CA1056517A - Augmented alkalinity for water-cooled nuclear reactors - Google Patents
Augmented alkalinity for water-cooled nuclear reactorsInfo
- Publication number
- CA1056517A CA1056517A CA268,421A CA268421A CA1056517A CA 1056517 A CA1056517 A CA 1056517A CA 268421 A CA268421 A CA 268421A CA 1056517 A CA1056517 A CA 1056517A
- Authority
- CA
- Canada
- Prior art keywords
- alkalinity
- water
- liod
- heat transfer
- cooled nuclear
- 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
Links
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C15/00—Cooling arrangements within the pressure vessel containing the core; Selection of specific coolants
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C1/00—Reactor types
- G21C1/04—Thermal reactors ; Epithermal reactors
- G21C1/06—Heterogeneous reactors, i.e. in which fuel and moderator are separated
- G21C1/14—Heterogeneous reactors, i.e. in which fuel and moderator are separated moderator being substantially not pressurised, e.g. swimming-pool reactor
- G21C1/16—Heterogeneous reactors, i.e. in which fuel and moderator are separated moderator being substantially not pressurised, e.g. swimming-pool reactor moderator and coolant being different or separated, e.g. sodium-graphite reactor, sodium-heavy water reactor or organic coolant-heavy water reactor
- G21C1/18—Heterogeneous reactors, i.e. in which fuel and moderator are separated moderator being substantially not pressurised, e.g. swimming-pool reactor moderator and coolant being different or separated, e.g. sodium-graphite reactor, sodium-heavy water reactor or organic coolant-heavy water reactor coolant being pressurised
- G21C1/20—Heterogeneous reactors, i.e. in which fuel and moderator are separated moderator being substantially not pressurised, e.g. swimming-pool reactor moderator and coolant being different or separated, e.g. sodium-graphite reactor, sodium-heavy water reactor or organic coolant-heavy water reactor coolant being pressurised moderator being liquid, e.g. pressure-tube reactor
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
ABSTRACT OF DISCLOSURE
A nuclear power plant using heavy water with dissolved LiOD as the heat transfer medium in the primary heat transfer system by having feedwater containing LiOD and regulating the amount of LiOD in the feedwater so as to maintain the alkalinity of the solution within the system at a concentration in excess of 0.2 mmol/kg. In the preferred version of the invention the alkalinity is sustained in the range of 0.3 to 1.2 mmol/kg.
A nuclear power plant using heavy water with dissolved LiOD as the heat transfer medium in the primary heat transfer system by having feedwater containing LiOD and regulating the amount of LiOD in the feedwater so as to maintain the alkalinity of the solution within the system at a concentration in excess of 0.2 mmol/kg. In the preferred version of the invention the alkalinity is sustained in the range of 0.3 to 1.2 mmol/kg.
Description
10565I7- `
This in~ention rel~tes to ~ ~ethod o~
oper~t~ng a nuclear re~ctorr especially a reactor of the heavy water ~oderated type such that the alkalinitv is maintained at ~n appropr~ate concentration to diminish the formation of radioactive corrosion products and reduce the radiation dose which the operating personnel may receive from radioactive corrosion product~, The hea~y water (D2O~ in the primary heat transport s~stems (PHTS) of CANDU reactors is maintained in à slightl~ alkaline condition~ in order to minimize corrosion, corrosion product transport and the generation of radioactive corrosion products within the system, As the CANDU reactors are desi~ned and operated at present, the alkalinity is maintained in the range of deuteroxyl ion (¦OD ¦~ concentration 0.05 to 0.2 millimoles OD per kilogram of D2O by having within the PHTS circuit an ion-exchange resin bed ~IX) in the LiOD
form. More precisely the bed consists of a mixed bed of cation plus anion exchange resin with the cation resin placed into the system initially in the lithium form, i~e., saturated with lithium cation, Li~, and the anion resin initially in the deuteroxyl form, i.e. saturated with deuteroxyl anion~ OD .
