THREE PRESSURE PEAKS ANALYSIS FOR THE TEPCO FUKUSHIMA DAIICHI UNIT 2 BY THE SAMPSON CODE

摘要

In view of the 1F decommissioning project, the Institute of Applied Energy (IAE) has been analyzing the course of the accident using the SAMPSON code with an aim to investigate its progression in detail. For 1F Unit-2, certain discrepancies between measurement values and analysis results still exist. For example, although three pressure peaks occur after a manual activation of a safety relief valve (SRV), its mechanism is yet unclear. This study seeks to elucidate the mechanism for the three pressure peaks using a new presumption for the relocation of the debris through the lower part of the core. The current results could reproduce the basic tendency for each peak. However, some deviations between simulation results and measured values indicate the necessity for further improvement of the thermal-hydraulic model used in SAMPSON.