LOSS-OF-COOLANT ACCIDENT REACTOR COOLING SYSTEM

• US 20140321597A1
• Filed: 05/28/2014
• Published: 10/30/2014
• Est. Priority Date: 05/21/2012
• Status: Active Grant

• Current Assignee: Smr Inventec, LLC
• Original Assignee: Smr Inventec, LLC
• Inventors: SINGH, Krishna P., RAJKUMAR, Joseph
• Granted Patent: US 10,096,389 B2
• Time in Patent Office: Days
• US Class Current: 376/298
• CPC Class Codes: G21C 13/02 Details
• CPC Class Codes: G21C 15/12 from pressure vessel; from containment vessel
• CPC Class Codes: G21C 15/18 Emergency cooling arrangements; Removing shut-down heat
• CPC Class Codes: G21C 9/004 Pressure suppression
• CPC Class Codes: G21D 1/00 Details of nuclear power plant control G21D3/00
• CPC Class Codes: G21D 1/006 primary side of steam generators secondary side of steam generators F22B1/00, F22B35/00 or F22B37/00
• CPC Class Codes: Y02E 30/00 Energy generation of nuclear origin
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors

Abstract

A nuclear reactor cooling system with passive cooling capabilities operable during a loss-of-coolant accident (LOCA) without available electric power. The system includes a reactor vessel with nuclear fuel core located in a reactor well. An in-containment water storage tank is fluidly coupled to the reactor well and holds an inventory of cooling water. During a LOCA event, the tank floods the reactor well with water. Eventually, the water heated by decay heat from the reactor vaporizes producing steam. The steam flows to an in-containment heat exchanger and condenses. The condensate is returned to the reactor well in a closed flow loop system in which flow may circulate solely via gravity from changes in phase and density of the water. In one embodiment, the heat exchanger may be an array of heat dissipater ducts mounted on the wall of the inner containment vessel surrounded by a heat sink.

Claims

1. A passive reactor cooling system usable after a loss-of-coolant accident, the system comprising:

a containment vessel in thermal communication with a heat sink;

a reactor well disposed in the containment vessel;

a reactor vessel disposed at least partially in the reactor well, the reactor vessel containing a nuclear fuel core which heats primary coolant in the reactor vessel;

a water storage tank disposed in the containment vessel and in fluid communication with the reactor well, the tank containing an inventory of cooling water; and

a heat exchanger disposed in the containment vessel, the heat exchanger in fluid communication with the reactor well via a closed flow loop in which the flow is driven via gravity;

wherein following a loss of primary coolant, the tank is configured and operable to flood the reactor well with cooling water which is converted into steam by heat from the fuel core and flows through the closed flow loop to the heat exchanger.

2. The system according to claim 1, wherein the steam condenses in the heat exchanger forming condensate, and the condensate flows via gravity back to the reactor well.

3. The system according to claim 1, wherein the heat exchanger comprises an array of heat dissipater ducts integrally attached to the containment vessel.

4. The system according to claim 1, wherein the heat sink comprises an annular reservoir holding water that surrounds the containment vessel.

5. The system according to claim 4, wherein the water in the annular reservoir has a temperature lower than the temperature of the steam which condenses the steam.

6. The system according to claim 4, wherein the annular reservoir is formed between the containment vessel and an outer containment enclosure structure.

7. The system according to claim 2, wherein the closed flow loop includes:

inlet steam piping fluidly coupling a top portion of the reactor well and heat exchanger, and

outlet condensate piping fluidly coupling the heat exchanger and water storage tank.

8. The system according to claim 1, wherein the reactor well and water storage tank are formed in a concrete monolith disposed in the containment vessel.

9. The system according to claim 1, wherein the water storage tank is fluidly coupled to the reactor well by at least one flow conduit having a dump valve disposed therein, the dump valve configured to control the flow of cooling water to the reactor well by moving from a closed position to an open position.

10. The system according to claim 1, further comprising an insulating liner assembly disposed on an outside surface of the reactor vessel, the liner assembly comprising a plurality of spaced apart metal liners having air gaps formed between the liners.

11. The system according to claim 10, further comprising a top flow-hole nozzle disposed at the outside surface of reactor vessel which is in fluid communication with the air gaps formed between the liners and the reactor well,

wherein the top flow-hole nozzle is configured and operable to evacuate steam produced within the liner assembly and discharge the steam to the reactor well.

