System and method for annealing nuclear fission reactor materials

1. A method for annealing at least a portion of at least one metallic component of a nuclear fission fuel assembly of a nuclear fission reactor, the method comprising:

determining an annealing temperature range for at least a portion of at least one metallic component of a nuclear fission fuel assembly of a nuclear fission reactor;

in a reactor core of the nuclear fission reactor, annealing at least the portion of the at least one metallic component of the nuclear fission fuel assembly within the annealing temperature range by, responsive to determining an annealing temperature range, establishing at least the portion of the nuclear fission fuel assembly within the annealing temperature range by adjusting operational parameters of the nuclear fission reactor to establish operating conditions of a region of the nuclear fission reactor containing the at least one metallic component within the determined annealing temperature range for a period of time selected to produce annealing of at least the portion of the at least one metallic component;

stopping annealing at least the portion of the at least one metallic component of the nuclear fission fuel assembly within the annealing temperature range; and

post-anneal treating at least the portion of the at least one metallic component of the nuclear fission fuel assembly by lowering temperature from the annealing temperature range to a quenching temperature range.

2. The method of claim 1 , wherein the at least one metallic component includes at least one component chosen from cladding, a cooling component, a structural member, a thermally conductive member, and nuclear fission fuel material.

3. The method of claim 2 , wherein metal of the metallic component includes at least one metal chosen from steel, refractory metal, a refractory metal alloy, a non-ferrous metal, and a non-ferrous metal alloy.

4. The method of claim 1 , wherein the annealing temperature range is greater than an operating temperature range of the nuclear fission fuel assembly.

5. The method of claim 1 , further comprising moving the nuclear fission fuel assembly to a location within a reactor core of the nuclear fission reactor after annealing.

6. The method of claim 1 , wherein adjusting operational parameters includes raising temperature of the region of the nuclear fission reactor containing the at least one metallic component from a operating temperature range of the reactor core toward the annealing temperature range.

7. The method of claim 1 , wherein adjusting operational parameters includes maintaining temperature of the region of the nuclear fission reactor containing the at least one metallic component substantially within the annealing temperature range.

8. The method of claim 1 , wherein adjusting operational parameters includes providing heat from an external heat source.

9. The method of claim 1 , wherein adjusting operational parameters includes:

providing coolant to the reactor core at a coolant flow rate;

substantially maintaining the coolant flow rate; and

reducing an amount of heat transferred from the coolant.

10. The method of claim 1 , wherein adjusting operational parameters includes:

providing coolant to the reactor core at a coolant flow rate;

substantially maintaining the coolant flow rate; and

reducing an amount of heat transferred to the coolant.

11. The method of claim 1 , wherein adjusting operational parameters includes:

providing coolant to the reactor core at a coolant flow rate; and

lowering the coolant flow rate into the region of the nuclear fission reactor containing the at least one metallic component.

12. The method of claim 1 , wherein adjusting operational parameters includes:

providing coolant to the reactor core at a coolant flow rate; and

reversing direction of coolant flow into the region of the nuclear fission reactor containing the at least one metallic component.

13. The method of claim 1 , wherein adjusting operational parameters includes:

providing coolant to the reactor core at a coolant flow rate; and

raising temperature of coolant entering the region of the nuclear fission reactor containing the at least one metallic component.

14. The method of claim 1 , wherein adjusting operational parameters includes replacing at least a portion of a first coolant having first heat transfer characteristics with second coolant having second heat transfer characteristics.

15. The method of claim 1 , wherein adjusting operational parameters includes raising pressure in the region of the nuclear fission reactor containing the at least one metallic component.

16. The method of claim 1 , wherein adjusting operational parameters includes lowering pressure in the region of the nuclear fission reactor containing the at least one metallic component.

17. The method of claim 1 , wherein a number of the at least one nuclear fission fuel assemblies is fewer than all nuclear fission fuel assemblies of a reactor core of the nuclear fission reactor.

18. The method of claim 1 , wherein a number of the at least one nuclear fission fuel assemblies is substantially all nuclear fission fuel assemblies of a reactor core of the nuclear fission reactor.

19. The method of claim 1 , further comprising:

during annealing, testing material properties of at least a portion of the at least one metallic component of the nuclear fission fuel assembly; and

wherein annealing is stopped responsive to testing material properties of at least a portion of the at least one metallic component of the nuclear fission fuel assembly.

20. The method of claim 1 , further comprising post-anneal treating at least the portion of the at least one metallic component of the nuclear fission fuel assembly by raising temperature from the quenching temperature range to a tempering temperature range.

21. The method of claim 1 , wherein annealing is performed after commencement of transition of reactivity condition of at least a portion of the nuclear fission reactor from a first state to a second state.

22. The method of claim 21 , wherein:

the first state includes power range operation; and

the second state includes a shut-down state.