Predictive Methods in the Assessment of Alloy 600 PWSCC Failures in Operating Pressurized Water Reactors

This paper reviews the role of fundamental factors such as stress, temperature and material microstructure in contributing to the PWSCC susceptibility in Alloy 600 components of operating PWRs. The effect of residual stresses from fabrication, cold work and welding as well as cyclic work hardening are considered. The influence of fabrication practice and the resulting microstructural parameters such as grain size, carbide distribution and ghost boundaries are considered. The paper considers the development of deterministic and probabilistic PWSCC susceptibility models to predict failures in the components and explain how these are applied to operating units. Investigation of service failures in the base metal and welds are considered.