[2J04-08] Fukushima Daiichi NPS Accident

[2J04] Investigation on accident progression of 1F2 during the 7 hours after the depressurization using MELCOR-2.2

*Shotaro Osako¹, Akifumi Yamaji¹, Xin Li² (1. Waseda University, Cooperative Major in Nuclear Energy, 2. Waseda Research Institute for Science and Engineering)

Keywords:Fukushima Daiichi Nuclear Power Station Unit2, 1F2, Estimation of thermal status of the fuel debris, MELCOR-2.2, Accident progression analysis

In order to improve the accuracy of estimating the fuel debris and core conditions of Fukushima Daiichi-Unit2(1F2), it would be useful to estimate the accident progression, which would be consistent with the three pressure peaks in the RPV and the D/W pressure transition during the period of 78-83 hours after the reactor scram. However, such analysis results have not been presented. This study presents sensitivities of possible gas leakage from RPV to D/W, incomplete SRV closure, amount of core slumping, heat transfer in the RPV lower plenum, and core oxidations on the estimated core thermal energy using MELCOR-2.2.