Thermal-structural coupled analysis for estimating RPV damage in FDNPS Unit 2

福島第一原子力発電所2号機のRPV損傷推定のための熱ー構造連成解析

山下 拓哉  ; 下村 健太 ; 榮 和朗*; 橋本 昭彦*; 永江 勇二 

Yamashita, Takuya; Shimomura, Kenta; Sakae, Kazuaki*; Hashimoto, Akihiko*; Nagae, Yuji

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 TEPCO Fukushima Daiichi Nuclear Power Station (FDNPS). 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 is 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). This study aims to provide information that will aid the decommissioning of FDNPS. Therefore, we performed a thermal-structural coupled analysis to estimate the RPV damage of the FDNPS Unit 2. The results of the accident progression analysis and internal investigation were taken into account in conducting the analysis. The RPV failure locations estimated from the analysis were comprehensively evaluated and reflected in the three-dimensional estimation diagram.