Post-irradiation examination on particle dispersed rock-like oxide fuel

To evaluate the irradiation behavior of the rock-like oxide fuel, irradiation experiments were carried out. Three fuels were prepared; a single phase fuel of yttria-stabilized zirconia containing UO2 (U-YSZ) and two particle-dispersed fuels of U-YSZ particles in spinel or corundum matrix. U-YSZ particle sizes were about 100–200 μm. These fuels were irradiated in Japan Research Reactor No. 3 for about 280 days. Post-irradiation examinations such as visual inspection and γ scanning were carried out. No significant appearance changes were observed. The swelling behavior of the fuel pellets was negligible for all fuels. Axial and radial distributions of typical fission products (FPs) were analyzed by γ scanning. Cs moved partly to the gaps between the pellets and to the insulators. The distribution of 134Cs was different from that of 137Cs, especially for corundum-based fuel. The single phase fuel of U-YSZ showed great retention of 137Cs.