Systems and methods for geothermal reactor passive cooling

Patent metadata

Field	Value
Publication number	US-2020027594-A1
Application number	US-201816206201-A
Country	US
Kind code	A1
Filing date	Nov 30, 2018
Priority date	Dec 4, 2017
Publication date	Jan 23, 2020
Grant date	—

Abstract

Passive safety systems cool reactors using surrounding ground as a heat sink. A coolant flow channel may loop around the reactor and then pass outside, potentially through a containment building, into surrounding ground. No active components need be used in example embodiment safety systems, which may be driven entirely by gravity-based natural circulation. The coolant loop may be air-tight and seismically-hardened and filled with any coolant such as water, air, nitrogen, a noble gas, a refrigerant, etc. The ground may include a soil of grey limestone, soft grey fine sandy clay, grey slightly silty sandy gravel, etc. or any other fill with desired heat-transfer characteristics. Coolant fins and/or jackets with secondary coolants may be used on the coolant loop. The coolant loop may be buried at any constant or variable depth, and the reactor and containment may also be buried in the ground.

First claim

What is claimed is:

1 . A passive safety system for removing decay heat from a nuclear power system, comprising:
a reactor vessel; a divided flow channel surrounding a perimeter of the reactor, wherein the divided flow channel includes a coolant downcomer, and a coolant riser between the coolant downcomer and the reactor, wherein the coolant downcomer and coolant riser are in fluid communication at a bottom of the divided flow channel; and a coolant loop connecting the to the coolant downcomer and coolant riser above the divided flow channel, wherein the coolant loop is buried at least three feet in the ground.

2 . The system of claim 1 , wherein the reactor vessel includes a molten metal, molten salt, or a gas as a primary thermal exchange fluid, further comprising:
a containment structure surrounding the reactor vessel, wherein the containment structure and the reactor vessel are under the ground.

3 . The system of claims 1 , further comprising:
an emergency pump power supply; a sodium cold trap; a shutdown control; and a control room, wherein the emergency power supply, the sodium cold trap, the shutdown control, and the control room are all under the ground.

4 . The system of claim 1 , wherein the coolant riser and the coolant downcomer are in direct fluid communication only at the bottom of the divided flow channel, and wherein a fluid is configured to flow through the coolant loop, coolant downcomer, and coolant riser to cool the reactor vessel without any active component.

5 . The system of claim 1 , wherein the coolant riser is insulated from the coolant downcomer and in heat transfer communication with the reactor vessel.

6 . The system of claim 1 , wherein the coolant riser, the coolant downcomer, and the coolant loop are fluid-tight and filled with at least one of water, air, nitrogen, a noble gas, and a refrigerant.

7 . The system of claim 1 , wherein the ground includes soil in direct contact with the coolant loop, and wherein the soil includes at least one of grey limestone, soft grey fine sandy clay, and grey slightly silty sandy gravel.

8 . The system of claim 7 , wherein the coolant loop is buried approximately 3-6 feet in the soil.

9 . The system of claim 1 , wherein the coolant loop includes a plurality of heat transfer fins extending from its outer surface into the ground, and wherein the coolant loop includes an inner pipe and an outer pipe with a secondary coolant between the inner pipe and the outer pipe.

10 . The system of claim 1 , further comprising:
a damper system in the coolant loop, wherein the damper system includes a damper configured to move, at a threshold temperature, from a closed position restricting the coolant flow to an open position permitting the coolant flow, and wherein the damper system is configured to passively fail with the damper in the open position.

11 . A method of constructing a nuclear reactor, the method comprising:
burying a coolant conduit in the ground outside of a containment of the nuclear reactor; and connecting the coolant conduit to a coolant heat riser and a coolant downcomer inside the containment so as to form a closed loop.

12 . The method of claim 11 , further comprising:
burying the nuclear reactor, the coolant heat riser, the coolant downcomer, and the containment for the reactor below the coolant conduit.

13 . The method of claim 11 , wherein the burying includes burying the coolant conduit approximately 3-6 feet in soil.

14 . The method of claim 13 , wherein the soil is in direct contact with the coolant conduit, and wherein the soil includes at least one of grey limestone, soft grey fine sandy clay, and grey slightly silty sandy gravel.

15 . The method of claim 11 , wherein the coolant conduit is fluid-tight and filled with at least one of water, air, nitrogen, a noble gas, and a refrigerant.

16 . A method of operating a nuclear reactor, the method comprising:
shutting down the nuclear reactor; and allowing a coolant to flow in a coolant heat riser up around the reactor to absorb decay heat from the reactor, through a coolant conduit buried in ground surrounding the reactor, and back to the coolant heat riser in a loop.

17 . The method of claim 16 , wherein the ground includes soil in direct contact with the coolant conduit, and wherein the soil includes at least one of grey limestone, soft grey fine sandy clay, and grey slightly silty sandy gravel.

18 . The method of claim 17 , wherein the coolant loop is buried approximately 3-6 feet in the soil.

19 . The method of claim 16 , wherein the reactor vessel includes a molten metal, molten salt, or a gas as a primary thermal exchange fluid.

20 . The method of claim 16 , wherein the heat riser and the coolant conduit are together fluid-tight and filled with at least one of water, air, nitrogen, a noble gas, and a refrigerant.

Assignees

• Ge Hitachi Nuclear Energy Americas Llc

Inventors

• Hunt Brian S
• Rasmussen Scott E

Classifications

• G21C15/18 Primary

  Emergency cooling arrangements; Removing shut-down heat · CPC title

• G21C11/022

  inside the reactor vessel · CPC title

• G21C17/025

  for monitoring liquid metal coolants {(molten metal sampling in general G01N1/125)} · CPC title

• G21C15/182 Primary

  comprising powered means, e.g. pumps · CPC title

• G21C15/247

  for liquid metals · CPC title