PASSIVE EMERGENCY FEEDWATER SYSTEM

• US 20090129530A1
• Filed: 05/15/2008
• Published: 05/21/2009
• Est. Priority Date: 11/15/2007
• Status: Active Grant

• Current Assignee: NuScale Power, LLC.
• Original Assignee: Oregon State University (Oregon University System)
• Inventors: Groome, John T., Reyes, Jose N. JR.
• Granted Patent: US 8,170,173 B2
• Time in Patent Office: Days
• US Class Current: 376/282
• CPC Class Codes: G21C 1/32 Integral reactors, i.e. reactors wherein parts functionally associated with the reactor but not essential to the reaction, e.g. heat exchangers, are disposed inside the enclosure with the core G21C1/02 - G21C1/30 take precedence
• CPC Class Codes: G21C 15/18 Emergency cooling arrangements; Removing shut-down heat
• CPC Class Codes: G21C 15/26 by convection, e.g. using chimneys, using divergent channels
• CPC Class Codes: G21C 9/00 Emergency protection arrangements structurally associated with the reactor , e.g. safety valves provided with pressure equalisation devicesemergency cooling arrangements G21C15/18
• CPC Class Codes: G21C 9/012 by thermal accumulation or by steam condensation, e.g. ice condensers
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors

Abstract

A power module assembly includes a reactor vessel containing a reactor core surrounded by a primary coolant. A containment vessel is adapted to be submerged in a containment cooling pool and to prohibit a release of the primary coolant outside of the containment vessel. A secondary cooling system is configured to remove heat generated by the reactor core. The heat is removed by circulating liquid from the containment cooling pool through the primary coolant.

Claims

1. A power module assembly comprising:

a reactor vessel containing a reactor core surrounded by a primary coolant;

a containment vessel adapted to be submerged in a containment cooling pool and to prohibit a release of the primary coolant outside of the containment vessel; and

a secondary cooling system configured to remove heat generated by the reactor core, wherein the heat is removed by circulating liquid from the containment cooling pool through the primary coolant.

2. The power module assembly according to claim 1 wherein the secondary cooling system comprises a heat exchanger configured to circulate a secondary coolant within the reactor vessel.

3. The power module assembly according to claim 2 wherein the secondary cooling system is configured to remove the liquid from the containment cooling pool during an emergency operation.

4. The power module assembly according to claim 3 wherein the emergency operation comprises a loss of coolant accident.

5. The power module assembly according to claim 3 wherein the emergency operation comprises a loss of secondary coolant flow.

6. The power module assembly according to claim 3 wherein the emergency operation comprises a loss of on-site power.

7. The power module assembly according to claim 1 wherein the secondary cooling system comprises one or more vents configured to vent the liquid into the containment cooling pool after being circulated through the primary coolant.

8. The power module assembly according to claim 7 wherein the liquid circulates through the primary coolant by natural circulation due to a temperature difference between the liquid and the primary coolant.

9. The power module assembly according to claim 1 wherein the secondary cooling system comprises one or more inlets located near the bottom of the containment cooling pool.

10. A cooling system for a nuclear reactor comprising:

an inlet line configured to deliver coolant to a heat exchanger;

an outlet line connected to the heat exchanger and configured to remove heat from the nuclear reactor;

an inlet port adapted to supply emergency feedwater to the inlet line; and

an outlet port connected to the outlet line and configured to vent the emergency feedwater, wherein the cooling system is configured to circulate the emergency feedwater through the heat exchanger by natural circulation.

11. The cooling system according to claim 10 wherein the natural circulation occurs as a result of a temperature change of the emergency feedwater and an elevation difference of the inlet port and the outlet port.

12. The cooling system according to claim 10 wherein the inlet line is connected to a feedwater pump and the outlet line is connected to a steam turbine.

13. The cooling system according to claim 12 wherein the natural circulation of the emergency feedwater occurs without the assistance of the feedwater pump.

14. The cooling system according to claim 10 further comprising an accumulator tank configured to inject coolant into the inlet line when a loss of feedwater flow is detected.

15. The cooling system according to claim 14 wherein the accumulator tank provides coolant to the heat exchanger until natural circulation of the emergency feedwater is established.

16. A method of cooling a nuclear reactor comprising:

detecting a loss of feedwater condition;

replacing a feedwater flow from a secondary cooling system with an emergency feedwater supply; and

circulating the emergency feedwater through a heat exchanger to remove heat from the nuclear reactor, wherein the emergency feedwater is circulated through natural circulation.

17. The method according to claim 16 wherein the emergency feedwater supply comprises a containment cooling pool surrounding the nuclear reactor.

18. The method according to claim 17 further comprising venting the emergency feedwater into the containment cooling pool.

19. The method according to claim 16 wherein the natural circulation is due to a difference in temperature between the emergency feedwater supply and the emergency feedwater circulating through the heat exchanger.

20. The method according to claim 16 wherein the natural circulation is sustainable for more than three days.