_---.-.'_;-;;OAK RIDGE NAT|ONAL I.ABORA_ORY .. operated by - UNION 'CARBIDE CORPORATION s " ?'fi:j-fNUCLEAR DIVISION - for the . ’ U S _ATOMIC ENERGY COMMISS!ON ORNI. TM-'907 Revis_ed' e CDPY NO. - i.&z A ._pA_T_E_;-__- December 28, 1967 MSRE DESIGNVAND” OPEBATIONS REPORT FUEL HANDLmO AND PROCESS];NG PMNT - | R. B. Lindsuer o S R ' NOTICE This_ ‘document - contains information of a preliminary “nature:.. " IliTl. ' R L ‘ * " ond was preporec! primarily for internal use at the Ock Ridge Nahonal e : Laboratory. It is_subject -t revision or correction and therefore does e e ‘ ‘not represent a fma! report. ' ; mmmosmzs QOCUMINT, 15 DRIMITER 'LEGAL NOTICE ' This report was pnpaad as an account of Govomment sponlorod *work Nelthor the Unlhd Sfofes, nor the Commission, nor any person acting on behalf of the Commlssion: - A. Makes any worronty or representation, expressed or implied, with respect to the accuracy, N " completeness, or usefulness of the information contained in this report, or that the use of eny information, cppurmus, mefhod “or precon diseloud in this nport muy not infringo privotely owned rights; or -B Assumes any liabilities with rospcct to the use of or for damages rnuhing ‘rom tho use of- -any Informuflon, apparatus, method, or process disclosed in this report, As used in the above, “'person acting on behalf of the Commission’® includes any -mployee or contractor of the Commissicn, or employee of such contractor, to the extent that such omployoe ot contractor - of the Commlulon, or .mployn of such contractor prepares, dissemmntos, or - provides access to, any informetion pursuant to hcs omploymenf or contract with the Commlssnofi, e " or his employment with such conh'ucfor. !:)a{‘;?”‘ - o Bow ) Ry o s} : 47)@1;‘ & ' ‘PREFACE 111 This report is one of & series that describes the design and _operation of the Molten Salt Reactor Experiment All the reports have ‘been issued with the exceptions noted oRNL.-n&-,?es . MSRE Design and Operations Report, Part I, e Description of Reactor Design by . R. C RObertson ORNL-TM-T29 MSRE Design and Operations Report, Part II, - "~ Nuclear and Process Instrumentation, by J . R. 'I'allackson ORNL-TM-730 MSRE Design and Operations Report, Part TIT ‘ 7 Nuclear Analysis, by P..N, Haubenreich, J. R Engel B E, Prince, and H. C. Claiborne ORNL—TMrT31¥* MSRE Design and Operations Report Part IV, - ‘ Chemistry and Materials, by F. F. Blankenship and A Taboads ORNL-TM~T732 - MSRE Design and Operations Report, Part V, ' Reactor Safety Analysis Report, by S. E, Beall, P. N. Haubenreich, R. B. Lindauer, and J. R. Tallackson ORNL-TM-2111% MSRE Design and Operations Report, Part V-A, - : Safety Analysis of Operation with 233y by P. N. Haubenreich, J. R. Engel, C. H. Gabbard R. -H.- Guymon, and B. E. Prince ORNL-TM-733 . MSRE Design and Operations Report, Part VI, (Revised) - Operating Limits, by S. E. Beall and . . : : : Ro H Guymon o "'p""ORNL-TM-9OT MSRE Design and Operations Report ‘Part VII ~ (Revised) ‘Fuel Handling and Processing Plant, by R ‘B Lindauer . ORNL-TM-908 MBRE Design and Operations Report Part VIII R - Operating Procedures, by R. H. Guymon | . ORNL-TM-909 IMSRE Design and Operations Report Part IX Safety Procedures and Emergency Plans, by A, N, Smith - \ lEGAL NOTICE . This report was prepnred as an account ot Government lponsored work. Neithar the United States, mor the Commission, nor any person acting on behalf of the Commission: " 'A. Makes sny warranty or representation, expreased or implied, with respect to the nccu- . racy, completeness, or usefulness of the information contained In this report, or that the use of any information, apparatus, mefl:od or process duclosed fn this report may not infringe ' . privately owned rights; or B. Assumes any lisbilities with respect to the use of, or for damages multl.ug trom tha ; use of &ny information, apparatus method, or process disclosed in this report. As used in the above, ‘“‘person acting on behalf of the Commission® includes any em- " | ployee or ‘contractor of the Commission, or employee of such contractor, to the ‘extent that “- - such employee or contractor of the Commission, or employee of such contractor prepares, disseminates, or providea access to, any informatfon pursuant fo his omployment or contract with tba Commiuion or his employment with such contractor, H rmmmrnnwmewmwp,m e et b bt St L e e e R LA SRR R AL+ e e o b e e o e ireae e, AN DIETRROTION OF THiS QOCUMENT, (5 ONLIMITED iv 3 x% | | ORNL-TM-910 MSRE Design and Operations Report, Part X, _ . : - . Maintenance Equipment and Proce&ures, by - , E. C. Hise and R. Blumberg ORNL-TM-911 - MSRE Design and Opera'bions Repor'b Par'b XI, Test Program, by R. H. Guymon, P end J. R. Engel » *% - MSRE Design and Operations Report ‘Part XII Lists: Drawings, Specifications, Line Schedules, Instrument Tabulations : (Vol. l and 2) ~ . These. reports sre in the process of being issued. *¥*% ' - These reports are not going to be issued. . N. Haubenreich, m'@ (¥ = bln'. <9 - v o e .. TABLE OF CONIENTS - 1., INTRODUCTION « o o + o v & «-. . . . 2. PROCESS DESCRIPTION . + & o » o 4 o oo v o o - 2.1 Ho-HF Treatment for Oxide Removal. e 2.2 Uranium Recovery . .;. o e e s e e s 3. EQUIPMENT DESCRIPTTION . . . . 0 v v v o o o 4 . 3.1 Plant Layout o v oo v b w0 e 3.2 Meintenance . . e e e e . 3,3 In-Cell Equipment; DRI .. 3.4 Out-of-Cell Equipment. | . : 3.5 Electrical System '._ e e e e e e e e 3.6 Helium Supply System . . . . : : 3.7 Instrumentation. . . . « o o + o 4 & . . .a' 3.8 Brine SYBLEM « v v v v v 0 o o 6 e e o 0 . s L, SAFETY ANALYSIS . o v v v v v v o o s v e o 4,1 Summery end Conclusions, . . . . . . . h.a Bases for Calculations,. e e e e e et o 4.3 Qaseous Activity . C e e e e e k., )y Penetrating Radiation. e o e e e e e s ¥ [ o co;J F"b;kfig 1k 14 . 14 , 19’ 35 39 b1 L k9 hll.9 . b9 . 53 29 6 » 4 L ¥, " o a¥ S, 1. 1 Summagz MSRE DESTCN AND OPERATIONS REPORT © Part VI FUEL HANDLING AND PROCESSING PLANT 'R, B. Lindauer :L.— : II\]TROIIICTION This revision covers changeh‘in equipment and in operating plans over the past 3 years as a result of the following: (1)fhn§§e;Ze£Ze during He-HF treatment of flush salt in April 1965. (Ref. 1) o e (2) Use of fuel salt containing 230 kg of 33% enriched uranium " instead of 60 kg of 93% enriched uranium. (3) The decision to process fuel salt after 30 days instead of | | - 90 days ‘decay. ' : - : 7 (%) Volatilization of . noble metal fission products (Mo, Te,Ihx ete.) ' ._ from the salt during reactor operation. . . (5) The decision to filter the salt after fluorination before re- , turning it to the reactor system, . Also, at the request of the Radlochemical Plants Committee, more detailed information is provided on the maximum credible accident moni- ' tors and alarms and emergency or backrup services.__ Coar .- + 2. PROCESS DESCRIPTION 2.1 Hp-HF Treatment for Oxide Removal ‘Moisture or oxygen inleakage into the reactor salt system or use of . helium cover gas containing moisture or oxygen could cause oxide accumu- ,y'lation in the salt and, eventually, precipitation of solids. Tn' the flush © o or coolant salts, the precipitated solid would be BeO, which has a solu- L bility of.approximately 290 ppm at.1200°F (see Fig. 2.1): Zirconium . ' | : ORNL DWG. 68-2728 i 1 i 1 | i gso qeo . 980 ipoo 050 1100 (150 T 200 o~ | TEMPERATURE °F » | | - . Figure 2.1. Oxide Solubility as a Function of Temperature. " i v b b { pe ’ o - .. & ) tetrafluoride was added to the fuel salt as an oxygen getter to prevent "small amounts of oxygen from. causing uranium precipitation. If the flush salt is contaminated with.fuel salt up to approximately 0.01 mole of zir-. - conium per kg of salt (~ l% fuel in flush salt), there would be insuf- ficient zirconium present: to exceed the solubility of ZrOz at 1112°F and eany precipitate would;be BeO. Above‘this zirconium condentration, exceeding the soldbility'limit-would cause ZrOsz precipitation. When sufficlent Zr0z has precipitated to reduce the Zr:U ratio to ~ 5, co- precipitation of ZrOz and Uogrvill occur. The effect of 3% contamination of the flush selt with fuel salt is shown.in Fig. 2.1. ‘Oxides Will be removed by treating the fuel or flush salt in the fuel storage tank. (see Fig. 2. 2) with s mixture of Ha and HF gas. In . the treatment. process, HF will react with the oxide to form the fluoride ‘and water, the water will beievolved along withrthe_hydrogen and excess " HF. The Hs will preventaerceSSive corroSion of the INOR-8 structural material by“maintaining a reducing'condition in, the salt. The gases will x‘pass through an NaF bed for decontamination before monitoring for water determination, The gas stream will then ‘pass through a caustic scrubber 1 . for neutralization of the HF.. The hydrogen will go to the offgas system. The‘treatment will- be terminated when water is no longer detected in the 'offgas stresm. A finel sparglng vith helium will remove,dissolved HF. 2.1. 2 Hydrofluorination f . Hydrogen fluoride will be obtained in 100-1b cylinders. One cylinder \.rwill provide sufficient HF for 92 hr of processing at a flow rate of 9 liters/min (Ha HF = 10 l) The HF cylinder will be partially submerged r.rin a water bath heated with 1ow-pressure steam to provide sufficient pressure for the required flow rate.w Since heating of the cylinders 7above 125°F is not recommended ‘there is a pressure. alarm on. the exit -gas set at 22 psig The HF gas will pass through an electric heater to ;raise the temperature above 180°F and reduce the molecular weight to 20 lf: for accurate flOW'metering.- The hydrogen flow will be started‘before the THF flow to minimize corrosion._ The hydrogen flow rate will be set at \ ‘the rotameter at the gas supply station west of the building The hydro-~ 'gen fluoride flow rate will be regulated by the controller on the \ ORNL—DWG 63-3{23AR . osaLT 200°F NaF ABSORBERS IN CUBICLE . - : SAMPLER % ‘ v . CHARGING . : -, w : , : ’ : ' HIGH BAY AREA I s, " ' Yy = —_— ——— . ey FUEL PROCESSING CELL COLD TRAP " SALT TO OR FROM DRAIN AND FLUSH TANKS ACTIVATED CHARCOAL TRAP P : wasTe | | FUEL - a _ SALT | 1STORAGE ' ‘ TANK - SYSTEM ABSOLUTE B 4 - P ! AF U | FILTER \\_ ’ ‘ | : ) TO VENT 750°F TRA NaF BED . NEUTR E.IZER - Figure 2.2. MSRE Fuel-Processing System. " " :1. o o panelboard in the high-bay area. The'salt backup prevention valve must be closed with the manual switoh until flow is started, at which time the differential pressure switch will maintain ‘the valve in the closed po- -wsition unless the tank pressure exceeds the HQ-HF pressure. The offgas stream leaving the fuel storage tank will consist of hy- drogen, water, _excess hydrogen fluoride, and helium. Volatilization of fission and corrosion products is expected to be much lower than during fluorination because of the reducing effect of the hydrogen. Fission - products that are partially volatilized 88 fluorides during fluorination, - such as ruthenium,_niobium, and antimony, are expected to exist in the metallic state. Any chromium in the salt from corrosion is expected to be in the nOnvolatile +2 or +3 valence state. The offgas ‘stream will pass through a heated line to the NaF trap. The line will be heated to - e.200°F to prevent condensation of Hao-HF The salt temperature is not oritical during Hg-HF treatment since corrosion and fission product volatilization are not important For. rapid oxide removal it is necessary that all the oxide is in solution. ~ The salt temperature should be adjusted about 50°F higher than that 1nai- | cated by the oxide analysis and solubility curves. The temperature | should not be maintained higher than necessary since this lowers the HF , solubility and consequently the HF utilization. - The hydrogen fluoride and Hz flow Will be stopped when no more water is detected in the offgas stream. The salt will then be sparged with helium. to remove dissolved HF ‘and to purge ‘the system of HF and hydrogen." _f;The gas stream will ‘be checked for hydrogen before it enters the offgas 1_fduct by passing a small stream through a . hydrogen monitor. S o 2.1. 