Oxidation behavior and some material properties of sintered (U,Zr)O specimens

Takano, Masahide ; Nishi, Tsuyoshi; Sudo, Ayako 

For the removal operation of fuel debris of the Fukushima Daiichi Nuclear Power Plant, some material properties of sintered (U,Zr)O solid solution specimens were measured. Their heat capacity and thermal conductivity were determined in the temperature range from room temperature to 1073 K. Micro Vickers hardness and electrical resistivity were also measured at room temperature as a function of U fraction. In addition to these material properties, the correlation between phases and O/M ratios of U-Zr-O system under oxidizing conditions was investigated. In the (U,Zr) hyperstoichiometric region, the hypothetical O/U ratio in the solid solution was found to be independent of either U fraction and crystal structure. Further, three orthorhombic phases in the U-Zr-O system under more oxidizing conditions were identified, and their phase relationship was successfully defined.