The effect of cladding restraint on fission gas release behavior

This paper describes the results of a study on FP (fission product) gas release behavior under PCI (pellet-cladding interaction) restraint. The test data on the small gap fuel showed that an intense PCI caused FP gas to be released in a different manner from the well-known diffusion dependency. The comparison of the irradiation data of different pellet end shape fuels also clarified that the extent of PCI could vary release behavior. The chamfer pellet fuel exhibited in its gas release a linear time response, for which an interpretation was tried by a simple model comprised of bubble growth under compressive stress and gas release in a pressure gradient. (orig.)