Characteristics of fuel melting and relocation in metallic-fueled fast reactor core and its feasibility for eliminating recriticality

The paper gives a concept for eliminating recriticality so that a fast reac tor core can have high potential to terminate severe accidents and prevent their progression into further disruption leading to a large-scale inter-su bassembly molten configuration. The basic idea to eliminate recriticality e vents is to remove a certain amount of fuel materials out of the core in or der to keep the core subcritical. This concept is called as Controlled Mate rial Relocation (CMR). Based on the concept, we propose an example of CMR d evising consisting of annular fuel pins for a metallic-fueled fast reactor core. By this devising, we can define the fraction of core fuels that shoul d be preferentially removed out of the core to eliminate the recriticality potential. We have analyzed melting and relocation behavior of metallic fue l pin, which has annular fuel meat, under accidental condition leading to c ore degradation. We have also examined the possibility of eliminating neutr onic recriticality for a metallic-fueled fast reactor, where the annular fu el pins are partially embedded in the core for realizing the CMR concept. ( C) 2000 Elsevier Science Ltd. All rights reserved.