Keywords:Fukushima Daiichi Nuclear Power Plant, Decommissioning, Fuel debris, Geopolymer
In order to complete the decommissioning of the Fukushima Daiichi Nuclear Power Plant, it is necessary to develop construction methods and technologies related to the large-scale retrieval of fuel debris remaining in the RPV. In the existing small-scale method, a method of gradually picking debris divided into small pieces using a robot arm is being studied. In this construction method, there is a plurality of complicated processes, which requires a great deal of time and cost. Therefore, by coating geopolymer inside RPV, which is a material with excellent heat resistance, radiation resistance and nuclide confinement performance, the fuel debris remaining in the RPV and the internal structures will be integrally solidified, which would lead to take them out safely and efficiently. In this study, the applicability of the geopolymer was examined by clarifying the physical properties of the geopolymer required for the above-mentioned large-scale fuel debris retrieval method. In addition, from the viewpoint of satisfying the required functions for construction, the physical properties according to the type and amount of the geopolymer additive were evaluated.