Self-radiation damage in plutonium and uranium mixed dioxide

Kato, Masato   ; Sugata, Hiromasa*; Endo, Hideo

In Plutonium compounds the self-radiation induces expansion of lattice parameter and change in thermal conductivity. The expansion of the lattice parameter and thermal recovery of radiation damage in plutonium and uranium mixed dioxide (MOX) were studied in this paper. MOX powder had been kept in an ambient atmosphere for about two years. The lattice parameter of the powder was expanded up to about 0.23%. The change in lattice parameter was formulated as a function of amount of self-radiation. Three thermal recovery stage of radiation damage were observed in temperature ranges below 400C, 400-800C and above 800C. The recovery rate of three stages in total lattice expansion was about 25%, 55% and 20%, respectively, and activation energy in each recovery was estimated to be 0.14 eV 0.54 eV and 1.1 eV.