CA1137025A - Process for the extraction of tritium from a liquid heavy water stream - Google Patents
Process for the extraction of tritium from a liquid heavy water streamInfo
- Publication number
- CA1137025A CA1137025A CA000354954A CA354954A CA1137025A CA 1137025 A CA1137025 A CA 1137025A CA 000354954 A CA000354954 A CA 000354954A CA 354954 A CA354954 A CA 354954A CA 1137025 A CA1137025 A CA 1137025A
- Authority
- CA
- Canada
- Prior art keywords
- tritium
- column
- heavy water
- stream
- liquid heavy
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D59/00—Separation of different isotopes of the same chemical element
- B01D59/22—Separation by extracting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D59/00—Separation of different isotopes of the same chemical element
- B01D59/28—Separation by chemical exchange
- B01D59/32—Separation by chemical exchange by exchange between fluids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D59/00—Separation of different isotopes of the same chemical element
- B01D59/38—Separation by electrochemical methods
- B01D59/40—Separation by electrochemical methods by electrolysis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D59/00—Separation of different isotopes of the same chemical element
- B01D59/50—Separation involving two or more processes covered by different groups selected from groups B01D59/02, B01D59/10, B01D59/20, B01D59/22, B01D59/28, B01D59/34, B01D59/36, B01D59/38, B01D59/44
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B4/00—Hydrogen isotopes; Inorganic compounds thereof prepared by isotope exchange, e.g. NH3 + D2 → NH2D + HD
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Inorganic Chemistry (AREA)
- Separation By Low-Temperature Treatments (AREA)
- Physical Or Chemical Processes And Apparatus (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
T I T L E
PROCESS FOR THE EXTRACTION OF TRITIUM FROM
A LIQUID HEAVY WATER STREAM
I N V E N T O R
Allan H. Dombra ABSTRACT OF DISCLOSURE
A process for the extraction of protium and tritium from a liquid heavy water stream comprising contacting the liquid heavy water with a countercurrent gaseous deuterium stream in a column packed with a catalyst such that tritium is transferred by isotopic exchange from the liquid heavy water stream to the gaseous deuterium stream, passing the gas enriched in tritium from the column through means for removing tritium therefrom and returning the gas lean in tritium to the column, taking a portion. of the liquid heavy water stream after it leaves the column and passing it through an electrolysis stage to produce a gaseous deuterium output which is returned to the column and a gaseous oxygen output that is sent to waste or to other uses, obtaining the remaining fraction of the liquid heavy water output from the column, said heavy water being reduced in tritium content.
PROCESS FOR THE EXTRACTION OF TRITIUM FROM
A LIQUID HEAVY WATER STREAM
I N V E N T O R
Allan H. Dombra ABSTRACT OF DISCLOSURE
A process for the extraction of protium and tritium from a liquid heavy water stream comprising contacting the liquid heavy water with a countercurrent gaseous deuterium stream in a column packed with a catalyst such that tritium is transferred by isotopic exchange from the liquid heavy water stream to the gaseous deuterium stream, passing the gas enriched in tritium from the column through means for removing tritium therefrom and returning the gas lean in tritium to the column, taking a portion. of the liquid heavy water stream after it leaves the column and passing it through an electrolysis stage to produce a gaseous deuterium output which is returned to the column and a gaseous oxygen output that is sent to waste or to other uses, obtaining the remaining fraction of the liquid heavy water output from the column, said heavy water being reduced in tritium content.
Description
~ ~ ~37~
l~liS invention .relates to a.pr.ocess ~or the simultaneous extraction of ~rotium and tritium from a liquid heavy w~er stx~am. -Nuclear power reactors of the type using heavy w~lt.er ~D2O) as coolant and moderator incur a progressive build-up of tritiated heavy water (DTO) in the D~O~ and this can lead to problems of controiling radiation exposure at :
the nuclear power stations. This D2O impurity is produced con-tinuously in the reactor as the D2O is subjected to neutron ~.
10 irradiatioll. In present Canadian nuclear ~enerating stations, .
the a~Jerage tritium levels are~the order o-f 1 curie per kg f ~2 in the primary heat transport systems and :over 10 curies per ky of D2O in the moderator systems and these .le~els are ~ rising. Thus the tritium, while present in.comparatively minute qu~nti~ies, because o~ its radioactlvity should desireably be extrac.ted from reactor systems to maintain ~ :
concentrations at current levels or lower. ~ .
