OAK RIDGE NATIONAL LABORATORY OPEFRATED BY UNIOH CARBIDE CORPORATION NUCLEAR DIVISION f POST OFFICE BOX X CAK RIDGE, TENNESSEE 137830 ORNL-MIT-117 R COPY NO. November 18, 1970 DATE: SUBJECT: Removal of Tritium from the Molten Salt Breeder Reactor Fuel AUTHOR: M.D. Shapiro and C.M. Reed Consultant: R.B. Korsmeyer ABSTRACT Molten Salt Breeder Reactors will produce large quantities of tritium which can permeate most metals at elevated temperatures and In this project it was assumed thereby contaminate the environment. that the tritium can be removed from the salt stream by a hydrogen- helium purge and that the helium can be separated for recycle with a = palladium membrane. Several systems for concentrating and storing i the tritium were conceptualized, designed, and economically evaluated. b Cryogenic distillation of liquid hydrogen appears to be the most eco- & nomical system. A cryogenic system with a capacity of 4630 gmoles of gg hydrogen per hour at a 1000-fold tritium enrichment has an estimated ” . A - - ¥ capital cost of $328,000 and an estimated annual operating cost of E% $81,000 (excluding depreciation}. n ......... o e NOTICE - This report was prepared as an account of work CTJ spenscred by the United States Goevernment. Neither &3 the United States nor the United States Atomic Energy et Co::nmxssxon, ner any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any i fegal liability or respensibility for the aceuracy, come- . pleteness or usefuiness of any information, apparatus, by product or process disclosed, or represents that its use “fiw would not infringe privately owned rights. ™~y q' Qak Ridge Station School of Chemical Engineering Practice Massachusetts Institute of Technology NOTICE This document contains informatien of a preliminary ’ nature and was prepared primarily for internal use ot the Oak Ridge Nafiona! Laboratory. !t is subject to revision or cor- rection and therefore does not represent a final repert. The in- formation is only for cfficial use and no release to the public shall be made without the approval of the Law Department of Union Carbide Carporation, Nuclear Bivision. SISTRIBUTIOR OF THIS DOCURMENT 1S URLIMITED Contents Page T. SUMMAYY ¢vveiavncencorssnsancess Ciee et ssransaret s Meeecsne esee A 2. Introduction ....e.e. P re i ebteret ettt an e e ebressaatenn 4 3. Design and Evaluation of A]ternéte Separation Systems ......... o 3.7 Approach ...viviiieiiiiiecencnnennn i aeean e .. B 3.2 Feed Pretreatment ...... eessesssrsestesatrtasetearesiarns b 3.3 Storage of Tritiated Water ............... et ceceseneans 7 _3.4 Water Distillation cevvvvieicecnrinonrrconnnnconrns reeees 7 3.5 Thermal Diffusion ...cicvivernnienconsrinnnens seesvesananes 9 3.6 Cryogenic Distillation .....cvivviiiveennnn vernenca ceenae 9 4, Discussion of Separation Systems ........ovevvevevnnonse S 16 5. Conclusions and Recommendations ............. esareansaenesnons 16 6. Acknowledgement ..... eereserarenes ettt eeircca st o as s 17 7. ApPPendiX ..cciiiiiiiiiiii ittt cc e e 18 7.1 Basis for Water Distillation Costs ....... N 18 7.2 Thermal Diffusion System ............;.,.,.,.,.,,,..,,..‘. 21 7.3 Cryogenic Distillation System ....ovvecveriirorsrreocnoons 22 7.4 Computer Codes ....... ceerean esssserecasan Cetecssoosasecs 26 7.5 Nomenclature ...... eercaasaaaes e asecenen e veeenan wes 29 7.6 Literature References ...,....cvivseennrenenrecennnsnnnoen 30 . SUMMARY One characteristic of Molten Salt Breeder Reactors (MSBR} is the rela- tively large quantity of tritium which would be produced in the salt fuel stream. Tritium, like hydrogen, can permeate most metals at elevated temp- eratures, and thereby contaminate the environment. An efficient means of removing and concentrating tritium from the fuel stream is essential to the development of MSBR. In this project it was assumed that the tritium can be removed from the fuel stream by a hydrogen-heiijum purge and that the helium can be separated from the hydrogen for recycle via a paliadium membrane. Four systems were