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

Shirasu, Noriko  ; Kuramoto, Kenichi*; Yamashita, Toshiyuki; Ichise, Kenichi ; Ono, Katsuto; Nihei, Yasuo

To evaluate irradiation behavior of the ROX fuel, irradiation experiment was carried out using 20% enriched U instead of Pu. Three fuels were prepared; a single phase fuel of YSZ containing UO (U-YSZ), two particle-dispersed fuels of U-YSZ particle in spinel or corundum matrix. The U-YSZ particles were prepared by crashing presintered U-YSZ pellets and by sieving them. These fuels were irradiated in Japan Research Reactor No.3 for 13 cycles, about 300 days. Though many cracks were observed in the pellets by X-ray photographs, significant appearance changes were not observed for all fuel pins. Distribution of typical FPs was analyzed by the scanning over the fuel pin. Non-volatile nuclide remained in the fuel pellet. On the other hand, a part of Cs moved to the gaps between the pellets and to the insulators. Cs and Cs showed different distributions at the plenum. Fuel pellets were taken out from fuel pins without bonding. Spinel decomposition and subsequent restructuring were not observed probably due to low irradiation temperature.