TrLtium oxide (or "tritiated water") can be concentrated by various proces~ses such as vacuum distillation or elec~rolytic cascase (several stages of water electrolysis)~
However, these proc~sses are o-f limited use.fulness because of high to~îcity Qf triti~m in the oxide form, the low separation factor for water.distillation, a~d ~he high power consumption ~or the electrolysers. A more practical method ~.
i5 to either convert the tritiated heavy water to the ele.~ental form, for examp7e, by water electrolysis or to.extrAct tritium from wat~r by ca~alytlc exchange with a deuterium stre m. ~he much less ~oxic elemental form can then be enriched by known .
processes such as distillation at cryogenic temperatures~
.
. A process for removin~ protium and txitium from heavy water by vapour-phase catalytic exchan~e is described in United Sta~es Patent No. 3,505~0~7 issued to E. Roth on April 7, 1980~ ~lthough the process described and ~lai~ed in this patent inclu~es the s-teps of tapping the hea~y ~ -water containecl in a nuclear reactor and subjecting said tapped h~avy water to an isotope exchange reaction with ga~eous deuteri~tm~ it is obvious from the'disclosure tha~ the "tapped hea~y water'l is heavy water vapour. Because the exch~n~e is between water vapour and gas, -the two streams flow to the column concurrently and the process mus-t operate at elevated temperatures ~80 to-400C using catalystsj~ This process involves the use of man~ stages and evaporators and condensers at each equilibrium exchange step and this is most disad~nta-.
~eous, both in energy consumption and the ~omplexity of theprocess.
A process for hydrogen isotope concentration between liquid water ana hydrogen gas is described in United States Patent No. 3,981,g76 issued September 21, 1976 to W.H~
Stevens and assigned to Atomic Energy o Canada Limi ed. This patent points out ~hat the process may'be used to reduce the tritium concentration, present as DTO, in heavy water that ~0 has~been used in an operating nuclear reactor. This i~
achieved by increasing the concentration of tritium in liquid water by dona-tion ~rom gaseous d uterium dexived'~rom th~
liquid water. The deuterium is produced from heavy watex in a deuterium gas generatorO
The following are patents on the removal o~ extraction of tritium from heavy and light water~
4,173,620 M. Shimizu issued Nov. 6, 1979 4,190,~15 Butler et al issued Feb. 26,1980 4,191,626 Hammerli et al issued Mar~ 4, 1980`
' Thes~ three patents are concerned ~ith systems employing a catalytic exchange column and an electrolysis '~ cell. In ~hese systems all of ~he liquid water passing through
l~liS invention .relates to a.pr.ocess ~or the simultaneous extraction of ~rotium and tritium from a liquid heavy w~er stx~am. -Nuclear power reactors of the type using heavy w~lt.er ~D2O) as coolant and moderator incur a progressive build-up of tritiated heavy water (DTO) in the D~O~ and this can lead to problems of controiling radiation exposure at :
the nuclear power stations. This D2O impurity is produced con-tinuously in the reactor as the D2O is subjected to neutron ~.
10 irradiatioll. In present Canadian nuclear ~enerating stations, .
the a~Jerage tritium levels are~the order o-f 1 curie per kg f ~2 in the primary heat transport systems and :over 10 curies per ky of D2O in the moderator systems and these .le~els are ~ rising. Thus the tritium, while present in.comparatively minute qu~nti~ies, because o~ its radioactlvity should desireably be extrac.ted from reactor systems to maintain ~ :
concentrations at current levels or lower. ~ .
TrLtium oxide (or "tritiated water") can be concentrated by various proces~ses such as vacuum distillation or elec~rolytic cascase (several stages of water electrolysis)~
However, these proc~sses are o-f limited use.fulness because of high to~îcity Qf triti~m in the oxide form, the low separation factor for water.distillation, a~d ~he high power consumption ~or the electrolysers. A more practical method ~.
i5 to either convert the tritiated heavy water to the ele.~ental form, for examp7e, by water electrolysis or to.extrAct tritium from wat~r by ca~alytlc exchange with a deuterium stre m. ~he much less ~oxic elemental form can then be enriched by known .
processes such as distillation at cryogenic temperatures~
.
. A process for removin~ protium and txitium from heavy water by vapour-phase catalytic exchan~e is described in United Sta~es Patent No. 3,505~0~7 issued to E. Roth on April 7, 1980~ ~lthough the process described and ~lai~ed in this patent inclu~es the s-teps of tapping the hea~y ~ -water containecl in a nuclear reactor and subjecting said tapped h~avy water to an isotope exchange reaction with ga~eous deuteri~tm~ it is obvious from the'disclosure tha~ the "tapped hea~y water'l is heavy water vapour. Because the exch~n~e is between water vapour and gas, -the two streams flow to the column concurrently and the process mus-t operate at elevated temperatures ~80 to-400C using catalystsj~ This process involves the use of man~ stages and evaporators and condensers at each equilibrium exchange step and this is most disad~nta-.
