LAUSR

Abstract 304L SSs are used for structural components of Light Water Reactor (LWR) nuclear power plants and have been shown to face Irradiation Assisted Stress Corrosion Cracking (IASCC). This degradation phenomenon has been of great concern regarding structural integrity of reactors for lifetime extension of LWRs but is still not completely understood. This study evaluates the evolution of mechanical properties (hardening) and susceptibility to stress corrosion cracking regarding different radiation induced microstructures. These microstructures were chosen to explore representative conditions encountered in Pressure Water Reactor (PWRs) conditions but also the effect of various populations of cavities as extreme case of those reported at higher flux and temperature. Irradiation microstructures are produced by heavy ions irradiation under two different temperatures (450 °C and 600 °C) and with or without helium implantation. The evolution of microstructure, hardness and cracking susceptibility are characterized after irradiation. Calculations based on defects population are found to be in agreement with hardening measurement for irradiations with no helium implantation only. Cracking susceptibilities are characterized after slow strain rate tests performed at 4% plastic strain under PWR environment. Cracking susceptibility changes for different irradiations and quantitative assessment of the effect of irradiation microstructure on IASCC phenomenon are discussed.