ORNL-TM~334L4 Contract No. W-ThO5-eng-26 Reactor Division N AN EXPERIENCE WITH SODIUM FLUOROBORATE CIRCULATION I MSRE-SCALE FACILITY A. N. Smith NOTICE This report was prepared as an account of work Sponsored by the United States Government, Neither the United States nor the United States Atomic Energy Commission, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, com- Pleteness or usefulness of any information, apparatus, product or process disclosed, or represents that its use S E PTEMBER -l 972 would not infringe privately owned rights, NOTICE This document contains informa?ion oflafiizeiimifizry nature and was prepared primarily f?r 1nt§rn: e e Oak Ridge National Laboratory. It 1s subjec f? oot correction and therefore does not represent a fina OAK RIDGE NATIONAL LABORATORY Oak Ridge, Tennessee 37830 operated by UNION CARBIDE CORPORATION for the U.S. ATOMIC ENERGY COMMISSION T T QGO TMENT 1 1IN BATTIY PISTRISUTVIN OF TEIS DGOITMENT 16 TN N A CONTENTS BB R A T v ettt et ittt e sttt rannnensoeeessoesoetasensoeenseenananes 1 TN RODU CT IO 44t e tseteetnneenneruonsenesnsesnesoenonnanssnnnes 2 RS OB B T I S vttt ettt ernrsreeoenoetnaesennonenseenanennes 3 SUMMARY OF TEST RESULS vttt erenreatoresoonnsennsonsoesenss S N €1 T - T 3.2 Pumping Characteristics ....viiiiriiiienieeneeeeneeennns 3.3 Control of the Salt Composition ...vvevreriereernnenens 3.4 Controlled Deposition of Corrosion Products ........... 3.5 Analysis and Correction of Restrictions on the Off-Gas System tiveretniieinentnensoeeroeassenssennss 3.6 Miscellaneous ObServabions ...veeeeeeeeeeeenennnseneenns L. DESCRIPTION OF TEST FACILITY v vvvenreneenennenneneennennenes Bl GEMETAL vttt ittt et e i it e, 4.2 Salt Piping and COmMPONENtS ..vveeeererenenrnneneannnnns 4.3 Salt Sampling DEVICE +vuuvvrvrrrernnreneeneeoreneensnns 4.4 Hesting and Controlled Ventilation .....evveverenenenn. L5 Gas System Desigh . ive e ineineneineeneeeneenoneeenenns L6 BFE; DiSPOSAL «uvuutunninnnniiniieiiannaansnanannnennns h,7 Instrument and CONtrols . uvueeeseeeeerereeeeeeneeeeoeees iii 5. TEST PROCEDURES, OBSERVATIONS, AND CONCLUSIONS FCR THE PRINCIPAL TESTS 5.1 5.2 5.3 5.4 Pumping Characteristics ......ciciiieiiiiierninennnnncens Control of the Salt Composition .......cevivieiieenann. 5.2.1 Operation of the BF, partial pressure control sysStem ..iveteneeienenestoenranneannnas 5.2.2 Methods for monitoring salt composition ........ 5.2.3 Evaluation of the thermal conductivity method .. Corrosion Product Deposition ......cievivieirveinnncnns Off-Gas System Flow Restrictions ......cevvvevensnvonsn 5.4.1 Plugging €XperienCe .....civeeenenceerneronansss 5.4.2 Off-ga8 tES8TS vvrirrrerirorernrstenossnnnneasnss 5.4.3 Discussion and evaluation of test results ...... 5.4.4 General conclusions from off-gas tests ......... ------------------------------------------- Page O V1oV o oy o ~N N 1 O & =P o 0 o D 19 19 26 31 36 40 48 53 54 56 71 77 iv 6. CHRONOLOGY, PERTINENT OBSERVATIONS, AND OTHER TESTS ......... 79 £.1 ChYONOLOZY vt eteeeuuaeseeonnsososssnanaansssssnonanans 79 6.2 Analyses Of Salt SampPles ..veeerrerorooreanoscescnncens 83 6.3 Pretreatment and Transfer of Salt Charges .e.oeeeeseesras Bl 6.4 Freeze Valve Operation ..veeereeereereceesooaearoeassnns 88 6.5 Rubbler Tube Operation ....eeeieeseereeeesosssasassosns 90 6.6 Experience with Salt Ievel Instruments ....evvoevessosns 93 6.7 Back Diffusion at the Pump Shaft .vevevrvrerrorionannns 95 6.8 A Salt Leak to the AtmMOSPHEIrE ..vvvveerennrnnnennieansns 96 6.9 Experience with Handling BF, «.cevvcvivrerienonnnnonnn. 98 £.10 Corrosion EXpPeri€rCe ....eeeeervereereerasseneonnsosonss 99 6.11 Green S8l vuui it initereeniareatieroieiaaaaeaa 103 6.12 Valves in BF, Service ............ciieiiiienianianiann, 105 7. RECOMMENDATIONS FOR FURTHER DEVELOPMENT WORK ...vvvvnvennonas 106 7.1 Tmpurities in the Salt ..uuieereeereeneneroosossnsrsons 106 7.2 Corrosion Product Deposition ...eeeereeenrcrasosnsonnos 106 T.3 Salt Level Instruments .....iviirtieeneritiencnecnanannaas 107 7.4 Off-CGas System Restrictions vveeeivereruveceoeneneannns 107 7.5 Control of Salt Composition ...veieivirreeeerteesonsnnns 107 7.6 TIntermixing of Molten Salts vvvevvvrrrnonnenennanncenan 108 7.7 Solid Phase Transition ....euvveverenineneronnnennonss .. 108 7.8 BF, Recycle System ....vveeiivneiiiuneiierrrnrennenon, 108 ACKNOWLEDGMEITDS v s st e st et s s s evnnennnesessssseananenossassesooans 109 REFERENCES 2 et e vt etes et aenenenenneneesenensessessarensensanenes 110 BIBLIOGRAPHY ettt st et i ssnoseoananssraassasasassossossassssses 110 APPENDTX A. SELECTED PHYSICAL ANWD CHEMICAT, PROPERTIES OF PROCESS MATERIALS .. ittt i insn i vennsonensannnanans 113 APPENDTX B. REFERENCE DRAWINGS .+ ieiiierenrnerernanssnosnensnnos 121 APPENDIX C. MATERTAL SPECIFICATTIONS . vvenrrvnocoareanooanonnssns 122 APPENDIX D. DERIVATION OF EQUATION FOR CALCULATION OF BE, PARTTAL PRESSURE .. iiititenenreoenrsnssoensnsoenns 123 APPENDIX E. FREEZE-THAW STRESS TEST ....v0vvirirnerroreennnennns 125 EXPERTENCE WITH SODIUM FLUOROBORATE CIRCULATION IN AN MSRE-SCALE FACILITY A. N. Smith ABSTRACT A eutectic mixture of sodium fluoroborate and sodium fluoride was circulated isothermally at a rate of about 800 gpm for 11,567 hr in s h-in.-IPS Inconel test loop as part of the program to evaluate the fluoroborate salt for use as a secondary coolant for the Molten-Salt Breeder Reactor. Except for brief periods at 900, 1150, and 1275°F, the bulk salt tempersgture was controlled at 1025°F. The obJjective of the experiment was to obtain general experience in the handling and circulation of the fluoroborate salts, with emphasis on the pumping characteristics and on the design and operation of the gas system as it related to handling BFé and controlling the salt composition. The test results indicated {1) that water test dats may be used to predict the performance of molten-salt pumps with the fluoroborate salt, (2) that reliable performance may be obtained from systems handling BF, gas if precautions are taken to exclude water and water- related impurities, (3) that control of the salt composition should not be a problem, and (4) that the thermal conductivity of the gas phase above the salt surface may be used as an indicator for monitoring the salt composition. Preliminary tests were made to examine the fea- sibility of protecting reactor heat transfer surfaces by preferential deposition of corrosion products in a cold trap. Further work is recommended in this area. The test work indicated that flow restric- tions in the off-gas line can be eliminated by pretreatment of the salt to remove volgtile impurities and by the use of a hot-mist trap and a cold filter in the off-gas line at the pump bowl outlet. Additional work is needed to improve our understanding of the ef- fects of cross-mixing between the fluoroborste salt and the reactor fuel salt and the nature and properties of the acid impurities in the fluoroborate salt. Key words: reactors, secondary coolants, sodium fluoroborate, fused salts, boron trifluoride, coolant loops, Molten-Salt Reactor Experiment, molten-salt pumps. 