Development and validation of a new experimental device for studies of iodine stress corrosion cracking of zirconium alloys

Abstract : Zirconium alloys are widely used in the nuclear industry as cladding material due to their good thermo-mechanical, chemical and neutronic properties as well as an excellent general corrosion resistance in many environments. Nonetheless, Iodine-induced Stress Corrosion Cracking (ISCC) is an identified failure mechanism that can occur in nuclear fuel cladding as a result of Pellet Cladding Interaction (PCI) during incidental power transients in the reactor. In this study a new experimental device allowing studies of ISCC in a controlled chemical environment is presented. The experiments are performed in an environment that is free of contaminants. First results show that the time to rupture of the specimen is inversely related to the iodine partial pressure. The lowest tested iodine partial pressure, 150 Pa, resulted in an ISCC crack. Post-Mortem microstructural observations provide evidence of iodine corrosion of Zircaloy-4.