A Liquid-Metal Fast Breeder Reactor Core Design with Seed Blanket Modular Assemblies

A liquid-metal fast breeder reactor core design employing seed-blanket-type modular assemblies is presented. The seed region contains PUO₂-UO₂ fuel and the blanket region contains depleted UO₂ fuel. These assemblies constitute the inner core while conventional mixed-oxide assemblies are employed in the outer core region. The results of design studies and analysis show that a large reduction in the sodium void reactivity can be obtained. The core fissile loading is larger than that for a homogeneous core. The analysis of an unprotected loss-of-flow (LOF) accident shows drastically reduced potential for a LOF-driven transient overpower accident. These results and conclusions are similar to those obtained for other heterogeneous core designs.