vessels, and operating components. This system is distinct from the Health Physics Monitoring System, Sect. 2.9, which is designed to warn personnel throughout the reactor area. Signals from the process monitoring system detectors located on or near pipes and components are used to produce alarm control signals and safety system input signals when activity levels indicate abnormel conditions. These monitors also provide information which indicates operating conditions of various parts of the reactor system. 2.10.2 System Description Two kinds of detectors are used in the process monitors, ion chambers and Geiger-Mueller (G-M) tubes. The G-M tubes are used to monitor levels up to 100 mr/hr. Three types of ion chambers are used. One is a stand- ard, commercial Reuter-Stokes chamber (Fig. 2.10.1) used to cover a range of 30 mr/hr to 300 r/hr. The second (Fig. 2.10.2) is an ORNL model Q-2818 and is used to cover a range of 100 mr/hr to 5 x 10% r/hr. The third (Fig. 2.10.3) is a special high-level ion chamber used to cover a range of 10% to 107 r/hr. This chamber is of special design to withstand the high radiation intensity and temperature present in the reactor and drain- tank cells during reactor power operation. It also has mineral-insulated cables sheathed with stainless steel to satisfy the cell containment re- quirements. A typical G-M tube monitoring channell consists of an Anton 106C G-M tube supplying the input signal to an ORNL model Q-1916 logarithmic response gamma radiation monitor. This model Q-1916 instrument was de- veloped to meet the requirements of most gamma radiation monitoring of reactors and in-pile loop systems. It has been in use at ORNL since 1958. The G-M tube (Fig. 2.10.4) is enclosed in a stainless steel housing less than 1 in. in diameter and 8 in. long, and it can be located up to 500 ft from the electronics. No preamplifier is used. The scale indica- tion on the monitor is proportional to the logarithm of the radiation level over a three-decade span.. Full-scale indication is normally 100 mr/hr, but it can be ‘increased to 1 r/hr by use of a different G-M tube and by appropriate changes in the electronics. While the unit has a normal range of 100 mr/hr, it can handle levels in excess of 100 r/hr without impairing its alarm and control functions. The monitor provides an upscale electronic alarm. The alarm level may be set at any point over the readout range, and the alarm point may be read on the meter while the setting is being made without tripping the alarm circuit. A relay which is energized during normal in-limit operation provides the alarm and control signels. 0RNL Instrumentation and Controls Div. Ann. Progr. Rept. July 1, 1958, ORNL-2647- 352 Figure 2.10.5 is a block diagram of & typical Q-1916 monitor, with circuit details shown in Fig. 2.10.6. The G-M tube detector is operated at 900 v, and the radiation level indicated is determined from the average current through the tube rather than from the pulse rate. Radiation in- tensity causes the tube to conduct. The voltage drop across a resistor in series with the G-M tube provides the input signal to the averaging filter. The filter's output, an analog signal, is fed to & dc amplifier having a logarithmic response. The amplifier is used to drive the alarm limit detector, panel meter, and recorder. The alarm limit detector drives a DPDT relay which is used for alarm and control signals. The monitor is fabricated using modular construction; the Q-1916 monitor assembly contains three plug-in modules (Fig. 2.10.7), each of which is a complete monitor. A single power supply (Fig. 2.10.8) for all three modules is located along the back of the chassis. A single-channel unit with integral power supply is also availsble. The Q-1916 monitor was chosen because of its operating simplicity, availability, small de- tector size, ease of monitor replacement, fast response, and fail-safe features. An E-H Research laboratories model 202 electrometer is used to measure and indicate the signal produced by the ion chambers. This electrometer incorporates a 5889 low-leakage input tube and double feed- back. Negative feedback reduces the effect of cable and source capaci- tance, thereby improving transient response; positive feedback reduces the input capacitance at low frequencies and further extends electrometer response. The seven input resistors from 10%® ohms to 3 X 1012 ohms, selectable in seven steps, provide a wide operating range. The elec- trometer has an adjustable alarm set point on the front-panel meter. An alarm reset button is provided to reset the instrument after an alarmed condition has cleared. It contains a DPDT relay to provide alarm and control signals and it produces an output signal scaled to drive a O-to- 10-mv recorder. A 150-v power supply is provided for chamber polarization. Figures 2.10.9 and 2.10.10 are a front panel view of the electrometer and the circuit schematic respectively. Excluding the Chemical Processing Plant a total of 16 G-M tube monitors and 12 ion chamber detectors are used for process monitoring at the MSRE. A list of these monitors, their function, and their location is shown in Table 2.10.1. The column in Table 2.10.1 labeled "Number of Units and Type of Coincidence Circuit" describes the number of complete monitor channels at one location and how they are used to increase reliability. In a one-of-two circuit, either monitor reaching the alarm set