Controlling a nuclear reaction

Patent metadata

Field	Value
Publication number	US-2022246317-A1
Application number	US-202217693685-A
Country	US
Kind code	A1
Filing date	Mar 14, 2022
Priority date	Dec 29, 2017
Publication date	Aug 4, 2022
Grant date	—

Abstract

A nuclear power system includes a reactor vessel that includes a reactor core that includes nuclear fuel assemblies configured to generate a nuclear fission reaction; a riser positioned above the reactor core; a primary coolant flow path that extends from a bottom portion of the volume through the reactor core and through an annulus between the riser and the reactor vessel; a primary coolant that circulates through the primary coolant flow path to receive heat from the nuclear fission reaction and release the heat to generate electric power in a power generation system; and a control rod assembly system positioned in the reactor vessel and configured to position control rods in only two discrete positions.

First claim

I/we claim:

1 . A nuclear power system, comprising:
a reactor vessel that comprises a reactor core mounted within a volume of the reactor vessel, the reactor core comprising one or more nuclear fuel assemblies configured to generate a nuclear fission reaction; a riser positioned above the reactor core; a primary coolant flow path that extends from a bottom portion of the volume below the reactor core, through the reactor core, within the riser, and through an annulus between the riser and the reactor vessel back to the bottom portion of the volume; a primary coolant that circulates through the primary coolant flow path to receive heat from the nuclear fission reaction and release the received heat to generate electric power in a power generation system fluidly or thermally coupled to the primary coolant flow path; and a control rod assembly system positioned in the reactor vessel and configured to position a plurality of control rods in only two discrete positions, such that the plurality of control rods are fully withdrawn from the reactor core in a first discrete position of the only two discrete positions and the plurality of control rods are fully inserted into the reactor core in a second discrete position of the only two discrete positions.

2 . The nuclear power system of claim 1 , wherein the control rod assembly is configured to adjust the plurality of control rods from the first discrete position to the second discrete position by at least one of:
releasing the plurality of control rods to fall to the second discrete position from the first discrete position; or forcibly urging the plurality of control rods from the first discrete position to the second discrete position.

3 . The nuclear power system of claim 1 , wherein the plurality of control rods are sufficient to shut down the nuclear fission reaction or maintain the nuclear fission reaction at a sub-critical state in the second discrete position.

4 . The nuclear power system of claim 1 , further comprising a control system communicably coupled to the power generation system and configured to control a power output of the nuclear fission reaction independent of the control rod assembly system during a normal operation of the nuclear power system.

5 . The nuclear power system of claim 4 , wherein the control system is configured to perform operations to control one or more parameters of the power generation system comprising:
determining that the power output of the nuclear fission reaction is greater than an upper value or less than a lower value; based on the determination, controlling the power generation system to adjust at least one of a turbine inlet steam valve or a feed water pump to adjust the power output of the nuclear fission reaction; and subsequent to the adjustment, determining that the power output is within a range between the upper and lower values.

6 . The nuclear power system of claim 5 , wherein the operation of controlling the power generation system to adjust at least one of the turbine inlet steam valve or the feed water pump to adjust the power output of the nuclear fission reaction comprises at least one of:
adjusting the turbine inlet steam valve toward a fully closed position to decrease the power output of the nuclear fission reaction, or adjusting the turbine inlet steam valve toward a fully open position to increase the power output of the nuclear fission reaction; or decreasing an output flowrate of the feed water pump to decrease the power output of the nuclear fission reaction, or increasing the output flowrate of the feed water pump to increase the power output of the nuclear fission reaction.

7 . The nuclear power system of claim 4 , wherein the control system is configured to perform operations to control one or more parameters of the chemical injection system comprising:
determining that the power output of the nuclear fission reaction is greater than an upper value or less than a lower value; based on the determination, adjusting an amount of a chemical injected into the reactor core from the chemical injection system to adjust the power output of the nuclear fission reaction; and subsequent to the adjustment, determining that the power output is within a range between the upper and lower values.

8 . The nuclear power system of claim 7 , wherein the operation of adjusting the amount of the chemical injected into the reactor core from the chemical injection system comprises at least one of:
increasing the amount of the chemical injected into the reactor core from the chemical injection system to decrease the power output of the nuclear fission reaction; or decreasing the amount of the chemical injected into the reactor core from the chemical injection system to increase the power output of the nuclear fission reaction.

9 . A method for controlling a nuclear fission reaction, comprising:
operating a nuclear power system to initiate a nuclear fission reaction, the nuclear power system comprising:
a reactor vessel that comprises a reactor core mounted within a volume of the reactor vessel, the reactor core comprising one or more nuclear fuel assemblies configured to initiate and maintain the nuclear fission reaction during a normal operation,
a riser positioned above the reactor core, and
a primary coolant flow path that extends from a bottom portion of the volume below the reactor core, through the reactor core, within the riser, and through an annulus between the riser and the reactor vessel back to the bottom portion of the volume;
circulating a primary coolant through the primary coolant flow path to receive heat from the nuclear fission reaction;
transferring the received heat into a power generation system fluidly or thermally coupled to the primary coolant flow path to generate electric power; and
operating a control rod assembly system positioned in the reactor vessel to adjust a position of a plurality of control rods from a first discrete position of only two discrete positions to a second discrete position of the only two discrete positions, such that the plurality of control rods are fully withdrawn from the reactor core in the first discrete position and the plurality of control rods are fully inserted into the reactor core in the second discrete position.

10 . The method of claim 9 , wherein adjusting the plurality of control rods from the first discrete position to the second discrete position comprises at least one of:
releasing the plurality of control rods to fall to the second discrete position from the first discrete position; or forcibly urging the plurality of control rods from the first discrete position to the second discrete position.

11 . The method of claim 9 , wherein the plurality of control rods are sufficient to shut down the nuclear fission reaction or maintain the nuclear fission reaction at a sub-critical state in the second discrete position.

12 . The method of claim 9 , further comprising controlling a power output of the nuclear fission reaction independent of any control rod assemblies during the normal operation.

13 . The method of claim 12 , wherein the nuclear power system further comprises a chemical injection system in fluid communication with the primary coolant flow path, the method further comprising:
controlling the power output of the nuclear fission reaction independent of any control rod assemblies by controlling one or more parameters of at least one of the power generation system or the chemical injection system during normal operation.

14 . The method of claim 12 , further comprising:
determining that the power output of the nu

Assignees

• Nuscale Power Llc

Inventors

• Callaway Allyson
• Bristol Ben
• Rooks Kenneth
• Linik Larry

Classifications

• Y02E30/30

  Nuclear fission reactors · CPC title

• G21C9/024

  Rupture diaphragms · CPC title

• G21C9/022

  Reactor fuses · CPC title

• G21C9/033

  by an absorbent fluid · CPC title

• G21C7/24

  Selection of substances for use as neutron-absorbing material · CPC title