conceptualized, designed, and economically evaluated toc con- centrate or store the hydrogen and tritium: storage of unconcentrated tritiated water, water distillation, gaseous thermal diffusion and cryo- genic distillation of 1iquid hydrogen. On the basis of this evaluation the most economical system, cryogenic distillation, would provide a 1000- fold tritium enrichment at an estimated capital cost of $328,000 and an annual operating cost of $81,000, 2. INTRODUCTION There is presently interest at ORNL in the development of Molten Sait Breeder Reactors {MSBR}. A characteristic of these reactors, however, is the generation of large quantities of tritium (half 1ife 12.36 yr). Tritium, 1ike hydrogen, has a very high permeability through most metals at tempera- ture and concentration levels of the moiten salt; therefore if 1t is not removed, it will escape from the reactor and contaminate the environment. Tritium is a weak beta emitter (18.6 kev), but it exchanges readily with hydrogen and as tritiated water can enter the body by penetrating the skin. The effect of radiation in a very localized area and the transmuta- tion of tritium to helium within the body may be of biological significance (1. One proposed method of removing the tritium from the MSBR fuel stream is by means of a helium-hydrogen purge (2). The hydrcgen stream would then be separated from the helium and the tritium would be concentrated and stored as tritiated water (HTO). Since tritium is an isotope, its concentration will depend mainly on physical separation processes. In the MSBR concept the primary salf stream is comprised of molten salts of uranium, tithium, beryilium, and thorium. The primary salt cir- culates through the reactor where a critical mass is achieved and fission occurs. The sensible heat generated by fission is transferred to a steam cycle by means of a secondary salt stream. The flow plan is illustrated in Fig. 1, TO TRITIUM RECOVERY H _ 6 "0 PURGE (Ho-He) ¥ l it iy ] o -~ — HEAT MSER EXCHANGERS STEAM CYCIE [ ) ~ SRCONDARY Bl SALT PRIM\RY GALT MASSACHUSETTS INSTITUTE OF TECHNOLOGY SCHOOL OF CHEMICAL ENGINEERING PRACTICE AT OAK RIDGE NATIONAL LABORATORY MSBR FLOW PLAN DATE DRAWN BY FIL 30 0cr 70| _ALS CE p E S N 0 X -117 FIG, Tritium is produced in the primary salt stream by neutron absorption. The reactions producing tritium and the estimated production for a 1000 Mw(e) reactor are listed in Table 1. Table 1. Tritium Production in a 1000 Mw(e) MSBR (3) Ternary Fission 31 curies/day 6Li(n, o} T 1210 Li(n, an) T 1170 19¢(n, 10) T 9 2420 curies/day v 0.25 gm tritium/day 3. DESIGN AND EVALUATION OF ALTERNATE SEPARATION SYSTEMS 3.1 Approach In this study it was assumed that the tritium could be remcved from the fuel stream by a mixed helium and hydrogen purge. The hydrogen and tritium would then be removed from the purge stream and concentrated. The selection of the most feasible system for effecting the desired concentra- tion was based on a preliminary design and cost estimate for each system. The systems studied were storage of the unconcentrated tritium as tritiated water, water distillation, thermal diffusicon, and cryogenic distillation of Tiguid hydrogen. The design for all the systems was based on 111,000 gmoies of hydrogen per day at an H/T = 106, A 100- to 1000-fold enrichment was desired (i.e., H/T = 103 to 10% in the product stream} with a 99 to 99.9% recovery of the tritium. In all cases the product tritium is to be stored as water on the MSBR site (2). For all processes the separation equipment will be en- closed in a separate building to isolate any possible tritium leak. 3.2 Feed Pretreatment The purge stream will contain helium, hydrogen, and tritium as well as gaseous fission products such as krypton, xenon, icdine, and hydrogen fluo- ride. It is proposed to pass the purge stream through a charcoal bed to g adsorb some of the gaseous fission products. To separate the helium for recycle from the hydrogen and tritium, & palladium "kidney" would be employed. A palladium membrane which passes 15 scfh of Hp costs approxi- mately $5000 (4). When the six-tenths power formula is applied to scale to the capacity required for the MSBR, an estimated purchase cost of $136,000 is realized. It is estimated that the installed cost of the palladium kidney is four times the purchase cost of the kidney, or approximately $544,000. The same cost will be associated with each of the four alternate systems. A second item which is common to the four processes is the oxidation equipment and its installed cost is estimated to be $136,000. 