point initiates the desired alarm or control action. If either monitor fails, the other unit is still available to monitor the system and produce the required action should it be required. With but one exception & failure of the monitor power supply produces control and alarm signals as does any other failure which causes the monitor response to appear like that caused by a high radiocactive level (see sect. 1.5). The one-of-two system is used in those applications where the output control action can be tolerated during an on-line test. In the two-out-of-three coincidence systems, two monitors are re- quired to produce an alarm or control action. This arrangement allows Teble 2.10.1. Process or . Radiation level Number of Units Instrument Detector _—-ms & o and Type of Control or ggmfggizg - No. Detector Iocation® Background Alarm- Set, Coincidence Alarm Function® Monitoring Function " : Point Circuit Fuel pump bubbler RE#596A, B, C G-M tube Eagt of < 7 mr/hr 20 mr/nhr 3 Alarm; close To prevent fission gas backup inlet lines ‘ transmitter Two of three bubbler inlet in fuel pump and pump over- room at 840- valves flow tank bubbler helium sup- £t level ply lines and ensure contain- ment validity Coolant pump sweep RE-528B, C G-M tube Vent house < 7 mr/or® 20 mr/hr 2 Alarm; emergency To monitor coolant salt for gas One of two fuel drain; fuel in leskage through fuel pump off break in heat exchanger Helium supply line RE-500D G~-M tube Water room < 5 mr/hr 20 mr/hr 1 Alarm only To monitor for fission gas One of one backup in helium supply ' header Fuel sample box RE-675A, B G-M tube High bay < 7 mr/ar® 10 mr/hr 2 Alarm; close To indicate and comtrol exhaust Cne of two valves in line amount of fission gas geing ‘ to filter pit to stack Fuel pump oil RE-0T1B G-M tube Service < 7 mr/nr 20 mr/hr 1 Alarm only To indicate activity buildup tenk. tunnel One of one in cil Coolant pump oil RE-OT2B G-M tube Service < 7 mr/hr 20 mr/hr 1 Alarm only To indicate activity buildup tank tunnel One of one in oil Reactor cell con- RE-565B, ¢ G-M tube Vent house < 7 mr/nr¢ 20 mr/hr 2 Alarm; emergency To indicate fuel leak into tainment air One of two fuel drain; conteinment ares and prevent close valve excessive amounts from dis- w . HCV-565A1 charging to stack &B Off-gas sampler RE-524, 528 G-M tube Sempler box < 7 mr/hr 100 mr/hr 2 Alarm only To indicate leaks in the off- at vent One of two gas sampler system house Charcoal bed dis- RE-5574, B G-M tube Vent house < 7 mr/br® 20 mr/hr 2 Alarm; close To check operation of charcoal charge - One of two fuel and cool- filters and prevent excess ant system activity discharge to stack vent valves; and pump lube oil systems close off-gas vent valve Fuel sampler vec- RE-678C, D Ion chamber High bay < 7 mr/hr¢ 25 r/hr 2 Alarm only To indicate when sample ex- uum line One of two change area is free of fission gas Reactor cell space RE-827A, B, C Ion chamber Blower house < 5 mr/hr® 50 mr/hr 3 Alarm; cloge To indicate break in the water coolers 1 and 2, Two of three valves 1in lines in the cells and prevent drain-tank cell water supply activity from escaping the con- space cooler, and lines tainment area fuel pump cool- ant water return line header Reactor cell RE-6000-1, 2, 3 TIon chamber . Resctor cell 3 Indication only Indicate operating levels in the ‘ No slarm circuit cell Drain-tank cell RE-600C-4, 5, 6 Ion chamber Drain-tank 3 Indication onily TIndicate operating levels in cell No alarm circuit the cell Radistor pit RE-6010 Ton chamber Radiator pit 1 Indication only Indicate operating levels in No alarm circuit the radiator pit 83ce Dwgs. E-HH-A-55588 and D-HH-B-41668. bSee instrument flow dlagrams for controlled element. cAfter shielding detector. 354 the monitors to be tested, channel by channel, without actuating the - final alarm and control or safety circuits. Each monitoring channel o/ can be tested completely up to and including the alarm light and the alarm and control relay in the module. The two-out-of-three coincidence arrangement is used where maintenance and on-line testing of any single channel must be accomplished without producing control action and where false output control action caused by a failure or malfunction of a single channel is highly undesirable. All the detectors, except the high-level ones in the reactor and drain-tank cells and the radiator pit, are capable of being tested with a radiation source. A %0Co source is used to test each location. In areas where substantial background radiation exists, the low- level detectors are provided with lead shields (Fig. 2.10.11). Shielding reduces the background and improves the signal-to-noise ratio, thus pre- venting spurious slarms from a rise in activity level at another lo- cation. These shields consist of lead sheet formed into the required shape or of concentric lead-filled pipes. The shields are designed2 to facilitate the replacement of detectors and are huilt with access holes to accept a radiation source for calibrating and testing the monitors. No shields or test sources are provided for the high-level ion chambers since their operating range is in the neighborhood of 10° r/hr. The high-level chambers are mounted at selected locations in the reactor and drain-tank cells. Three chambers are located near the wall of the reactor cell, one at elevation 844.5 ft, one at elevation 838.5 ft, and one directly over the reactor to measure control rod drive dose. Two