3 NaF Trapping 'y remotely removable NaF bed is provided in the fuel processing i'cell to remove small amounts of volatilized fission or corrosion productS“ - from the offgas stream 'The trap will be maintained ‘at 750°F to prevent '”7g5adsorption of HF. Since the vapor pressure of HF over NaF is 1 atm at "h1532°F the trap could be operated at a “‘somewhat lower temperature, but '750°F will be required to prevent UFg adsorption during fluorination (see Sect. 2.2.3), and this temperature was selected for both operations. ' 2.1.4 Monitoring for Water The removal of oxides Pfrom the salt will be followed by passing a S 2 cc/min side stream of the gas stresm from the NaF trap. through a - ‘ - water monitor (See Fig. 2. 3). This monitor- consists of an NaF trap for | removal of HF from. the sample stream.before it is passed through an 'electrolytic hygrometer. ‘The part of the monitor through which the '.radioactive sample passes is located in the absorber cubicle for contain-; ment. Integrationiof the monitorrreadings indicates the total emount of oxide removed : ' | ' A more elaborate but less accurate method of determining the oxide removal by cold-trapping, was installed before the water monitor was de- " veloped. Since the monitor performed very well during the flush salt processing, the cold trap serves only as a backup for the monitor and & qualitative check on the end point., | As originally conceiVed several- S runs would have been required.under steady operating conditions to ob- tain data for correlation of cold trap volume with oxide content Be-f cause of the excellent performance of the monitor these runs have not . e ‘been made. However, the absence of water in the gas streem.will be seen i | in the cold trap system by the termination of condensation and.reduced heat load on the trap. 2.1.5 Offgas Handling 4 , The hydrogen fluoride will be neutralized in a static caustlc scrubber tank. + Hydrogen and helium from the- scrubber will pass ‘through an activated-charcosal trap and a flame arrester before entering ‘the cell ventilation duct, . The cell ventilation air will pass through an absolute - filter, located in the spare cell, before going to the main filters end stack. As mentioned before, 1ittle activity is expected in the offgas stream- during Ho-HF treatment ' Since the fluorine disposal system will not be used during HQ-HF treatment but will still be connected to the scrubber inlet line, the system must be purged to prevent diffusion and condensation of HgO-HF in ' 5 A the disposal system. This will be done by connecting'Ne;cylinders at | A the S0z cylinder menifold. As an additional precaution, the SOz preheater ' '\Eg f .9 ) ) V=14 Xv-il " ORNL DWG. 68-2T729 [Frow ConTR. xm] Jour WET o Dy Ni - OVEN 1got2e °F A fi, i Lt_. . . S e —_— —p | ffomP | . Figurégz;é} _Water Andlyzer.' V-6 . To SPARE ‘QELL . VENT . should be heated because the stainless steel preheater would be es- pecially subject to corrosion by the wet HF. . 2 i.6 Liguid Waste Disposal - The caustic scrubber will be charged with 1300 liters of 2 M KOH prepared by dilution of & 45% KOH solution._ Three 115-gal. batches of 2M (10%) KOH will be prepared in & portsble mix tank in the high-bay -area and charged through a line provided with a menual valve and a check | ~_valve, Dilution to 2 M will be required because of the possibility of gel formation in KF solutions of greater than 2.M. - : At 9, 1-liters/min HF flow, the KOH - will have to be replaced every | 4 days when the final concentration is 0.35 M. Tt will, therefore, be necessary to Jet the KOH solution to the liquid waste tank and replace it with fresh caustic when 8 100 -1b HF cylinder has been consumed. 2.2 Urenium Recovery 2 2o 1 Summarx The fuel or flush salt should be allowed to decay as long as possible ‘before fluorination to minimize the discharge of the volatile fission- product fluorides that will be formed by the oxidizing action of the fluorine. The most important volatile activities are iodine, tellurium, niobium, ruthenium, ‘and- antimony. However, salt samples during reactor * operation have shown only iodine remaining in the salt in large concen- - trations. ' After decay, the salt batch will be fluOrinated in the fuel storage tank., The offgas containing UFs, excess fluorine, and volatile activity will pass through s high-temperature NaF trap for decontamination and - chromium removal before absorption on lofi%temperature”NaF absorbers. Excess fluorine will be reacted with S0z to prevent'damage t0'the'Fiber- glas filters. Before filtration the offgas will be further decontami-‘ ‘nated by passage through an activated charcoal bed. ' The absorbers will be transported to another facility where they will fbe desorbed and “the UFg cold_trapped and.collected in product cylinders. Ot .0y - 2.2.2 Fluorinmation: " Uranium will be recovered from ‘the molten salt by sparging with ' fluorine to convert the Ufigto volatile UFs. The fluorine will be diluted with en equal volume of helium when fluorine is detected in the offgas ’ i stream to reduce the number of times. the fluorine trailer must be changed; This should have 1ittle effect on the overall processing time, since utilization is expected to be low after most of the ‘uranium has been volatilized A total gas flow of ebout 50 liters/min should provide good agitation, The salt sample line will be purged with helium during fluorinstion to prevent- UFg diffusion and will be heated to prevent = ~ condensation, The temperature of'the melt_will_be maintained as low as - practical Q~_30'to 50°F above the ligquidus of 813°F) to keep corrosion and fission-produCt-volatilization to & minimumg Boiling points of some _volatilb-fluorides-are listed in Table 2.2. The heaters on the upper -half and top'df'the tank-will'not be used during'fluorination to reduce - salt entrainment but they will be turned on after fluorination to melt down splatter and condensation. Teble 2. 2 Boiling Points of Fluoride Salts 'Salt__._f Boiling Temperature \’ lebg . . o - : . ™, 39 (sublime) MoFg R 95" UFg. 130 ™ a2 SbFs 300 MoFs o - Lo CmR oWk TeFg. . 543 ' soFs 55k 4 o595 o - ZrF, o - 1658 (sublime) -CrFs . ~2000 10 There will be an initial induction period before evolution of UFg begins, The extent of £his'per1od will depend onfthe amount of uranium in the salt and the degree of agitation of the salt. A minimum of 0.5 mole of fluorine per mole of uranium will be required to eonrert 8ll . : 5 the UFy to UFs. After this, UFg will begin to form and be evolved. At ' 50 liters/min of fluorine; UFg evolution can begin‘dbout 2'hr after the start of fluorinetion. Since the vapor space between fhe salt and the first absorber is ~ 1300 liters, another 15 min will prdbably be re- quired before ebsorption begins. Volatility Pilot Plant data show that essentially no fluorine is ~evolved until at least 1 mole of fluorine per mole of-uranium has been added or the system has bperated 6 hr at 50 liters/min, However, until more. is known sbout the sparging efficiency and the effect of the fuel | storage tank geqmetry and salt compog&ition, the fluorine disposal system will be put in operation at the start of fluorine flow with sufficient SOa to react with 50 liters of fluorine per minute. - - Evolution of UFg will be followed by means of the absorber fempera- ;o tures. Fluorine breakthrough should be detectable by'temperature rise in" _ the fluorine reactor. When fluorine breakthrough is detected, the fluorine flow will be reduced to one-half and an equal flow of helium will be started This will maintain the necessary degree of mixing while pro- viding sufficient fluorine to prevent the back reaction ' t] 2 UFg - 2 UFs + Fa. Corrosion can consume as\much as 3 liters of.fluorine per minute (0.2 mil/hr). | With the 35%-enriched uranium fuel salt it will be necessary to replace the absorbers three times. Before this can be done,,the salt mst be sparged with helium to remove dissolved UFg and fluorine and to purge the gas space of UFg. After sparging before absorber changes and ‘at the end of flubrination, the salt will be sampled to check on the uranium removal. It will be necessary to replace the fluorlne trailer every 3- 1/2 hr at a fluorine fiow rate of 50 liters/min or every T hr with one-half flow. . gfi}, o i » g'.. b D " however, so’ downtime shouid not be long. o . S © There is sufficient space at the gas supply station to have only one trailer connected at a time. Additional trailers will be at the site, Corrosion will be much.more severe under the strongly oxidizing con— | fditions of fluorination than during “the Ho-HF treatment. A_corrosion . rate of 0.5 mil/hr was ‘experienced in the Volatility Pilot Plant in a . - nickel vessel'_ Fluorination of the high»uranium-content salt (fuel salt C) . . may take as long as 50 hr, but recovery of small amounts of uranium from the flush salt should require mich less time. A. So-hr fluorination would" - cause an average corrosion of approximately 3% of . the fuel storage tank ~wall at 0.2 mil/hr ~ Corrosion of the fuel storage tank.may be less than in the VPP because of the. smaller surface- to-volume ratio, the use of dilute fluorine, and the lower fluorination temperature, also corrosion | tests indicate that INOR-B may be more corrosion resistant than nickel. 2.2.3 NaF Trapping The NaF bed will be important during fluorination for uranium.re- . -covery because of the greater volatilization of fission end corrosion . products then during oxide removal The bed will again be maintained at 750°F; which. is above the decomposition temperature of the'UFs-anaF complex (702°F at 1000 mm) Any volatilized PuFg will absorb on the NaF and ‘provide separation from the uranium,_ Sodium fluoriderat 750°F. will 7remove essentially -all of therniobium and ruthenium from the fluorinator ' offgas stream, and these will be the .pri_nc.i_pal activities that could cause - _ ' product contamination.*Morefibdinewill_volatize-but.vill not absorb on . hot or-cold NeF. Essentialiydall'the chromium‘fluoridedvill he absorbed. :Chromium is troublesome‘not only because of the gamma activity of the ff51Cr formed by neutron activation but also because of the inactive alchromium that' will collect in valves and Small lines and cause plugging and seat leakage. All piping “to and from the NaF bed:must he heated to - above 200°F ‘to prevent UFs. condensation. Table 2. 