1. INTRODUCTION As currently conceived, molten-salt breeder reactor (MSBR) systems require the circulation of a secondary coolant salt to transfer the nu- clear heat from the fuel salt to the steam generator in the power con- version (Rankine cycle) system (see Fig. 1). A mixture of lithium and beryllium fluorides was used as the secondary coolant in the Molten-Salt Reactor Experiment (MSRE), and the performance of this salt indicates that it is suitable for MSBR use. The main disadvantages of its use are high cost (gbout $12/1b) and relatively high melting point (850°F). Another material, a sodium fluoroborgte-sodium fluoride eutectic mixture [NaBF, -NaF (92-8 mole $)], has evoked interest because it costs less (about 4% of the cost of the Li-RBe salt) and because its melting point (725°F) is low enough to minimize the probability of salt freezing in the steam generators.l An extensive program has been under way at ORNL to qualify the fluo- rotorgte salt for use as the secondary coolant for MSBR service. In addition to studies of basic physical properties, engineering properties, and materials compatitility, the program originally called for testing the fluoroborate salt mixture in the MSRE coolant system under reactor operating conditions. To help us determine design and operational changes that would be needed at the MSRE for the coolant test, it was decided to make g preliminary test in an existing isothermal pump test stand, which was capable of operating at the flow rate (850 gpm) and temperature (1000 to 1200°F) of the MSRE. This report describes this preliminary test. Conceptual work started in June 1967; initial loop operation started in March 1968, and the test work extended through June 1970. After the preliminary test was under way, a program change resulted in the cancel- lation of plars to use the fluoroborate salt in the MSRE coolant system. Consequently, the work reported here represents the current total expe- rience with the ecirculation of fluoroborate salt in an MSRE-scale fa- cility. VENT -COOLING PRESSURE —== COOLING COOLANT SALT PUMP FROM CHEMICAL ORNL -DW(G 68-4492 PROCESSING REACTOR - o1 - STEAM SUPERHEATERS STEAM SUPERHEATERS L ' i | | \ { i 1 | J CATCH BASIN® TO CHEMICAL PROCESSING PRESSURE _ AND VENT T < _/ HEAT REJECT @ STACK FUEL DRAIN TANK TO CHEMICAL FREEZE VALVE PROCESSING PF) PROPORTIONAL FLOW VALVE GAS SEPARATOR —— FUEL #»% STEAM GENERATING UNIT NO. 2 + ———— COOLANT xxx STEAM GENERATING UNIT NO. 3 ———w STEAM »x#% STEAM GENERATING UNIT NO. 4 Fig. 1. STEAM GENERATING UNIT NO.1 . PRESSURE AND VENT COOLANT SALT DRAIN TANK TEMP TEMP POINT °F FLOW PCINT °F (¥; 1000 200 f1¥sec as 850 (Zy 1300 200 9 850 3 1300 50 43 600 (& 1150 75 (%) 1000 (55 850 75 3 1000 (6 1150 75 a8 700 &) 1150 0-20 ) 950 & 1150 16.2 8] 1250 25 850 16.2 (i9) 600 g 1150 10 &0 100 Flow diagram for 2000-MW(e) station. TS T2 FLOW 75 H3/sec 10 2.56 x 10% 1b/hr 2561 'nOS 1.26x 10° 1 26x10°% 4 ft¥sec a4 420,000 ft ¥min 420,000 2. TEST OBJECTIVES When the fluoroborate* salt is heated above its melting point, it dissociates in accordance with the equation NaBF, < NaF + BF; . The de- gree of dissociation and the resulting partial pressure of BF; over the melt is a function of the temperature (see Appendix A, Sect. A.2). At 1025°F the equilibrium BF; decomposition pressure is 1.4 psia; at 1150°F, which is the design temperature at the coolant pump inlet for the MSER, the BF; decomposition pressure is 4.9 psia or one-third of atmosphere. By way of contrast the Li-Be coolant salt at 1025°F has a vapor pressure of gbout L X 10'6 psia. In a system such as the MSRE coolant system, which operated at a total overpressure of 20 psia, the pump bowl gas space and the associated off-gas stream would contain from 7 to 25% BF;, depending on the temperature at the salt-gas interface. This rather significant partial pressure of BFy suggested the possibility of problems in the contrel of salt composition, in pump operation, and in the opera- tion of the cover-gas system. In addition, so far as we know, this was the first attempt to circulate molten fluoroborate salt in large-scale equipment, and it appeared likely that some unforeseen problem might arise. Therefore, the original objectives of the sodium fluoroborate circulating test loop can be summarized as follows: 1. Examine the pumping characteristics. Compare head-flow data with similar data for the Li-Be salt. Determine minimum overpressures necessary to suppress cavitation. 2. Determiné what problems might be involved in monitoring and con- trolling the composition of the salt. 3. Accumulate experience in the operation of a fluoroborate circu- lation system. In particular, make observations on freeze valve opera- tion, salt sampling, and the handling and control of gases containing BF; . In general, make note of anything that might be useful in the de- sign or operation of a fluoroborate system. *Unless otherwise indicated, the terms fluorobtorate or sodium fluoroborate will be used herein to designate the NaBF,-NaF (92-8 mole %) eutectic mixture. After the test work was under way, two other items assumed sufficient importance to warrant designation as a major objective. L., Examine the possibility of preventing undesirable accumulations of corrosion products (such as on heat exchanger surfaces) by providing for preferential deposition in a cold trap. 5. Determine the nature of mists and vapors discharged from the pump bowl vapor space into the off-gas line. Develop separators, traps, filters, or other devices that will manage these materigls so as to mini- ‘mize flow restrictions and fouling of control wvalve trim in the off-gas system. 3. SUMMARY OF TEST RESULTS 3.1 General The test work produced no evidence of any engineering problem that would preclude the use of NaBF;—NaF eutectic as a secondary coolant for molten-salt reactor systems. 3.2 Pumping Characteristics The results of hydraulic performance and cavitation tests indicate that head-flow and cavitation characteristics using fluoroborate salt should be predictable from water test data taken with similar pumps. Cavitation inception pressures for a flushing batch of salt were 7 to 16% higher than similar data for a clean batch of salt. This effect was attributed to an increase in BF, partial pressure resulting from contami- nation of the flushing salt by the residual MSRE-type (Li-Be-~U-Th) salt remaining in the loop from prior test fiork. 3.3 Control of the Salt Composition Efforts to evaluate methods for composition control were hampered by our inability to determine the composition of the salt with suffi- cient accuracy and precision., However, after due consideration of the test data, we believe that the composition of the salt remained essentially constant over the 11,000-hr period of circulation, ahd we further conclude from this that the use of a BF; overpressure system was successful as & composition control method. Of techniques considered for monitoring the salt composition, the test work indicated that the off-gas thermal conduc- tivity method is feasible and that chemical analysis of salt samples by use of currently available techniques is unsatisfactory. 3.4 Centreolied Deposition of Corrosion Products Data were obtained on the relative size and chemical composition of deposits formed on a 'cold finger'" which was inserted beneath the surface of the salt pool in the pump bowl. The ultimste objective was to deter- mine if cold trapping could be used in reactor secondary coolant systems to control corrosion product concentrations and thus to inhibit the for- mation of harmful deposits on the steam generator heat transfer surfaces. However, the test results were too megger to permit any meaningful con- clusions. 