of the three chambers in the drain-tank cells are mounted on the walls, and a third is mounted between the two fuel tanks on the thermocouple gig tray. The chambers are filled with nitrogen, employ alumina insulators, and are built with mineral-insulated signal and high-voltage cables. The chamber is 7-7/8 in. long and 1-1/16 in. in diemeter. The chamber sensitivity is 4 X 10712 amp r~! hr; 98% saturation is obtained in a field of 107 r/hr with 350 v applied. Only one chamber is monitored at a time. This is done by using a single electrometer and a six-position selector switch. The selector switch connects the signal from any selected chamber to the electrometer. Two high-voltage power supplies are used, each supplying 350 v to three chambers. All the process monitoring electronic instruments except those used with the sampler-enricher system and the pump lube oil tanks are mounted in nuclear boards 4 and 5.2 The other detectors are mounted in panels associated with their respective systems. To obtain the required reliability for the monitoring system, the ac input power to the monitors is obtained from the 25-kva emergency power system. In addition, in the 2 Process line detector shields, ORNL Reactor Division Drawings D-HH-B-41527, 41528, 40551, and 40552. 3 Nuclear control board panels 4 and 5 layout, ORNL Reactor Division Drawings D-HH~A-41532 and 41533. kaJ 355 one-out-of-two monitor system, each channel has its own separate power bus, providing added éperating relisbility. With the exception of the six high-level, in-cell monitors, all monitor outputs are transmitted to the data system for alarm detection and logging. FEach monitor is provided with an individual alarm indica- tion. In addition, the alarm signal from each monitor station is trans- mitted to annunciators in the auxiliary control room. These annunciator signals are interconnected and transmitted to a single annunciator in the main control room, labeled "Process Radiation Monitors." 356 ,3 ™ H. o O - o I o Stokes Standard Ion Chamber. Reuter- .10.1. 2 Fig. Fig. 2‘10.2' ORNL Model Q-2818 Ion Chamber. LSE . Fig. 2.10.3. MSRE Special High-Level Gamma Ion Chamber. PHOTO 89246 8S€ Fig. 2.10.4. G-M Tube Assembly. PHOTO 89243 6S€ 360 Rgg:“AT'IAON AVERAGING LOGARITHMIC DETECTOR FILTER AMPLIFIER GM _ - > . T [B] STRIP CHART RECORDER OR DATA LOGGER UP TO 500 ft OF 3- CONDUCTOR SHIELDED CABLE Fig. 2.10.5. UPPER LIMIT DETECTOR ORNL-LR-DWG 3M{66AR ALARM INDICATOR TO RELAY ®-CONTROL CIRCUITS - PANEL o METER —— CONTACTS TO — ANNUNCIATORS ALARM SET POINT Block Diagram of Q-1916 Radiation Monitor. - 124 @ J R/ : frey dw ol e CAL Ras o it anr)—Lu - < R 100 e R9 ° Y)Y 1% Im : c' Imeg /% *l m L ; ‘ i "PTI-tDng"f-' 34?'4' A R WA 170 i K0 i ;fivb 4. femez| 3 - - S RH T \tl‘f’ 2 . : Fmeg | 20 S/ 1 rxf - A e e ; | ‘,‘”_”,' Treo %ue . Amp. 3 0., ‘ . Y . ~/150¥ l--A 3 : | | i - ! 7 : ADJ. - {72 e e e e e e ey Scx [ - Al Aty . ‘ . 3 r 1 | A\ !— ‘ A - A ’ | s | " T ts il 2 - ! - Feeabsck . . e 3 _ Nefwark fer Y te AR -1 A { ; (See 5160 ] ¢ Ay 1 Cnéa r3e : ' ) 2 T 17:5:7 | Amph 106805 +250V 3 0¢ L@M@dfi! 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Molliday | Steex ! 3 Sease: o - Lo o L ‘E MSRE STACK MONITORING SYSTEM - £ : | Stack Plattorm ¢ Founddlion Lagoul - Developed ‘ STACK SAMPLER LOCATION ¢ | o \Sedle: None I+ WOV Nemd W.P Reces. - Cuplen CENTRAL ALAKM PANEL ASSY. < Add VY Power Failure Moo -0 8314 e I way Switch 1 | A surlt 3-40-6: 3 Condulet “T" INSTRUMENTATION AND CONTROLS DIVISION ] wo. — pare. [ero [seve | 47 LoV Lamp with globes umire OAK RIDGE NATIONAL LABORATORY T < . ; otmn oy N-F.-E.. s Sce D304 for wiring ; UNION CARBIDE MUCLEAR COMPANY i R R L ] : Mt "/ e " | J HH ! «*&—"’—L_{!,{ £?é ‘ 3 aras aaskiond = Q23701 & Fig. 2.11l.1. MSRE Stack Monitoring System, Showing Stack Sampler Location and Central Alarm Panel Assenbly. % 374 ORNL-DWG 67-696 N1 m|@ - -‘—-—-—a-—-—-—-—-—-w—- ————L STACK GAS FLOW @ FILTER | REQ'D CUT FROM WHATMAN NO. 41 ol lald FILTER PAPER Y-12 STORES O INCH LOAD CARTRIDGE WITH 6-14 ITEM NO. 15-157-4450 ACTIVATED COCOANUT CHARCOAL ASSEMBLY NO. 269 FISHER SCIENTIFIC CO. CATALOG NO. 61 OR EQUAL + 4 3 | "33 ~ 1-mm WALL |‘—1§“‘—" | ! > sg o F:I_.‘Q - ?Q END PLUG @ HOUSING @ STRAINER MAT'L. CUT TO PROPER WIDTH MAT'L. CELLULOID- MAKE MAT'L 40-mesh FROM {-0z POLYETHYLENE FROM 32-mm 0.D. CENTRIFUGE SST SCREEN WIRE BOTTLE, ORNL STORES ITEM TUBE ORNL STORES ITEM NO 2 REQ'D. NO. 15-014-9602 15-242- 2483 2 REQ'D. 1 REQ'D Fig. 2.11.2. Charcoal Cartridge for In-Stack Sampler. w 75 ORNL-DWG 64-1200 — L W Y SS9 Ny ////// S \ |_— SHIELD S NA\ST T F |_— GM TUBES N N S \\IIIII = \/\\///\/‘\ S S S S S, N S Sy |- PLASTIC CENTRIFUGE N, =~ 7~ TUBE WITH PERFOR- f.:-,-:: /| ATEDEND / \f /—— CHARCOAL TRAP ) % = Sy Sy //////////////// , 7 A— B-oz PLASTIG,WIDE- * MOUTH BOTTLE WITH - PERFORATED CAP ke S 7 —==— 0~RINGS TN = << ¢ : [ A g :\ N " AN ! TS ‘ Ll \‘( N ) T ) N I _ Py A N \ N N 2 hy N X N N ™ R I \ . e " Fig. 2.11.3. 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FUNCTIONAL BLOCK DIAGRAM 3 T/ad D.C Purfattars Med 1-10__|4¥% == __Re-loy RI-iey > - . o — t | A1 buitt Jés P INSTRUMENTATION ANt Ll iB, iy et - —— DATE PO s OAK RIDGE NATIONAL LABURATORY TR | - ’———@i ; ) Sample| UNION CARBIOE NUCLEAR COMPANY wkq loses] T Janpie Al 8LDG. 3/05 : P, oy ‘ ’ s - — - - ' I mep, I 14 I/Md . ‘L, H W o) i 1 B / ) A et — | r Qe 370 e e mm—— , Fig. 2.11.4. Functional Block Diagram of MSRE h Stack Monitoring System. 