~eous, both in energy consumption and the ~omplexity of theprocess.
A process for hydrogen isotope concentration between liquid water ana hydrogen gas is described in United States Patent No. 3,981,g76 issued September 21, 1976 to W.H~
Stevens and assigned to Atomic Energy o Canada Limi ed. This patent points out ~hat the process may'be used to reduce the tritium concentration, present as DTO, in heavy water that ~0 has~been used in an operating nuclear reactor. This i~
achieved by increasing the concentration of tritium in liquid water by dona-tion ~rom gaseous d uterium dexived'~rom th~
liquid water. The deuterium is produced from heavy watex in a deuterium gas generatorO
The following are patents on the removal o~ extraction of tritium from heavy and light water~
4,173,620 M. Shimizu issued Nov. 6, 1979 4,190,~15 Butler et al issued Feb. 26,1980 4,191,626 Hammerli et al issued Mar~ 4, 1980`
' Thes~ three patents are concerned ~ith systems employing a catalytic exchange column and an electrolysis '~ cell. In ~hese systems all of ~he liquid water passing through
2-~37Q~S
th~ cataly-tic exch~nge column is pa,ssed to the,electrolytic cell for conversion to hydrogen and oxyyen gases. Therefore -the electrolysis stage'n&eds to be large consuming a large amount of electrical eneryy.
In Canadian Patent application nurnber 320,154 filed January 22, 197g, applicant disclosed a system ~or the extraction of tritium from a liquid heavy water stream~ The present invention is an extension of that invention that '~
provldes a wider range'of application~
' lQIt is an obj`ect of the present invention to pro~ide a process for simultaneous extraction of protium and tritium from liquid heavy water that operates at or near am~ient temperatures and pressures.
It is another obj'ect of the invention to pxQvide a process fox removal of protium and tritium from ~ ,, llquid heavy water extracts, rather than concentrates, protium and tritium from hea~y water.
These and other objects of the invention are ,~ ~ ' achieved by a process for the extraction of protium and 20 tr~tium from a liquid heavy water stream comprising contacting ' the liquid heavy water with a countercurrent gasebus deuterium strea~ in a column packed with'a catalyst such that tritium "'~
is transferred'~by isotopic exchange ~rom the liquid heavy water s-tream to the gaseous deuterium stream, passiny the gas enriched in tritium from the column throuyh means for removing ~' txitium therefrom and returning the gas lean in tritium to ' the'column, taking a portion of the liquid heavy water ;, stream after it leaves the column and passing it throu~h an electrolysis stage to produce'a yaseous deuterlum output which 3Q is retu~ned to the'column and a gaseous oxyyen output th,at is sent to waste'or to other uses, obtaining the remaining ~, fraction of the l~quid hea~y water output from the column,
th~ cataly-tic exch~nge column is pa,ssed to the,electrolytic cell for conversion to hydrogen and oxyyen gases. Therefore -the electrolysis stage'n&eds to be large consuming a large amount of electrical eneryy.
In Canadian Patent application nurnber 320,154 filed January 22, 197g, applicant disclosed a system ~or the extraction of tritium from a liquid heavy water stream~ The present invention is an extension of that invention that '~
provldes a wider range'of application~
' lQIt is an obj`ect of the present invention to pro~ide a process for simultaneous extraction of protium and tritium from liquid heavy water that operates at or near am~ient temperatures and pressures.
It is another obj'ect of the invention to pxQvide a process fox removal of protium and tritium from ~ ,, llquid heavy water extracts, rather than concentrates, protium and tritium from hea~y water.
These and other objects of the invention are ,~ ~ ' achieved by a process for the extraction of protium and 20 tr~tium from a liquid heavy water stream comprising contacting ' the liquid heavy water with a countercurrent gasebus deuterium strea~ in a column packed with'a catalyst such that tritium "'~
is transferred'~by isotopic exchange ~rom the liquid heavy water s-tream to the gaseous deuterium stream, passiny the gas enriched in tritium from the column throuyh means for removing ~' txitium therefrom and returning the gas lean in tritium to ' the'column, taking a portion of the liquid heavy water ;, stream after it leaves the column and passing it throu~h an electrolysis stage to produce'a yaseous deuterlum output which 3Q is retu~ned to the'column and a gaseous oxyyen output th,at is sent to waste'or to other uses, obtaining the remaining ~, fraction of the l~quid hea~y water output from the column,
-3-~., :. .
