CHARACTERIZATION OF FUEL DEBRIS BY LARGE-SCALE SIMULATED DEBRIS EXAMINATION FOR FUKUSHIMA DAIICHI NUCLEAR POWER STATIONS

摘要

The understanding of characteristics of the damaged fuel debris in Fukushima Daiichi Nuclear power station is one of the important issues for the defueling operations such as removing from the reactor, handling and storage. Actual fuel debris are considered to be experienced rapid quench by cooling water injection, and to have heterogeneous morphology due to complicated solidification process of the mixture of melted UO_2 and structural components. Hence it is necessary to conduct large-scale experiment of simulated debris to estimate the characteristics of heterogeneous debris and the effect of non-equilibrium solidification process. The objective of this study is to investigate the characteristic of fuel debris by using large-scale experimental facility. Two types of fuel debris were investigated. One is heterogeneous debris consists of metal and ceramics produced under slow cooling condition. The other is powder debris produced under water quenching.