377 1,064 -,625% 375~ 713 *—;-, - Keyway | L—/ 2.437 3.875 Cl'“d' 1 OYgDia \0 - Etched Board - | Kes5¢c3-16C 8 Pig. 2.11.5. Remote Alarm Relay Schematic. 378 ot ME BED b 13 L 2 MC Suppiy WX pntod in reto -~ 48 ~ather i To Central Moxk: Gaiiig dnserfrim g1 .l Finel v JE 201 I Coutacror [ 923705 caiy @ FILTER TAPE DORIVE ConTROL @ 20707 (21 ] "Il.fffl TAPE DRIVE P LIS - s Erprgn] Q@ I8 Apna, - | a4 ¢ . . N-0) - - e e Car-7 -~ . - :x.*oo’.-(_,-)-—’--rl-—————l— ) T i » O] RATE METER (3) fq‘)r-r r8008 KIB 281" 6Aghae loding Q23137 .o 8-r TAT . 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I Zaml veem Sfrack =) ”e l',on.f Llets AP £8P Cad Y20 et 7 Rlarons f Racorders * — ‘z,f:;. o8 “ OPERATIONAL SCHEMAT/C NEG | it v f rd --.‘ r 1h b it 3 AM=] Ruhess? to Fload P2370-13 for Fping Delails Siae of Cabin 9.237¢0-13 - Tbeth Aaf Stdc —— of Cabimet base _!M d I Nir 3 1 x5 ......-\ P - *-Tyua, y _‘ 56 v ‘ @ Sange f ot ' . > - ir dioafer eve S Iroper > e veve 1 < 4 S e gror f-d,.rvw_: ; Cande Y Car0 Mo | _:,:a;:-. o L d s Central Alarm ; '; Ke Pana! ‘ | ! 8/dy. 1503 J | ! 21 n B ) , ridc 7 Cormnetan g P Dotowrgr oo L EMENTARY O/ A 1on7) £ | Remeli Aldrm Eiae 7203 Central Alrm NOTES: cae T 24 i -\ ] i #ro 3 224 | i z 1 : G ' orm 1 . (1 (<] : + Sryont cn 9 II5e Sryant 2 : 70 , i ' ~~ o JA ré SH prne A 20100008 311, Tepe Broax Moskile See 23702 1= Aglyusl series resister 3¢ Thal Range Indicarer reads 25K whan count-mife mater is 3a7 e 25K range. This requires apprea. 480 K of rus, 2~ This Dwge. derived from @2325-2° 3 For inslaliation of Tape Drwve’ see Dy oenwj Interconnaction Diagram 92’”fl Functrona! Block Diagram @30- Foter 'upe T .ve rertbre “hoes:s 3857 MnGE DA DR MO, — bl /. //, M olladRy MSRE Stacw MoniTomING SYSTEMS. BeTa- GAMMA OreLrATIONAL SCHEMATIC -ELEMENTARY DisarAam Pump Fiutee Tares Daive Fig. 2.11.6. Pump, Filter Ta e =z Drive Control, and Alarm Panel Circuits. 379 2.12 DATA LOGGER-COMPUTER 2.12.1 Introduction A digital data collecting and compubting system is used on the MSRE to augment the conventional instrumentation system (Figs. 2.12.1 and 2.12.2). It is designed to collect and process 350 analog and 112 on- off contact signals (at present it processes only 291 analog signals). The remaining signals can be added by merely wiring in the signal leads and altering the system program. Signal processing includes conversion of the analog signals to digital values in engineering units; alarm monitoring by comparing the signals against preset upper and lower alarm limits; and calculations to provide heat balances, total pover, reactivity, and other operational and analytical information. These digital values may be logged on typewriters, displayed by a digital lamp unit, or recorded on magnetic tape, at the system operator's option. 2.12.2 Basic System Equipment Description The system consists of a Bunker-Ramo model 340 digital computer, operating console, analog and digital input-output cabinets, typewriters, x-y plotter, digital display lamp bank, and two magnetic tape unitst (Fig. 2.12.3). The analog input-output equipment is housed in three 23- by 84-in. cabinets (Fig. 2.12.4). These cabinets contain four dec amplifiers, an input signal multiplexer composed of mercury wetted contact relays, an analog-to-digital converter, a thermocouple reference unit, power supplies, and the input-output terminals with associated filters and signal conditioning circuits., The dc amplifiers and the converter were manufactured by the Redcor Corporation, Canoga Park, California. The analog signals from the process instruments are transmitted by signal leads to the first two cabinets, where they are scanned by the multi- plexer, then amplified, digitized, and transmitted to the computer memory. I%fie analog input system is designed to handle analog input signals ranging from millivolts de to 220 v dec or ac.1??2 The lower-level sig- nals are amplified to 10 v dec, while the higher-level dc signals are attenuated to the 10-v range and ac signals are rectified before at- tenuation. ' The anslog input signals are transmitted to the input terminals and then through 60-cycle noise filters before reaching the input 13, F. Pierce and D. C. Shattuck, Instrumentation and Controls Div. o 2E, N, Fray and J. T. DeLorenzo, Instrumentation and Controls Div. Amn. Progr. Rept. Sept. 1, 1963, ORNL-3578, p. 107. Note: Figure 9.4.1, this reference, contains an error. The lower block, labeled "Linear Count Rate Meter," should read "Logarithimic Count Rate Meter." 380 multiplexer., These filters have a manually set variable 60-cycle re- jection of from 6 to 50 db. They are mounted on plug-in cards in the \_J two analog input cabinets, In addition, digital filtering (integration) is applied to selected input signals, most of which are thermocouple signals used in precise calculations. The analog-to-digital converter operates on a O- to 10-v dc range. All analog signsls are converted to digital values on this basis, with the proper scaling done under program control. Digital signals are compared with preset alarm limits and can be selectively transmitted to digital-to-analog converters to produce up to 36 analog signals for recorders, oscillographs, an x-y plotter, or for control. Three cabinets, indicated as I/O Nos. 1 to 3 in Fig. 2.12.4, house the digital input/output equipment. This equipment handles the contact input signals from relays, typewriters, and the input keyboard and