Fuel Assembly Design for Plutonium Conservation in a Light Water Reactor with Hard Neutron Spectrum

The FLWR is a boiling water reactor type with a core consisting of hexagonal-shaped fuel assemblies with a triangular-lattice fuel rod configuration, which has been proposed in order to ensure a sustainable energy supply in the future based on well-established light water reactor technologies. This paper proposes a new concept of fuel assembly design named FLWR/MIX. The first stage of FLWR is designed to conserve plutonium effectively with a fissile plutonium conversion ratio of around 1.0, keeping negative void reactivity characteristics. Enriched UO₂ fuel rods are arranged in the peripheral region of the assembly, surrounding the mixed oxide (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 is promising under the framework of the UO₂ and MOX fuel technologies and related infrastructures that have been established for the current LWR-MOX utilization.