~.~37~5 said hea-~ water being reduced in tritium cont~nt~ , In drawings ~hiGh illustrate an embodi~ent of th~- inve~tion, Figure l is a flow diagram of th0 process in its si~ lest form, and Figure 2 is a ~lowsheet of a complete system incorporated in a heavy water moderated~and cooled nuclear reactor.
Referring to Figure 1, a liquid heavy ~ater feed is passea throuyh a purification stage lO. Depending on the quality of the feedwater, the feedwater purification ~tage will include a-filtering system to~remove suspended soli~s, an i~n-exchange~system to remove ionic compounds and a standard degassing system to remove dissolved gases,'such as ~2 and N2. If the fee~ater is contaminated w1th oil or other organic materials, it will be purified by charcoal ,' adsorp-tion or chemical metho~s. Normally, the heavy water , ~-ithdrawn from reactor systems is relatively clean and wil~
be p~ssed onIy through a ~iltering and an ion~exchange system.
~Q The tritium to deuterium (T/D) atom ratio in the heavy water stream is in the arde~ of part~ ~er million (typically O.l -~ r J ~ C ~
, 1 10 ppm) a~d the ~YihffYjrh~,tr~tiu~n-deuterium species, are ' DTO and D2O. After purification5 the liquid ~tream is fed to the top o~ a ~atalytic isotope exchange co~umn 11 in which the tritium is extracted ~rom the liquid stream by contacting it with a counter-~flowing gaseous stream of DT - D2 in the co'umn pack~d with a water~repellent,catalyst~ The process ~, is opera~ive with~any type of catal~st that i~ ~at~r-repell~r.t but the preferred type is that~described in, United States -30 Patent No. 3,888,974 issuPd June lQ, 1975 to WrH~ Stevens and assigned to Atomic Energ~ of Canada Limited. This catalyst `' consists of at least one'cataiytically active' metal 'selected 31 13~6~2~
from Group VIII of the Periodic Table having ~ substantially liquid-~z~er-repellent organic resin or polymer c~ating thereon which is permeable to.water vapour and hydrogen gas~
This ti-pe of catalyst is al~o described in the aforementioned ~.
Paten~ No. 3,9Bl,976 and United States Paten No. 4,025,560 issued r~1ay 24, 1977 to JOhn H. Rclston et aI and assigned to Atomlc ~nergy of Canada ~imited. After passin~ through the ~:
column a major proportion o~ the detritiated liquid heavy water is returned to the nuclear reactor or ot~er source~
The deutsrium gas entering the bottom of the column 11 is lean in tritium ~DT component) and after leaving the colum~ is enriched in tritium lDT~. This gas is purified i~ gas purification stage 12 and sent to a cryogenic distilla~
tion stage 13 that lowers the concentration of the DT-T2 in the gas after which i.t is returned to the bottom of the column ~`
11. rrhe feedyas purificatio~ system or the cryogenic unit is designed to remove traces of impur~iti~s which condense and solidi~y as the temperature o~the ~ _ ea~ drops ~ ~:
~mois~ure CO2~ N2~ 2~ CO). Typically, the ~eed~as purifica- ~
.
~ion Lrain includes molecular sieve driers, regenerative heat ~xchangers and cryogenic silica gel or cl~arcoal absorbers.
Distillation staye 13 gives as output a conce.ntrated DT-T~
gas stream which would normally be ~ithdrawn into suita~le container~. The cryogenic D~ distillation stage 13 may be replaced with other isotopic separation processes such as :
the~mal dif~usion or gas chromotography.
A proportion of the upgraaea heavy water : from catalytic exchange column 11 is passed through ~ electrolysis stage 14 and deuterium gas is returned to ~he .~ 30 ~listillation column recycle loop either to the gas stream - ent~ring the exchange column or alter~ati~ely to the stream leavin~ ~he colur.~ as shown by broken line 14a.
37~
The process tr~ns~ers protium and tritium rrom heavy water ~o the cryogenic unit by either contacting feedwater with a carrier D2-gas over catalysts:
~iDO ~ D~ ~ D20 ~ HD . . ;
Catalyst Exchange DT0 ~ D2 ~ D20 -~ DT
D20~1DO-DTO ~ D2-HD-DT(02) Blectxolysis The process, in this case, performs a three-component transPer (D~0-~ID0-DT0 to ~2-HD-DT) as ;
sho~n above. :
Por the extraction of tritium two gas~liquid :
exchange reactions occur simultaneously:
(Q) + DT(g) ~ D2(g) + DT(Q~ ~....... (1) K~ 62 (25G~ -0(~j ~ HT~g) p ~Iq(g) + ~ITO(Q) ...... ~2)- K2 = 6~8 (25C) ~; These are in equilibriu~i with gas-phase reactions:
2 H2 ~ (3) K3 =~: 3.26 D2 ~ HT ~ HD ~:DT ~..(4) K~ - 2.20 H2 + DT ~ HD + HT .~.(5) K5 - 1.48 and liquid-phase reactions:
D20 ~ H20 ~ 2HD0 ....... ~t6) K6 = 3.8 (25 C) D20 + HT0 ~ HD0 -~ DT0~.(7) K7 E20 ~ I)TO ~ HDO ~ HTO~.~ (8) K8 ~:
. -~ : K6 ~: K7K~ . :
where ICl, R2 t ~Cn are the appropriate equilibrium constants.