contains the control units for all the output devices., The contact in- put signals are transmitted to the arithmetic and control unit of the computer to perform operations under computer program control. The digital output signals from the arithmetic and control unit are trans- mitted through the digital input-output unit to operate relays, type- writers, and the digital lamp display unit. The computer consists of the basic digital computer, the master input/output control unit, and the memory units. The computer con- taining the basic electronics is housed in three labeled cabinets, central processor, core memory, and drum memory (Fig. 2.12.4). Input/out- put is housed in one cabinet labeled Master I/O. The basic 340 computer has all-solid-state circuitry with the fol- lowing specifications. ( | Core memory 12,288 words, expandable to 16,384, in blocks of 2048 Drum memory 28,672 words, expandable to 49,152, in blocks of 4096 Machine cycle time 6.0 msec Data word length 28 bits including sign plus one parity bit on all memory operations Instruction format Two fields: a l4-bit operation field and a l4-bit operand field Addressing Direct addressing of up to 16,384 words, single level indirect, and immediate operand addressing Number system 2's complement binary Operation Arithmetic, control, and core memory circuits: parallel; magnetic drum memory circuits: serial Clock frequency Arithmetic, control, and core memory circuits: 478 kc; magnetic drum memory circuits: 239 ke Registers Environmmental conditions Software Input-output subsystems Priority interrupt 381 Three major arithmetic registers, three index registers, and addi- tional registers for peripheral -equipment Standard operation to 85°F cabinet . temperature., The power consump- tion at 115-v single-phase, 60~ hertz is 2000 w, The total sys- tem power consumption is approxi- mately 7000 w, including the two tape drives which operate on 208 v, three phase An integrated package designed for process control; includes real time executive, utility package, assembler, and FORTRAN IT com- piler, and library of subroutines 350 analog inputs, expandable to over 2000; 32 digital outputs, expandable to over 1000 Handles over 100 levels of program priority (program operating time schedule) 2.12.3 Peripheral Equipment Description Aside from the computer itself and the analog input and output subsystems, there are a number of peripheral devices which provide communication between the operators and the machine. The devices are listed below and can be seen in Fig. 2.12.1. Four typewriters: two with 30-in. carriage and two with 16-in. carriage Tfio magnetic-tape units Paper-tape punch reader Input keyboard - x=y plotter Console: function matrix and digital display In normal operation, four IBM typewriters are used to provide hard-copy records of reactor data (see Fig. 2.12.4 for location of the typewriters). Two 30-in.-carriage typewriters are used to record es- sentially all logs and calculation results. The periodically appearing results are all typed on one device on preprinted forms; results of demanded operations are typed on the second typewriter. One of the two 16-in.-carriage typewriters is installed in the reactor control room to 382 record alarm conditions associated with analog signals and calculation results, The second 16-in. typewriter (console) records all operations performed at the computer console. The principal depository for reactor data is magnetic tape. The values of all the analog signals are stored on magnetic tape every 5 min, In addition, all intermediate and final calculation results are stored on tape. (The typeout of calculation results is generally less frequent and more limited in extent.) Two tape drives (IBM model 729-2) are available, with the second unit normally in standby. However, the second unit can be used for off-line functions such as data processing or program development while the first unit is on line, The paper-tape punch and reader (Teletype model BPRE-2 and Digi- tronics model 2500 respectively) are used primarily in connection with programming functions, for example, assembly and compiling. There is normally no input or output of reactor information through these devices. The input keyboard (Invac model PK-164) operates in conjunction with the on-line program development package (OLPD) in the computer. From the standpoint of reactor operation, it is the means of entering data for the trend logging and plotting functions. The x-y plotter (Moseley type 2D2) is capable of plotting any input variable as a function of time or of any other input varisble. Parameters for both coordinate axes must be entered by the operator. The computer console is the focal point for use of the computer by the reactor operators. It contains the function matrix as well as the digital switches for the selection of the various request functions. The console also houses the panel for digital display of signal values (Fig. 2.12.5). 2.12.4 System Operation 2.12.4,1 Collection and Processing of Analog and Digital Input Signals At the present time there are 291 analog signals from the reactor system connected to the computer. The types and numbers of signals are sumarized in Table 2,12.1.32?