3 shows the expected | “'behavior of the volatile fluorides on NaF. RS ' Table 2.3 - Fluoride Absorption on NaF - & Absorption Absorption , | at T50°F ~ .at 200°F Fluoride (NaF Trap) (UFg Absorbers). . Iodine . ' ' No , No _ - - Tellurium ‘No | ~ No , ‘ Molybdenum - No fPartial breskthrough - - Uranium No Yes ' =~ Neptuniim No Yes Technetium No ‘ . Yes . Zirconium Yes | Less than at T50°F Niobium Yes Less than at TS50°F - Antimony . Yes Less than at TS50°F "Ruthenium Yes ~ Less than at T50°F B Plutonium Yes : Less than at T50°F J Chromium ~ Yes Less than at T50°F : N 2.2.4 UFg_Absorption The decontaminated UFg gas from the T50°F NaF bed will flow to five NaF absorbers in series, which are located in a sealed cubicle 1n the high-bay ares. These absorbers will be cooled with air, as required, to prevent uranium loss. At 300°F the vapor pressure of UFg over the UFg-2NaF camplex will be 0.1 T, end uranium losses will be significant (2.4 g of U per hour with a flow of 50 liters/min). The capacity of NaF for'UFg varies ihversely with the temperature, since the more rapid re- action at higher temperatures inhibits penetration of the UFg by eealing off the eXte;nal pores with UFg-QNaF.a .To obtain maximum ceapacity the cobling-air should therefore be turned dn as soon as a temperature rise is indicated The absorber temperatures should not exceed 250°F Also, ‘with low fluorine concentration at elevated temperatures there could be & reduction of UFg-2NaF to UFs-2NaF, which would remain with the NaF when the UFg was desorbed from the NaF. The loading of the ebsorbers can be , r!f011owedrby bed temperatures, and the air'Can be aéjusted as required. The air will be discharged to the cell by a small blower in the cell. 0 n " < ol u....,‘_,‘m _“ e Y 13 A portable alpha activity monitor will be used to detect leaks of UFg in the cubicle. - In the ‘event of & leak in the absorber cubicle, the - fluorine flow would be stopped and the cubicle would be purged with air- - and opened for repairs. The . location of the leak should be detectable either visually or with an alpha brobe. " Vhen fluorination has been completed the absorbers will be discon— nected and sent to another facility for desorption and cold trapping of - the UFg. It will be necessary to stop fluorination vhen the absorbers ‘are loaded»and replace the absorbers as noted above. This will require 8 complete purging of the system to remove all UFG from the connecting A.:PiPins- 2 2.5 Excess Fluorine Disposal . Since an average efficiency of less than 25% is expected during fluorination, there will be a 1arge excess of fluorine. - If this fluorine were allowed to flow through the offgas filters, damage to the Fiberglas might result with release of any accumulated activity. To prevent this,' ~the excess fluorine-will be reacted with an excess of SOz. Both the soa 'and the Fa will be preheated: electrically to 300 to LOO°F and then fed "into e Monel reactor wrapped.with steam coils. The steam will serve the .dual purpose of keeping the reactor warm to initiate the reaction and of fcooling the reactor after the reaction 1s started. The reaction is _strongly exothermic and proceeds smoothly at L00° F. The product is : cSOgFg,‘a relatively inert gas._ An activated alumina trap is installed downstream of the Fé reactor for a backup of the soa system., This trap -~ will dispose of any unreacted fluorine resulting from insufficient S0z ':'or other malfunction in the 802 system. ' 2. 2 6 Offges Handling The fluorination offgas stream from the activated alumina trap will 'then pass through the empty caustic scrubber tank. The scrubber tank ;foffgas will pess through the activated-charcoal traps ‘for additional ‘ ‘,ffissionuproduct removal before entering ‘the cell ventilation duct Just . upstresm of the sbsolute filter in the spare cell, The cell air will then - go to the main filters and be discharged from the 100 -t containment stack. 1L 3. BQUIPMENT DESCRIPTION 3.1 Plant ILayout | The main portion of the fuel—handling and -processing system is in - - the fuel-processing cell, immediately north of the drain tank cell in ' ' Building 7503, as shown in Figures 3.1 and 3.2. The gas supply station 1is outside the building, fiest of the drain tenk cell. The offgas filter, hydrogen flame arrester, activated-charcoal trap, and weste salt removal line are in the spare cell east of the fuel-processing cell' The system “will be operated from the high-bay area over the cell, where a smell instru- :ment panelboard is located., Also in the hithbay area are the salt- charging area, the UFs absorber cubicle, the salt sampler for the fuel _storage tank, and an instrument cubicle., The instrument cubicle contains - the instrument transmitters and. check and block valves connected directly to process equipment and it is sealed and monitored. Figures 3.3 and 3.hfiare photographs of the fuel-processing cell and theroperating ares, respectively. - ' ' 4 ' 3.2 Maintenance ‘Since corrosion is expected to be very low during Ha-HF treatment and only four fluorinations are planned maintenance\problems are not ex- pected to be severe . The system, with a few exceptions, has therefore been designed for direct maintenance, with savings in cost and complexity of equipment. The exceptions are the NaF trap, activated alumine trap, - salt filter, and two air-operated valves, The NaF trap may become plugged by volatilized chromium: fluoride during fluorination. In this case it would be moved to one side and 8 new trap installed It is therefore_flanged into the system and has disconnects for thermocouples . and electrical power. The alumina trap and salt filter is also flanged' for replacement The valves haVe flanges with vertical bolts and dis- connects for the air lines, The valves, filter and traps are located " under roof plugs sized to pass through the portable maintenance shield This shield can also be used for viewlng and for ‘external- decontamlnation " . of equipment should this be required because of a leak All heaters in | i fiE,) the cell have duplicate spares 1nstalled y S 0w : - ' . ‘ #, v ' A " ORNL-DWG 83-434TA FUEL PUMP " LUBE OIL SYSTEM 7 SERVIC EL COOLANT PUMP LUBE OIL SYSTEM BATTERY ROOM \ MAINTENANCE ‘ SHOP - CHEMICAL LABORATORY TO FILTERS AND STACK INSTRUMENT TUBE . " FUEL PUMP VENTILATION e L 'SPECIAL EQUIP, ROOM REACTOR TO VAPOR COND. SYSTEM NT PUMP _ MAINTENANCE PRACTICE CELL - INDUCTION - | REGULATOR -CELL COOLANT SALT DRAIN TANK uoungsvlf-vcsm _ . STACK VENT HOUSE . N 'DRAIN TANK NO.2 FUEL ~ FLUSH SALT STORAGE TANK " DECONTAMINATION CELL — : ) . SHIELD : FUEL SALT : RADIATOR AODITION ' .. STA ~ FUEL : , L PROCESSING ORAIN CELL ~ TANK NO. ! . e S REACTOR , - "ELEC. SERVICE AREA BELOW CELL ANNULUS BLOWERS TOR BLOWERS Figure 3.1. First Floor Plan of MSRE Building. ~ DUCT AND BLOCK VALVE T ! ’ o o - - . S ' ORNL=-DWG 64-3974 fon CRANE COOLANT SALT 'PUM SSHIELD - ~ BLOCKS | REACTOR CELL 1 besommr—mmen AN ' DECONTAMINATION f CELL ‘ FUEL PUMP » FUEL SALT . ADDITION SHIELD STATION BLOCKS - SHIELD BLOCKS . HEAT EXCHANGER RADIATOR \ -LIQUID WASTE CELL ORAIN TANK CELL ' RADIATOR BYPASS DUCT ‘ FUEL STORAGE TANK FUEL : g I PROCESSING . 2 CELL: COOLANT SALT ORAIN TANK DRAIN REACTOR : \ FUEL DRAI \ - - TANK NO.1 LINE VESSEL ‘ " - FUEL DRAIN . ‘THERMAL TANK NO. 2 SHIELD, ¢ Figure 3.2. Elevation Drawing of MSRE Building 9T n \ . ' . " ' ‘ ' ay . " - ¥ if | Figure B.H}_“Ofiéffiti v ng-Aréa -, for‘MSRE“Fuéi;ProcéssingvCell. o m‘- W 2y 9 . » n’ .19 ~ '-', If a serious piping or equipment leak occurs before processing has been completed or if entrance into the cell-is required for other reasons after irradiated fuel hes been processed aqueous decontamination "may be required The recommended method 1is described in Report ORNL—2550 _ (Ref 3) and consists of (l) barren salt flushes to displace as much &s Q ”possible of the irradiated salt (2) aqueous ammonium oxalste ‘flushes to " remove the salt film, (3) nitric acid-aluminum nitrate flushes to remove - metallic scale from the surfaces, and (4) sodium hydroxide-hydrogen | 3 3 1 TFuel Storage Tank peroxide sodium tartrate flushes for gas line decontamination. 3 3 In-Cell Equipment The fuel storage tank in which chemical processing will take place is similar to the reactor drain tanks - The tank is shown in Figure 3.5, and design data are. given in Table 3 1. The height of the storage tank was increased by 30 in. over the ,height of the drain and flush tanks to minimize salt carryover due to sparging during chemical processing. About 38% freeboard is provided - | above the normal liquid level The tank is heated by four sets of heaters in the bottom, the lower half, ‘the upper half and the top of the tenk, Each set of heaters is controlled separately with powerstats. Every heater has 8 duplicate in- " stalled spare with leads outside the cell ‘The heaters are mounted on a :frame that is supported from the floor to minimize the tare weight on the . '.weigh cells, | " | | “The tenk has two dip tubes, ‘one. for ges sparging and the other for ,fcharging and discharging salt The sparge line is a’ l—in.,pipe that is "closed at the bottom and has four 1/2-in, holes 90° epart near the bottom. ,,,The salt dip tube lies on the bottom of the tank at the center to mini-. -~ mize holdup (approximately 0. 1% of & full batch). Tiquid level is deter- | ;mined by weighing the tank with two pneumatic weigh cells, The“weigh‘.' - ecell calibration can be checked by an ultrasonic single point probe. When ~the tank is not being pressurized for ‘salt transfer, the sparge dip tube | 'and PdI-69h provide another continuous salt level indicator. Other instru- -ments provided are 13 surface—mounted thermocouples and a pressure-recorder SUPPORT JHNGs\\-_ 6 in. |PS‘T*~ AlIR ’OUTLET 20 ORNL-DWG 65-2509 SAMPLER LINE ' SALT INLET ~AND - GAS OUTLET 'BAF «—HEATERS =——1-in. AIR SPACE COOLING AR Figure 3.5. Fuel Storage Tank. 116 in. T4y 21 Table 3.1 Fuel StoragesTank Design Data ‘ & "o | _Consfructionhmaterial ~ INOR-8 . Height, in, - | -~ 116 Diameter, in. .. - 50 Wall thickness, in. o o o . Vessel R , . 1/2 ;'DiShed hesds - - - 3/4 Volume at 1250°F, £t7 -~ - | Total | | | . 117.5 ~ Fuel (min, normal fill conditions) . T3.2 Gas blanket (max, normal £111 conditions) 4.3 ~ Salt transfer heel, max - = | | 0.1 Design‘temperaturer°F o o “ - 1300 . Design pressure, psig = o o 50 Heater capacity, kw Bottom (flat ceramic) o 5.8 . ‘Lower half (tubular) __ 11.6 Upper half (‘tubular) o B 5.8 Top (tubular) 5 . 6 ‘Insulation, in. 6 Reference drawings o , Tank assembly - D-FF-A-40430 Tank support E-NN-D-55432 Tank housing - E-NN-D-55L433 - Tank heaters . E-NN-E-56413 - Tank heater details E-NN-E~5641L4 - Thermocouple 1ocations T - D-HH-B-L052T7 " An interlock'isJprovidedmtfiat prevents SalsvbackupVinlthe gas sparge ,,-line'in case the tank pressure exceeds"the spargeégas pfessure;‘ Another h'interlock prevents backup of tank offgas (UFg, HF, Fg, or fission gases) ~into the sample line, which is also connected to the pressurization'— | pressure recorder 1ine in the high-bay area, This is done by closing the - HF-FE valve if the tank pressure ‘exceeds the helium purge pressure.' The | 4l vent valve in the offgas line opens if the tank pressure exceeds the‘design , 22 o pressure of'50'psi The tank,pressure will alarm above the normal pressure o ~of 5 psi to indicate any plugging in the offgas line, trap, valves, eb- sorbers,vor caustic scrubber,’ ,332 NaF. Trap ' The NaF trap will be required mainly during fluorination to provide ‘additional decontamination of the UFg gas’ and to remove volatile chromium fluorides from the gas stream. A kilogram or more of chromium fluoride _ could be volatilized during fluorination, and 1t would collect in lines andrvalves and eventually,c&use plugging.