Studies aimed at clarifying thermal-hydraulic behavior during the 1F accident; Study of debris-relocation behavior during the 1F accident

Sato, Ikken*; Yamashita, Takuya  

Understanding fuel debris behavior during the accident and its final distribution and properties is crucial for fuel debris retrieval at the Fukushima Daiichi Nuclear Power Station (1F). By comprehensively synthesizing existing knowledge, including internal plant investigations, accident-stage plant data, and consistent analytical evaluations, this study estimates the most probable fuel debris behavior for 1F Units 1 to 3. The estimation focuses on the thermal conditions of the debris during each relocation stage from the reactor pressure vessel (RPV) to the pedestal. Finally, we identify key issues for future investigation.