3.5 Analysis and Correction of Restrictions on the Oif-Gas System Initial operations were characterized Ty flow restrictions in the off-gas line. The trouble was traced to a mixture of materials (salt mists, acids, metal corrosion products) carried from the pump bowl by a purge-gas stream and deposited in urdesirable places by condensation and/er gravity. 'West results Indicate the problem can be controlled by a properly designed system of traps and filters in the off-gas line at the pump bowl ocutlet. Also the problem may be ameliorated by pretreat- ment of the salt to minimize impurities and by designing the pump so as to minimize formation of salt mist in the pump bowl gas space. 3.6 Miscellaneous Observations Handling and circulation of the fluorotorate salt were accomplished without difficulty using routine molten-sglt handling techniques. An incident involving leaskage of salt to the atmosphere dramatized the essential lack of secondary effects. The importance of providing a clean, leak-~tight system for handling BF; was confirmed. The performance of the salt freeze valve and of various instruments for measuring pressure and flow in both the salt and gas systems appeared to be reliable and adequate. L. DESCRIPTION OF TEST FACILITY h.,1l General The test work was done in an existing facllity that was modified to meet the requirements of the fluoroborate test. The facility was con- structed in 1956 and was operated for many thousands of hours circulating NaK in order to obtain performance data on model PKP pumps for the Air- craft Reactor Test (ART). In 1962 the facility was reassigned to the Molten-Salt Reactor Program and between 1962 and 1966 was operated for more than 17,000 hr in the circulation of molten-fluoride salts of the type (Li-Be-U-Th) used in the MSRE. Changes made prior to the start of the fluoroborate test included provisions to obtain salt samples, revi- sions to The purge- and off-gas systems to provide proper equipment for handling BF; gas, revision to the drain line freeze valve to better simulate the MSRE installation, and revisions to the containment and ventilation systems to insure proper containment and disposal of any vapors that might accidentally leak from the loop. As a result of prob- lems that arose during the course of the fluoroborate test work, the BF; feed system was modified, and miscellaneous revisions were made in the purge- and off-gas systems primarily to cope with flow restriction problems. For design details of the complete facility see the drawings listed in Appendix B. 4.2 Salt Piping and Components The salt piping is shown in simplified outline in Fig. 2. The pump and piping were fabricated from Inconel. The pipe size was 4 in. IPS except for about 4 ft of 3 l/E-in. IPS at the pump discharge. The pump l_;:j ORNL DWG 72-2073 —200-hp MOTOR { ™ PKP PUMP DISCHARGE PRESSURE _ ) PMD {09 VENTUR' METER. SALT FLOW THROTTLE _ VALVE — FREEZE VALVE - — DRAIN LINE VENTURI THROAT PMD'C48 VENTURI INLET PMC1044A - - DRAIN TANK g 4> _ e 2. Simplified schematic of fluoroborate circulation loop. was located at the point of maximum elevation. From the pump discharge the salt flowed in order through an ufiper horizontal section, a verti- cally oriented 180° return bend, a lower horizontal section, a venturi element, and a throttle valve. From the valve, which was at the point of minimum elevation, the flow proceeded directly upward about 3 ft to the pump suction. Each horizontal section was about 16 ft long and was pitched slightly to facilitate draining of the loop. An 8-ft® Inconel drain tank served as storage space for the salt inventory when the fa- c¢ility was not in operation. A 3/h-in.-IPS drain line connected the dip leg in the drain tank to the bottom of the throttle valve housing in the loop. Transfer of salt was accomplished by means of gas pressure, and a freeze valve (see Section 6.4) was provided to isolate the drain tank from the loop. Table 1 lists principal data relating to loop geome- try. The pump, designated as model PKP, is a forerunner of the pumps used in the MSRE fuel and coolant systems. It is a centrifugal sump pump with integral pump tank and vertical shaft (Fig. 3). During the fluoroborate test work the pump speed was 1800 rpm. The upper exterior surface of the impeller is equipped with ribs which function to control the rate of leak- age (fountain flow) from the volute into the pump tank by way of the upper shaft seal.® Baffles and a thermal shield serve to protect the bearing cavity from excess temperature. A forced-circulation oil system lubricates the bearings and cools the thermal shield. The shaft 0il seal is a metal-graphite rotating mechanical s§al. 0il that leaks past the seal drains into a catch basin (Fig. L4). A top hat or dam is provided to minimize the tendency for leskage oil to flow down the pump shaft to the pump bowl. A continuous flow of inert gas (helium or argon) serves as a shaft purge. At the shaft annulus the flow is split into two streams. One stream, equal to about 90% of the total, flows down the shaft into the pump bowl vapor space, serving to inhibit back diffusion of pump bowl vapors. The remaining portion of the purge gas flows up the shaft over the rotating seal and through the oil catch basin. The piping is arranged so that most of the accumulated oil is forced out of the catch basin with the gas stream and into an oil catch tank further downstream. il CATCH BASIN - ——-- = - - ‘Z?QQ-L THERMAL BARRIER--._ | P90 T ‘z‘ P BAFFLES—— T - v T o MAXIMUM < : : PERMISSIBLE LEVEL —— /3 ,_fi_hrflfiw4l it i i gr A UPPER IMPELLER CASING A ‘ Hi | 5 NORMAL OPERATING LEVEL- —— t ;fi N ~ _//i%§§§ o MINIMUM PUMPING LEVEL - = " ‘\\“,’\ 3 ¥ . N l\‘\. INLET Fig. 10 ORNL-LR-DWG 243578 LOW TEMPERATURE ROTARY ASSEMBLY o 2 4 6 e INCHES "1 L1 - MECHANICAL 11 SHAFT SEAL ! > PUMP TANK i DISCHARGE T__ji__T PIPE . A E ; ; = / _;f/,,” = - < \ VOLUTE "IMPELLER 3. PKF purmp cross section. 11 QRNL DWG 72-2075 PUMP SHAFT Z L BEARING 7 % N cavity P / N ) / % N ot g ot | SHAFT TO OIL RETURN LINE fay 3~T0P % SEAL T har / N2 }t./’a % ERTREEN N / CATCH R N / N BASIN JiE 7~ s — N —— / N > LABYRINTHS 3 % b N ; FLOW CONTROLLER § % TO OFF-GAS - N SYSTEM N 7 olL l\\ 7 — CATCH ASSITED /é RN TANK % i3 SHAFT PURGE PUMP BOWL VAPOR SPACE FLOW CONTROL Fig. 4. Schematic diagram of shaft purge system on PKP pump. 12 The gas pressure in the bearing cavity is controlled at 1 -to 2 psi above the pump bowl pressure so that oil seal leakage flows into the catch basin. Table 1. Descriptive data on fluoroborate circulation loop Circulating Pump 1loop tank ~ tovel Salt volume, ft° 4.1 0.5 4.6 Salt mass, 1b L76 58 534 Gas volume,a £t 0 1.2 1.2 Surface area of wetted metal, 2 - 50 L 5L Free surface of salt, ft? 0 3 3 Length of piping, ft 4o Lo Linear velocity of salt at 800 gpm, fps 20 Typical Reynolds number at 1025°F 7.7 x 10° aAssuming salt level at 2 in. above volute midplane. 4.3 Salt Sampling Device Salt samples were obtalned by dipping a copper bucket into the salt in the pump bowl. Although the pump bowl inventory was not in the main circulating stream, the leakage through the pump shaft labyrinth (foun- tain flow) was estimated to be enough to cause a complete interchange with the circulating inventory every 2 min, and so the salt samples were assumed to be representative of the material in the circulating stream. The sample tubes were hydrogen fired before use to remove oxide scagle, and a special pipe housing was provided to prevent contact with air be- fore and during the sampling process. The sampling procedure was as follows: The sample device (Fig. 5) was screwed onto the pipe nipple on the pump bowl sample access pipe. The sample unit ball valve was opened, and the sample unit and nipple were purged and evacuated to re- move wet air and then were pressurized to about 2 psi above the pump 13 QORNL DWG 72-2076 SAMPLE STICK —— \ Ya-in.