The IX serves to sustain the alkalinity of the PHTS water and also to remove impurity cations and anions from the water. Removal of impurity anions tends to raise the alkalinity of the PHTS water because uptake of impurity anion displaces deuteroxyl anion from the resin into the water. Uptake of those cations which undergo association with OD at high temperature will also increase the alkalinity of the PHTS water at operatin~ temperature b~ replacing associated cation OD pairs with free ~i~ cation and OD anion.
Leakage of PHTS water from the system tends to reduce the qg~
l~S~517 alkalirlit~ o;E the S~5 tem becau~e,o~ -the loss ~f d~ssolyed LiOD in the'escaping water~ Wit~'this system ,of ~lkalinity control, the alkal~nit~ tends to stabilize in the~region Q~05 to 0.2 millimoles OD per kilo:gram of D20 ~mmol~k~) owing to the'characteristics of the'ion-exchange resin~
These characteristics-may be expressed in terms of the equilibrium constant K of the ollo~ing equilibrium reaction:
D2O ~ CLi~, OD , Resinl (p ~ OD / Resin)' ~ Li (A~u2 -~OD C~u~
where (,Li~, OD , Resin) represent the resin in the Li~ ~OD~
form and ~D~, OD , ~esin) represents the resin in the D~ - OD
form. Li~ C~qu) and OD CAqu~ represent the Li~ and OD
ions in solution in D20.
The IX resin has a buffering action such that disturbance of the solution concentration of LiOD from the vicinity of'0.1 mmol/kg tends to be compensated by ~ioD
release from or uptake b~ the resin. When the IX resin becomes depletea through leakag2 of LiOD solution ~rom the system, it is replaced by fresh resin in the LiOD form~
Because of the characteristic equilibirum (1~, the IX
resin is incapable of sustaining an alkalinit~ appreciably above the range'0.05 to 0.2 mmol/kg.
Formation of radioactive corrosion products occurs through the action of neutrons upon deposits of cor-rosion products on the surfaces within the core of the nuclear reactor. The amount of in-core deposit and hence the rate of generation of radioactive corrosion products is regulated in part by the solubility characteristics and speed of dlssolution characteristics of the deposits. Dissolution is accelerated and thinning of deposits is favoured by a high level of alkalinit~ in accordance with reactions C22, C3~ and analogous reactions of such'other metal oxides as ~ay form from the corrosion of the metals of the PHTS structure.
~5~7 Fe304 ~ D~ -~ 30D -~ 3D F.eO2 -~ D20 .(2) Ni Fe204 ~ D2 ~ :30D -~ D NiO2 ~ ~D FeO2 ~ D20 ~3~
It is an object of this invention to proYide a method of operating a nuclear power plant such as to reduce the generation of radioactive corrosion products to such degree as will minimize the radiation dose received by the operating personnel.
It is another object of the invention to provide a method of operating a nuclear power plant such as to promote dissolution and decrease the amount of deposited corrosion products within the reactor core.
These and other objects of the invention are achieved in a nuclear power plant using heavy water with dis-solved LioD as the heat transfer medium in the primary heat transfer system by having feedwater containing ~ioD and regu-lating the amount of LioD in the feedwater so as to maintain the alkalinity of the solution within the system at a concen-tration in excess of 0.2 mmol/kg. In the preferred version of the invention the alkalinity is sustained in the range of 0.3 to 1.2 mmol/kg.
In drawings which illustrate an embodiment of the invention, Figure 1 is a schematic flowsheet of a reactor and primary heat transfer system with a possible feed and control arrangement, and Figure 2 is a schema-tic flowsheet employing a dual feed solution system.