The overall separation factor a = ~ , :~
where x - ~H ~ D + T) ~ Y rJ may be ca~culated for the above reaction equilibirium but is difficult because o~ ~he lar~e number o~ simultan~ou~ reactions taking place.
Tn protium extra~tion the equilibrium reactions are~
~: H~~Q) ~ D2(g) ~ D2o~Q~ ~ HD(g) Kl = 3~3 at 25C :
D20 ~ H20 ~ 2HDO K2 -- 3- 8~6 D2 ~ H7 . ~a 2HD . ~ K3 - 3. 26 ~ = y (1 Yx~)- wgere x = D~H in liquid phase, and :: ~6 ~ :
~ gL37~2~
Y = D~DH in ~as phase.
The reaction howe~er can be maintained ~nly temporarily because deuterium is depleted in the cryogenic unit ~s illus-trated in Figure 1, one mol o~ D2 is transferred from gas to liquid Eor one mol of El2 stripped from the liquid,; the product leaving the column thexe~ore contains one e.ctca mol of ~2 compared to that enteriny the column with the feedw~t2r.
To maintain tbese reactions indefinitely, the "extra" D20 produced b~ the colu~n is continuously : .
decomposed and the D2 is returned ~o the cryogenic unit to avoid D~ depletion and thi~ is done in the electrolysis stage 14~ For reactor applications, the best method for this par~ia~ D2O product decomposition is electrolysis. However, ~ ~, chemical water decomposition ~such as M~ + D20 ~ MgO ~ D2), or ~ other methods, could also be used. , , ,; As shown~in Flgure 2, two exchange columns ~ .
~la and 11~ would be employed in a~system in relation to a nuclear reactor having a moderator system 15 and a heat transport system 16. Leakag~ recovery from both systems is stored in tank 17 and passed to column llb. The column enti,tled "detritiation" removes the bu~k of tritium ~nd ~ -rela~ively small quantity of protiumj while the column entitled 'lupgrading" removes the bulk of protium and relatively small quantities of tr,itium. Although theoretically one column as shown in Figure~l can be used,-such an arran~ement would be expensi~7e. The cxyogenic unit-catalytic exchange, coupling must be care~ul~y designed as this effects the overall performance of the plant to a greater extent than the other processes~ The key function of the cryogenic unit is to produc~ relatively pure D~, H2 and T2 streams. The D2 stream is returned to the catalytic exchange column (to pick up more ~7~
~3~2~
proti~Lm and tr~tium), the H2 can be discharged as ~aste, and the T2 is packaged and stored~
Each catalytic column feeds ~as to a separa~.F cryogenic distillation col~nn: (1) the protium d-s~ a~:ion column 18 (fed hy the upgrading exchange column) is desiyned to produce a highly concentrated H2 stream, but it does not concentrate trltium, the gas from the bottom of this column, ~ogether with the feed from the detritiation - column, is fed to (2~ the deu~erium distillation column 19 lG to produce a protlum/tritium-lean D2 s~ream in the middle, and pre concentrated protium and tritium streams at.the top and bo-ttom of the column/ respect.ively. The tops ~rom th1s column are returned to the protium column and bottoms are fed to a.smaller tritium dist.ill~tion column 20, for further s~paration.
':. : ' ~ ;~'''.
~.~37~5 said hea-~ water being reduced in tritium cont~nt~ , In drawings ~hiGh illustrate an embodi~ent of th~- inve~tion, Figure l is a flow diagram of th0 process in its si~ lest form, and Figure 2 is a ~lowsheet of a complete system incorporated in a heavy water moderated~and cooled nuclear reactor.