-0O0 Cu TUBE 50 in. ENDS OF TUBES SEALED OFF e - 7/32-in. HOLE , , SAMPLE VOLUME 3 ¢m® SAMPLE WEIGHT 5.6g e TEFLON SLIDING SEAL PURGE CONNECTION ———— PROTECTIVE HOUSING SAMPLE UNIT BALL VALVE fl\ PUMP TANK BALL VALVE PUMP TANK 07 7777 Fig. 5. ©Salt sampling device. 1L bowl pressure. The pump bowl ball vaglve was then opened and the sample tube inserted until the bucket bottomed in the pump tank. After an in- sertion pericd of 10 to 15 sec, the sample bucket was withdrawn into the protective housing, and the pump tank ball valve was closed. After a cooldown period of at least 15 min, the sample bucket was removed from its protective pipe housing, cut loose from the l/h-in.VCOpper tube ex- tension rod, and placed in a sample jar that had been flushed with argon to remove excess wet air. L.4 Heating and Controlled Ventilation The loop was heated with Calrod heaters applied to bare pipe and ceramic heaters installed on the pump tank, drain tank, and air cooling shrouds. The heagter input was controlled by manually adjusted Variacs. The circulating salt was cooled by using the suction of the ventilation blower to draw a controlled flow of air through annuli formed on portions of each horizontal section of the piping (Fig. 6). Except for the top portion of the pump, the loop proper was completely enclosed in sheet metal. The blower was used to maintain a slight negative pressure in the enclosure, so that any gas leakage from the loop would be diluted with air and discharged from the stack on the roof. The loop operating temperature was maintained by balancing the power supplied by the pump and by the resistance heaters against the power removed by loss to the surroundings and by the cooling air. L.5 GCas System Design Gas input was constant and was made up of three separate streams (Fig. 7): (1) the shaft purge, rnormally about 950 cnf /min of helium, whose function was to inhibit diffusion of pump bowl vapors into the bearing cavity; (2) the instrument line purge, about 230 crf /min of helium, which maintained a continuous sweep of purge gas through the line that was used to sense pump bowl pressure and also served as the vapor phase tap for the salt level indicator; and (3) the mixed-gas 15 ORNL-DWG 72-2077 = SALT CIRCULATION PUMP T0 s 7 / / SHEET METAL ENCLOSURE ~400,000 Btu/hr / STACK PUMP ENERGY CUBICLE FOR BFs GAS 2500 cfm SYSTEM VENTILATION CONTRQLS- FAN a —— Fig. 6. Loop ventilation and temperature control. 16 ORNL-DWG 72-2078 /SHAFT PURGE, 950cm3/min : ' TO : LOWER SHAFT SEAL < o ' PURGE FLOW, 100cm%/min o7 A MAIN TO PUMP BOWL PRESSURE CONTROL VALVE (D " 40-psig +HELIUM HEADER @ 'I:UMP BOWL . RESSURE TRANSMITTER : * '%l OIL_CATCH o oS D3—L1 - K - i oo TAN 1400 cm>/min —] ~INSTRUMENT LINE PURGE : . 230 em¥/min FROM PUMP BOWL __ . = } - PRESSURE TRANSMITTER 1 PUMP BOWL : i - : SALT LEVEL : s " pUM | (FR) INDICATOR A PORESSURE. MIXED GAS HELIUM : : Y CONTROL 370 em3/min _..C_.)-Q—_— 1 . " VALVE l N . - ‘—- ! SALT PUMP @ CONSTANT AP FLOW CONTROLLER B FuTeER BF3. 50 cm¥/min (BASED ON 1025°F SALT TEMPERATURE) s LT feed, about 370 cn?/min of helium plus BI,, which provided the necessary BF; feed to the pump bowl and also served as the high side tap for the salt level indicator. The BF; flow required for 1025°F operation was 50 cr® /min. When the loop was operated at other salt temperatures, the BF; flow was varied accordingly, and the helium was adjusted to keep the total mixed-gas flow at 370 cnf /min. There were two effluent gas streams from the system. One was a small fraction of the shaft purge, about 100 crf /min, which flowed up the shaft and served to keep oll leakage swept out of the pump. This flow was controlled at a constant value. The other effluent, the main off-gas stream, consisted of the remainder of tThe shaft purge and the other gas flows that entered the pump bowl vapor space. The flow rate in the main off-gas stream was dependent on the pump bowl pressure con- trol valve, which operated to keep the pump bowl gas overpressure gt the desired set point. Since the other gas flows were constant, when the system was at steady state the off-gas flow was constant and egual to the total input minus the lower seal purge flow. Ball valves with packed stem seals were used in the salt sample access line to permit passage of the sample tubes and the cold-finger assembly. The experimental traps and filters in the off-gas line also were equipped with ball-type isolation valves because the gtraight- through flow path minimized the tendency for salt particles and other contaminants to collect in the valves. Otherwise, the gas system was equipped with globe-type valves that had packed stem seals in existing areas and with some few exceptions demountable bellows stem seals in newly installed areas. Check valves and relief valves were of the spring-loaded poppet type. Body material was brass and trim was brass or Teflon, although in some cases stainless steel valves were substituted because of availability. End connections were 1/4-in.-OD tubing or 1/k in. IPS, except where larger sizes were dictated by specific operating require- ments. All valves were selected from existing, commercially available models. L.6 BF; Disposal The loop was operated for the most part with the salt temperature at 1025°F and the total overpressure at 38.7 psia. At 1025°F, the BE, partial pressure is 1.35 psi, and so the BF, concentration in the off- gas stream was about 3.5% by volume. After passing through the loop pressure control valve, the off-gas stream was passed through a mineral- oil bubbler to inhlibit back diffusion of moisture. The gas stream was | then vented into the 1l2-in. suction line to the stack blower. The off- gas flow rate was 1.5 liters/min, and the blower flow was 2500 cfm; so the concentration of BFy in the stack was (1.5/28.3)(0.035/2500), or 0.7 ppm. Dilution by the atmosphere probably reduced the concentration by a Tfactor of 100, so this method of disposing of the BF; kept the atmospheric concentrgtion well below the continuous exposure limit of 1 ppm. 4.7 Instrument and Controls Approximately 32 sheathed Chromel-Alumel thermocouples were provided on the salt system to monitor the salt temperature. One thermocouple well was lmmersed in the sslt in the pump bowl and another was installed in the drain tank; all other thermocouples were strapped to surfaces of piping and components. Salt pressure was measured by pressure transmitters (PT), which use a flexible thin-metal diaphragm and an NaK-filled transmission line to relay pressure impulses to a remote receiver. 8Salt flow was indi- cated by the AP across a full-flow venturi, and the AP was measured by the difference 1n reading btetween a PT at the venturi inlet and another at the venturl throst. Salt flow could be varied tetween L4OO and 1000 gpm by ad- Justing the throttle valve. A metal tellows was used for the stem seal on the salt valve, and an automatic gas-pressurizing system was connected to a chamber surrounding the bellows to insure that the difference in pres- sure across the bellows was always controlled within acceptable limits. Spark plug probes were provided in the pump bowl and drain tank for single point indication of salt level. A gas bubbler tube, mentioned earlier, was provided in the pump bowl for continuous salt level indication over a range of 10.75 in. A high-frequency conductance probe was used very briefly for salt level indication (see Sect. 6.6). 