A concept of eliminating recriticality under core degradation accidents and its realization for metallic-fueled fast reactor core

摘要

The paper gives a concept for eliminating recriticality so that a fast reactor core can have high potential to terminate severe accidents and prevent their progression into further disruption of the degraded core. The basic idea to eliminate recriticality events is to remove a certain amount of fuel materials out of the core in order to keep the rest of the core in a permanent subcritical condition. This concept of core metarials removal is called as Controlled Material Relocation (CMR). Based on teh concept, we propose an example of CMR devising consisting of annular fuel pins for a metallic-fueled fast reactor core. By this devising, we can define the fractions of core fuels that should be preferentially removed out of the core to eliminate the recriticality potential. We have analyzed melting and relocation behavior of metallic fuel pin, which has annular fuel pin, under accidental condition leading to core degradation. We have also examined the possibility of eliminating neutronic recriticality for a metallicfueled fast reactor, where the annular fuel pins are partially embedded in the core for realizing the CMR concept.