Flux-shifting reactivity control system

Patent metadata

Field	Value
Publication number	US-2016189805-A1
Application number	US-201514985138-A
Country	US
Kind code	A1
Filing date	Dec 30, 2015
Priority date	Dec 31, 2014
Publication date	Jun 30, 2016
Grant date	—

Abstract

A control assembly for a nuclear reactor includes a first reactivity control assembly having a first neutron modifying material, a second reactivity control assembly having a second neutron modifying material, and at least one drive mechanism coupled to the first neutron modifying material and the second neutron modifying material. The first neutron modifying material and the second neutron modifying material are selectively repositionable relative to a fuel region of the nuclear reactor. The at least one drive mechanism is configured to provide the first neutron modifying material and the second neutron modifying material in different directions through the fuel region thereby shifting a flux distribution within the fuel region away from the second neutron modifying material.

First claim

What is claimed is:

1 . A method comprising:
sustaining a nuclear fission reaction within a fuel region of a nuclear reactor core, the nuclear reactor core having first moveable control assemblies insertable into a first side of the fuel region of the nuclear reactor core and second control assemblies insertable into a second opposing side of the fuel region of the nuclear reactor core, wherein the sustaining operation includes
moving at least one assembly of the first and second control assemblies into a first insertion configuration of the first and second control assemblies within the fuel region of the nuclear reactor core; and
moving at least one assembly of the first and second control assemblies into a second insertion configuration of the first and second control assemblies within the fuel region of the nuclear reactor core, wherein the first and the second insertion configurations sustain the nuclear fission reaction.

2 . The method of claim 1 , further comprising:
wherein the nuclear fission reaction yields a first neutron flux distribution dependent on the first insertion configuration of the first and second control assemblies; and wherein the nuclear fission reaction yields a second neutron flux distribution dependent on the second insertion configuration of the first and second control assemblies.

3 . The method of claim 2 , wherein the second nonzero neutron flux distribution is satisfied by a target total neutron flux over a predetermined period of time.

4 . The method of claim 2 , wherein the first flux distribution differs axially from the second nonzero flux distribution.

5 . The method of claim 2 , wherein the first flux distribution differs radially from the second nonzero flux distribution.

6 . The method of claim 1 , further comprising:
moving at least one assembly of third moveable control assemblies insertable into a third side of the nuclear reactor core section, the third moveable control assemblies being insertable into the nuclear reactor core section at a different angle than the first and second control assemblies.

7 . The method of claim 1 , wherein the moving operation further comprises:
moving at least one assembly of the first control assemblies and at least one assembly of the second control assemblies in at least a first direction, wherein the axial distance between the at least one moved assembly of the first control assemblies and the at least one moved assembly of the second control assemblies remains substantially constant during the moving operation.

8 . The method of claim 1 , wherein the moving operation further comprises:
moving at least one assembly of the first control assemblies and at least one assembly of the second control assemblies, wherein the distance between the at least one moved assembly of the first control assemblies and the at least one moved assembly of the second control assemblies is core symmetric.

9 . The method of claim 1 , wherein the moving operation further comprises:
moving at least one assembly of the first control assemblies and at least one assembly of the second control assemblies, wherein the axial distance between the at least one moved assembly of the first control assemblies and the at least one moved assembly of the second control assemblies changes during the moving operation.

10 . The method of claim 1 , wherein the nuclear fission reaction is a standing wave reaction.

11 . The method of claim 10 , wherein the first control assemblies and second control assemblies are disposed on substantially opposing sides of the standing wave reaction.

12 . The method of claim 1 , wherein at least one of the first or second control assemblies include a poison.

13 . The method of claim 1 , wherein the second neutron flux distribution is satisfied by a target total neutron flux over a predetermined period of time in a predetermined fuel region within the nuclear reactor core section.

14 . A system comprising:
a nuclear reactor core including a fuel region; first control assemblies insertable into a first side of the fuel region, the first control assemblies moveable into a plurality of first insertion configurations; and second control assemblies insertable into a second opposing side of the fuel region, the second control assemblies moveable into a plurality of second insertion configurations, wherein at least one of the first insertion configurations and at least one of the second insertion configurations sustain a nuclear fission reaction.

15 . The system of claim 14 , further comprising:
one or more drive mechanisms operably coupled to the first control assemblies and second control assemblies and configured to move the first control assemblies into a first insertion configuration and second control assemblies into a second insertion configuration to sustain the nuclear fission reaction in the fuel region according to a target nonzero neutron flux distribution.

16 . The system of claim 14 , further comprising a drive mechanism including an actuator coupled to the first control assemblies and second control assemblies and configured to selectively reposition the first control assemblies and second control assemblies relative to the fuel region.

17 . The system of claim 15 , wherein the target nonzero neutron flux distribution is a total neutron flux over a predetermined period of time.

18 . The system of claim 15 , wherein the target nonzero neutron flux distribution is a total neutron flux over a predetermined period of time in a predetermined portion of the fuel region.

19 . The system of claim 15 , wherein the target neutron flux distribution corrects one or more axial asymmetries in a neutron flux distribution in the nuclear reactor core.

20 . The system of claim 15 , wherein the target flux distribution differs axially from a neutron flux in the nuclear reactor core.

21 . The system of claim 15 , wherein the target flux distribution differs radially from a neutron flux in the nuclear reactor core.

22 . A nuclear fission reactor comprising:
means for sustaining a nuclear fission reaction within a fuel region of a nuclear reactor core, the nuclear reactor core having first moveable control assemblies insertable into a first side of the fuel region of the nuclear reactor core and second control assemblies insertable into a second opposing side of the fuel region of the nuclear reactor core; means for moving at least one assembly of the first and second control assemblies into a first insertion configuration of the first and second control assemblies with the fuel region of the nuclear reactor core and for moving at least one assembly of the first and second control assemblies into a second insertion configuration of the first and second control assemblies within the fuel region of the nuclear reactor core, wherein the first and the second insertion configurations sustain the nuclear fission reaction.

23 . The nuclear fission reactor of claim 22 , wherein the means for moving further comprises repositioning means for selectively repositioning the first control assemblies and second control assemblies relative to the fuel region.

24 . The nuclear fission reactor of claim 22 , further comprising:
means for detecting a current neutron flux distribution within the fuel region.

25 . The nuclear fission reactor of claim 23 , wherein the means for detecting a current neutron flux distribut

Assignees

• Terrapower Llc

Inventors

• Cheatham Iii Jesse R

Classifications

• G21C7/12 Primary

  Means for moving control elements to desired position (dropping rods in an emergency G21C9/02) · CPC title

• G21C7/18

  Means for obtaining differential movement of control elements · CPC title

• G21C7/08

  by displacement of solid control elements, e.g. control rods · CPC title

• G21D3/08

  Regulation of any parameters in the plant · CPC title

• G21C1/026 Primary

  Reactors not needing refuelling, i.e. reactors of the type breed-and-burn, e.g. travelling or deflagration wave reactors or seed-blanket reactors · CPC title