Session: 03-01: Major facilities experience in handling accidents and D/D&D

Paper Number: 111082

111082 - Thermal-Structural Coupled Analysis for Estimating Rpv Damage in Fdnps Unit 2 

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 coupled 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.

This study has been performed by the funds from the Japanese Ministry of Economy, Trade and Industry as The Subsidy Program “Project of Decommissioning, Contaminated Water and Treated Water Management(Development of Analysis and Estimation Technologies for Characterization of Fuel Debris (Development of Estimation Technologies of RPV Damaged Condition, etc.)".

Presenting Author: Takuya Yamashita Japan Atomic Energy Agency

Presenting Author Biography: Takuya Yamashita is a research engineer of the Japan Atomic Energy Agency (JAEA). He joined JAEA in April 2011, just after the Fukushima Daiichi nuclear accident, and worked in the Fast Reactor department until 2017. After that, he was reassigned to the Fukushima department by a quirk of fate. His work focuses specifically on the Fukushima Daiichi Nuclear Power Plant accident progression.