[2J04-08] Fukushima Daiichi NPS Accident

[2J06] Estimation of the In-Depth Debris Status of Fukushima Unit-2 and Unit-3 with Multi-Physics Modeling

(9)Fukushima-Daiichi Unit-3 Plant Data Analysis Focusing on Estimated Fuel Debris Relocation to the Pedestal

*Ikken Sato¹, Akifumi Yamaji², Masahiro Furuya², Yuji Ohishi³, Xin Li², Hiroshi Madokoro¹, Hirofumi Fukai² (1. Japan Atomic Energy Agency, 2. Waseda University, 3. Osaka University)

Keywords:severe accident of nuclear reactor, pedestal, relocation to pedestal, debris cooling

From the Fukushima-Daiichi Unit-3 plant-data during the estimated core-material relocation to the pedestal, i.e., from the late evening of March 14^th to the morning of March 15^th, possible heat transfer from the relocating materials (debris) to the suppression chamber (S/C) water was evaluated. With this evaluation, based on pressure histories of drywell and S/C, it is estimated that S/C water temperature increase was contributing to the observed containment-pressure increase during the expected debris-relocation period. This significant heat transfer that caused the S/C water heat up would have been realized as a result of significant debris cooling.