Stress Corrosion Cracking Mitigation and Fatigue Strength Improvement of Light Water Reactor Components Using Low Plasticity Burnishing (LPB)

Stress corrosion cracking (SCC) and fatigue can dramatically reduce the service life of light water reactor (LWR) components, including pressure vessels, steam generator nozzles, pressurized nozzles, and surge lines. Residual tensile stresses, generated from welding and fit-up, are significant contributors to SCC and fatigue failure. The introduction of compressive residual stresses into these critical regions can dramatically reduce the risk of failure, mitigate SCC, and improve fatigue strength. Low plasticity burnishing (LPB) is a reliable and reproducible method of producing deep compressive residual stresses in complex geometric components. Furthermore, LPB produces a very smooth surface finish, which aids in nondestructive inspection and examination. Finally, LPB tooling can be integrated with existing delivery platforms that are used for the manufacture and repair of LWR components. Therefore, this project will develop an LPB process to treat the critical regions of the LWR, providing a substantial increase in service life, reduced inspection frequency, and complete SCC mitigation. Commercial Applications and other Benefits as described by the awardee: The LPB technology could play a pivotal role in creating more reliable and efficient reactor systems that are capable of safely operating well beyond the current 40-year licensing period.