19 Pressure gages with silver-scldered phosphor-bronze Bourdon tubes were used for gas lines containing BF;. The pressure transmitters for BF; flow and salt level had wetted parts of stainless steel or Teflon. The O0- to 50-psig pump bowl pressure transmitter had a heliecal element. Caplllaries were used for gas flow elements. The capillary for the BF, flow element (FE-B9) was 0.031 in. in inside diameter by 45 in. long, and the calibrated BF; flow rate at 40 psig metering pressure and 809 scale (16.in. H,0) was 330 cnf/min. The BF; calibrations were done using a wet test meter filled with mineral oil. Constant AP flow con- trollers were used for control of gas flow, with the input flows refer- enced to the LO-psig supply pressure and the lower seal purge referenced to atmosphere. Off-gas letdown was controlled by a pneumatic control valve with stainless steel body and trim, gasketed bellows stem seal, and a CV of 0.0L1. The thermsl conductivity cell was constructed of tungsten-rhenium elements, brass element block, and silver-soldered stainless steel tubing leads. The cell temperature was controlled at 100°C, and sample and ref- erence gas Tlows were 100 cn?/min. The off-gas sample take-off point was Jjust upstream of the pressure control valve, so there was a time lag of 1 to 2 min between changes at the pump bowl outlet and cell response. Figures 8 to 10 show the main control panel, the BI; supply cubilcle, and the off-gas cubicle. 5. TEST PROCEDURES, OBSERVATIONS, AND CONCLUSIONS FOR THE PRINCIPAL TESTS 5.1 Pumping Characteristics The test was designed to obtain head-flow and cavitation inception data and, by comparing these data with water and liquid-metal data for the same pump, to lend assurance to the assumption that water test data may be used to predict the performance of similar pumps when handling fluoroborate salts.® A brief discussion of the tests is given below; for further informstion see Refg. 3 and L. control 20 panel, fluoroborate oo v} 2l ) Fig; 9. BF; supply cu'bicl»e‘..‘ PHOTO 75385 . { ! . - C ' . - \ ' ’ . 2 . » -Q —f . o 8 = o . . 0 : @ Q Y Gy , o _ ~ 0 | , _ o B ‘ 23 The tests were made at a pump speed of 1800 rpm and at various salt temperatures in the range 900 to 1300°F. TFor the head-flow tests the procedure was to adjust the salt temperature to the desired polint and then to vary the salt flow by adjusting the position of the loop throttle valve. The procedure for the cavitation inception tests was to adjust the salt temperature to the desired point and, with flow constant at 750 gpm, to reduce the gas overpressure in fixed decrements until the drop in discharge head per unit decrease in pressure showed a disproportionate change. The hydraulic performance data are compared with HzO and NaK data in Fig. 11. The excellent agreement between results from all sources creates confidence that the head-flow characteristics‘of the PKP pump could well have been adequately predicted, based on the results of available H,0 and NaK tests. As a corollary, we can conclude that the performance of simi- iar pumps, such as the MSRE coolant salt pump, could be adequately pre- dicted based on water test results. Cavitation data for the clean charge* of salt indicated that the inception of cavitation for fluoroborate salt can be correlated on the basis of NPSH (net positive suction head) and vapor pressure (see Fig. 12). Data for the flush charge of salt showed cavitation pressures from 7 to 16% higher than those for the clean charge. This effect 1s attri- buted to the fact that the flushing charge contained the residue of a molten salt (designated BULT-4) that had been used in the previous test work in the facility. The total charge of flush salt into the test fa- cility was 689 1b, and the estimated residue of fuel salt was 26 1b; so that a 16% rise in partial pressure at 1150°F resulted from adding about 4% by weight of fuel to the coolant. Tables 2 and 3 present data on the compositions of the salt charges. ¥The term "clean charge" is used to designate the mixture of salt that resulted when the new batch of NaBF, was added to the heel (esti- mated to be about 17 1b) of flush salt which remained in the system after draining out the flushing charge. 2k ORNL-DWG 68-13040 140 ? i O FLUOCROBORATE AT 900°F ® FLUOROBORATE AT {450 °F 120 b S | ' = //:/’NJK“ZOO F) BAFFLE PLATE DETAIL-TEST Ilo ONLY VERTICAL HOT-MIST TRAP DETAIL-TESTS LIaT0O llc -~ 8 in——] NOTES — ouT 1. COLD ELEMENT NOT USED IN ALL TESTS. V0 J . | pall 1 kFROZEN SALT FILTER (COLD ELEMENT) 2. ELEMENT DIAM — t.8in. 3. ELEMENT AREA —0.018 ft2 4. FLOW RATE—3 scfm/f12 AT 4.5 liters/min (STP) 2-in.PIPE MOLTEN SALT DEMISTER (HOT ELEMENT) HEATER AND iNSULATION HORIZONTAL HOT-MIST TRAP DETAIL—TESTS 1ila TO 111d Fig. 20. Details of off-gas nozzle and hot-mist traps for NaBF, cir- culating test, PKP loop. CRNL-DWG 72-2084 S4g-in. 1D TUBING GLASS PIPE 3in. 1D BY Z4-in. LONG—al LINEAR VELOCITY OF GAS AT 1.5 liters/min (STP) AND 24 psig WAS 0.0¢8 fps AND RESIDENCE TIME WAS {10 sec ASSUMING SPHERICAL PARTICLES OF sp gr = 2.0, A SETTLING RATE OF 0.018 fps IN HELIUM CORRESPONDS TO A PARTICLE SIZE OF Sp. THEREFORE, PARTICLES = 10u SHOULD REMAIN IN THE SETTLING TANK DETAIL OF SETTLING TANK (ST) % UNIT IN SERVICE "D L - I "“L"“““fl I-4 [1-43-69 TO 1-22-69 | *in. | 6in. i i o I-2 | 1-22-69 TO2~-9~69 | 2in. | 12in. |l DIAMETER D IiLII EE (J&j\ ' 1 iMPACT SURFACE : \ 1 | 0400 in.—mm - Ygin. DETAIL OF IMPACTOR UNITS—TEST Ib Fig., 21. Eettling tank and impactor units, tests Ia and Ib, NaBF, circulation test, PKP loop. 61 ORNL-DWG 72-2085 /’ NO. ELEMENT NG FILTER // ELEMENT MODEL NO. ! NO. 2 NO. 3 NO /' / | F—1o FM204 — — f F—tb | NEVACLOG | FM225 | FM204 E [ ' F—1c FM225 FM 204 —_— = by F | ' b NOTE: ALL ELEMENTS WERE STAINLESS STEEL 11X 3in . GLASS P!PEM FILTER DIAM—~1.75 in. REDUCERS AREA Q. O17 ft2 FLOW = 3.4scfm/ft% AT 1.5 liters (STP)/min NOTES 1. FILTER ELEMENTS TYPE FM ARE MADE BY HUYCK METALS, INC. MFR'S REMOVAL RATINGS WHEN FILTERING GASES: FM-225 98% LESS THAN 1,4 1 00% LESS THAN 5 p FM-204 100% LESS THAN 0.4 2. NEVA-CLOG FILTER MATERIAL 1S BY MULTI-METAL WIRE CLOTH, INC., AND CONSISTS OF TWO PERFORATED SHEETS FASTENED TOGETHER WITH ABOUT A '44in. SPACING BETWEEN THEM, AND ARRANGED SO THAT THE PERFORAT ONS IN ONE SHEET ARE NOT IN LINE WITH THOSE OF THE OTHER. THE PERFQRATIONS ARE 0.044 in. DIAM ON 043 in. CENTERS, EQUIVALENT TO 10% OPEN AREA FILTER TYRPE F-1 L T ' FILTER ELEMENT TYPE G FILTER ELEMENT TYPE 2232 —d L BY PALL TRINITY MICRO CORP., BY HOKE, INC., SINTERED GLASS PIPE | T SINTERED STAINLESS STEEL, STAINLESS STEEL, FILTER 3in iD ! } 2.75 in. DIAM X 6in. LONG, FILTER AREA 0.006ft2 MFR'S BY ; | AREA-0.36 12, MFR'S REMOVAL RATING 5-9 p 8in. LONG -] ! 1 RATING 98% 0.7x, 00% (.8 L-—S/:n—l JI | 8" i i FLOW = 0.15 scfm/ft2 FLOW = 8.8 scfm /f12 L-—-d AT 4.5 liters (STP)/min ‘ AT 1.5 liters (STP)/min D — | FILTER TYPE F-2 FILTER TYPE F-3 Fig. 22. Filters used during off-gas tests in NaBF, circulation test, PKP loop. 62 ~ ORNL-DWG 72-2086 3/-in. 0D TUBING 7 LINEAR VELOCITY OF GAS AT 1.5 liters/min (STP) GLAS_S PIPE AND 24 psig WAS 0.076 fps AND RESIDENCE 1[_;'4,:(' 0 TIME IN {{in. COLD SECTION WAS 12 sec 18in. LONG —al T ™ /WET-ECE BATH 1in. 2in. ) WET-ICE COLD TRAP (CT-WI) X . 