XENON DIFFUSIVITY IN THORIA- URANIA FUEL

摘要

Postirradiation annealing tests were performed to obtain the ~(133)Xe diffusion coefficients in uranium dioxide (UO_2) and mixed thorium-uranium dioxide [(Th-U)O_2] fuels. Specimens were a single-grained UO_2, a poly-crystalline UO_2, and a polycrystalline (Th-U)O_2. The (Th-U)O_2 specimen was a mixture of 35% ThO_2 and 65% UO_2. Each 300-mg specimen was irradiated to a burnup of 0.1 MWd/t U. Postirradiation annealing tests were performed at 1400, 1500, and 1600℃, continuously. The xenon diffusion coefficients for the nearly stoichiometric single-grained UO_2 agree well with the data of others. The xenon diffusion coefficients in the polycrystalline (Th-U)O_2 are approximately one order lower than those in the polycrystalline UO_2. The xenon diffusion coefficient in the (Th-U)O_2 increases with the increasing oxygen potential of the ambient gas.