Parameterization of oxide film models with respect to SCC initiation of 316SS under PWR conditions

Engineering alloys, such as austenitic stainless steels and nickel-based alloys used in nuclear power plants, protect themselves from their high temperature water environment by forming a passive oxide layer. It makes the materials resistant to uniform corrosion but, potentially, makes them susceptible to stress corrosion cracking. The oxide film can be modelled using Point Defect and Mixed Conduction Models. The PDM analytically addresses generation, transport and consumption of point defects such as vacancies and interstitials. The associated MCM treats the coupling between ionic point defects and electron transport. Parameterization of is performed against the evolution of the oxide layer thickness versus exposure time, compositional profiles of Fe, Cr, Ni and O through the oxide layer and in-situ electrochemical impedance spectroscopic (EIS) measurements. Here we demonstrate the parameterization of a one-dimensional model for 316-type stainless steel in PWR water. Preliminary results for a two-dimensional model are also discussed with respect to the role of the oxide and its interface with the alloy substrate during initiation of stress corrosion cracks.