Fuel assembly design for plutonium conservation in a light water reactor with hard neutron spectrum

Uchikawa, Sadao; Okubo, Tsutomu; Nakano, Yoshihiro 

The FLWR is a BWR-type reactor with hard neutron spectrum based on the well-experienced LWR technologies. The present paper has proposed a new concept of the fuel assembly design for the first stage of FLWR to conserve plutonium effectively with a fissile-plutonium conversion ratio of around 1.0, keeping negative void reactivity characteristics. The enriched UO fuel rods are arranged in the peripheral region of the assembly, surrounding the MOX fuel rods in the central region. Performance evaluation shows that the FLWR/MIX concept is effective for controlling the void reactivity characteristics in the tight-lattice fuel rod configuration and promising under the framework of the UO and MOX fuel technologies and related infrastructures which have been established for the current LWR-MOX utilization.