Referring to figure 1 a nuclear reactor 10 has its heat of reaction:transported to a boiler 11 by primary heat transfer system 12 incorporating pump 13, purification system 14, feed tank 15, and inlet pumps 16 and control valves 17, 18. The heat transfer liquid is ~S65~7 normally heavy water (D20~ ~nd the maXe~up supply is fedinto tank 15 via valve 19. The feed solution to the PHTS
consists of D20 containing LiOD previously adjusted to the desired alkalinity. The alkalinity of the system is maintained and controlled by the control of the ion con-centration (in this case OD ion concentration in D20) which is measured by analysis of samples from appropriate points in the system e.g. sample points 20, or by meters at such locations. Control o alkalinity is achieved by the controlled adding of Li2o powder or LiOD solution to the system as shown at 21 via valve 22.
Alternatively, as shown in figure 2 a dual feed solution system may be employed whereby a concentrated solution of LiOD in D20 from tank 24 is metered and mixed into a pure D20 feed from tank 25 on such proportion as to maintain the desired alkalinity. This is done via valves 25, 26l pumps 27, 28, metering devices 29, 30 and mixer 31.
This in~ention rel~tes to ~ ~ethod o~
oper~t~ng a nuclear re~ctorr especially a reactor of the heavy water ~oderated type such that the alkalinitv is maintained at ~n appropr~ate concentration to diminish the formation of radioactive corrosion products and reduce the radiation dose which the operating personnel may receive from radioactive corrosion product~, The hea~y water (D2O~ in the primary heat transport s~stems (PHTS) of CANDU reactors is maintained in à slightl~ alkaline condition~ in order to minimize corrosion, corrosion product transport and the generation of radioactive corrosion products within the system, As the CANDU reactors are desi~ned and operated at present, the alkalinity is maintained in the range of deuteroxyl ion (¦OD ¦~ concentration 0.05 to 0.2 millimoles OD per kilogram of D2O by having within the PHTS circuit an ion-exchange resin bed ~IX) in the LiOD
form. More precisely the bed consists of a mixed bed of cation plus anion exchange resin with the cation resin placed into the system initially in the lithium form, i~e., saturated with lithium cation, Li~, and the anion resin initially in the deuteroxyl form, i.e. saturated with deuteroxyl anion~ OD .
The IX serves to sustain the alkalinity of the PHTS water and also to remove impurity cations and anions from the water. Removal of impurity anions tends to raise the alkalinity of the PHTS water because uptake of impurity anion displaces deuteroxyl anion from the resin into the water. Uptake of those cations which undergo association with OD at high temperature will also increase the alkalinity of the PHTS water at operatin~ temperature b~ replacing associated cation OD pairs with free ~i~ cation and OD anion.
Leakage of PHTS water from the system tends to reduce the qg~
l~S~517 alkalirlit~ o;E the S~5 tem becau~e,o~ -the loss ~f d~ssolyed LiOD in the'escaping water~ Wit~'this system ,of ~lkalinity control, the alkal~nit~ tends to stabilize in the~region Q~05 to 0.2 millimoles OD per kilo:gram of D20 ~mmol~k~) owing to the'characteristics of the'ion-exchange resin~
These characteristics-may be expressed in terms of the equilibrium constant K of the ollo~ing equilibrium reaction:
D2O ~ CLi~, OD , Resinl (p ~ OD / Resin)' ~ Li (A~u2 -~OD C~u~
where (,Li~, OD , Resin) represent the resin in the Li~ ~OD~
form and ~D~, OD , ~esin) represents the resin in the D~ - OD
form. Li~ C~qu) and OD CAqu~ represent the Li~ and OD
ions in solution in D20.
The IX resin has a buffering action such that disturbance of the solution concentration of LiOD from the vicinity of'0.1 mmol/kg tends to be compensated by ~ioD
release from or uptake b~ the resin. When the IX resin becomes depletea through leakag2 of LiOD solution ~rom the system, it is replaced by fresh resin in the LiOD form~
Because of the characteristic equilibirum (1~, the IX
resin is incapable of sustaining an alkalinit~ appreciably above the range'0.05 to 0.2 mmol/kg.