3.3 Storage of Tritiated Water The hydrogen and tritium would be oxidized after passing through the palladium kidney and the resulting tritiated water condensed and sent to a storage tank. Storage of tritiated water will require steel tanks en- cased in a concrete tank. Should a leak develop, the liguid would be con- tained, but an additional tank would be required to effect a transfer before final repairs could be made (5). The tanks were sized to hold 30 years production of tritium, the expected lifetime of the reactor. The Tiquid will have to be stored until the activity has decreased to less than 1% (approximately 110 yr). At a production rate of 2000 Titers/day, a tank capacity of approximately 5.8 million gallons is required. With an esti- mated capital cost of $1/gal (5), the two-tank system would have a capital cost of $11.6 million. Annual operating cost for this sytem would be the cost of the hydrogen and oxygen burned to form the water ($143,000) and the maintenance cost [2% of the capital cost (13)], $232,000. (See Appendix 7.1 for details.} 3.4 Water Distiilation During World War II the United States built and successfully operated several water distillation plants to produce heavy water. The low vaiue of the relative volatility (o), however, required the use of high reflux ratios and a large number of plates in the distillation column. Distillation to separate tritiated water (HTO) is not as difficult as that for heavy water, since the value for o is several percent higher. A plot of relative volatility versus pressure indicates that such & system should be operated under vacuum to take advantage of the higher value of o (see Fig. 2). A computer program was written to size the distillation column. The design of the column is based on the use of a high efficiency packing such as Sulzer CY (designed for use in heavy water systems). This packing was found to have 21 theoretical plates/meter and a pressure drop | of 0.19 torr/theoretical plate (6) for heavy water separations at a liguid g Toading of 2000 kg/M2-hr and a column head pressure of 120 mm Hg. Move favorable conditions might be achieved with the tritium system by lowering the head pressure of the column. i.08Q— 1.07¢ 1.064 1.05¢ 1 . 04 (Proom 30 Relative Volatility, o 75 100 125 150 l | | 175 200 225 Pressure, mm Hg MASSACHUSETTS INSTITUTE OF TECHNOL.OGY SCHOOL OF CHEMICAL ENGINEERING PRACTICE . AT OAK RIDGE NATIONAL LABORATORY H,0 RELATIVE VOLATILITY (a - £5-) (1) ATE DRAWN BY FILE NQ. FIG. NGV 7g CEPS-X-117 2 AT 9 As shown in Fig. 3 the number of theoretical plates is a sharp function ocf the reflux ratio. Figure 4 is a schematic diagram of the propcsed water distillation design. The optimum systems and operating conditions were determined by varying the reflux ratic for different enrichment and recovery factors (see Tables 4 and 5 in Appendix 7.1). Table 2 shows the major de- sign specifications and the cost estimates for the optimized systems. Cap- ital _costs for 99% recovery are $422,700 at H/T = 104 and $362,600 at H/T = 103. For 99.9% recovery, capital costs are $536,600 at H/T = 104 and $484,600 at H/T = 103. Although the cotumn packing and building costs are hiflher for K/T = 10°, the overall cost is less than for H/T = 10% because of the associated storage costs. The cost of recovering 99.9% of the tritium for H/T = 103 is 33% higher than the cost for 99% recovery. Operating costs in all four cases are essentially the same, $220,000 annually. The cost of Ho is the major operating expense, $128,000 annually. A break- down of the column costs for other reflux ratics is in Appendix 7.1. 