抄録
The diffusion parameters of 133Xe in irradiated sintered pellets of several different uranium carbides were measured in postirradiation annealing experiment in the temperature range of 1, 000°1, 400°C.
A rapid increase of 133Xe release was observed when the pellets reached 200°600°C while being heated to 1, 000°C. It was considered that this rapid release of 133Xe could be explained, not by the diffusion model, but by the desorption phenomenon of 133Xe evolved and adsorbed on the pellet surface during irradiation.
The apparent diffusion coefficient (D') obtained here appears to depend mainly on the actual surface area of the pellet and not on the fraction of its theoretical density. The values of D' obtained here for carbides at 1, 400°C were of the same order of magnitude as the values reported for sintered 97% dense UO2 pellets.
The diffusion coefficients (D) of all samples were found to be in the range of 1×10-191×10-18cm2/sec at 1, 000°C and 1×10-162×10-15cm2/sec at 1, 400°C, having activation energies of 5078 kcal/mol.