Formation of radioactive corrosion products occurs through the action of neutrons upon deposits of cor-rosion products on the surfaces within the core of the nuclear reactor. The amount of in-core deposit and hence the rate of generation of radioactive corrosion products is regulated in part by the solubility characteristics and speed of dlssolution characteristics of the deposits. Dissolution is accelerated and thinning of deposits is favoured by a high level of alkalinit~ in accordance with reactions C22, C3~ and analogous reactions of such'other metal oxides as ~ay form from the corrosion of the metals of the PHTS structure.
~5~7 Fe304 ~ D~ -~ 30D -~ 3D F.eO2 -~ D20 .(2) Ni Fe204 ~ D2 ~ :30D -~ D NiO2 ~ ~D FeO2 ~ D20 ~3~
It is an object of this invention to proYide a method of operating a nuclear power plant such as to reduce the generation of radioactive corrosion products to such degree as will minimize the radiation dose received by the operating personnel.
It is another object of the invention to provide a method of operating a nuclear power plant such as to promote dissolution and decrease the amount of deposited corrosion products within the reactor core.
These and other objects of the invention are achieved in a nuclear power plant using heavy water with dis-solved LioD as the heat transfer medium in the primary heat transfer system by having feedwater containing ~ioD and regu-lating the amount of LioD in the feedwater so as to maintain the alkalinity of the solution within the system at a concen-tration in excess of 0.2 mmol/kg. In the preferred version of the invention the alkalinity is sustained in the range of 0.3 to 1.2 mmol/kg.
In drawings which illustrate an embodiment of the invention, Figure 1 is a schematic flowsheet of a reactor and primary heat transfer system with a possible feed and control arrangement, and Figure 2 is a schema-tic flowsheet employing a dual feed solution system.
Referring to figure 1 a nuclear reactor 10 has its heat of reaction:transported to a boiler 11 by primary heat transfer system 12 incorporating pump 13, purification system 14, feed tank 15, and inlet pumps 16 and control valves 17, 18. The heat transfer liquid is ~S65~7 normally heavy water (D20~ ~nd the maXe~up supply is fedinto tank 15 via valve 19. The feed solution to the PHTS
consists of D20 containing LiOD previously adjusted to the desired alkalinity. The alkalinity of the system is maintained and controlled by the control of the ion con-centration (in this case OD ion concentration in D20) which is measured by analysis of samples from appropriate points in the system e.g. sample points 20, or by meters at such locations. Control o alkalinity is achieved by the controlled adding of Li2o powder or LiOD solution to the system as shown at 21 via valve 22.
Alternatively, as shown in figure 2 a dual feed solution system may be employed whereby a concentrated solution of LiOD in D20 from tank 24 is metered and mixed into a pure D20 feed from tank 25 on such proportion as to maintain the desired alkalinity. This is done via valves 25, 26l pumps 27, 28, metering devices 29, 30 and mixer 31.
Claims (3)
1. A method of operating a water-cooled nuclear power plant of the heavy water moderated type comprising maintaining the alkalinity level of the fluid in the primary heat transfer system of the plant in the range 0.3 to 1.2 millimoles OD- ion per kilogram of D2O.
2. A method as in claim 1 wherein the alkalinity is maintained at about 0.6 millimoles OD- ion per kilogram D2O.
3, A method of operating a water-cooled nuclear power plant comprising using as the primary heat transfer system liquid, a solution of D2O containing LiOD and maintaining the alkalinity level of the solution in the range 0.3 to 1.2 millimoles OD- ion per kilogram of D2O.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA268,421A CA1056517A (en) | 1976-12-21 | 1976-12-21 | Augmented alkalinity for water-cooled nuclear reactors |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA268,421A CA1056517A (en) | 1976-12-21 | 1976-12-21 | Augmented alkalinity for water-cooled nuclear reactors |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1056517A true CA1056517A (en) | 1979-06-12 |
Family
ID=4107567
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA268,421A Expired CA1056517A (en) | 1976-12-21 | 1976-12-21 | Augmented alkalinity for water-cooled nuclear reactors |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1056517A (en) |
-
1976
- 1976-12-21 CA CA268,421A patent/CA1056517A/en not_active Expired
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