‘ The trap is shown in Figure 3. 6 andgdesign data are given in Table 3.2, : ‘ . - Table 3.2 | NaF Trap Design . Data 7 Construction material | | . Inconel Height, in. I 18 Dismeter, in. | SR 20 Wall thickness, in, o | o : . ‘ | Sides ' .J ) | 1/8 Dished heads g 1/ Loading, kg of NaF pellets o 70 Design_tempefature, °F ‘ o ,"f i 750 Design pressure, psig B .50 Heater capacity, kw ' | | : Center ‘ ' S 2.5 Outer surface : ‘ S 9 Insulation, in, . - ) o Approximate loaded weight, 1b ' | 500 ‘. B Reference drawings _ fl | | o | | Tank details . - D-FF-C-554k6 Heater details . __ . 'E-NN-E-56412 &) {8in. 23 LIFTING BAIL 7 THERMOWELLS ' OUTLET ! 'I“ | i in s e i e e e i st Sk ‘ l...‘..‘.'._...___._;.._,;..-._._..........._....._.. , hk‘BAFFLE e i Rl 1 e ) 1 l BE I A ol e | t 4 1 N P l HEATING | - | | | | o 3 | | | "ORNL-DWG 65-2511 s PIPE OPEN] AT TOP ONLY f2in JL“_&::::415 ;Figufé'3.6. ._:.__2Oim | N ’. ‘_ | | | l I LIFTING FRAME | I | 1 | I I . ] N h b o 1 | at NaF Tr&p. 24 - The gas ‘enters on the outside of an. internal cylindrical baffle and ',leaves inside the baffle, end ‘thus the gas path is almost 2 ft fora .12-in. depth of pellets. Gas velocities are kept below 4 £t/min to -pre- vent carryover of fines containing absorbed fission-product fluorides, The trep has thermowells at the inlet, center, and exit. Heat is controlled by separate variacs for the center and the outside of the bed. Spare heaters are installed | I | Since there is a possibility of plugging of this trap with chromium - during fluorination, it is designed for remote replacement The inlet | iand exit lines are provided with ring- Joint flanges at the trap and some distance away to permit removal of sections of the lines for access to the trap. Thermocouple and electrical disconnects ere‘provided on_the trap. and e standard. lifting bail issmounted on & strap-over the trap. Heat generation in the NaF trap at the end of fluorination could be v as high as L4000 Btu/hr 1f all the °°Nb after 30-d decay remains in the salt during reactor operation and collects in the trap during processing. Of this heat, 1100 Btu/hr will be removed by the process gas stream and ~ 2000 Btu/hr through the insulation with the heaters off.. To remove the remaining 900 Btu/hr and ensure that the exit half of the bed (internal annulus) does not exceed 800°F, air cooling is provided in the center' ~ pipe. A heat transfer coefficient of 1 Btu/hr-£t®:°F will remove ~ " 1000 Btu/hr with 8 cfm of air. ‘The trap will be by-passed if aqueous decontamination is necessary to permit direct maintenance on cell components. In this case the trap will be replaced with a Jumper line to permit flow of solutions through A ,the entire system. 3. 3 3 Cold Trap The extent of oxide removal from the salt during H24HF treatment will be determined.by cold trapping the offgas stream.and measuring the volume of water and HF condensed. The cold.trap is shown in Figure 3.7, and design data are given in Table 3.3. The inlet end of the trep is in the ' northwest corner of the cell and the trap extends eastward with a 3° .kslope. The inletiand_outlet brine connections are reducing tees at each end\of the jacket. < 25 ORNL-DWG £5-2512 THéRMowsLL\ o . . o %-InCORK y.in IPS STEEL JACKET , ANSULATION A B VAPOR OUTLET J © 4-in. IPS MONEL PIPE - ' HyHE-m0 [ _ ; N l —BAFFLES . * . - - 7. ' | " [ . ~ INLET - _bd : : . | _ — - . : 1: Rin. ' S ' THERMOCOUPLE _ _ 10 ft 4!0.\__’ | ) < Y2-in. IPS MONEL PIPE | | | —~ CONDENSATE OUTLET L L Yg-in.-00 RINE | : 4 (BRINE INLET. 0.065-in.- WALL e | MONEL TUBING > ¥4-in.-0D COPPER TUBING Figure 3.7. Cold Trap and Siphon Pot.. 26 _Table 3.3 Cold Trap;and Siphon Pot Design Datg Construction.material - ' : Monel ' "Cold. trap | T : o Maximim vapor velocity, ft/min | _ 1800 Maximum expected heat load, Btu/hr o . 2500 Heat transfer surface ares, ft : ‘ 2.3 Siphon pot volume, cm® | 55 Brine system _ ‘ _ '~ PBrine - o * _ _ Freon-1l Brine flow rate, gpm | . . 5 ~ _Brine head, ft (max) | o Lo Brine‘Volume, gel (min) ; o 2.5 'Reference drawing , ' E-NN-D-55439 3.3.4 Siphon Pot | The oondensate from the cold trap collects in & pot that auto- _ matically siphons when full The pot is shown in Fig. 3. T,_and design data are given in Table 3.3. The exit gas passes over & thermowell for - accurate determination of the offgas temperature. The pot is cooled - by the brine_before the brine enters the cold-trap jacket, The siphon tube has & surface thermocouple outside of the thermal insulation to de- tect each siphoning. | | | 3.3.5 Caustic Scrubber ~ The caustic scrubber is shown in Fig. 3. 8 and design data aré given‘ in Table 3.4. The tank is provided with coils enclosed in a heat transfer fmedium During Ho-HF treatment cooling water will be eirculated through the coils to remove the heat of HF neutralization. During fluorination, the tank will be drained. | _ ’ . The tenk is provided with a thermowell, &.liquid-level bubbler tube, and a jet suction line, Tho used caustic is jetted to the 1iquid-waste tank when the molarity has‘bsen reduoed'from'E.Oto,approximately | .0.3 M KOH. A caustic charging line is provided from the highsbay aresa. ] o7 ORNL-DWG 65-2513 ol ~_ THERMOWELL CAUSTIC CHARGING - LINE - E] GAS ~ GAS QUTLET JET ~ SUCTION LiQuUID | LEVEL BUBBLER TUBE ;_;‘]r- N COOLING & WATER OUTLET" - 84 in, »n ~ HEAT . TRANSFER T S S O S O O N0 G — w— e . COOLING & . WATER g ——— = - O O S oS O S O S O SO S0 F1s Q 3 o S Figure 3.8. Caustic Scrubber. - 25 Table 3.4 . Caustic Scrubber Design Dats Construction meterial | | Tnconel " Height, in. o | 8L Dianeter, in, ' S ko ;'Wall.thickness, in, o ' Vessel ° L 3/8. - Dished heads = o 3/8 Volume, liters - . | Totel - 1600 Normal ' 7 : .-~ 1300 Design temperature, °F 200 Design pressure, psig 50 _ Heat transfer area, £42 | L5 Liquid head, psi . 2.15 . - Reference drawing E-FF-C~ 55hh1 The offgas from the scrubber tank is routed to the spare cell nhere it passes through an. activated-charcoal trap and a flsme arrester before discharge into the cell ventilation duct The gas should be free of air ~ or oxygen up to this point, since all purges ere made with helium. A gensitive pressure indicator will show any restriction in the offgas line o or flame arrested. 3.3.6 NaF Absorbers The absorbers for collecting UFg on NaF pellets are made of carbon -steel which is sufficiently resistant t0 fluorine for- the short exposures involved. The absorbers will be used for processing only one batch and will thenibe discarded to the burial ground. The absorbers are shown in Fig. 3.9 and design data are given in Table 3.5._‘A bed depth of 10 in. (24 kg of NaF) will be used. ’ | Each absorber is mounted in an open top container with an air dis- tributor pipe.in the bottom. Cooling air flows around the outside and up ' through the open 2-in. center pipe. Air can. be controlled separately to - each absorber. ” 0 " THERMOWELL - ORNL- DWG 65-2514 MATERIAL: CARBON STEEL - B | QAIR COOLING _INLET - OUTLET_ \ PIPE OPEN AT \TOP AND BOTTOM _ — : s ek =T 4 L ey e M me N S e m e s - - o 12in. . . . . . | . 7 - :‘3]‘:1‘ BAFFLE - —— 14 in,— —— Figure:3;9}7JNéF Absorbers. 30 Table 3.5 | NaF Absorber Design Data Construction meterial . Carbon steel Height, in. . - 12 . Diameter, in. . . C 1k - Wall thickness, in. | Sides : S "',' : 1/k ' Dished heads | ' S 3/8 Design temperature, °F 150 | Design pressure, psig | 50 Loading, kg of NaF pellets | 2l - Bed depth, in. . o 6 -9 Reference drawings | - Absorber details D-FF-C-5544T Absorber container details ,. - D-FF-C-55448 A Each sbsorber is provided with a thermowell immersed in the NaF pellets near the gas inlet Since absorption of UFg %o form UFG'ENaF liberates 23.9 kecal per mole, the start of UFg absorption and the break- through to the succeeding absorber in the train can be followed by ob- serving the temperature rise. _ The absorbers are -connected with jumper lines having ring- joint _ flanges with pigtails for local leak detection before sealing the cubicle. | The lines in the cubicle all have tubulaer heaters to prevent UFg conden- __,sation. No spares are installed because the cubicle is accessible to the high-bay area when processing is stopped 3.3.7 Fluorine Disposal System ~ The excess fluorine is disposed of by reacting it with 802 to form SOgFé, which is a relatively inert gas and can be safely passed through the Fiberglas filters in the offgas system. Design of the system is based on the system in use at_the'Goodyear Atomic Corporation'at bet3<"’ 'mouth, Ohio. Since the quantity of fluorine to be disposed of is similar, the seme size eduipment'is used, except.for the fluorine preheater, The & N N " 31 fluorine at Portsmouth is diluted to about 10%, while the fluorination | ',offgas will be nearly 100% fluorine toward the end of the processing. The fluorine preheater can therefore be the seme size as the S0z preheater. . Some construction details have been changed to adapt the equipment to ’, remote radioactive service. The equipment is shown in Fig 3 10, and the design data for the sys- 'tem are given in Table 3.6. - Both gas streams are preheated to 400°F ‘before contacting in the fluorine reactor. -Each preheater has three sepa- rate heaters with installed spares - Each heater is controlled separately by an off-on switch. The low-pressure steam coil on the inlet half of the fluorine reactor supplies heat at the start to initiate +the reaction and acts as & coolant to remove the heat of reaction after the reaction ‘ begins., Tt is desired to keep the temperature below 1000°F to minimize corrosion. An activated alumina trap, Fig. 3.11, is installed downstream of the “Fz reactor as mentioned in Section 2.2.5. The trap is installed with | ring Joint flanges and located in an accessible position to facilitate replacement in case of plugging The trap is constructed of 6- -in. inconel . - pipe and contains ~ 3 £t3 of activated alumina, enough to contain 1 trailer of. fluorine.r Two thermowells are provided near the inlet to indi- - cate fluorine breakthrough from the SOz system. The flanges are connected to the leak detector system outside the cell, 3. 3.8 Cubicle Exhsuster ‘,_ o - The air in the absorber cubicle is maintained at a negative pressure ';f_with respect. to the high-bay area by an exhauster located in the fuel- processing cell., This is an exhauster with a capacity of 250 cfm at 10.5 in, Hx0. Tt is driven by a 3/h hp -3450- rpm 4ho-v 3- phase notor. :ffThe suction 81de is connected to the cubicle by a k- in._steel pipe routed -thhrough the space west of the cell. The discharge is open to the cell | 'without any connecting piping. ‘A L-in, plug cock is provided in the 'frsuction line in the cnbicle, with an access flange on the cubicle to - permit closing the valve_with:the,gasketed top in place_for.leak checking. - 32 . ORNL-DWG 65-2515 SO,Fy OUTLET . S-in. - : ‘ - o , T . MONEL PIPE—___| ,—2-in. PIPE N ____;__;_____T;___j__. 