Effective Use of Plutonium through its Multi-Recycling with High Moderation LWRs

High moderation cores of LWRs loading full MOX fuel assemblies have been studied to enhance the effective use of Pu, based on two types of assembly compatible to the core internals of ABWR and APWR respectively. Results of equilibrium condition analysis for the full MOX cores have shown that nuclear and thermal hydraulics parameters satisfy standard LWR design criteria. Results of the typical system transient, accident and stability analysis have also shown that the cores are feasible and acceptable in the criteria. Survey for introducing the cores into a future fuel cycle system of Japan has been studied, in which Pu is postulated to be used once (single-recycling) or repeatedly (multi-recycling). Results have been compared to the conventional LWR full MOX cores with standard moderation. The resultant effect of multi-recycling has got advantage over the effective use of Pu. The multi-recycling has lead to save natural U demand by over 3%, increase power generation from Pu by 50% of cumulative value, and decrease Pu fissile residual in spent fuels by 29%. It has been also showed that high moderation cores are effective to reduce long-lived fission products and minor actinides. (authors)