Referring to Figure 1, a liquid heavy ~ater feed is passea throuyh a purification stage lO. Depending on the quality of the feedwater, the feedwater purification ~tage will include a-filtering system to~remove suspended soli~s, an i~n-exchange~system to remove ionic compounds and a standard degassing system to remove dissolved gases,'such as ~2 and N2. If the fee~ater is contaminated w1th oil or other organic materials, it will be purified by charcoal ,' adsorp-tion or chemical metho~s. Normally, the heavy water , ~-ithdrawn from reactor systems is relatively clean and wil~
be p~ssed onIy through a ~iltering and an ion~exchange system.
~Q The tritium to deuterium (T/D) atom ratio in the heavy water stream is in the arde~ of part~ ~er million (typically O.l -~ r J ~ C ~
, 1 10 ppm) a~d the ~YihffYjrh~,tr~tiu~n-deuterium species, are ' DTO and D2O. After purification5 the liquid ~tream is fed to the top o~ a ~atalytic isotope exchange co~umn 11 in which the tritium is extracted ~rom the liquid stream by contacting it with a counter-~flowing gaseous stream of DT - D2 in the co'umn pack~d with a water~repellent,catalyst~ The process ~, is opera~ive with~any type of catal~st that i~ ~at~r-repell~r.t but the preferred type is that~described in, United States -30 Patent No. 3,888,974 issuPd June lQ, 1975 to WrH~ Stevens and assigned to Atomic Energ~ of Canada Limited. This catalyst `' consists of at least one'cataiytically active' metal 'selected 31 13~6~2~
from Group VIII of the Periodic Table having ~ substantially liquid-~z~er-repellent organic resin or polymer c~ating thereon which is permeable to.water vapour and hydrogen gas~
This ti-pe of catalyst is al~o described in the aforementioned ~.
Paten~ No. 3,9Bl,976 and United States Paten No. 4,025,560 issued r~1ay 24, 1977 to JOhn H. Rclston et aI and assigned to Atomlc ~nergy of Canada ~imited. After passin~ through the ~:
column a major proportion o~ the detritiated liquid heavy water is returned to the nuclear reactor or ot~er source~
The deutsrium gas entering the bottom of the column 11 is lean in tritium ~DT component) and after leaving the colum~ is enriched in tritium lDT~. This gas is purified i~ gas purification stage 12 and sent to a cryogenic distilla~
tion stage 13 that lowers the concentration of the DT-T2 in the gas after which i.t is returned to the bottom of the column ~`
11. rrhe feedyas purificatio~ system or the cryogenic unit is designed to remove traces of impur~iti~s which condense and solidi~y as the temperature o~the ~ _ ea~ drops ~ ~:
~mois~ure CO2~ N2~ 2~ CO). Typically, the ~eed~as purifica- ~
.
~ion Lrain includes molecular sieve driers, regenerative heat ~xchangers and cryogenic silica gel or cl~arcoal absorbers.
Distillation staye 13 gives as output a conce.ntrated DT-T~
gas stream which would normally be ~ithdrawn into suita~le container~. The cryogenic D~ distillation stage 13 may be replaced with other isotopic separation processes such as :
the~mal dif~usion or gas chromotography.
A proportion of the upgraaea heavy water : from catalytic exchange column 11 is passed through ~ electrolysis stage 14 and deuterium gas is returned to ~he .~ 30 ~listillation column recycle loop either to the gas stream - ent~ring the exchange column or alter~ati~ely to the stream leavin~ ~he colur.~ as shown by broken line 14a.
37~
The process tr~ns~ers protium and tritium rrom heavy water ~o the cryogenic unit by either contacting feedwater with a carrier D2-gas over catalysts:
~iDO ~ D~ ~ D20 ~ HD . . ;
Catalyst Exchange DT0 ~ D2 ~ D20 -~ DT
D20~1DO-DTO ~ D2-HD-DT(02) Blectxolysis The process, in this case, performs a three-component transPer (D~0-~ID0-DT0 to ~2-HD-DT) as ;
sho~n above. :
Por the extraction of tritium two gas~liquid :
exchange reactions occur simultaneously:
(Q) + DT(g) ~ D2(g) + DT(Q~ ~....... (1) K~ 62 (25G~ -0(~j ~ HT~g) p ~Iq(g) + ~ITO(Q) ...... ~2)- K2 = 6~8 (25C) ~; These are in equilibriu~i with gas-phase reactions:
2 H2 ~ (3) K3 =~: 3.26 D2 ~ HT ~ HD ~:DT ~..(4) K~ - 2.20 H2 + DT ~ HD + HT .~.(5) K5 - 1.48 and liquid-phase reactions:
D20 ~ H20 ~ 2HD0 ....... ~t6) K6 = 3.8 (25 C) D20 + HT0 ~ HD0 -~ DT0~.(7) K7 E20 ~ I)TO ~ HDO ~ HTO~.~ (8) K8 ~:
. -~ : K6 ~: K7K~ . :
where ICl, R2 t ~Cn are the appropriate equilibrium constants.