% See Fig. 2.12.6 for a complete list of all input signals. These signals are arranged in a scan table that contains 350 entries. Under normal conditions the raw analog signals for all 350 points are scanned, compared with high and low alarm limits, and stored in core once each 5 sec. In order to provide a more frequent loock at selected variables, some analog signals appear at several points in the table. For instance, the outputs of the three neutron safety channels are arranged so that one of the signals is read every 200 msec. Another reason for multiple entry in the scan table is to permit integration (digital filtering 3Ronald Nutt, Instrumentation and Controls Div, Ann, Progr. Rept. 4R. C. Robertson, MSRE Design and Operations Repdrt, Part I, Description of Reactor Design, ORNL-TM-728 (to be published). 383 Table 2.12.1. Analog Input Signals Number Type of Signals Thermocouple Conventional 169 Integrated 17 Pressure 20 Flow 13 Amplifier gain 4 Weight 5 Power and voltage 4 Liquid level 11 Punp speed and tachometer 6 7 Position Nuclear 13 Process radiation 23 Total 292 over 1/60 sec) of the signal for greater accuracy and resolution. Tem~ peratures that are used in calculations are integrated and converted to the nearest 0.1°F in the range from 900 to 1300°F. Thus, the signal must appear a second time, unintegrated, to provide information over the entire operating range. As a result of these multiple appearing signals, the 350-entry scan table contains 346 actual analog signals with four spare locations. Realistic high»and/or low process limits are imposed on most of the analog signals. In the remaining cases the limits are set at the instrument extremes. The normal computer response to an out-of-limits condition is to actuate the logger annunciator in the main control room and to print a message on the control-room typewriter identifying the variable, its value, and the time. BSuch a message is typed in red when the variable first goes out of limits and in black when it returns within limits. No other information (except for a 4-hr out-of-limits log) is typed while the signal is either out of or within limits. There is one group of 65 analog signals (type 2) that is recorded on magnetic tape, in engineering units, each 5 sec while any one of the signals is out of limits. The typed messages for this group of wvariables are similar to those for the other signals. The recording function can be inhibited by operator request on any or all of the signals that will produce this action. _ : , An out-of-limits condition on any one of another group of 22 analog signals (for instance, neutron flux) switches the computer to a "fast scan" mode of operation. In this mode the scan table is reduced to 64 384 important variables and all 64 are scanned, converted to engineering units, and stored on magnetic tape once each 1/4 sec. This mode of operation continues for 1 min, without 1limit checking, after its ini- tiation. At the end of that minute the normal scan is resumed until another signal to start "fast scan" is detected. The "fast scan" mode of operation can also be inhibited by operator request on any or all of the signals that will produce it. Once each 5 min, regardless of the scanning mode, all 350 signals are read, converted to engineering units, and stored on magnetic tape. 2.12.4.,2 TLogging Functions The computer generates and types out a number of periodic logs, which are tabulated below: 1-hr log (54 analog signals) 8-hr log (175 analog signals) Daily report (21 parameters) Out-of-limits log (once every 4 hr) Calculation results The 1- and 8-hr logs simply present the values of selected analog sig- nals to record the status of the system. In both cases the values that are printed are the same as those that were recorded on magnetic tape during the last 5-min taping operation. The daily report summarizes a number of operating parameters such as integrated power, time at tem- perature, and numbers of thermal cycles on important components. The out-of-limits log is an hourly summary of all analog signals (up to 40) that are out of limits at that time along with their current values, Selected results of some calculations, such as the average reactor in- let and outlet temperature, are also typed on the log sheet periodically. 2.12.4.3 Calculations Aside from the routine functions, such as units conversion, the computer performs a number of on-line calculations using current reactor data.%™® Many of these calculations include alarm functions to call at- tention to abnormal conditions. The calculations are normally performed on a periodic basis with the results being printed usually less fre- quently. Many of the calculations can be performed at nonscheduled times on operator demand; results of nonscheduled calculations are al- ways printed. Table 2.12.2 summarizes the schedule for some of the major calcu- lations. 