30in, — \ o . _L THERMOWELLS {7 HEAT | > TRANSFER 18in. R - RODS 100 in. STEAM | .. \ OUTLET == _ Y / ol THERMOWELLS - 44 in. S0, AND F, = " PREHEATERS - STEAM | R | INLET EIGHT g-in. DISTRIBUTOR \ HOLES FOR F, . | > F INLET | 'S0, INLET F, REACTOR Figure 3.10. Fluorine Disposal Systém. cN 33 o ORNL DWG. 68-2730 INLET R | oeurcer o IniconelL Pive i 3L Table 3.6 FluorinetDisPosal System Design Dsta o ' : "_ . | f L Construction material S - ’ S0z preheater 7 - Type 30hL stainless steel Fo preheater and reactor ‘ - Monel Length, in. , ! _ . Preheaters , 30 Reactor | S , : | Qverall - : : - ‘ 112 | o - Reaction zone L 96 - - Diemeter, in. IPS ‘ Preheaters , ’ 2 ~ Reactor ' ' ' - > ) Design fluorine flow, liters/min s 100 Design temperature, °F : o S - . Preheaters B 600 Reactor - 750 : Design pressure, psig = ‘ .50 _ Heat capacity of heaters on each’ , , ‘ preheater, kw 1 1.5 - S Insulation, in. | | - 2 o ‘Reference drawings | - , S0z preheater - | - D-FF-C-55L45 ) Fo preheater . -~ D-FF-C-55L4lL - F2 reactor j , D-FF-C-55442 Preheater heaters ) 5 E-NN-E-56410 The blower is controlled by & menual switch with an interlock to a solenoid valve in the cooling air supply to the absorbers This ensures that the cooling air cannot be turned on inadvertently with the blower - off and thereby pressurize the cubicle. - R | ~ , . 1 ' . - L o 0 ’135 '3.4"t0ut-of~0ell Equipment - 3 h 1 Activated-Charcoal Traps f An activated-charcoal trep is located in the’ offgas line in the spare :cell - The main function of this trap is the removal of iodine frcm the roffgas stream. The trap consists of two 2- 3/8-in —diam, 10~ l/2—in.—iong ~'canisters in series each with a charcoal depth of 3/h in. The canisters are installed in a Flanged 6-in. Monel pipe so that they can be replaced ° if necessary. Each canister contains l 5 1b of 6- lh mesh charcOal and is rated to process air at & maximum of 25 ft3/m1n. Each canister has an "_exposed surface of 1 ft2 " The pressure drop through one canister at - 25 ££3/min 1s 0.15-1n. Hz0. | | A deep-bed back-up charcoal trap is installed downstream of the 2-canister trap. This. second trap contains ~ 3 £t> of Cheney 727 impreg- nated charcoal which hes e high efficiency for removal of orgsnic 1odides "even under conditions of high moisture. This trap 18 constructed of 6- in. monel pipe with construction similar to the activated alumina trap (Figure 3.11). S - L - 3.h,2 'Fiame Arrester' Since the\system will:be completely purged of air before processing 'Qbegins and all"purge_and‘spargefgases will be helium or nitrogen, there 1is no possibility of producing an'explosive mixture with hydrogen in the \1i-equipment ‘The only location involving an explosion hazard should be the | ,point of discharge of the offgas into the offgas duct. ,At this point the | 1maximum concentration of. hydrogen in the air is 1.4% with a hydrogen flow _Jirate of 20 liters/min and a cell air exhaust of 125 cfm. This is well - below the lower explosive limit of hydrogen in air of h% The cell ex- it?haust flow rate will be checked at the time of processing to confirm ‘that f'"there is sufficlent dilution.js__' ' R As an added precaution, a. flame arrester is installed in the offgas . ,line ‘between the activated-charcoal trap and the cell exhaust duct in the : spare cell with a union downstream for removal for cleaning or replacement. The unit is a Varac Model SlA and consists of ccpper gauze and disk "lamlnations % 3.4.3 Offgas Filters ‘The fuel-processing cell ventilation air and ‘the vessel offgas will ~ pass through a 2-in. -deep ol- by 2k-in. Fiberglas prefilter and a 11- l/2—in | deep 2k- by 2h-in, Fiberglas absolute filter before passing through the ‘main filters and contaimment staék, ?here are-three 12-in,-diam butterfly . " valves for 1solation and for bypassing of the £ilters for replaoemént A -locally’ mounted differential—pressure transmitter indicates the pressure drop 8CTOSE the filters on the fuel-processing system panel board 'The caustic scrubber offgas, after passing through the charcosl trap and the flame arrester, discharges into the duct just upstream;of the bypass tee. This equipment is located in the spare eell with sufficient space | . allowed for the_addition~of:2 ft of shielding (for = total of 3-1/2 £t) ‘between the filters end the fuel-processing c¢ell. This should be sufficient shielding to permit filter changing with an irradiated fuel batch in the .storage tank. 3.h.4 HF Trep The fluorine used will contain up to 5% HF, which could_cause plugging of the UFg absorbers by formation of NaF.2HF, NaF-BflF; ete.,) if not re- - | moved. Therefore the trap shown in Fig. 3.12 and described in Table 3.7 -is provided in the fluorine line at the gaslsupply station. The inlet of the trap is maintained at 212°F by steam to prevent plugging (by prevention of the formation of the higher hydrogen'fluoride complexes)vbecause of the'bigh partial pressure_of HF. Farther into the NaF bed, the HF partial pressure is lower and the higher complexes are T not formed even at the lower‘temperature.» The exit of the trap is water - 7 cooled to about 100°F, which is below the operating temperature of the UFg absorbers, and the trap should therefore remove any HF that could otherwise collect in the absorbers. The reaction is exothermic and liberates 16.4 kecal per mole of HF absorbed _ | “, With a fluorine flow of 50 liters/min, a processing time of 20 hr, " and an HF content of 5%, the trap has sufficient capacity for the fluori- ‘_nation of five batches'if only 50% of the NaF is complexed to NaF-HF. o Since the average HF content is less than 5%, one loading should have suf- &3}- ficient capacity for all the fluorinations planned at the MSRE., If . necessary, the NaFgcan be discarded and recharged. _— e 37T " ORNL-DWG 65- FLUORINE - - FLUORINE N . ouT 2516 —I - + U _ o " 'STEAM N D:J\ | ——17 waTeR ouT ( - . STEAM OUT O— ] - | :[] WATER IN Figure 3.12. HF Trap filled with NaF Pellets. ~ 8-in. IPS PIPE 32in. B Tafile 3.7 HF Trap Design Data Construction material . . = Nickel-plated carbop'steél Height, in. =~ . 32 ' Dismeter, in. IS -« -8 Design temperature, °F _._ 7250 Design PreSsgre; psig - I 75 f Operating temperatures, °F - - Inlet - 212 Outlet L 100 TaF capacity, ft> | 1.9 Design flow rate, liters/min - , 100 ‘Reference drawing - _ D-FF—C-SShh3", '3.4.5 HF Heater The HF heater is installed in the gas line from the HF cylinder ~after ‘the flow control valve, The purpose of this heater is to dissociate the HF gas to the monomolecular form for accurate flOW'metering. This ‘requires the addition of approximately 1.2 Btu/liter of gas or approxi- mately 20 Btu/min at the maximum HF flow rate anticipated (1T liters/min). Another 1 Btu/min of sensible heat is required to heat the gas from 120°F, the temperature of the gas at 25 psig 1§a§1ng the'cylinder, to 180°F, the tefiperature required to reach the monomolecular form."This 21 Btu/min is equivalent to 370 w. Two tubular heaters are used to provide a total of 1120 w. | | | | ‘ S - The heater is strapped to the_Outsidehof a‘2-in,iMonel pipe sbout' 22 in, long packed with nickel wooi for heat transfer. Thé fiodl'is con- fined at the ends by 6dmesh.Mbnel cloth. A thermowell is provided near the outlet. ; ~ S ~ 39 ;-3.h 6 Salt-Samplér. ‘The salt sampler in the fuel-processing system is mounted on the _roof plugs over the fuel-processing cell and is connected directly to the top of the fuel storage_tank by & vertical 1- l/2—in. pipe. The sam- pler is ‘the original fuel-pump sempler-enricher mockup shown in Fig. 3.13. It is the'same as the fuelépumplsampler, with the following exceptions- 7 R It 1is designed for a maximum of 1k psig instead of 50 psig. Area 1C 1is protected from overpressure by a pressure relief valve that -vents to Area 2B which is vented to the cell through the space around the 1-1/2—in, sampling line. | . '2. No maintenance valve is required since the system can be shut down and purged if maintenance on the sampler is required. 3. Area 2B will contain the - vacuum pumps in addition to the opera- tional valve, - ’ L. A bellows is installed between the operational valve and the ' sample line instead of between the valves and Area 1C, ' The sampler will not be used during processing. The fuel storage tank will be purged with helium before the operational valve is opened for sampling.. The main purpose of the sampler is to verify that the salt is satisfactory for return to the drain tank after processing. After Hz-HF treatment the sample will be analyzed to determine that HF has been reduced to satisfactory levels. After fluorination the - sample will verify _ .vthe complete removal of uranium. Also, sampling of flush. salt before pro- o cessing will indicate the amount of fuel salt pickup. | _' | The sampler will have,_in general, the seme - instrumentation as the' "_fuel-pump sampler and will be operated in the same manner.4 | r'3.5_hElectricaliSystem 7 Electrical power for the fuel-processing system is supplied by a _"75—kva L80/120 - 208-v 3¢ transformer feeding a load center on the east “gide of the remote maintenance practice cell on the 840~ ft level This : supply Peeds two' power panels, CP—A and CP-B. ‘The starter and switch | for the cubicle blowerfare located at the load center but'have a;separatei~ Y ~ ORNL-DWG 63-5848R VAL VALVE AND SHAFT SEAL _ : . E ‘CAPSULE DRIVE UNIT LIGHT ~ LATCH ' - JOINT {SHIELDED ACCESS PORT WITH DEPLETED URANIUM) AREA IC - - {PRIMARY CONTAINMENT) SAMPLE CAPSULE MANIPULATOR . ~ AREA 3A {SECONDARY CONTAINMENT) . SAMPLE TRANSPORT CONTAINER LEAD SHIELDING OPERATIONAL AND MAINTENANCE VALVES AREA 2B (SECONDARY CONTAINMENT)" SPRING CLAMP DISCONNECT " TRANSFER TUBE (PRIMARY CONTAIN LATCH STOP PUM (B) CRITICAL CLOSURES REQUIRING A BUFFERED SEAL - o MIST SHIELD 10 1 2 GLIDE i . FEET [ Figure 3.13. MSRE Sampler Enricher. ‘ &Y e, supply since the blower requires hho-v. Most of‘the equipment and pipe ' heaters are controlled hy switches or powerstats located at two heater control panels, HCV-12 and HCP-13, ‘at the south end of the heater control area on the 840-ft level east of the cell block. The pipe_heaters'in the absorber cubicle are controlled by & switch at the cubicle in the high-bay . area. The line and equipment heaters are listed in Tables 3.8 and 3.9. The pipe line and equipment heater, blower motor, and motorized ~damper 1eads are routed from the heater control panels through a Jjunction box on the west side of the decontamination cell on the 84L0-ft. level, At this Junetion box the spare heaters can be connected to the control panels - 1f necessary. Each control may have from one to nine separate heaters. ~ Leads from each group of heaters are brought out to a junctlon box. De- fective heaters can be replaced only by entering the cell. - After the cell becomes radiocactive, only an entire group can be replaced unless the cell is decontaminated to permit direct maintenance. In case of loss of TVA power: “ 1. = All equipment and line heaters and the cubicle blower will be inoperative. : _-; - - 2. Helium will be available for sparging, purging, and salt transfer. . _ 3.