2in. LINEAR VELOCITY OF GAS AT {.5liters/min {STP) N AND 24 psig WAS 0.75fps AND RESIDENCE TIME WAS 2.5 sec L~ Y5-in.-0D SS TUBING 10 in. l«—DRY-ICE-TRICHLOROETHYLENE BATH ) DRY-ICE COLD TRAP (CT-DI) Cold traps used during off-gas system tests, NaBF, circula- Fig. 23. tion test, PKP loop. 63 ORNL-DWG 72-2087 HEATER _ FILTER (F-1a) TEST la 12-49-68 TO t-{3-69 PUMP BOWL WET~ICE COLD TRAP (CT—-wWD SETTLING TANK (ST)—" - N FILTER (F-1b) TEST Ib IMPACTOR I-f 1-13-69 TO {-22-69 PUMP BOWL TEST Ib IMPACTOR I-2 IMPACTOR {-22-69 TO 2-9-69 A (I-1, 1-2) FILTER (F-1b) HEATER TEST Ic 2-9-69 TO 3-7-69 PUMP BOWL Fig. 24. Arrangement of off-gas test equipment, tests Ia to Ic, NaBFy, circulation test, PKP loop. 6k ORNL-DWG 72-2088 TEST ILa 3-25-69 TO 5-13-69 NOTE: HMT-V{ WAS EQUIPPED WITH DISK AND DONUT BAFFLE ARRANGEMENT .. PUMP BOWL ~\, -=dd \\\\ WET-ICE COLD TRAP T~ (CT-WI) TEST IOIb 5-26~-69 TO 6-26-69 NOTE: HMT-v2 WAS EQUIPPED WIiTH 14.3q9 WIRE MESH (YORK MESH} COMPACTED IN 2 LINEAR in. GIVING A VO!D FRACTION OF 93 % PUMP BOWL ™~ WET-ICE COLD TRAP T (CT-WI) HMT-V3 TEST Oc 6-26-69 TO 10-30-69 NOTE: HMT-V3 WAS EQUIPPED WITH A SINGLE 34in. DIAM BAFFLE AT INLET END PUMP BOWL WET-ICE COLD TRAP {(CT-WI) Fig. 25. Arrangement of off-gas test equipment, tests Ila to Ilc, NaBF, circulation test, PKP loop. 65 ORNL-~DWG 72-2089 -‘ABOVE SALT MELTING POINT J' BELOW SALT MELTING POINL i | o | | EFILTER [@ 7 | L e—)—300°F * SHOT-MIST TRAP MORIZONTAL MODEL 1000°F 1] WET-ICE COLD TRAP (CT-WI) PUMP BOWL TEST TIME PERIOD HOT MIST TRAP HOT ELEMENT COLD ELEMENT IIlo {1-7-69 TO 11-24-69 HMT-HA1 FM=-225 - NONE USED 11Ib 12-5-69 TO 12-23-69 HMT-HZ2 NEVACLOG NONE USED 11I¢ {-20-70 TO 3-4-70 HMT-H3 Fm-225 FM-225 1I1le 3-24-70 TO 4-13-70 HMT-H3 FM-225 FM-225 Fig. 26. Arrangement of off-gas test equipment, tests IIIa to IIIc, NaBF, circulation test, PKP loop. Table 9. Chronological summary of tests and data collection rates for salt mists and condensed liquid Collection data Cumulative ! Test Date clrculating Remarks Component Total time Total weight Average Pr time onr stream collected rate ph::z? (br) (br) (&) (/nr) In 12-19-68 Test facility started up after modifying off-gas line to : investigate off-gas emissions; collection equipment in- cludes settling tank (ST), wet ice cold trap (CT-WI), ; and filter {Fl-a) | 1-13-69 622 Settling tank, wet ice cold trap, and filter removed from ST 622 63 0.10 s systen CT-WI 622 L 0.007 L i Fl-a 622 -8 0.013 s : Tt 11369 Thpactor umlt (I-1) and Til¥er (FI-0) installed 1-15-69 670 Pressure drop at pump bowl outlet is 6.5 psi; restriction cleared by increasing temperature of off-gas line at pump bowl outlet 1-22-69 830 Impactor unit, I-1 removed I-1 210 97 0.6 S 1-22-69 Impactor unit I-2 installed F1-b 210 1k 0.07 5 1-30-69 1020 Pressure drop at pump bowl outlet is k.5 psi; restriction cleared by increasing temperature of off-gas line at pump bowl outlet Ic 2-9-69 1250 Impactor unit I-2 removed because of restriction in inlet I-2 430 5 0.012 s line 3-6-69 1870 Pressure drop at pump bowl outlet is 8.0 psi; restriction cleared by heating off-gas line 3-7-69 1900 Test facllity shut down to install hot-mist trap Fl-b 1070 y 0.004 s IIa 3-25-69 Test faclility started up after installation of vertiesl hot-mist traps with internal disk-donut baffles (HMT-V1); collection equipment includes sintered metal filter PF-2, absolute filter Fl-c, and wet ice cold trap CT-WI 4-21-69 650 Removed filter Fl-c Fl-c €50 0.02 0.0003 - 5-2-69 900 Replaced sintered metal filter F-2 with sintered metal F-2 900 T 0.008 filter F-3; reinstalled filter Fl-c 5-13-69 11ks Test facility shut down to change hot-mist trap HMT-V1 1145 9 0.008 S F-3 2Ls5 5.1 0.02 8 Fl-c¢ 255 0 0 s CT-WI 1145 T 0.006 L I 5-26-69 Test facility started up with vertical hot-mist trap with wire screen demister (EMT-V2); collection equip- ment includes sintered metal filter F-3 and wet ice cold trap CT-WI 6-26-69 1910 Test facility shut down to change hot-mist trap F-3 765 15.1 0.02 5 CT-WI ThO 6.4 0.009 L 1Ie 6-26-69 Test facility started up with vertical hot-mist trap with single haffle plate at inlet; collection equip- ment includes filter Fl-c¢ and wet ice cold trap CT-WI 10-30-69 K610 Test facility shut down to install horizontal hot-mist Fl-c 2700 50 0.02 S trap CT-WI 2700 12 0.005 L IIIs 11-7-69 Test facility started up with Tirst horizontal hot-mist trap (EMT-H1); collection equipment includes sintered metal filter F-3 and wet ice cold trap CT-WI 11-24-69 k1o Test facility shut down to change hot-mist trap HMP-H1 k1o 5.3 0.013 s - F-3 320 2.5 0.008 s CT-WI ho 3.3 0.008 L O ITTv 12-5-69 Test facility started up with second horizontal hot-mist N trap (HMT-H2); same collection equipment 12-23-69 8h0 Test facility shut down to change hot-mist trap HMT-H2 430 1.8 0.00k - s F-3 k30 1.8 0.00k 5 CT-WI k30 2.5 0.006 L II1c 1-20-70 Test facility started up with third horizontal hot-mist trap (HMT-H3); same collection equipment 3-Lk-70 1840 Test facility shut down to change hot-mist trap and pre- HEMT-H3 1000 33 0.03 8 pare for water injection test F-3 1000 0.4 0.000L s CT-WI 1000 5.6 0.006 L 3-24-70 Test facility started up to run water injection test; : hot-mlst trap is same as in test IITe; collection equip- ment includes wet ice cold trap CT-WI and dry ice cold trap CT-DI h-o-T0 2055 Check trap weights CT-WI 215 1.8 0.008 L CT-DI 200 0.24 0.012 L k-2.70 2056 Injected 10 g H,0 1nto loop CT-WI 265 2.7 0.01 L 4-13-70 2320 Test facility shut down CT-DI 265 ) 0.85 0.003 L s 8, S = salt; L = liquid. 67 line was at the salt melting point (725°F) at sbout 1/4 to 1/2 in. away from the pump bowl. By applying power to the heater, the temperature profile could be shifted so that the temperature of the line did not drop below the salt melting point until a point 4 in. or more away from the pump bowl. At 5 1/2 in. from the pump bowl, an adapter was installed that converted the off-gas line from 1/2- to 5/16-in.-ID tube. About 30 in. downstream of the adapter, traps and filters were installed to separate and collect the materials that were emitted with the off-gas stream. The facility was operated with the above arrangement for 1900 hr (Table 9). The procedure was to operate without power to the off-gas line heater until excessive pressure drop at the pump bowl outlet indi- cated the formation of a salt plug. The heater was then turned on and the temperature of the line increased until a sharp decrease in pressure drop indicated that the plug had melted. Using this method, restrictions at the pump bowl outlet were cleared sfter 670, 1020, and 1870 hr of cir- culation (Fig. 27). At the start of the tests, the collection equipment consisted of a 3-in.-ID glass settling tank (ST), a 1-in.