5G. W. Allin and H. J. Stripling, Jr., Instrumentation and Controls 6J. L. Anderson et al., Instrumentation and Controls Div. Ann. Progr. Rept. Sept. 1, 1963, ORNL-3578, p. 100, 385 Table 2.12.2. Major Routine Calculations . Normal Printout Demandable Calculation Tnterval Interval ? Reactivity balance 5 min 1 hr Yes Average reactor inlet and 1 hr 1l hr Yes outlet temperature Reactor-vessel temperature 10 min 1 hr No difference Cell-atmosphere average 1 hr 8 hr Yes temperature Heat balance 4 hr 4 hr Yes Salt inventory 8 hr g hr Yes 2.12.4.4 Miscellaneous Functions Some of the miscellaneous functions that are, or can be, performed by the computer are listed below. Trend log (up to 26 variables) Trend plot | Digital display Contact and analog outputs On-line program development (OLFD) Data retrieval and processing General-purpose computing The first three items, trend log, trend plot, and digital display, are means of providing visual information for operator guidance. The variables to which these functions are applied can be selected at will by the operators. The last three items in this list are all related in that they are nominally off-line functions ‘that can be performed with the computer on line. The system program requires only about 30% of the capability of the computer under normal . circumstances, this utilization increases to about 40% in the "fast scan" mode of operation. In ad- dition, the system.program requires only about two-thirds of the core memory. Thus, there is ample capabllity for background processing of off-line material., The purpose of the computer is to provide close surveillance, rapid processing, and compact storage of large amounts of reactor data. Since it is associated with a reactor experiment, it is not possible to define all the data and calculations that are required for a complete analysis of the system. Therefore a great deal of data are being col- lected which may be used much later or which may never be used, 386 2.12.5 References and ORNL Drawings For more details on all parts of the system, refer to the documents and drawings listed. For details on the operation of the system from the reactor operator's viewpoint, refer to item 11 in the Reference List, Computer Manual for MSRE Operators. 1Interim Report to Oak Ridge National Laboratory Relating to a Digital Data Acquisition System for Use with the Homogeneous Reactor Test Facility, CF-60-3-159, R. K. Adams et al. (Mar. 29, 1960). 2Final Report to Osk Ridge National Laboratory Relating to s Digital Data Collecting and Computing System for the EGCR Test Loop Facility, R. K. Adams et al. (June 22, 1960). 3MSRE Data Collecting and Handling Requirements, A Study Report, MSR-61-112, G. H. Burger (Aug. 15, 1961). 4Specification for a Digital Data Collecting and Computing System for the Molten Salt Reactor Experiment Located at Oak Ridge National Laborstory, Oak Ridge, Tennessee, JS-81-170 (May 1, 1962). 5Use of On-Line Computer in MSRE Operation, CF-62-3-26, P. N. Haubenreich and J. R. Engel (Mar. 6, 1962). 6Toward Closed Loop Control in Nuclear Plants, Nucleonics, 71 (June 1962). 7High Speed Monitor for Closed Loop Control, Colin G. Lennox and Albert Pearson, Nucleonics, 73 (June 1962). 8Input Signal Functional Tabulation, SC-I&C-EGM-6230. MSRE Digital Data Collecting and Computer System Calculations, May 17, 1963, 10TRWC Proposal for a TRW-340 Digital Data Collecting and Computing System, TRWC-63 157. 1loomputer Manual for MSRE Operators. 120ross Reference Listing of MSRE Instrumentation and Control System Drawings, CF-63-2-2, R. L. Moore. 13MSRE Data Logger Signal Intercomnection Wiring, ORNL Drawings D-HH-B-57456, 57457, 57458, 57459, 57460, and 57461. Fig. 2.12.1, Bunker-Ramo 340 Computer Input-Output Equipment. PHOTO 80019 L8¢€ Fig. 2.12.2. Bunker-Ramo 340 Computer Central Processor. C PHOTO 80412 83¢ 389 ORNL-DWG 64-64E1AR INPUT KEYBOARD ANALOG SIGNALS TO REMOTE £y 3 LOGGING OPERATOR CONSOLE INDICATORS, CONTROLLER'S, ETC. | TLOTTER TYPEWRITERS ‘ ’ ! r I PROGRAM CONTROL , PAPER-TAPE UT i INDICATING LIGHTS, PUNCH INPUT- | AND AND OUTPUT i ALARMS READER TYPEWRITER f N\ i 36 ANALOG 32 DIGITIZED OUTPUTS CONTROL 3 OUTPUTS AND | PROGRAM | '——-'l INPUT-0QUTPUT INSTRUCTIONS o | 350 ANALOG EQUIPMENT AND CONTROL. A = INPUT SIGNALS DIGITAL , REACTOR i DIGITAL INPUT COMPUTER \ ) SYSTEM [ . (MULTIPLEXER, INSTRUMENTS VOLTAGE DIVIDERS, | DIGITAL OUTPUT ———:1 112 "ON-OFF" FILTERS, l | T [~ SIGNALS AND AMPLIFIERS) CONTROLDIGITAL rerrrr————- Fig. 2.12.3. Computer System. i INFORMA'i’ION 2 MAGNETIC TAPE UNITS Block Diagram of MSRE Digital Data Collecting and ® 390 ORNL-DWG 64-628R AL A © M N ] N j _ - - } | tl \ SPARE PARTS ' S N STORAGE TABLE DESK N N N T~ \ Y POWER PANEL P ' N £ N = 1 N - N N = N N N \ 3 \ N N N N | N ANALOG TO 1/0 NO. Y N § ANALOG [ANp’th'o? DIGITAL 170 170 & §. N SIGNAL | 1N CONVERSION| NO.3 | NO. 2 | POWER N N INPUT | OUTPUT " gysTEmM SUPPLIES N N \ N N N N w ¢ N N o £ CR E w © § N * N o 2 ~ N § = N N w2 N N Zo N 3 MASTER | CENTRAL | CORE DRUM POWER i | /0 | PROCESSOR [ MEMORY | MEMORY | SUPPLIES N \ \ \ \ N N N\ '\ - MAGNETIC N TAPE N N R RN MAGNETIC 30in. = 30in. ' | TAPE {LOGGER LOGGER \ \ Uy pLOTTER PAPER TAPE PUNCH AND READER | N r COMPUTER _ I N CONSOLE T m I N CONSOLE ~—KEY BOARD S TYPEWRITER N N N DESK N N \ ESNSNSSN 1 ~=——16 in. LOGGER ‘ & Fig. 2.12.4. Layout of Data Room., = 391 Fig. 2.12.5. 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B ML | & 1 | ol Th-Re- | Ye Jveee [ Aot | ¢ 18| the WM DT ¢4 [aran | tew [asi | 0 (e — OAK RIDGE NATIONAL LABORATORY Ta-201A10 At s | w0 Tee-1 et | A Jet | ey WWEH-c4 [man]1ey [pr T v o3 [307 (_._ OPERATED BY Te- e A 16 Tailt | » .y 9 T™-nc- 1.04.] A ey | 138 WM=CDl ¢4 [aran | 1oy [ALL | & [y [11) MASCELL ANEOUS UNION CMIDE Nucm COMPW e -281 Ve [reeeintl | & o3 'S Tas Ré- 4 el | A oy | 184 WE 21 €4 | vaa] 14 LAt |+ 1 |l Erh- IVA_ lwired e Lt DIVISION OF UNION CARBIDE CORPORATION .?"