Analysis of deposits inside the reactor at Fukushima Daiichi Nuclear Power Station in JFY 2017-2018; The Subsidy programs "Project of Decommissioning and Contaminated Water Management in the FY2016 Supplementary Budget, (Development of Technologies for Grasping and Analyzing Properties of Fuel Debris)

Nakayoshi, Akira  ; Mitsugi, Takeshi ; Sasaki, Shinji  ; Maeda, Koji  

At the TEPCO's Fukushima Daiichi Nuclear Power Station (1F), an investigation inside the reactors has been carried out, and R&D has been made on methods of fuel debris retrieval and storage after retrieval. In order to carry out the decommissioning work safely and steadily, understanding characteristics of fuel debris in the reactors is required. Therefore, in the development of technologies for grasping and analyzing properties of fuel debris project, the characteristics of simulated fuel debris, such as hardness, drying behavior, etc., of fuel debris for design of removal and storage, have been investigated and estimated, and provided to other projects conducting the decommissioning work. As part of this project, U-containing particles in samples (e.g., deposit on the investigation equipment, sediment in the reactors, etc.) obtained during the internal investigation of the reactors of 1F units 1 to 3 were analyzed. This report summarized the results of FE-SEM/WDX, FE-SEM/EDS, STEM/EDS, and TEM analysis, which were extracted from all analysis results obtained, as a database for the evaluation of the generation mechanism of U-containing particles. The analyses were performed at the JAEA Oarai Research and Development Institute and Nippon Nuclear Fuel Development Co., LTD.