-diam wet-ice cold trap (CT-WI), and a porous metal filter (Fl-a). After 622 hr the settling tank and cold trap were removed, and during the next 630 hr two different models of impactor units were tested. After 1250 hr the second impactor unit was removed, and the final 650 hr of operation (test Ic) were completed with only the porous metel filter (Fl-b) in the line. Table 9 summarizes solid and liquid collection rates for this test period. After completion of test Ic, a salt plug was found in the irnlet to the porous metal filter (Fig. 28). Following completion of the first group of M=1.52 Boron trifluoride (also boron fluoride) BF, 67.82 5.6 —148.5 -196.8 2.37 10 732 10 Description. Boron triflucride is a colorless gas that fumes in moist alr and has a pungent, suffocating odor. It is nonflammable and does not support combustion. It is normally packaged in cylinders as a nonliquefied gas at a pressure of 2000 psig at 70°F. It is very solu- ble in water with decomposition (forming fluoroboric and boric acids) and igs hegvier than sir. *"Boron Trifluoride," p. 33 ff. in Matheson Gas Data Book, The Matheson Co., Inc., East Rutherford, N.J., 1961. b Toxicity. Boron trifluoride is very irritating to the respiratory tract. Exposure of the skin or eyes or the breathing of boron tri- fluoride should be avcoided. Although the relative toxicity of the gas to humans has not been established, no medical evidence of chronic ef- fects has been found among workmen who have fregquently been exposed to small amounts for periods up to seven years. At high concentrations boron trifluoride will cause burns on the skin similar to, but not as penetrating as, hydrogen fluoride. First-aid suggestions. Observe procedures specified by the Indus- trial Hygiene Department. If official procedures are not available, treat irritstion or burns of the eyes or skin with copious amounts of water and obtain services of a physician or trained clinician as soon as possible. The treatment of BF; burns is normally the same as that used for anhydrous hydrogen fluoride burns. Precautions in handling and storage. The following rules should be followed in the handling and storage of boron trifluoride. 1. Cylinders should be stored in & dry, cool, well-ventilated area. Cylinders may be stored in the open, but in such cases should be pro- tected against extreme weather and from the dampness of the ground to prevent rusting. 2. Since boron trifluoride is reactive with water, alcohol, ether, and other compounds, introduction of the gas below the surface of a liquid may create a hazard owing to the possibility of suckback into the cylinder. This should be guarded against by the use of traps or check valves. 3. Equipment exposed to boron trifluoride should not be used with other gases, particularly oxygen, since the gas may have oll vapors that will coat out on equipment and may cause fires when combined with oxygen under pressure. legk detection. Small leaks may be detected visually by checking for an accumulation of fluid (product of reaction between BF; and atmo- spheric moisture) or with the aid of an aqueous ammonia squeeze bottle (formation of white fumes). If the lesk is large enough, reaction with atmospheric moisture will produce visible "smoke." 1177 Materials of construction. Dry boron trifluoride does not react with the common metals of construction, but if moisture is present, the hydrate aclds identified gbove can corrode all common metals rapidly. In consequence, lines and pressure reducing valves in boron trifluoride service must be well protected from moist air. Cast iron must not be used becaguse active fluoride attacks it structure. If steel piping is used for boron trifluoride, forged steel fittings must be used with it instead of cast iron fittings. Materials recommended for the handling of dry boron trifluoride are steel tubing or pipe, stainless steel, copper, nickel, Monel, brass, and aluminum, and the more noble metals. These metals will stand up adequately to at least 200°C. Pyrex glass is also suitable up to about 200°C at low pressures. For moist gas: copper, Saran tubing, hard rubber, paraffin wax, and Pyrex glass show fair resistance; plastic materials, such as Teflon, Epons, polyethylene, and pure polyvinyl chloride are not attacked at 80°C; rubber tubing, phenclic resins, nylon, cellulose, and commercial polyvinyl chloride are readily attacked. Chemical properties. (a) With elements: Alkali and alkaline-earth metals reduce boron trifluoride to elemental boron and the metal fluoride. Gaseous or liquid boron trifluoride does not react with mercury or chromium, even at high pressures for long periods. Red-hot iron is not attacked by boron trifluoride. (b) With oxides: When boron trifluoride is allowed to react with slaked lime, calcium borate and fluoroborate are formed with evolution of heat. With anhydrous calcium oxide or magnesium oxide, the metal fluoride and the volatile boron oxyfluoride are formed. (c) With halides: BCl, and BF,; do not react when heated to 500°C. Aluminum chloride or aluminum bromide react with boron trifluoride when gently heated to give the corresponding boron halide and aluminum fluo- ride. Boron trifluoride forms no coordination compounds when passed at 1 atm over the solid chlorides of copper, silver, or potassium at tem- peratures from =75 to 530°C. (d) As a catalyst: Boron trifluoride acts as an acid catalyst. It catalyzes numerous types of reactions, namely, esterification, nitrations, oxidations, reductions, halogenations, etc. A.5 TInconel and Hastelloy N Nominal composition (wt %) C Mn Si Cr Ni Fe Mo Inconel 0.0k 0.35 0.20 15 78 7 Hastelloy N 0.06 0.50 0.50 7 70 L 17 A.6 Helium and Argon Helium Argon Molecular weight L 40 Specific volume, fta/lbm 90 9 =3 1 21 Specific heat, Btu 1b~ mole” (°F) 5.00 5.00 21 21 21 Thermal conductivity, Btu hr~ £t~ (°F) 0.082 0.0094% 1 21 _5 _5 Viscosity, 1b rt sec , 32°F, 1 atm 1.25 x 10 1.43 x 10 TEMPERATURE (°C) 119 ORNL- DWG 67-9423AR 1000 \i.\ l. LIQUIDUS | g995°C T & SOLIDUS | 900 {—- 7% ~ CRYSTAL INVERSION =~ | E ~e | | | \ [ 800 | *~\ L LIQUID - 206 NoF +LIQUID N ! L 600 | o NaBF, N (HIGH- TEMPERATURE FORM) 1\ 408 500 | A +LIQUID ———— e | S 400 +384°C - R [ ] | __Naf + NoBF, (HIGH-TEMPERATURE FORM)__ 300 b I (‘ ) l | 243°C i 5 l 5 | | 5 00 " NaoF + NaBF, (LOW-TEMPERATURE FORM) NaF 20 40 60 80 NaBF,, NaBF, (mole %) Fig. A.1l. Phase diagram for the system NaF-NaBF,. 120 ORNL-DWG 72~ 2096 98 —— 1 100 S REFERENCE: SEE APPENDIX VAPOR PRESSURE (psio)} » o i | 8CQ aGo 1200 1100 1200 1300 1400 TEMPERATURE (°F) Fig. A.2. BFj3 partial pressure vs temperature for NaF-NaBF, mixtures. ORNL Dwg. No. D-h89L2 D-48okkL D-2-02-054-9779 D-2-02-054-9780 D-2-02-054-9783 D-2-02-054-978k D-2-02-054-9785 D-HH-7-41778 Q-1512A~1RD SK-JWK-11-20-68 B-2-02-054-1926 B-2-02-05L4-1927 D-2-02-054-7440 121 Appendix B REFERENCE DRAWINGS* Title Flow Diagram for Fluoroborate Circulation Test Elementary Flectric Schematic for Fluoroborate Circulation Test Tlow Diagram Be Molten Salt PKP-1 Pump Test Loop Alarm Schematic Electric Heater Layout Thermocouple Layoutl Gas Control Cabinet Capillary Restrictor Thermal Conductivity Cell Power Supply Resistance Type Level Indicator Fluid Line for Freegze Valve Air Tube for Freeze Valve Sample Device *Partial listing. 122 Appendix C MATERTAT: SPECIFICATIONS C.1 NaBF, The sodium fluoroborate used in the PKP fluoroborate circulation test was received under Order No. 33Y-63903, April 10, 1967, from the Harshaw Chemical Company. The vendor gives {memo of 5-12-67) the chemi- cal analysis as follows (wt %): NaBF, 99.08 Ca 0.01 Og 0.025 Fe 0.023 Pb 0.00k4 Water insoluble <0.01 Si 0.01 Hg O 0.01 C.2 NaF The sodium fluoride used was cp grade obtained from Laboratory Stores. C.3 Bfs The BF; was purchased from J. T. Baker Chemical Company under Order No. 79S8-1266, August 28, 1967. Our specification was as follows: BFy minimum, 99.7% v/v Maximum impurities, % v/v Air or noncondensasbles 0.65 S0, 0.001 S04 0.001 SiFy, 0.02 We did not analyze for impurities at ORNL. We did, however, make a test at the facility in an attempt to determine if there was any water or hydroxyl compounds in the BF; . The test consisted in passing several liters of the BF, through a dry-ice trap and then analyzing the trap contents using the Karl Fischer method. No evidence of water was found. 