- ‘ TR At | B 1% | teo . - EeM- DL luewe. [ Shan f 2 a T n_[1a2 OAX RIDGE, TENNESSEE ¢ ek G | et | b | et |26l e S T "oo . Tewc-T (3o werecoc] a [os |1ret LR On, DiMENSIONS UMLESS JMOLTEN HALT BEACTOR SXPERIMENT %" 7503 DEN™ 519 ? Y REVISIONS \ FRAGTIONS & RAIA LOGGED SioHAL INTERcouutelion Wikl . e . DECWALS & e ] _GAL ASSIGHMENT JABULATION Qe 14 Gb mass & - APROVED | g M, HIRGER LN - REw o _ oy D- B [57457| 0[] 1 120{94RH 628D 1 s - Fig. 2.12.6. Data Logger Signal Interconnection Wiring Signal Assignment Tabulation. | mea e 393 2.13 MSRE Beryllium Monitoring System1 Atmospheric beryllium concentration is monitored by 15 air sampling stations located at strategic places throughout the reactor building. The beryllium content of the air is monitored by drawing air through filter papers which are then collected and analyzed for beryllium content. The radiator air stack air is monitored by an arc spectrograph. Air is drawn through the spectrograph for a set period and then analyzed by the light spectrographic method. The result of the analysis is printed on a recorder located in the spectrograph cabinet. The spectrograph is equipped with a manual switch so that the coolant cell can be monitored during reactor maintenance operations. iN. E. Bolton and T. C. Whitson, Revised Beryllium Control Program for MSRE, ORNL~CF-63-11-44. (Supersedes ORNL CF-~63-7~63.) 1. R. K. Abele 2. R. K. Adams 3. G. M. Adamson L. R. G. Affel 5. L. G. Alexander 6. G. W. Allin T. A. H. Anderson 8. J. L. Anderson 9. R. F. Apple 10. C. F. Baes 11. J. M. Baker 12. S. J. Ball 13. C. J. Barton 14, A. E. G. Bates 15. H. F. Bauman 16. S. E. Beall 17. R. L. Beatty 18. M. Bender 19. C. E. Bettis 20. E. S. Bettis 2l1. R. E. Blanco 22. F. F. Blankenship 23. J. 0. Blomeke 24, R. Blumberg 25. E. G. Bohlmann 26. C. J. Borkowski 2T7. G. E. Boyd 28. H. R. Brashear 29. J. Braunstein 30. M. A. Bredig 31. R. B. Briggs 32. H. R. Bronstein 33. F. R. Bruce 34. G. D. Brunton 35. J. B. Bullock 36. 0. W. Burke 37. D. A. Canonico 38. S. Cantor 39. W. L. Carter 4Lo. T. M. Cate 41. G. I. Cathers L2, 0. B. Cavin 43. A. Cepolino LYy, J. M. Chandler 45, C. W. Collins 46. E. L. Compere 4LT. K. V. Cook 395 INTERNAL DISTRIBUTION RROOYESEHHIOERAYE QIO I W LN SN QUORHP ORGSO 000 GG o ORNL-TM-T29 Cook Corbin Crowley Culler Dale Davis DeBakker Ditto . Dworkin . Dyslin . Eatherly . Engel . Epler Ferguson . Ferris Fraas Friedman Fry Frye, Jr. Gabbard Gallaher Goeller Grimes . Grindell . Guymon . Hammond . Hannaford Harley Harman Harms Harrill . Haubenreich Heddleson Herndon Hightower Hill Hoffman Holmes Horton Hudson Hungerford nouye . Jordan Kasten . Kedl Kelley Kelly Egt;*?:?flffl?d?dg}?@zglp.flfflb*dmmwmwmm-?bhdlgbjhdw*meMQQE{t‘bl—]’:I! Y9 EH 95. 96-97. 98. 99. 100. 101. 102. 103. 10L. 105. 106. 107. 108. 109. 110. 111. 112. 113. 11k, 115. 116. 117. 118. 119. 120. 121. 122. 123. 12k, 125. 126. 127. 128, 129-132. 133. 134, 135. 136. 137. 138. 139. 1ko0. 1h1. 142, 143. 1k, 145, 146. 147. 148-1L49. 150. ?.fi??fl??fl!fl?*dp?fl?‘?flf#i‘d?flp?fl?flb?flI:—'C—cfls‘)’;flmwCEHQGEUEWZHQPSUZQOWQPCAUU)EO at ic 396 Kennedy Kerr Kirslis Knowles Koger Krakiovak Krewson Kryter Lamb Lane Lin . Lindauer . Litman . Llewellyn . Long . Lundin . Lyon . MacPherson . MacPherson . Manning Martin Mauney cClain McClung McCoy McDuffie McGlothlan McHargue McWherter McNeese Metz . Meyer . Minue . Moore . Mossman . Nelms . Neumann . Nichols Nicholson . Osakes . Parker Partain riarca Perry Pickel Piper Potts Prince Ragan Redford hardson 151. 152. 153. 15k, 155. 156. 157. 158. 159. 160. 161. 162. 163. 16k, 165. 166. 167. 168. 169. 170. 171. 172. 173. 17k, 175. 176. 177. 178. 179. 180. 181. 182. 183. 18L. 185. 186-191. 192. 193. 194, 195. 196. 197. 198. 199. 200. 201. 202. 203. 20k . 205. 206. 0. Robbins C. Robertson C. Robinson C. Roller W. Rosenthal P . C. Bavage . F. Schaffer E. Schilling Dunlap Scott Scott Seagren Sessions Shaffer Simpson Skinner Slaughter Sliski Smith Smith Smith Smith Smith . Spencer Spiewak Squires Steffy Stoddart Stone Stone Strehlow . Stripling . Sweet . Tallackson . Taylor erry . Thoma Toth . Trauger Tucker . Ulrich . Walker . Watson. Watts . Weaver . Webster Weinberg Weir Werner - QXD YuoO=RREHE 9@ HoapyhyuyEY"qEnEES .Z:ffl?s‘.flf):':flf—if')_flbdUL—";USH"—I';U.'I%W'JUCHE!';UU’JHfl"UOCD":IP'-fl(DZUMO';E{C-c GCIo=EHmH"HprnnaxnuwEHdgamdE g ErnHdOO 207T. 208. 209. 210. 211. 212. 213. 232-233. 234, 235, 236-237, 238, 239, 240. 241, 242, 243, 2kl , oks5, 246, 247, 248, 249263, 264 . 397 K. W. West 21k, J. P. Young M. E. Whatley - 215. E. L. Youngblood J. C. White 216. F. C. Zapp H. D. Wills 217-218. Central Research Library L. V. Wilson : 219-220. Document Reference Section G. Young 221~-230. Laboratory Records Department H. C. Young 231. Laboratory Records, ORNL R.C. EXTERNAL DISTRIBUTION D. F. Cope, RDT Site Office, ORNL A. Giambusso, Atomic Energy Commission, Washington W. J. Larkin, Atomic Energy Commission, Oak Ridge T. W. McIntosh, Atomic Energy Commission, Washington H. M. Roth, Atomic Energy Commission, Oak Ridge M. Shaw, Atomic Energy Commission, Washington W. L. Smalley, Atomic Energy Commission, Oak Ridge G. H. Burger, Mining and Metals Division, Union Carbide Corporation, Niagara Falls, N.Y. E. N. Fray, General Electric Company, San Jose, California S. H. Hanauer, University of Tennessee, Knoxville, Tenn. T. W. Kerlin, University of Tennessee, Knoxville, Tenn. C. L. Matthews, Atomic Energy Commission, Oak Ridge J. A. H. Kersten, P/A Kema, Utrechtsweg 310, Arnhem, The Netherlands K. A. Warschauer, Jacob Marislaan 48, Arnhem, The Netherlands William Kerr, Director, Michigan Memorial, Phoenix Project, Ann Arbor, Michigan Division of Technical Information Extension Laboratory and University Division, AEC, ORO