- Diesel generator power will provide absorber cooling and instru- ment air and standby supply for instrument power. | .3.6.iHelium Suppxy Systen-‘” - - The helium supply to the fuel processing System is_from the 250-psig . helium header in the diesel house where it is reduced frcm 250 psig to ho psig. At the fuel—processing panelboard in the high-bay ‘area, this supply is reduced at & 20-psig transfer header and a 13. 5-psig purge ahd . i: sparge header. The transfer header has an air-operated block valve that S cannot be opened unless freeze valve ‘and drain tank vent valve positions ‘are correct to receive a salt batch from the fuel. storage tank The pur-. pose of this interlock 18" to prevent accidental filling of the reactor or transfer to & tank already containing a salt batch Tsble 3.8 Line Heaters Maximfim Fuel storage tank to roof plug : Heat Heat m Maximum Heeter per - Heated per Voltage Current No. Location . Control Length Foot Setting Setting | (w) (£t} (w) (v) (amp) H-110-5 ' Cell wall penetration 1020 5,1 200 120 8.5 H-110-6 Cell wall to Line 111 4584 25 - 187 . 1k . 32.8 H-110-7 Freeze Valve lllto fuel storage tank 1496 8 187 40 10.7 . H-110-L End ‘of penetration 270 %0 3 H-111-1 Freeze Valve 111 to cell wall 3743 20 187 1o 26.7 H-111-2 . Cell wall to high bay 2620 1k 187 o 18.7 H-112-1 ‘Line 110 to spare cell 2432 13 187 - 1ko 17.h - ‘H-690-1, -2 Fuel storage tank to Valve HCV-69L | ’ | ia o H-694-2 Fuel storage tank to cell wall 2629 ly'f 187‘ lho_ 18'7 H-691-1, -2 Fuel storage tank to NeF trap | | | o : H-692-1.to 4 NaF trap to absorbeér cubicle 1245 60 21 120 10.4 H-692-V Valve HCV-692 - : . | H-692-5 to 12 Absorber cubicle 390 21 . 19 120 3.3 ;H~69hrl' Valve HCV-694 to Tine 994 : 300% 16 o0 120 a7 H-994-1, - u - T ®Switch controlled; all others controlled by Powerstat. . et - I\l ® 3 - Table 3.9 Equipment Heaters™ Maximum e Number Voltege Heat —_— Type of of Setting Rating Equipment Control Elements (v) (w) ,'Fggl storage tank S ! - | Top . - Powerstat L 120 2,000 Upper side - Powerstat: 6 236 5,800 Lower side Powerstat 12 - 236 11,600 Bottom Powerstat 8 - 226 5,800 ~ NaF trap o '_ Side Powerstat 2 240 9,000 _Center Powerstat 1. 120 2,250 . SOz preheater - o | o No. 1 ‘Switch 1 120 500 No. 2 - Bwitch 1 120 500 ‘No. 3 Switch 1 120 500 " F2 preheater | | - - No. 1 - Switch - 1. 120 500 No. 2 . Switch 1 120 500 ~ No. 3 ° Switch 1 120 500 HF in-line heater Switch 2 208 1,120 Freeze Valve 110 | o B L Valve Powerstat R 115 1,200 Pots Powerstet . ‘ ‘.h 110 2,210 | Freeze Valve 111 L ,]7]~._ | | S - Valve - - Powerstat L 115 1,200 . Pots . Powerstat 2- - 15 1,200 ~ Freeze Valve 112 - G | | . Valve ' Powerstat L - 115 1,200 ~ Pots - Powerstat 2 . 115 1,200 ~ ®A1) heaters are tubular except those on freeze valves and fuel storage tank bottom, which are ceramic. Duplicate spares are installed .on all equipment except the HF heater. _ | _ heat Heater controls are on Panels The purge and sparge header has sufficient pressure (13 5 psig) to permit sparging a salt bateh at 100 liters/min but has insufficient pres- sure to force salt over the loop in Line 110 (14.6 psig, min). This header is provided with a pressure-relief valve set at 1.0 psig; which will resesl st 12.6 psigr ‘Should ttis valve stick openh or the helium supply pressure be lost for any othgr reason, an interlock on the helium - purge flow to the system will close the Hp-HF~F2 supply block valve, stop | the evolution of fission-product gases, and prevent the possible pressur- . izing of corrosive or radioactive gases up the sample line to the high- | bay area., - ' j Other functions of the low-pressure header are to supply gas for instrument- and sample-line purging, for purging the salt charging . line above the freeze valve prior to salt transfer, and for purging the HF and Fo lines from the gas supply station to the fuel storage tank, | 3.7 Instrumentation . 3.7.1 Thermocouples All the temperature-measuring points in the fuel-processing system ,‘ are listed in Table 3. lO.E Two 12-pcint recorders (0 ~ 250°F and O - 1000°F) and one 2h-point recorder (0 - 300°F) are installed at the fuel-proce351ng system panelboard and will record all measurements normally required for processing, | | The readings of the 46 thermocouples installed on the fuel storage - tank, salt 1ines, and freeze valves will ‘be recorded only in the main: control room, since they willflbeirequired primarily for salt transfer. The fuel storage tank temperatures will be checked occasionally. during ~ processing, but changes should be slow, . B 3.7. 2 Anmuneiators | The fuel-processing system anmunciator points are listed in Table 3.11. There are 11 annunciators on the chemical plant panelboard In addition | there are 3 radiation alarms that indicate high gamms, activity in the | lcharcoal“absorbers, a high gamms sctivity in the instrument cuhicle, and a ¥ [l { i Temberatu b5 ~ Table 3.10 re-Measuring Points A thber Qperafiingf ‘ s : - of Temperature - Location - Points (°F) Recorder From brine | 2 -10 - 13 30012 - Siphon pot 1 owo 0 - 250°F Siphon line 1 40 - 100 Caustic. scrubber 1 80 Activated alumina trap 2 . 100 HF flowmeters 2 200 UFg flowmeters ° 2 200 Cold trap inlet 1 200 ‘Switch-12 Misc. points 1 20 - 1000 3002 HF heater ’ 1 250 " 0 - 1000°F | Fé'disposai-system B 7 %00 Sodium fluoride trap 3 800 Absorber cubicle 1 200 3003 ‘Charcoal trap T 100 0 - 300°F Sodium fluoride absorbers 5 100 - 300 | ?Process‘gas lines ° ' 1T - 200 Fuel'StOragé Tank o 'l3'f '900l*.1200- 7 j$emp0rary Line 110 ‘_ . 8 1900 - 1200 fecofder.in Idne 111 7T 900 - 1200 reactor comtrol o Line 112 3 900 - 1200 room for | " Freeze Valve 110 . 5 80 - 1000 :f ,éalt . Freeze Valve 111 5 80 - 1000 tremsfer Freeze Valve 112 5 80 - 1000 | Table_3;ll Annmuncistors ' Alarm Instrument ‘ - ‘ ‘ ' . ' No.* | S Service - | _ , Type R . Setting PAIA-AC Absorber cublcle to highbay Low differential pressure = 1 in. Had PIA-CSN ' Caustic scrubber'vent | | High pressure 1 psig PATA-FEC Fuel-processing cell to high bay Low differential pressure :"0 L PIA-530 Helium supply | - Low pressure - 1T psig PIA-604 - Helium purge header , | Low pressure . L 12 psig PRA-608 | . Fuel storage tank vent | | High pressure. | 30 psig PICA-690 'Fluorine. supply - B Low pressure ' . .25 psig PATA-694 ~ Purge to: HF~F2 supply . Low. differential pressure 1 psig PIA-£96 . HF supply = | High pressurc - - 5 psig FTA-608 Helium purge'. | - . low flow - - 3 liters/min TA-HFH - HF heater. . Low temperature . 200°F RTA-QO4 Sample line gamma activity High activity R RIA-IC Instrument cubicle gamma activity = High activity RIA-9kO Cell exhaust air gamme activity High activity . RIA-AC Absorber cubicle air monitor High activity B The lh instruments .above the line across the table have panelfimounted annunciators, o ‘the other has an alarm on the instrument : : ‘ on E L [} Annmuncistor b The’panelfmounted4annunciators&willtservethe following purposes: Designation . Purpose u 'PATA-AC Indicate lack of negative pressure in the sbsorber cubi- RN cle, possibly due to blower failure or excessive ab- R i . sorber cooling air. . | PIA-CS o f.Indicate positive: pressure in the scrubber vent ‘possibly - due to plugging of the flame arrester or activated- charcoal traps. : PAIA-FFC ,‘Indicate lack of negative pressure in the fuel-processing o cell, possibly due to fan failure, filter plugging, or excessive air inleakage. | PIA-530 Tndicate & failure in the helium supply system or ICV‘530. - PIA-604 =~ Indicate a failure in the helium supply system or BCV-60L. PRA-608 Indicate high pressure in ‘the fuel storage tank vapor gpace; this could be caused by plugging in the offgas - ‘line, NaF trap, Valve HCV-692, ebsorber train, or. serubber inlet PICA-690 rIndicate the gas pressure in the fluorine trailer, with a ' o -~ full trailer pressure of 55 psig, an alarm at 20 psig will indicate the consumption of about 12,000 standard ‘liters of fluorine and that replacement of the trailer “is required . _ PdIA-69h. ’ .Indicate that the H2~HF-F2 gas pressure has been reduced to within'l psig of the pressure in the fuel storage -tank vapor space and there is danger of a back up of salt. into Gas Supply Line 690 - PIA-696 Indicate that the HF gas pressure in the cylinder is ~ reaching a dangerous level; this could be caused by . - failure of the temperature cohtrol valve regulating the steam to the hot-water drum around the cylinder.» FIA-608 -~ Indicate a lack of purge flow to the fuel storage tank and the possibility of backup’' of gaseous activity to the instrument cubicle; this could be caused by lack of “helium pressure or flowmeter plugging or. incorrect L o setting.: : . TASHFE Indicate insufficlent heating of the HF gas, which could L e result- in incorrect flOW'metering. o : . x-RIAf99h : | ‘sIndicate insufficient helium. purge down Sample Line 99h RIA-IC TIndicate backup of activity in Line 609, 690, or 99k. " RIA-94O - Indicate activity leak (probably iodine) into cell or ex- cessive iodine passing through charcoal traps. RIA-AC Indicate activity leak in absorber cubicle.. 48 high gamma, activity in the cell exhaust air. A portable alpha gir moni- tor will alarm on high air activity in the absorber cubicle and there ' will be & high gamma level alarm on the fuel storage tank sampler line. 2.7.3 Instrument Power. Instrument power is supplied from Instrument - Power Panel Nb. 2 and ~ No. 3. ‘The normal supply for these panels is the 62. 5-kwa inverter. If there is a loss of the inverter power, there will be an sutomatic transfer to the standby feeder. Through snother automatic transfer switch, TVA or a diesel generator will supply_the_standby;feeder. . i .. 3.8 Brine System - The siphon pot and cold trap are cooled by circulating freon‘brine (trichloromonofluorcmethane), The maximum cooling loads are approxi- " mately 2500 Btu/hr in the cold trap and an approximately 1200~ Btu/hr heat loss from the piping and equipment. A 1- 1/2‘hp water-cooled refrigeration unit should provide sufficient capacity for brine temperatures as low as -20°F. Brine is circulated by a carned-motor pump through insulated '3/4-in.-0D copper tubing. The refrigeration unit and circulating pump are located on the 8h0 ft level west of the cell ¥ 4 is regained ’ R ko b, SAVEY AmALYSTS h.l! Summaryiand Conclusions The maximum credible accident isva ges leak during fluorination.".A minimum of L minutes is available to stop fluorine. flow between detection of 1317 in the cell ventilation duct and before leskage of sufficlent 'iodine to produce a l-rem dose at the nearest point outside the controlled area., During fluorination of fuel salt less than 0 3 curies of 1311 will _ pass through the charcoal traps under the most severe conditions, Because of the high loss of noble metal fission products (Te, Mo, Ru, ete. ) during reactor operatipn, the maximum possible release of ‘these isotopes is well within permissible limits, , The greatest penetrating-radiation level in the operating ares will be from 31T passing through the gas space in the UFs absorbers. This can be easily shielded to reasonable levels. ’ : S Loss of TVA electrical power (described in Section 3. 5) would cause - no hazard and would only.require suspension of processing until power L.2 Bases for Calculstions Ch2a Diffusion Factor -i ‘f";f I | f'_ f:__ o o - Gaseous activity coneentrations wvere calculated using Sutton's equa- “4ion for diffusion from a continuous point source- o B a ih2/c2x2'n; - S omefTmx=TR - where ) ';,. i ;-)('==diffusion factor, ff.