Method of flux separation in nuclear reactors and structure therefor

Claim 1

IN A NUCLEAR REACTOR WITH FISSIONS OCCURRING PREDOMINANTLY AT THERMAL ENERGIES, THE COMBINATION COMPRISED OF FIRST AND SECOND FUEL REGIONS, SAID FIRST REGIONS BEING FORMED OF RELATIVELY HIGH ENRICHMENT NUCLEAR FUEL ELEMENTS AND MODERATOR, SAID REACTOR HAVING A MAXIMUM VOLUMERTIC RATIO OF MODERATOR MATERIAL TO FUEL MATERIAL IN SAID FIRST FUEL REGIONS OF 1:2, SAID SECOND FUEL REGION BEING FORMED OF RELATIVELY LOW ENRICHMENT NUCLEAR FUEL ELEMENTS AND MODERATOR MATERAL, SAID REACTOR HAVING A VOLUMETRIC RATIO OF MODERATOR MATERIAL TO FUEL MATERIAL IN SAID SECOND REGIONS OF AT LEAST 1:1, AND INTERNAL REFLECTOR MATERIAL INTERPOSED BETWEEN AND COMPLETELY SEPARATING SAID FIRST AND SECOND FUEL REGIONS, SAID REFLECTOR MATERIAL BEING OF THICKNESS SUFFICIENT TO MAINTAIN THE THERMAL NEUTRON FLUX WITHIN SAID FIRST FUEL REGIONS ADJACENT SAID REFLECTOR MATERIAL AT A MAGNITUDE NO GREATER THAN ONE-HALF THE THERMAL NEURONFLUX MAGNITUDE WITHIN SAID SECOND FUEL REGIONS ADJACENT SAID REFLECTOR MATERIAL.