Comprehensive Analysis and Evaluation of Fukushima Daiichi Nuclear Power Station Unit 3

The estimation and understanding of the state of fuel debris and fission products inside the plant is an essential step in the decommissioning of the Tokyo Electric Power Company Holdings Fukushima Daiichi Nuclear Power Station (1F). However, the direct observation of the plant interior, which is under a high radiation environment, is difficult and limited. Therefore, in order to understand the plant interior conditions, a comprehensive analysis and evaluation are necessary, based on various measurement data from the plant, analysis of plant data during the accident progression phase, and information obtained from computer simulations for this phase. These evaluations can be used to estimate the conditions of the interior of the reactor pressure vessel (RPV) and the primary containment vessel (PCV). Herein, 1F Unit 3 is addressed as the subject to produce an estimated diagram of the fuel debris distribution from data obtained about the RPV and PCV based on the comprehensive evaluation of various measurement data and information obtained from the accident progression analysis, which were released to the public in November 2022.