The overall separation factor a = ~ , :~
where x - ~H ~ D + T) ~ Y rJ may be ca~culated for the above reaction equilibirium but is difficult because o~ ~he lar~e number o~ simultan~ou~ reactions taking place.
Tn protium extra~tion the equilibrium reactions are~
~: H~~Q) ~ D2(g) ~ D2o~Q~ ~ HD(g) Kl = 3~3 at 25C :
D20 ~ H20 ~ 2HDO K2 -- 3- 8~6 D2 ~ H7 . ~a 2HD . ~ K3 - 3. 26 ~ = y (1 Yx~)- wgere x = D~H in liquid phase, and :: ~6 ~ :
~ gL37~2~
Y = D~DH in ~as phase.
The reaction howe~er can be maintained ~nly temporarily because deuterium is depleted in the cryogenic unit ~s illus-trated in Figure 1, one mol o~ D2 is transferred from gas to liquid Eor one mol of El2 stripped from the liquid,; the product leaving the column thexe~ore contains one e.ctca mol of ~2 compared to that enteriny the column with the feedw~t2r.
To maintain tbese reactions indefinitely, the "extra" D20 produced b~ the colu~n is continuously : .
decomposed and the D2 is returned ~o the cryogenic unit to avoid D~ depletion and thi~ is done in the electrolysis stage 14~ For reactor applications, the best method for this par~ia~ D2O product decomposition is electrolysis. However, ~ ~, chemical water decomposition ~such as M~ + D20 ~ MgO ~ D2), or ~ other methods, could also be used. , , ,; As shown~in Flgure 2, two exchange columns ~ .
~la and 11~ would be employed in a~system in relation to a nuclear reactor having a moderator system 15 and a heat transport system 16. Leakag~ recovery from both systems is stored in tank 17 and passed to column llb. The column enti,tled "detritiation" removes the bu~k of tritium ~nd ~ -rela~ively small quantity of protiumj while the column entitled 'lupgrading" removes the bulk of protium and relatively small quantities of tr,itium. Although theoretically one column as shown in Figure~l can be used,-such an arran~ement would be expensi~7e. The cxyogenic unit-catalytic exchange, coupling must be care~ul~y designed as this effects the overall performance of the plant to a greater extent than the other processes~ The key function of the cryogenic unit is to produc~ relatively pure D~, H2 and T2 streams. The D2 stream is returned to the catalytic exchange column (to pick up more ~7~
~3~2~
proti~Lm and tr~tium), the H2 can be discharged as ~aste, and the T2 is packaged and stored~
Each catalytic column feeds ~as to a separa~.F cryogenic distillation col~nn: (1) the protium d-s~ a~:ion column 18 (fed hy the upgrading exchange column) is desiyned to produce a highly concentrated H2 stream, but it does not concentrate trltium, the gas from the bottom of this column, ~ogether with the feed from the detritiation - column, is fed to (2~ the deu~erium distillation column 19 lG to produce a protlum/tritium-lean D2 s~ream in the middle, and pre concentrated protium and tritium streams at.the top and bo-ttom of the column/ respect.ively. The tops ~rom th1s column are returned to the protium column and bottoms are fed to a.smaller tritium dist.ill~tion column 20, for further s~paration.
':. : ' ~ ;~'''.
Claims (3)
1. A process for the extraction tritium from a liquid heavy water stream comprising:
a) contacting the liquid heavy water with a countercurrent gaseous deuterium stream in a column packed with a catalyst such that tritium is transferred by isotopic exchange from the liquid heavy water stream to the gaseous deuterium stream, b) passing the gas enriched in tritium from the column through means for removing tritium therefrom and returning the gas lean in tritium to the column, c) taking a portion of the liquid heavy water stream after it leaves the column and passing it through an electrolysis stage to produce a gaseous deuterium output which is returned to the gas stream passing through the column and the means for removing tritium, and a gaseous oxygen output that is sent to waste or to other uses, d) recovering the remaining fraction of the liquid heavy water output from the column, said heavy water being reduced in tritium content.
a) contacting the liquid heavy water with a countercurrent gaseous deuterium stream in a column packed with a catalyst such that tritium is transferred by isotopic exchange from the liquid heavy water stream to the gaseous deuterium stream, b) passing the gas enriched in tritium from the column through means for removing tritium therefrom and returning the gas lean in tritium to the column, c) taking a portion of the liquid heavy water stream after it leaves the column and passing it through an electrolysis stage to produce a gaseous deuterium output which is returned to the gas stream passing through the column and the means for removing tritium, and a gaseous oxygen output that is sent to waste or to other uses, d) recovering the remaining fraction of the liquid heavy water output from the column, said heavy water being reduced in tritium content.
