Standing wave nuclear fission reactor and methods

Abstract

Disclosed embodiments include nuclear fission reactor cores, nuclear fission reactors, methods of operating a nuclear fission reactor, and methods of managing excess reactivity in a nuclear fission reactor.

What is claimed is: 
     
         1 . A nuclear fission reactor core of a nuclear fission reactor, the nuclear fission reactor core comprising:
 a central core region and a peripheral core region located radially outward from the central core region;   a first plurality of nuclear fuel assemblies in the central core region, the first plurality of nuclear fuel assemblies containing fissile nuclear fuel material;   a second plurality of nuclear fuel assemblies in the central core region, the second plurality of nuclear fuel assemblies containing fertile fuel and/or fissile fuel bred up from fertile fuel in the nuclear fission reactor material;   a third plurality of nuclear fuel assemblies in the peripheral core region, the third plurality of nuclear fuel assemblies containing fertile nuclear fuel material;   means for absorbing neutrons in the peripheral core region;   means for breeding the fertile nuclear fuel material into fissile fuel; and   means for shuffling at least one of the first plurality of nuclear fuel assemblies and at least one of the second and/or third plurality of nuclear fuel assemblies to establish a standing wave of fissioning fissile nuclear fuel material in the central core region.   
     
     
         2 . The nuclear fission reactor core of  claim 1 , wherein the means for shuffling includes means for shuffling at least one of the first plurality of nuclear fuel assemblies and at least one of the third plurality of nuclear fuel assemblies between the central core region and the peripheral core region to establish the standing wave of breeding fissile nuclear fuel material and fissioning fissile nuclear fuel material. 
     
     
         3 . The nuclear fission reactor core of  claim 2 , wherein the means for shuffling includes means for shuffling at least one of the first plurality of nuclear fuel assemblies and at least one of the second plurality of nuclear fuel assemblies within the central core region to establish the standing wave. 
     
     
         4 . The nuclear fission reactor core of  claim 3 , wherein the means for shuffling includes means for replacing at least one of the first plurality of nuclear fuel assemblies in the central core region with at least one of the second and/or third plurality of nuclear fuel assemblies. 
     
     
         5 . The nuclear fission reactor core of  claim 4 , wherein the means for absorbing neutrons includes means for absorbing neutrons in a first portion of the third plurality of nuclear fuel assemblies in the peripheral core region. 
     
     
         6 . The nuclear fission reactor core of  claim 5 , wherein the means for absorbing neutrons includes means for absorbing neutrons in a second portion of the first plurality of nuclear fuel assemblies shuffled from the central core region to the peripheral core region after burn up. 
     
     
         7 . The nuclear fission reactor core of  claim 6 , wherein the means for absorbing neutrons in the peripheral core region comprises at least one neutron absorber assembly in the peripheral core region. 
     
     
         8 . The nuclear fission reactor core of  claim 1 , further comprising:
 means for flowing reactor coolant in the central core region; and   means for flowing reactor coolant in the peripheral core region.   
     
     
         9 . A nuclear fission reactor comprising:
 a reactor vessel;   a nuclear fission reactor core having a central core region and a peripheral core region located radially outward from the central core region in the reactor vessel,
 the central core region including:
 a first plurality of nuclear fuel assemblies containing fissile nuclear fuel material; 
 a second plurality of nuclear fuel assemblies containing fertile nuclear fuel material; and 
 a plurality of movable reactivity control assemblies; 
 
 the peripheral core region including:
 a third plurality of nuclear fuel assemblies containing fertile nuclear fuel material; and 
 a plurality of neutron absorber assemblies, locations of the plurality of neutron absorber assemblies based upon a predetermined stage of core life of the third plurality of nuclear fuel assemblies and any other nuclear fuel assemblies of the peripheral core region; 
 
   means for establishing a standing wave of fissioning fissile nuclear fuel material, the means for establishing including shuffling at least one of the first plurality of nuclear fuel assemblies and at least one of the second and/or third plurality of nuclear fuel assemblies.   
     
     
         10 . The nuclear fission reactor of  claim 9 , wherein the means for shuffling includes means for shuffling at least one of the first plurality of nuclear fuel assemblies and at least one of the third plurality of nuclear fuel assemblies between the central core region and the peripheral core region. 
     
     
         11 . The nuclear fission reactor of  claim 10 , further comprising a reactor coolant system comprising a plurality of fuel assembly flow receptacles defining:
 a first plurality of reactor coolant flow orifices in the central core region; and   a second plurality of reactor coolant flow orifices in the peripheral core region;   wherein the first and second pluralities of reactor coolant flow orifices include fixed orifices.   
     
     
         12 . The nuclear fission reactor of  claim 11 , wherein the first and second pluralities of reactor coolant flow orifices further include variable orifices.