3.5 Thermal Diffusion Thermal diffusion is based cn a temperature gradient in a mixture of gases which gives rise to a concentration gradient, thereby effecting a partial separation. Jones and Furry (9) have presented a detailed discus- sion on the theory and design of thermal diffusion systems for binary sepa- rations. The thermal diffusion constant between two species with masses m] and m2 is equal to (mp - m])/(mz + m), and for a hydrogen-tritium system this ratio is 1/3 which is considered high. In a thermal diffusion column the separation rate is fixed by the temperature and pressure of the system. Theory requires that the rate of production of each column be small compared with the rate of thermal djf- fusion., The production rate of tritium in an MSBR is so large that 103 to 10% thermal diffusion columns operated in parallel would be necessary. Based on the theory of Jones and Furry, Verhagen and Sellschop (11) designed and operated a thermal diffusion system for tritium enrichment. A scaleup of their apparatus would require 5150 parallel systems for a 1000-fold en- richment with a power load of 100,000 kwh. The power consumption at $0.004/kwh would cost $2.9 million per year. (See Appendix 7.2 for appa- ratus details and operating conditions.) 3.6 Cryogenic Distillation Due to recent advances in cryogenic engineering, several plants have been constructed which separate deuterium from hydrogen by cryogenic dis- tillation of the liquid hydrogen feed. The relative volatility of H2 to HT is not available, but it is believed to be equal to, if not greater, than the relative volatility for the Ho-HD system (o ® 1.6 at 1.5 atm). This is considerably higher than the relative volatility for the water-tritiated water system (o ¥ 1.05). A second advantage is the Tower consumption of Ho and 02. For the separation of tritium by water distillation, all the Ho from the purge stream is oxidized to water, but in the cryogenic system 10 (NTP) Number of Theoretical Plstes 1 ' g 600 = 550 — 500 ] 450 - H/T=103 400 99.9% Recovery - -/TwlO4 350 — 1/T=10> 300 — 99% Recovery H/T=}O4 ] i ] 1 | ] | j | | ] 26 27 28 29 3¢ 11 32 33 34 35 36 37 Reflux Ratio MASSACHUSETTS INSTITUTE OF TECHNOLOGY SCHOOL OF CHEMICAL ENGINEERING PRACTICE AT OAK RIDGE NATIONAL LABORATORY NUMBER CF TEEQRETICAL PLATES VERSUS REFLUX RATIO DATE DRAWN BY FILE HO. FIG, 4NOV 70 | MRS CEPS-X-117] 3 i 11 Steam Ejector Condenser Y Distillate ———————— Feed Packed Column Tritium f!?] Recovery Reboiler Steam MASSACHUSETTS INSTITUTE OF TECHNOLOGY SCHOOL OF CHEMICAL ENGINEERING PRACTICE AT OAK RIDGE NATIONAL LABORATORY WATER DISTILLATION SYSTEM DATE DRAWN BY FILE NO. FIG, 4 NOV 70 | M8 CEPS-X-117 4 12 Table 2. Cost Estimate of Optimum Water Distillation Systems (See Appendix 7.1 for Details) Recovery 99% 59% 99,9 99. 9% Product H/T 104 103 104 103 Column Diameter 1.32 M 1.32 M 1.32 M 1.32 M Number Theoretical Plates 275 323 362 412 Designed No. Plates = 1.1 (NTP) 303 355 398 453 Column Height 14.4 M 16.9 M 19.0 M 21.6 M Reflux Ratio 32 32 35 35 Installation Column Cost $90,600 $106,200 $138,000 $157,200 Flow Distributors 1,500 1,200 1,200 1,200 Packing ' 139,000 163,000 200,000 228,000 Building 19,600 23,000 25,900 29,500 Covering 3,060 3,400 4,100 4,100 Ejector {installed) 2,000 2,000 2,000 2,000 Site Preparation 1,000 1,060 1,000 1,000 Instruments 50,000 50,000 50,000 50,000 Total 306,700 349,800 422,200 473,000 Storage Tanks 116,000 11,600 116,000 11,600 Total $422,700 $361,400 $538,200 $484,600 Operating Costs, $/yr (Depreciation Not Included) Steam $10,570 $10,570 $11,530 $11,530 H, Usage 128,160 128,160 128,160 128,160 02 Usage 14,685 14,685 14,685 14,685 Labor 45,000 45,000 45,000 45,000 Maintenance € 5% Investment 21,135 18,070 26,910 24,230 Total $219,550 $216,485 $226,285 $223,605 13 only the final product is burned, and the remainder, more than 99% of the Ho can be recycled. The tiquid hydrogen distillation system