}:7- Q= release rate, curies/sec, | ’ - x = distance downwind of stack meters, h = ! effective stack height,-meters, . \\ 50 . ¢ = diffusion constant, U = wind veloeity, meters/sec, n = soabilrty parameter. - The following EGCR site dlffu51on parameters were used &s recommended by | the U. S Weather Bureau- " Invercsion Normal Parameter Conditions Conditions ,ca - 0.0 - 0. 09 T 1 ( n | 0.35 0. 23 As indicated in Table h.i; the diffusion factor for a stack release under normal conditions is ot & maximum at a distance of 325 meters from the stack, and'the ground conCentration‘is a factor of 20'1ess'at the uearest point outside the restricted area, as shown in Fig. h.1. | The MSRE stack is 100 ft high and has a flow capability of 20,000 £+ /min. An effective stack height of 163 ft, or 50 meters, was ‘calcu- lated:® ’ L. 77 - Qv . 8 =————= X = 63 £t , h v max 1+o.h3%’3 S where b nex = Plume height above stack, ft, u = mean wind speed, T.3 ft/sec V., = stack velocity, 47 ft/sec . Q = stack flow, 333 ft>/sec. Thus the effective height is 100 £t + 63 £t = 163 £t = 50 m. e 4.2,2 Meximum PermiSsible_Expostres For normal operation, the maximum exposure frOm'gaseous aotivity is 7lim_ted to 10% of the MPEC for each isotope. Since processing will be done no more frequently than once per year, exposures are averaged per 'quarter for occupational workers and per year for persons outside the controlled area, The limit for occupational workers is,'therefore, 130 mrem/isotope. Persons outside‘the.cofitroiled area have a total | 51 - Table Lh,1 "Di‘ff".usion Factor!X , Versus Distance Downwind - Distance X , Diffusion Facfora , ' Dovnwind . ~ Inversion Conditions. - Normal Conditions (m) Ground Release Stack Release Ground Release Stack Release 100 2.1x10%2 . o 8.0x10% 2.9x107 160 9.8x10°3 <07 - "3,5x10™% 11x107° . 200 6.3x107 . 0™ . 2,3x107* 2,3%10-S 325 3.0%x10°% . <107 - 1,0x107* 3.7 %107 500 - 1.5x 107 2.1x 1077 4.7%x 10 3.0x107° ‘750 T.7x 0% 8.2x10% 23x10° 1.8x107° 1,000 k8x10™ 3.5x120° Lhkx10° 1.2x107° 1,200 3.5%x10* = L5x 1075 1.0 x 10™5° 9.1 x 10°® © 2,000 1.5 x 10 6.2 x10°° k.0 x 107° 3.8 x 10-© 3,000 7.7x105 Lox105 = 2,0x10° 2.0x10° 1,000 18 x 10 3.6x10°° 1.2x10° 1.2x107® - 5,000 3.3x 105 - 2,7x10° 8.,0x 1077 8.0 x 1077 10,000 11x 10°° 1.0x20°° . 2.3x107 2.3 % 1077 B x release rate (curies /sec) = concentration of activity in air - (uefee). . exposure limit of 520:mrem"'per“jres.r g6 the limit is-there'fore 52 mrem/isotope‘. L 7 The release of 1311 is 1imi'ted further to 0.3 curies from any one facili‘by. - For the maximum credible accident 'the ma.ximum exposure is l:lmi‘bed : 'to 10 rem for occupational workers and 1 rem for persons outside the con~- o rtrolled area. Normal atmospheric conditions are assumed to prevail during norma.l ' ,operation while an inversion is considered possi'ble during the maximum ."_"credible accident | o 52 ORNL-LR-DWG 4406R2 FEET 0 5000 10,000 o % % % 1 2 MILES _ TO ORGDP. ~5 mile WHTE WING MELTON GATE HILL - €8 - : ‘ - DAM ; e‘\ . ) ?\’\Q _ S e AN fiog s NEAREST POINT OUTSIDE RE: STRICTED AREA w 53 A 4.3 Gaseous Activity — ! 4.3.1 Activity Release from the Contaiment Stack | h 3. l 1 Activity Released When Not Processing. A fully irradiated ' fuel batch will be held in the fuel drein tank, with the offgas passed to a charcoal bed, until the_xenonlemission cannot cause a radiation level in excess of 2. 5 mr /hr at the point of maximum ground concentration. From Fig, h 2 it cen be seen that an approximately four-dey decay period is\ required before transfer to the fuel storage tank which is not vented through a charcosl bed, Since there is about 50 £t> of gas space in the processing equipment an- irradiated fuel batch will not be transferred to | the fuel storage tank for 10 days at which time the decay rate will equal the production rate and xenon accumulated in the gas space could not re- sult in excessive release when purging is started. _ © b.3.1.2 Activity Released During Hp-HF Treatment. Although there has been no work done on fission-productrbehavior under the highly re- ducing conditions of the Ho-HF treatment very little if any fission- product volatilization is expected All the fission products that could g form volatile fluorides are more noble than the structural metals, - chromium, iron, end nickel. Nickel, which is the most noble of the structural metals will be limited to less than 1 ppm as NiFp with a 10:1 Ho-to-HF ratio, Therefore, although no equilibrium quotients are "javailable for the fission-product fluorides, it is unlikely that any f"niobium, Tuthenium, antimony, tellurium, ‘or iodine will exist in the salt has the fluoride. H0wever, it is possible that HI could form and become . volatile, The activated charcoal trap will provide good decontamination '_'for HY. ' , L o _ 'j“_ ;' L, 3 1. 3 Activity Released During Fluorination. Recent "freeze'q' 'f'valve" ‘samples of fuel salt have shown >99% removal of noble metal (Te, - ‘Ru, Nb, Mo) fission products during reactor operation. Table h 2 shows 'feexposures from Te, Nb, and Ru to be below the MEC. Removal of 99% of the iNb and Ru in the NaF trap is expected while no decontamination of Te is ~ allowed for. The charcoal traps will be tested by iodine 1injection and sampling to demonstrate a removal of at least 99. 998%. This removal effici- - ency limits, the 1311 release to less than 300 millicuries W1th 30 days decay. 5k ~~ ORNL-DWG 65-2517 PEAK XENON ACTIVITY (mr/hr) - 0.2 3 4 5 DECAY PERIOD BEFORE PROCESSIN,G (dqys) Figure L4.2. Rad1at1on Level at- Max:Lmum Ground Concentratlon from Xenon Released Durlng Processing of Fuel | Co s b s a4 by 55 - 'imposureS'fromtvolatile_Activities'in Fuei-Salt~ 1317 ;EamTe SN 1oaRu “Curies at 30 days decay ; 11, k00 N lSO 14800 - 1500 Nbrmal Operation o j' S - . | - o ' | Curies released over. hO hr , 10.28 150 L8 15 " ¢ of MEC.to occupational | o L L | workers - ' 0.25 o 3.8 1.5 - 4 of MEC outside controiled S S - _ ' ‘area : . 0.23 36 4.0 ‘1.2 Maximum Credible Accident & '7 o o Curies released in 6. 3 min, -~ 30, 0.k 12,6 k.o Maximm dose outside con- . I trolled area mrad - - 1000 - 0.k - 3.4 0.6 4.3.1.h Activity Released by Fquipment Failure, The meximum credi- ble accident is believed to be a leak during fluorination in the gas 'space of the fuel. storage tank or in the piping between the FST and the charcoal traps. This could be . caused by unusually high localized cor- i rosion. Such a leak_would:be detected first by the_duct_9ho radiation monitor. Figure 4.3 shows the time available to turn. off*the fluorine - ;flow and stop the processing after the alarm ‘has sounded - At the:maximum . ‘possible lesk rate (at the volatilization rate of 4.75 curies of I per - 'tj}minute) the monitor would reach alarm in 2 minutes. At the nearest o ;point outside the controlled area (3200 m), the accumulated dose would be ._’l rad 1f 30 curies of 131I were released This ‘would require 6.3 min or k.3 minutes after the alarm. This should be ample time to react to the ";yf?alaxm and turn off the fluorine Flov. Any leak smeller than this would - result in a longer time to reach the alarm point but the allowable re- - action time is much greater. T ‘ Table h 2 indicates that the dosages from the other volatile fission ’ products are very small compared with iodine. - 56 . - ) ‘ \ ORNL DWG. 68-2731 ° ’ 6o - ‘ 1o TIME. AFTER STAT oF tear MV Figure 4.3. Shutdown Time after Maximum Credible Accident. 57 Jh.3.2 Activity Release t0o the Operating Area " The highrbay area above -the fuel-processing cell will be used for operation of the fuel-processing system. The possible release of gaseous | activity into this area during fuel processing through the ‘roof plugs, from the absorber cubicle, from the salt sampler, and from lines pene- trating the cell walls was considered, - ) © h.3.2.1 Activity Released Through the Roof_ Plug_. Leakage of ac- tivity from the fuel-processing cell to the operating area is not con- sidered credible for the following reasons; - | 1. The cell is tightly sealed. All penetrations, piping, and wiring are grouted and sealed with mastic or pass through sealed boxes, 2. A negative pressure will be maintained during processing. - 3. Processing cen be Quickly stopped. This would be done ‘auto- maticelly in case of & power failure which would close the shutoff valve on. the ges supply. (Fg, HF, and Ho). The power failure would also stop the flow of cooling air to the cubicle. This air exhausts to the cell and is the only positive gas flow to the cell ‘A loss of ventilation not caused by a general power failure is highly improbable since there is- & spare stack fan and the fans can be run with diesel power.' o ‘4.3.2.2 Aetivity Released,from the Absorber Cubicle. The absorber\ ~ cubicle is a sealed box of 3/16-in.~thick steel located"nearjthe instru- - ment panel bosrd in the‘high?bay'area; ‘Tt is located in the high-bay area to facilitate handling of the portable absorbers following fluori- | nation By means of the cubicle blower, the cubicle will be maintained - at a negative pressure with resPect to the cell which will be negative “to the high#bay area. Failure of power to the blower will close the -,f solenoid valve in the air supply to the cubicle to avoid pressurization. ~ The maximum cubicle pressure with 1oo—ft3/m1n air flow will be /| checked to demonstrate that & pressure greater then 1 psig cannot be ob- tained with the blower off., 'If’ necessary, the maximim air flow'will be reduced below 100 ft3/min to prevent exceeding 1 psig. Prior to fluori- nation the vent valve will be closed the cubicle pressure will be reised to 1 psig, and the: leak rate will be ‘determined. Leakage must be less than 75 cc/min. This rate of iodine leskage would allow 10 min of working 58 ‘time in the hithbay area without masks. This is sufficient time to shut down and to evacuate the highsbay area, since the reactor will not be operating;during fuel processing. _ : . The presence of gaseous activity in the absorber cubicle will be de- tected.by'a monitor that will be continuously sampling the cubicle air during processing. If a leak occurs, processing can be suspended. The cubicle will then be purged with &ir to the cell, the cubicle top will | | be removed, and all. Jjoints will be checked for tightness. Smears from ~ each joint should indicate the location of the leak. 4.3.h, 3 Activity Released from the Cell Penetrations. All cell ~ penetrations connected directly to process equipment are provided with check valves, most of which are located in a sealed instrument cubicle , along with the’ instrument transmitters._ A backup of activity to the check valves would be detected by a radiation monitor in the-cubicle and " possibly by the area monitors in the high-bey area. | | In addition to the lines routed through the instnmnant cubicle, there are three other penetrations from the cell +to ‘the high—bay area: the salt sampler, which is discussed in the next section, “the salt- charging line, and the caustic-charging line. The salt-charging line will be'sealed with at least one freeze valve and capped when