Numerical simulation of the melt relocation behavior in fuel assembly scale structures

Yamashita, Susumu   ; Tokushima, Kazuyuki; Yoshida, Hiroyuki  ; Kurata, Masaki 

To simulate each process of the core melt progression in detail and contribute the improvement of severe accident analysis codes, we have performed the melt relocation experiments by using simplified fuel support pieces of the BWR. In addition, we are developing a numerical simulation code, JUPITER, to simulate the melt relocation in a fuel assembly scale. In this study, the JUPITER was applied to numerical simulations of the melt behavior of the complicated fuel support structures and the melt relocation experiment. As a result, the JUPITER is able to simulate melt relocation behavior in the complicated structures stably, and showed good agreement with the experimental results qualitatively. Therefore, it was confirmed that the JUPITER has potential to provide accurate understanding of the melt relocation behavior. In the near future, in order to simulate the more realistic behavior of the melt relocation, we will implement the eutectic reaction model to the JUPITER and also proceed the experimental analysis.