is based on a plant built by Gebrider Sulzer for heavy water production in DOMAT/EMS, Switzerland {18, 19). A schematic for this plant is shown in Fig. 5. The hydrogen feed is initially compressed to 3.7 atm, cooled in a series of three heat ex- changers {Nos. 1, 2, and 3), then liguified and re-evaporated in the feed liquifier before it enters the column. The vapor from the top of the col- umn is split into two streams. One stream passes through exchangers 3, 2, and 1 to cool the feed, and then is recycled to the hydrogen purge stream. The remainder passes through exchangers 4 through 8, exchanging against the returning reflux stream. It exits exchanger 8 at ambient temperatures, and enters the reflux compressor. Because of interstage compressor cocling, the H2 gas leaves the compressor at 14 atm and 300°K. The stream re-enters exchanger 8 and the expansion turbines, and finally exits exchanger 5 as saturated vapor at 4.5 atm. The saturated vapor then passes through the bottom of the column where it is condensed by boiling the liquid in the reboiler. The stream passes through exchanger 4, flashes to 1.5 atm, and enters the column as saturated liquid. The computer code used in Sect. 3.4 was modified for use with this system. Calculations showed that a column with 100 theoretical stages op- erating at a reflux ratio of two would yield a separation of H/T = 103 at a recovery of 99.9%. Although calculations showed that a reflux ratic of two was sufficient for the desired separation, the design was based on a reflux ratio of five to allow for variation of the operating conditions and to ensure a conservative cost estimate. With a packing material simi- lar to Sulzer CY, the column would be only 13 ft high at a liguid loading of 1500 kg/mZ-nr (6). As seen in Table 3 the column cost represents a small fraction of the total cost; therefore, the less difficult separations were neglected in the analysis. Capital cost is estimated at $328,100 and operating costs at $80,600 annually. The building for this system must not only isolate. the system, but alsc insulate the apparatus for the low temperatures involved. The distillation column and the low temperature heat exchangers and expansion turbines are enclosed in steel vacuum bottles to maintain cryogenic temp- eratures. No cost information was obtainable on the new high efficiency insulation currently being used on some cryogenic equipment. However, it is believed that the cost estimate presented is conservative. The cost of the expansion turbines was estimated from cost information for a 200 ton/ day oxygen plant. This unit has 100 times the capacity reqguired for the hydrogen liquification unit. Further details on the cryogenic distiltlation system, including an explanation of the cost estimate, are given in Appen- dix 7.3. R P , 3-Stage R Compressor Expansion Turbines —~»- eflux I A | Packed Column Ex = Heat Exchangers Product Ex 1 Ex 2 Ex 3 iFeed o Ry e raw HLiquifier ~fpe- 1O H é]e Recy Fee ] MASSACHUSETTS INSTITUTE OF TECHMOLOGY SCHOOL OF CHEMICAL ENGINEERING PRACTICE AT OAK RIDGE NATIONAL LABORATORY CRYOGENIC DISTILLATION SYSTEM DATE 15 Vol i DRAWN BY AL FtiLE NO. CEPS-X-~117 FIG. VAl 15 Table 3. Cost Evaluation of Cryogenic Distillation System Recovery 99,9% H/T in Product 103 Designed Number of Stages 100 Reflux Ratio 5 Cotumn Diameter 8 1in, Column Height 13 ft | Purchase Cost Factor Installed Cost Capital Cost Column $ 1,000 Packing 925 1,925 5 $ 9,600 Feed Compressor 8,700 Reflux Compressor 31,000 39,700 2 79,400 Heat Exchangers 46,000 2 92,000 Expansion Turbines 25,000 Instrumentation 50,000 Insulated Building 24,500 Vacuum System 9,000 4 36,000 Storage Tank 11,600 Total Capital Cost $§ 328,100 Annual Operating Costs (Depreciation not Included) Electricity a) Compressors 1,300 b) Vacuum System 200 H2 and 02 1,300 Labor 45,000 Maintenance at 10% Capital Cost 32,800 L Total Operating Cost $ 80,600 16 4, DISCUSSION OF SEPARATION SYSTEMS Storage of tritiated water without any form of concentration reguires a capital cost twenty