Testing and modelling the influence of irradiation on iodine-induced stress corrosion cracking of Zircaloy-4 Original Research Article

For a better knowledge of the effect of irradiation on iodine-induced stress corrosion cracking (I-SCC) of Zircaloy-4, a series of tests has been performed. The test procedure was based on the internal pressurization of portions of cladding tubes, fresh or after irradiation, in the presence of iodine. Using a special technique, a sharp internal crack can be made to get information on I-SCC crack growth rates. It was found that the irradiation reduces the stress intensity factor for I-SCC from 3.2 to 1.5 MPa m12 after one power reactor cycle. On the other hand, the lifetime under static iodine stress corrosion cracking was similar in both cases owing to irradiation hardening. Using these data, the SCC lifetime for pellet-cladding interaction behaviour can be inferred from the addition of initial intergranular and later transgranular crack growth times computed from crack growth rate measurements.