not charging salt. The‘caustic-charging line to the'caustic scrubber is provided with two memual velves. Caustic will not be charged during processing,.which , would be the -only time that pressure or activity could be found in the charging line, | l L | I . The waste-salt line to the spare cell will be sealed by a freeze \ valve in the processing cell. The method of waste salt disposal has not ‘yet been determined. = , | , | / 4,3.2.4 Activity Released fromw the: Salt ‘Sempler. The-fuel—proceSSing. - system sampler as mentioned in Section 3.4.6, is similar to the,fuel-pump sampler-enricher. Both samplers have similar instrumentation and will be ' ~used. with similar operating procedures ' The fuel-storage tank will not ‘ be sampled during processing. aBefore sampling,-the sampling line and fuel | storage tank will‘be purged of gaseous activity. The sample'capsule con- faining the solid sample will be moved from the'primary,containment area, 1c (see Fig. 3.13) to & secondary.containment area, 34, where the:sample‘ 59 - Cwill be sealed inside & transport container tube before being removed from' the sampler to & shielded carrier., k.4 Penetrating Radiation .41 Normel Levels o | | b1, 1\\Operating'Area. The radiation level in the high-bay area over the fuel-processing cell will be less than 10 mr/hr through the . Y} ft-thick high-density-concrete roof plugs under the most severe con- ditions with a fully irradiated four-day—decayed fuel salt batch in the fuel storage tank, Since processing would not be started until the batch had decayed for at least a few weeks, this level above “the cell should cause no concern. Operations will be. planned to limit exposure of indi- ‘viduals to less than 100 mr/week and signs will be posted indicating radiation levels at various points in the hithbay area. The salt sampler will be shielded with L in. of lead which should ~reduce the radiation level from a8 fuel salt sample to less than 10 mr/hr It will be necessary to shield the absorber cubicle during processing ' of 8 fully irradiated fuel batch Since "freeze-valve" salt samples ‘have shown that only'~ 1% of the calculated %Mo is in the circulating salt | 'stream, absorbed activity is expected to be very low" ‘and’ shielding of the absorbers should not be required. However 31T in the gas space. in the absorbers will require that ‘the absorber cubicle be shielded with 1/2-in. to . 1-in, of lead. The radiation levels will be monitored during pPro- ; cessing and additional shielding and radiation signs will be posted as . brequired | Sl : ‘- | '7' L, h l 2 Switch House. The only fuel»processing cell wall adjacent to an occupied area is the west wall bordering the switch ‘house,” The ,.h-ft area between the switch house ‘and the. cell will be filled with | " stacked concrete blocks. When a fully irradiated fuel batch is in the _"storage tank the level at the east wall of the switeh house should be ‘?;less than 5 mr/hr | R , = k3 Spare Cell. The east wall of the fuel-proce851ng cell ad- ‘ 'Joins the spare cell where the activated-charcoal trap, offgas filters,_‘ c'60 ; . dampers, differentisl-pressure transmitter, and hydrogen flame arrester are located A blanked weste salt line extends into this cell for future removal of waste salt Two feet of stacked concrete block . shielding is | provided between the cell well and the above equipment, This‘will provide Bufficient shielding (a total of 3-1/2 £t) to permit replacing the offges filters without exceeding planned exposures. The dose rate should be ~ less than 50 mr/hr o | : | | | o - The charcoal beds will be shielded with 16 in. of barytes concrete. This will reduce the redistion level at the filters to <30 mrem/hr with all the iodine from & fuel,batch.on the beds after 30 deys decay. ' bh1.h Decontemination Cell. The 18-in. north wall of the fuel- 'processing cell borders the decontamination cell. There would probably be & limited working time over the decontamination cell with ‘the roof plugs off and & fully irrediated batch in the fuel. storage tank, L.4.,1.5 Area Surrounding the Waste Cell, The maximum.activity ex- pected in the caustic solution from the hydrofluorination of & 28- day- | - decayed fuel batch is,ll,ooorcuries of iodine, assuming complete removal ~in the scrubber. During the time this activity is in the 1liquid waste tank, there must be limited access to the areas above and around ‘the waste cell and rediation warning signs must be posted L.4.2 Unusual Radiation Levels - , L 4.4.2.1 From Irradiated Salt.. There are two dip tubes in the fuel storage tank into which-salt could accidentally back up: the salt-transfer line and the gas-sparging line. The salt—transfer line is connected to the spare cell by the waste salt line and to the high-bay area by the salt-charging line. Both lines have freeze valves that are normally frozen, In addition, the end of each line will be capped when not in use, | ) : ? | ) S - The gas-sparging line passes through the area west of'the cell to ) the instrument cubicle and then to the gas supply station. An air valvel- }\located in the instrument cubicle actuates a valve in the cell which opens if the tank pressure exceeds the purge pressure and vents the line to the top of the tank to prevent salt backup. If a plug should occur, it could be thawed with installed electric heaters without entering the cell, [ ¥ 61 hbh,2.2 From Ceustic Solution. Most of the'iodine,in ‘the salt.may‘ be volatilized as HI during Ha-HF treatment There will probably be some 'deposition on metal surfaces before the HI reaches the caustic scrubber 'but most of the iodine reaching the scrubber will be collected there. * The meximim iodine concentration in the scrubber solution will be 2 c/gal from flush selt processing and 40 c/gal from fuel salt processing.r The caustic solution can either be diluted to 5 ¢/gal or allowed to decay for an additional ol days before transferring to the intermediate level waste system colleotion tenk. The piping and pump containing ‘the radioactive scrubber solution is shielded but masks, ‘protective clothing, and Health Physics surveillance are required for the sampling operation,. The solution could possibly get into unshielded lines in the ,ffollow1ng ways; . - S T L. Pressuring of the scrubber tank during processing and plugging of the vent line or flame arrester could force some solution up the jet fsteam'line, but this line isfshielded to approximately 25 £t from the jet and backup this far into a closed line is unlikely, The pressure alarms on both the fuel storage tank and the caustic scrubber would pro~ ' vide sufficient warning to stop processing before a dangerous pressure " was reached 2. Pressuring of the scrubber tank during Jetting plus plugging of the vent line or flame arrester and plugging of the jet ‘discharge line to the waste tank could cause steam to back up through the caustic 7solution. Considerable time would be required to build up sufficient : pressure (7 psig) to force solution up the sparge line to the absorber ”nqcubicle. Pressure. alarms and radiation monitors would provide warning ~ far in advance of any hazard. *3._7 A vacuum in the Jet line could pull solution into the steam lpe. If the jet discharge 1line should plug and jetting should stop, condensing steam could create such a vacuum. A check valve tees into ';the steam line and will prevent & -vecuum from forming in this line. b, Cooling of the fuel storage tank without gas purges to the 7 tank could cause & vacuum in the tank and offgas piping to the scrubber. A power failure could cause'cooling of the tank but would not stop the 62 helium purges. In the event of a prolonged power failure and_co¢ling_of ' the fuel storage tank, ihe caustic scrubber would be jetted to the waste - tank, , 4.4.2,3 From Radioactive Gas. The sempling line‘is the only gas | 1ine‘fr6fi\the fuel storagé'tankito the operating area. Steps will be .teken as indicated in Section 4.3.2.4 to keep gaseoué'actifity:dfit'of the '_'samplef.' Sparg;ng for 1 hr with helium should reduce the acfivity in.the, gas-space.fiy a factbr of 10°. Complete £illing of the'sampler access chember with atmosphere from the fuel storage tenk would result in & radiation level 10> times less than that from a fully irredisted fuel salt sample. ' o ' o - ‘N'_ SVRTI i R. B. Lindauer, Preoperational Testing of the MSRE Fuel Processing Facility and Flush Salt Treatment No. 1, ORNL—CF 65-7- 36 July, 1965, L. E. McNeese, An Experimental Study of Sorption’bf Urenium Hexa- fluoride by Sodium Fluoride Pellets and & Mathematical Analysis of Diffusion with Simulteneous Reaction, .USAEC Report ORNL-3h9h p. 82 Osk Ridge. Netional Laboratony, November 1963, , R. L. Jolly,. et el., Equipment Decont&minetion.Methods for the.Fused Salt-Fluoride Volatility Process, USAEC Report 0RNL-2550, Ozk Ridge National Laboratory, August 1958. ' R. C. Rdbertson MSRE Design and Operations Report Part I, Descrip- tion of Reactor Design, USAEC Report ORNL-TM-728, Oak Ridge National Leboratory, - Jamuary 1965, P. 2hk, | U. S. Department of - Commerce Weather Bureau, Meteorology and Atomic. Energy, USAEC Report AFCU- 3066 July 1955. F. A. Gifford, U. S. Weather Bureau, Oak Ridge, Tennessee, Personal Communication to L. A. Mann, Qak Ridge Nstional storatory, Januarv 21, 1961 | | Letter from F. R. Bruce %o Division Directors, February 5, 1965, ' Subject: Criteria for Controlling Release of 131T 40 the Atmos- phere, February 5, 1965 65 . o - . L OBNL—TM—9OTLRev. Tnternal Distribution . .1, R, G. Affel. . 35. A. I. Krakoviek . 2. T, A, Arehart - 36-38. R. B. Lindauer ¢ 3. C. F. Bges . . 39. R..N. Lyon 4, S. E Beall R - 40. H. G. MacPherson 5, E. 8. Bettis. ~ o 41. 'R. E. MacPherson -6, F, F, Blankenship- - = -L42. H, E. McCoy ~ T.. R, Blumberg L | 43, H. C. McCurdy - 8. E. G. Bohlmeom = - - bk, H, F. McDuffie 9. R, B, Briggs . - | , 45, €. K. McGlothlan - 10. R. E. Brooksbenk = _ 46, L. E. McNeese ~11. T. J. Burnett - | - k7, A. J. Miller 12. W. A. Bush = L - .48, R. R. Minue 13, W. L. Carter S ) h9. R. L. Moore 1k, @. I. Cathers . " 50. E. L. Nicholson 15. W. B. Cottrell C 51. L. C:. Oakes 16, J. L. Crowley - . = - - 52, A, M. Perry 17. F. L. Culler, Jr.. -~ 53. J. L. Redford 18. R. J. DeBakker = .. - ? - 54, M. Richardson R B .19. S. E., Dismuke - .. A - 55-64, M. W. Rosenthal - S -+~ 20, 8. J. Ditte . | 65. A. W. Savolainen - SR 21, J. 8. Drury o - ~66. R. W. Schaich ) 22, J.R.Engel . 6T, D. Scott f . 23. D. E, Ferguson o L 68. M. J. Skinner 24, A, P, Fraas ~ ~ _ 69., I. Spiewak 25. C. H. Gabbard = - ~ 70. R. C. Steffy, Jr. 26, R. B. Gallsher = - 7. D. A, Sundberg 27. W. R. Grimes o | 72. R. E. Thoma 28, A. G. Grihdell " 73. D. B. Trauger 29, R. H. Guymon . T4. A. D, Warden. 30. P. H. Herley T -T5. B. H. Webster 31. P. N. Haubenreich o ~ 76. A. M. VWeinberg 32.. P. G. Herndon . - 7T7. J. R. Weir '33. T, L. Hudson . - 78. M. E. Whatley 34, P.R.Kestem -~~~ .- 79, J.,C. White > o EEE R 80. G. D. Whitmen - 82-83 Central Research Library 8w S;_ngpas; ORGDP .. 84-85. ¥-12 Document Reference Section e . 86-110. Iaboratory Records (LRD) | 111, LEboratory Records - Record Copy (LRD-RC) | External Distribution o o - 112126, deision of Technical Information Exten81on (DTIE) .o 1et. Iaboratory and‘University Div181on (ORO)