12. The system according to claim 11, wherein the top flow-hole nozzle includes a flap configured to cover the nozzle, the flap being pivotably movable between an open position and a closed position.

13. The system according to claim 10, further Comprising a bottom flow-hole nozzle disposed at the outside surface of a bottom head of the reactor vessel which is in fluid communication with the air gaps formed between the liners and the reactor well,

wherein the bottom flow-hole nozzle is configured and operable to admit cooling water in the reactor well into the liner assembly.

14. The system according to claim 13, wherein the bottom flow-hole nozzle includes a flap configured to cover the nozzle, the flap being pivotably movable between an open position and a closed position.

15. A passive reactor cooling system usable after a loss-of-coolant accident, the system comprising:

a containment vessel in thermal communication with a heat sink;

a reactor well disposed in the containment vessel;

a reactor vessel disposed at least partially in the reactor well, the reactor vessel containing a nuclear fuel core and primary coolant heated by the fuel core;

a water storage tank disposed in the containment vessel and in fluid communication with the reactor well, the tank containing an inventory of cooling water; and

a heat exchanger disposed in the containment vessel, the heat exchanger in fluid communication with the reactor well via an atmospheric pressure closed flow loop;

wherein following a loss of primary coolant, the tank is configured and operable to flood the reactor well with cooling water;

wherein the cooling water in the flooded reactor well is heated by the fuel core and converted into steam, the steam flows through the closed flow loop to the heat exchanger and condenses forming condensate, and the condensate flows via gravity back to the reactor well.

16. The system according to claim 15, wherein the heat exchanger comprises an array of heat dissipater ducts integrally attached to the containment vessel.

17. The system according to claim 15, wherein the heat sink comprises an annular reservoir holding water that surrounds the containment vessel.

18. The system according to claim 15, wherein the reactor well and water storage tank are formed in a concrete monolith disposed in the containment vessel.

19. The system according to claim 15, wherein the water storage tank is fluidly coupled to the reactor well by at least one flow conduit having a dump valve disposed therein, the dump valve configured to control the flow of cooling water to the reactor well by moving from a closed position to an open position.

20. The system according to claim 15, further comprising an insulating liner assembly disposed on an outside surface of the reactor vessel, the liner assembly comprising a plurality of spaced apart metal liners having air gaps formed between the liners.

21. The system according to claim 20, further comprising:

a top flow-hole nozzle disposed at the outside surface of reactor vessel which is in fluid communication with the air gaps formed between the liners and the reactor well, the top flow-hole nozzle being configured and operable to evacuate steam produced within the liner assembly and discharge the steam to the reactor well; and

a bottom flow-hole nozzle disposed at the outside surface of a bottom head of the reactor vessel which is in fluid communication with the air gaps formed between the liners and the reactor well, the bottom flow-hole nozzle being configured and operable to admit cooling water in the reactor well into the liner assembly;

wherein the cooling water enters the liner assembly through the bottom flow-hole nozzle and is converted to steam by heat from the reactor fuel core, and the steam exits the liner assembly and flows into the reactor well through the top flow-hole nozzle.

22. The system according to claim 21, wherein the top and bottom flow-hole nozzles each include a closure flap configured to cover the nozzle, the flaps being pivotably movable between an open position and a closed position.

23. A method for passively cooling a nuclear reactor after a loss-of-coolant accident, the method comprising:

locating a reactor vessel containing a nuclear fuel core and primary coolant in a reactor well disposed inside a containment vessel;

at least partially filling a water storage tank fluidly coupled to the reactor well with cooling water;

releasing cooling water from the water storage tank into the reactor well;

heating the cooling water with the fuel core;

converting the cooling water at least partially into steam;

accumulating the steam in the reactor well;

flowing the steam through a heat exchanger;

condensing the steam thrilling condensate in the heat exchanger; and

returning the condensate to the reactor well;

wherein the coolant steam and condensate circulates through a closed flow loop between the heat exchanger and reactor well.

24. The method according to claim 23, wherein the steam is produced within an insulating liner assembly disposed on an outside surface of the reactor vessel, the liner assembly being fluidly coupled to the reactor well via flow-hole nozzles disposed at the bottom and top portions of the reactor vessel.

25. The system according to claim 23, wherein the heat exchanger comprises an array of heat dissipater ducts integrally attached to the containment vessel.

26. The system according to claim 23, wherein the condensing step further includes the heat exchanger rejecting heat from the steam to an annular reservoir holding water that surrounds the containment vessel.