times greater than for water distillation and thirty- five times that of cryogenic distillation. Thermal diffusion alsc represents an unsatisfactory sclution to the problem of tritium concentration. Moni- toring over 5000 two-stage thermal diffusion columns and maintaining control of the feed to each column appears horrendous; and the annual power cost of $2.9 mitlion certainly makes this system unfeasible. Water distillation is a technically sound alternative. However, its capital and operating costs are not competitive with those of cryogenic distillation. The packing represents the major capital expense, and since all of the hydrogen is oxidized to water, the major operating expense is the cost of hydrogen. However, if the hydrogen concentration in the purge stream is sufficiently high, it might be feasible to oxidize the hydrogen directly without the use of a palladium kidney and separate it from the purge stream as water. This would not be sufficient to make water distil- lation competitive with the cryogenic system based on operating costs. Cryogenic distillation has the lowest capital cost estimate as well as the Towest operating costs. Part of the economic advantage is realized by recycling 99.9% of the hydrogen to the purge stream. It should be noted that the cryogenic distillation was designed for a reflux ratio of five, although for 99.9% recovery at H/T = 10°, a reflux ratio of two is sufficient. Thus the system is capablie of recoveries in excess of 99.9% at concentrations Tower than H/T = 103, 5. CONCLUSIONS AND RECOMMENDATIONS 1. Cryogenic distillation of liquid hydrogen is the most economical of the alternatives studied. A cryogenic distillation §ystem which will enrich 4630 gmole/hr of hydrogen from H/T = 106 to H/T = 10° at 99.9% recovery has an estimated capital cost of $328,100 and an estimated annual operating cost of $80,600 (excluding depreciation). There is also the associated capital cost of $680,000 for the palladium pretreatment and oxidizing systems. 2. HWater distillation or storage of unconcentrated tritiated water represents too great a capital expenditure and annual operating cost. 3. Thermal diffusion is unattractive for concentrating tritium from a 1000 Mw(e) MSBR. 17 6. ACKNOWLEDGEMENT The authors would like to express their gratitude to R.B. Korsmeyer for the assistance and insight he provided during this project. His enthu- siasm was a constant source of encouragement. The assistance of J.T. Corea is also gratefully acknowledged. 18 el 7. APPENDIX 7.1 Basis for Water Distillation Costs 1. Column Shell thickness 0.5 in., type 304 stainless steel $1.25/1b fabricated (12) 2. Flow Distributors: 1 approximately every 5 meters $300 each (instalied) (13) 3. Packing $200/Ft> (14) 4, Building Cost 3 (25) 5. Building Insulation $2.70/ft $1/Ft% wall (15) 6. Steam Ejector $2000 instalied (13, 16) 7. Storage Tanks $1/9a1 (5) 8. Steam $0,25/106 Btu (Use of waste steam from the MSBR) 9. Raw Materials H2 = $0.0048/scf 0, Tiquid = $25/ton (17) 10. Labor 1 man/shift at $15,000 yr = $45,000 11. Maintenance at 5% of investment (13) 12. 7000 hr of Operation Per Year s Tables 4 and 5 reflect the costs of the various H20 distillation systems, Table 4. Cost of Various Water Distillation Systems For 99% Recovery with H/T = 10° For 99% Recove Reflux 25 27 30 32 35 40 25 27 30 Column Diam (M) 1.17 1.22 1.28 1.32 1.38 1.47 1.17 1.22 1.28 NTP 377 330 291 275 258 239 425 379 340 ANP = NTP x 1.1 415 363 320 303 284 263 471 417 374 Column Height (M) 19.8 17.3 15.2 14.4 13.5 12.5 22.4 19.9 17.8 Column Cost $18,300 $16,700 $15,400 $15,700 $14,800 $14,600 $20,800 $19,200 $18,000 Installation (5x) 91,500 83,500 77,000 75,500 74,000 73,000 104,000 96,000 90,000 Flow Distributors 1,500 1,500 1,500 1,500 1,500 1,500 1,500 1,500 1,500 Packing 150,000 143,000 138,000 139,000 143,000 150,000 170,000 164,000 162,000 Building 27,000 23,600 20,700 19,600 18,400 17,000 30,500 27,000 24,200 Covering 3,800 3,400 3,100 3,000 2,800 2,700 4,200 3,900 3,500 Ejector (installed) 2,000 2,000 2,000 