Modelling of Primary Water Stress Corrosion Cracking (PWSCC) of Nickel Based Alloys (NBAs) in Nuclear (PWR) Primary Coolant

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Nickel Based Alloy (NBA) materials and their associated weld metals are of interest to new build and advanced nuclear reactors due to their superior structural performance when compared with traditional steel materials. They are already implemented in US PWR reactors, noting the requirement for materials resistant to demanding environmental conditions for operating periods of ~60 to 80 years. Within the primary circuit of a PWR, structural materials are subjected to elevated temperatures in a high pressure water environment. As a result, some NBAs have shown susceptibility to Primary Water Stress Corrosion Cracking (PWSCC), and this has been confirmed by a significant programme of PWSCC laboratory testing conducted by Wood plc. Whilst it is apparent that strain levels within a material have a significant impact on PWSCC, mechanistic understanding of factors that increase PWSCC susceptibility is limited. Therefore, it is proposed that a continuum mechanics modelling approach is applied to understand the damage build-up within these materials during a PWSCC test. This approach can be extended to understand the more complex behaviour involved in testing of composite weld specimens of parent material, weld and associated heat affected zone