Breeder-type Operation based on the LWR-MOX Fuel Technologies in Light Water Reactors with Hard Neutron Spectrum (FLWR)

摘要

An advanced LWR concept, FLWR, is a BWR-type reactor with a core consisting of hexagonal-shaped fuel assemblies with a triangular lattice fuel rod configuration. It has been proposed by JAEA in order to ensure sustainable energy supply in the future based on the well-experienced LWR technologies. It aims at effective and flexible utilization of uranium and plutonium resources by adopting a two-stage concept of core designs, in which the first stage core can proceed to the second stage in the same reactor system during the reactor operation period, corresponding to the advancement of the fuel cycle technologies and related infrastructures. The core in the first stage of FLWR is for intensive utilization and preservation of plutonium based on the experiences of the current LWR and MOX utilization, and the one in the second stage realizes sustainable multiple plutonium recycling with a high conversion ratio over 1.0. The present paper will propose advanced fuel and core designs for realization of breeder-type operation in the first stage of FLWR. To achieve a high fissile-plutonium conversion ratio over 1.0, a new design concept of the MOX fuel assembly named FLWR/MIX has been developed, in which enriched UO_(2) fuel rods are arranged in the peripheral region of the assembly, surrounding MOX fuel rods in the central region. With respect to reduction of the plutonium inventory required for launching operation of FLWR and efficient utilization of MOX fuel, partial MOX loading cores have been also investigated, where the UO_(2) fuel assemblies of a tight lattice configuration with some water channels are loaded in addition to the FLWR/MIX fuel assemblies. Performance evaluation shows that the proposed concepts are feasible and promising under the framework of the UO_(2) and MOX fuel technologies and related infrastructures, which have been established for the current L WR-MOX utilization.