Some essence of the core status evaluation project (JFY2016-2017) for decommissioning of the FDNPS

Sato, Ikken 

It is necessary to maximize the knowledge with: (1) In-depth data analysis of 1F plant data, (2) Well-targeted experiments addressing the BWR-specific uncertainties, and (3) Evaluation of accident progression behavior based on integration of all the available information. In-depth analysis of Unit 2 and Unit 3 plant data was conducted as step (1). This step provided outlines of accident progression behavior in these units. This information is then reflected into SA code analyses. A series of plasma heating experiments using a test section simulating a part of BWR core were conducted to get insights for the above step (2). Core material relocation behavior in the high-temperature range up to ceramic fuel melting was observed in these tests. The above step (3) consisted of an evaluation of core thermal energy for Unit 2 and Unit 3.