2. A process as in claim 1 wherein the gaseous deuterium output from the electrolysis stage is returned to the gas stream entering the bottom of the column.
3. A process as in claim 1 wherein the gaseous deuterium output from the electrolysis stage is returned to the gas stream leaving the column.
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000354954A CA1137025A (en) | 1980-06-13 | 1980-06-13 | Process for the extraction of tritium from a liquid heavy water stream |
| RO104139A RO82100B (en) | 1980-06-13 | 1981-04-26 | Process for removing tritium from heavy water |
| KR1019810001504A KR840000967B1 (en) | 1980-06-13 | 1981-05-01 | Process for the extraction of tritium from a liquid heavy water stream |
| DE19813122498 DE3122498A1 (en) | 1980-06-13 | 1981-06-05 | Process for extracting tritium from a liquid heavy-water stream |
| CH3757/81A CH647480A5 (en) | 1980-06-13 | 1981-06-09 | PROCESS FOR EXTRACTING TRITIUM FROM A LIQUID HEAVY WATER STREAM. |
| JP9068281A JPS5727119A (en) | 1980-06-13 | 1981-06-12 | Method of extracting tritium from heavy water |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000354954A CA1137025A (en) | 1980-06-13 | 1980-06-13 | Process for the extraction of tritium from a liquid heavy water stream |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1137025A true CA1137025A (en) | 1982-12-07 |
Family
ID=4117288
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000354954A Expired CA1137025A (en) | 1980-06-13 | 1980-06-13 | Process for the extraction of tritium from a liquid heavy water stream |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5727119A (en) |
| KR (1) | KR840000967B1 (en) |
| CA (1) | CA1137025A (en) |
| CH (1) | CH647480A5 (en) |
| DE (1) | DE3122498A1 (en) |
| RO (1) | RO82100B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1995015807A1 (en) * | 1993-12-06 | 1995-06-15 | Atomic Energy Of Canada Limited | Geographically distributed tritium extraction plant |
| US6190531B1 (en) | 1999-07-27 | 2001-02-20 | University Of North Carolina | Concentration and removal of tritium and/or deuterium from water contaminated with tritium and/or deuterium |
| US10381121B2 (en) | 2013-11-13 | 2019-08-13 | Savannah River Nuclear Solutions, Llc | Decontamination of tritiated water |
| US11058994B2 (en) | 2019-01-18 | 2021-07-13 | Savannah River National Solutions, LLC | Tritium cleanup system and method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1526867A (en) * | 1966-08-09 | 1968-05-31 | Commissariat Energie Atomique | Improvements in means for removing protonium and tritium from heavy water |
-
1980
- 1980-06-13 CA CA000354954A patent/CA1137025A/en not_active Expired
-
1981
- 1981-04-26 RO RO104139A patent/RO82100B/en unknown
- 1981-05-01 KR KR1019810001504A patent/KR840000967B1/en active IP Right Grant
- 1981-06-05 DE DE19813122498 patent/DE3122498A1/en not_active Ceased
- 1981-06-09 CH CH3757/81A patent/CH647480A5/en not_active IP Right Cessation
- 1981-06-12 JP JP9068281A patent/JPS5727119A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1995015807A1 (en) * | 1993-12-06 | 1995-06-15 | Atomic Energy Of Canada Limited | Geographically distributed tritium extraction plant |
| US6190531B1 (en) | 1999-07-27 | 2001-02-20 | University Of North Carolina | Concentration and removal of tritium and/or deuterium from water contaminated with tritium and/or deuterium |
| US10381121B2 (en) | 2013-11-13 | 2019-08-13 | Savannah River Nuclear Solutions, Llc | Decontamination of tritiated water |
| US11087897B2 (en) | 2013-11-13 | 2021-08-10 | Savannah River Nuclear Solutions, Llc | Decontamination of tritiated water |
| US11058994B2 (en) | 2019-01-18 | 2021-07-13 | Savannah River National Solutions, LLC | Tritium cleanup system and method |
Also Published As
| Publication number | Publication date |
|---|---|
| KR840000967B1 (en) | 1984-07-02 |
| KR830005892A (en) | 1983-09-14 |
| JPS5727119A (en) | 1982-02-13 |
| CH647480A5 (en) | 1985-01-31 |
| RO82100A (en) | 1984-01-14 |
| RO82100B (en) | 1984-01-30 |
| DE3122498A1 (en) | 1982-06-03 |
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