The release behavior of metallic fission products from Triso-coated UO2 particles was studied by performing post-irradiation heating tests at temperatures ranging from 1600 to 1900C. It was found that 137Cs, 134Cs, 110mAg, 154Eu, and 155Eu were released from the particles, via the coating layers, during post-irradiation heating. The diffusion coefficient of 137Cs in the SiC layer was deduced from release curves which were based upon a simple diffusion model that assumed the existence of a one-layer coating. Fractional release measurements suggested that the diffusion coefficient of 110mAg in SiC was larger than that of 137Cs.

K.Minato, T.Ogawa, K.Fukuda, H.Sekino, H.Miyanishi, S.Kado, I.Takahashi.: Journal of Nuclear Materials, 1993, 202[1-2], 47-53