[1A01-06] Fukushima Daiichi NPS Accident

[1A02] Estimation of the In-Depth Debris Status of Fukushima Unit-2 and Unit-3 with Multi-Physics Modeling

(7)Preliminary evaluation of debris relocation and interaction with pedestal structures in Fukushima Unit-3 with MPS method

*Xin Li¹, Akifumi Yamaji¹, Ikken Sato², Masahiro Furuya¹, Hiroshi Madokoro², Hirofumi Fukai¹, Yuji Ohishi³ (1. Waseda Univ., 2. JAEA, 3. Osaka Univ.)

Keywords:severe accident , MPS method, decommissioning of Fukushima Daiichi reactors , numerical simulation

The decommissioning of Fukushima Daiichi (1F) Nuclear Power Plants requires knowledge of the in-depth debris status within the pedestals of 1F. As part of the Nuclear Energy Science & Technology and Human Resource Development Project (2019-2021), the Moving Particle Semi-implicit (MPS) method is being developed for simulation of multi-component liquid / solid relocation with solid-liquid phase changes. The developments include parallelization and calculation cost reduction strategies. A Preliminary evaluation of debris relocation and interaction with pedestal structures in Fukushima Unit-3 has been carried out with the developed MPS method in 1/10-scaled geometry. The preliminary results show that the structures can hold up the debris at ~2-3 meters above the containment floor with sufficient vapor cooling from the debris surface provided.