2,000 2,000 2,000 2,000 2,000 2,000 Site Preparation 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 Instrumentation 50,000 50,000 50,000 50,000 50,000 50,000 20,000 50,000 50,000 Subtotal 345,100 324,700 308,700 306,700 307,500 311,800 384,000 364,600 352,200 Storage Tanks 116,000 116,000 116,000 116,000 116,000 116,000 11,600 11,600 11,600 Total Capital Cost $461,100 $440,700 $424,700 $422,700 $423,500 $427,800 $395,600 $376,200 $363,800 Steam Cost/yr 8,330 8,980 9,940 10,570 11,530 13,130 8,330 8,980 9,940 Table 5. Cost of Various Water Distillation Systems 4 For 99.9% Recovery with H/T = 10 For 99.9% Recove Reflux 25 27 30 32 35 40 25 27 30 Column Diam (M) 1.17 1.22 1.28 1.32 1.38 1.47 1.17 1.22 1.28 NTP 614 516 431 397 362 329 660 561 482 ANP = NTP x 1.1 675 570 474 437 398 362 726 617 530 Column Height (M) 32.1 27.1 22.6 20.8 19.0 17.2 34.6 29.4 25.2 Column Cost $35,900 $29,000 $25,400 $24,100 $23,000 $22,200 $36,900 $31,500 $28,300 Installation (5x) 180,000 145,000 127,000 121,000 115,000 111,000 185,000 158,000 142,000 Flow Distributors 2,100 1,800 1,500 1,200 1,200 1,200 2,100 1,800 1,500 Packing 265,000 224,000 205,000 200,000 200,000 206,000 272,000 243,000 229,000 Building 43,800 37,000 30,800 28,400 25,900 23,400 47,200 40,000 34,400 Covering 6,200 5,000 4,300 4,400 4,100 3,800 6,400 5,300 4,700 Ejector (installed) 2,000 2,000 2,000 2,000 2,000 2,000 2,000 2,000 2,000 Site Preparation 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 Instrumentation 50,000 50,000 50,000 20,000 50,000 50,000 50,000 50,000 50,000 Subtotal 596,000 494,800 447,000 432,100 422,200 420,600 602,600 532,600 492,900 Storage Tanks 116,000 116,000 116,000 116,000 116,000 116,000 11,600 11,600 11,600 Total Capital Cost $712,000 $610,800 ¢563,000 $548,100 $538,200 $536,600 $614,200 $544,200 $504,500 Steam Cost/yr 8,330 8,980 9,940 10,570 11,530 13,130 8,330 8,980 9,940 21 7.2 Thermal Diffusion System The theory of Jones and Furry (9} states that the temperature and pres- sure fix the operating parameters of a thermal diffusion system. The calcu- tations are presented to illustrate that thermal diffusion systems of the scale required by an MSBR are uneconomical, From Equations 70-72 of Jones and Furry, we obtain for concentric columns: These equations are used subject to the constraint that 5 rz), cm STP standard temperature and pressure T temperature, °C AT temperature driving force, °C U overall coefficient of heat transfer W half the annular distance = %{r} - rz), chi W, work of adiabatic compression per mole, Hp o relative volatility, thermal diffusion constant M viscosity. poise D density, g/cc o mass transport rate of desired species, g/sec Subscripts 1,2 atomic mass of components 1 and Z respectively, or initial and final conditions of temperature or pressure 7.6 Literature References 1. Jacobs, D.G., "Sources of Tritium and Its Behavior Upon Release to the Environment, p. 1, USAEC Div. of Technical Information (1968). 2. Korsmeyer, R.B., personal communication, ORNL, November 20, 1970. 3. 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Sellschop, "Enrichment of Low Level Tritium by Thermal Diffusion for Hydroiogical Applications," Proc. Third Int. Conf. on Peaceful Uses of Atomic Energy, Geneva, 1964, Vol. 12, 398- 408, United Nations, New York (1965). 12. Russell, W., personal communication, Knoxville Sheet Metal Co., Knoxvilie, Tenn., November 4, 1970. 13. Peters, M.S., and K.P. Timmerhaus, "Piant Design and Economics for Chemical Engineers, 2nd ed., 655, McGraw-Hill, New York (1968). 14, Bragg, E.J., personal communication, Packed Column Corp., Spring- field, N.J., November 4, 1970. 15. Corea, J.T., personal communication, ORNL, November 1970. 16. Chilton, C.H., "Cost Engineering in the Process Industries," p. 112, McGraw-Hi11, New York (1960? 17. Ellis, E.C., personal communication, Purchasing Div., ORNL, November 11, 1970. 18. Becker, E.W., "Heavy Water Production," Review Series No. 21, Int. AEA, Vienna (1962). 19. 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