123 Appendix D DERIVATION OF EQUATION FOR CALCULATION OF BFs PARTIAL PRESSURE From Ref. 6: 1~ f ) Q, = (B ) (== where f = mole fraction NaBF,, Qp = equilibrium quotient, and Pb = partial pressure of BFy. Rearranging: f Py = (r=9)(Q,) - Also, from Ref. 5, Qp varies with temperature: B QP = exp(C - T) . Then P = (i—é}gd [exp(C — %)] : For a 92-8 mix: f _,0.92y (l — f) - (6f5g) =11.5 , and P = 11.5 [exp(c - é)J also In P =2.4lp +C -5 . b T From Ref. 5: lOg(P%, mm Heg) = 9.024 — ;922 ’ but In P =2.303 log P, = 20.782 — l%zé%i - 20.780 — 2;25uo ; also 1n(P, , mm Hg) = ln(Pb, psi) — 1n 51.7 = ln(Pb, psi) — 3.9L455 1000 Then 1n(P, , psi) = 16.837 -3%12%9 . (11) Comparing Egs. (7) and (11): 2,442 + C = 16.837 and C = 14.395; B = 2k,540 . Substituting in Eq. (4): 2&,5&0)] _ Pb’ psi = (j_""if“_—}') [exp(1k.395 — T R (12) Appendix B FREEZE-THAW STRESS TEST As the salt temperature is being increased, there is an abrupt solid- state expansion (density decrease) of about 15% when the temperature reaches 469°F. This phenomenon introduces the threat of damaging stresses in salt-filled components if the salt is cooled below the transition tem- perature and then reheazted. A bench test was run to study the effect of varistions in heating technique. A 2-in.-ID by 18-in.-long Pyrex glass tube was filled with the fluoroborate eutectic mixture to a depth of about 8 in. Heat was furnished by a Calrod helix whose inside diameter was about 1/L in. larger than the outside diameter of the glass tube, so that heat trans- mission was largely by radiation. An aluminum foil reflector surrounded the assembly. Thermocouples were used to indicate the surface temperature of the heater and the salt temperature on the tube center line about 2 in. from the bottom. The test assembly was then operated through three ther- mal cycles during which the salt was melted and then refrozen. In all three heatups, the heater temperature (Th in Fig. E.1) was controlled at from 75 to 300°F above the salt melting temperature, and in all three cases the melting was accomplished without difficulty. Then a fourth heatup was made wherein the heater temperature was controlled below the melting point of the salt. In this case, when the salt temperature TS registered about h55°F, the Pyrex tube suddenly shattered. The conclusion is tThat the poor thermal conductivity of the frozen salt causes a steep temperéture gradient, and, where the heater tempera- ture is above the melting point, a film of liquid salt forms at the salt container interface before the bulk salt temperature reaches the solid phase transition point. The liquid film serves to provide an expansion space to protect the container during the phase transition of the bulk salt. The results of this test suggest that, whenever the salt tempera- ture is raised through the solid phase transition point, mechanical stresses can be minimized by proper control of heater temperature. It will be necessary to consider other factors, however, such as system 126 geometry and the probability and possible effects of shifting and packing of salt crystals, before one can properly assess the solid phase transi- tion problem. 127 ORNL- DWG 72-2097 2000 T T l —o~ SALT TEMPERATURE, T i 1500 |~e~ HEATER TEMPERATURE, 7, 4 . ._.__| | | | 1000 |—— g S MELT CYCLE NO. 4 PYREX GLASS TUBE —.——¢—o—y—t"* *e CRACKED AT THIS POINT T_:—T‘ * 500 2 in. DIAM 500 fozpfi ol —— SOLID PHASE TRANSITION - 0 & PYREX GLASS TUuBEL : 1500 T T % . MELT CYCLE NO. 3 ! E 1000 “/::""'!‘f‘f - o { HEATER COIL -— m ! wl a = w — 1500 TEST APPARATUS 1000 500 TIME (hr) Fig. E.1l. Data from filuoroborate freeze-thaw stress test. O O-10vWi Fwno - 1 T ! o MR m—] O\ = 19-23. WM N O\ Co—~1 O\t Lo RN 78. 79-80. 8L. 82. 83-8k, 85. Tnternal Distribution 129 ¥. Apple . B. Beall Bender S. Bettis . G. Bohlmann B. Briggs . Cantor . Compere . Cottrell . Crowley . Culler . Engel . Fraas . Gallaher . Grimes . Grindell . Guymon Haubenreich Helms Hoffman Huntley Jordan Kasten Koger Krakoviak Krewson Lundin Lyon MacPherson MceCoy . McCurdy HE R RGP LT RERS I P H P LA NS ER I EEE 0 C)@EHEZffl?j?i?{?tfltUEjEiZiflGifijw'fitflt*t*Uifi 39. Lo, HEpEIEEEOD FRPURHSEHEEEY H. R. J. N. flfiipiggficflUltiw = ORNI,-TM- 334 McNeese McWherter . Metz . Meyer Miller Moore Perry Robertson Rosenthal Shgffer Sheldon Skinner Smith Spiewak <3 Ffi?fi?ihlfiib J . Stulting Sundberg Taylor Thoma, Trauger Weinberg Whitman Wilson Gale Young H. C. Young Central Resegrch Library Y-12 Document Reference Section Laboratory Records Department Laboratory Records Department (RC) External Distribution A. Agostinelli, Worthington Corporation, Harrison, N.J. 07029 C. E. Anthony, Electro-Mechanical Division, Westinghouse Electric Corporation, Box 217, Cheswick, Pa. 1502k F. F. Antunes, Ingersoll-Rand Company, Cameron Engineering Division, Phillipsburg, N.J. 08865 R. G. Barrett, Foster Wheeler, Livingston, N.J. 07039 R. N. Bowman, Pump Division, Bingham-Willamette Company, 2800 N.W. Front Avenue, Portland, Ore. 97210 A. H. Church, Mechanical Engineering Department, New York University, Bronx, N.Y. 10400 99. 100. 101. 102. 103. 104—105. 106. 107. 108. 109. 110, 111. 112. - 113, 11k, 115-132, 133-134, 135-137, 138-139. 130 Gary Clasby, Byron Jackson Pumps, Inc., P.0. Box 20177, Terminal Annex, Los Angeles, Calif. 9005k D. F. Cope, RDT, SSR, AEC, ORNL V. R. Degner, Rocketdyne Division, North American Aviation, Canoga Park, Calif. 91303 A. R. DeGrazia, RDT, USAEC, Washington, D.C. 20545 D. Elias, RDT, USAEC, Washington, D.C. 205L5 J. R. Fox, USAEC, Washington, D.C. 20000 A. Giambusso, USAEC, Washington, D.C. 20000 F. C. Gilman, Pump and Heat Transfer Division, Worthington Corporation, Harrison, N.J. 07029 R. Gordon, Aerojet-General, Azusa, Calif. 91702 C. W. Grennan, Colt Industrles, Chandler Evans Control Systems Division, West Hartford, Conn. 06100 Norton Haberman, USAEC, Washington, D.C. 20000 F. G. Hammitt, The University of Michigan, Ann Arbor, Mich. 48103 M. J. Hartmann, NASA-Iewis Research Center, Cleveland, Ohio 44100 C. H. Hauser, NASA-Lewis Research Center, Cleveland, Chio 44100 J. W. Holl, Pennsylvania State University, Garfield Thomas Water Tunnel, Ordnance Research Laboratory, University Park, Pa. 16802 Kermit Laughon, USAEC, OSR, ORNL Liquid Metal Englneerlng Center, c/o Atomics Internatlonal, P.0. Box 309, Canoga Park, Calif. 91303 (Attention: R. W. Dickinson) T. W. MecIntosh, USAEC, Washington, D.C. 20000 D. C. Reemsnyder, NASA-Iewis Research Center, Cleveland, Chio L4100 M. A. Rosen, DRDT, USAEC, Washington, D.C. 20000 Research and Technical Support Division, ORO M. Shaw, USAEC, Washington, D.C. 20000 W. L. Smalley, USAEC, Oak Ridge Operations W. A. Spraker, Engineering Research Division, Scott Paper Company, Philadelphia, Pa. 19100 H. A. Stahl, Cameron Division, Ingersoll-Rand Company, Phillipsburg, N.J. 08865 ‘B. Sternlicht, Mechanical Technology, Inc., Latham, N.Y. 12100 G. M. Wood, Pratt and Whitney Aircraft Corporation, East Hartford, Conn. 06100 Manager, Technical Information Center, AEC Technical Information Center (AEC) Director of Division of Reactor Licensing, Washington, D.C. 20545 Director of Division of Reactor Standards, Washington, D.C. 20545