In-Situ Structural Repair and Protection of LWR Components Using Cold Spray

A major problem facing the existing U.S. fleet of Light Water Reactor facilities is stress corrosion cracking of austenitic nickel and iron alloys, which comprise the bulk of wetted components in LWR facilities; up to 70% of wetted non-fuel areas in a typical facility, making this problem particularly widespread and especially prevalent with extended service life. Cold spray technology offers an effective solution to repair corrosion damage that can be applied at low temperature, therefore minimizing substrate heating, maintaining dimensional stability, and avoiding unwanted thermal effects (HAZ, thermal stresses, dilution layer formation, etc.). The repair will arrest crack growth, protect from further corrosion damage, and fully restore load carrying capacity of the component, and can be applied in-situ, eliminating the otherwise necessary component removal process. In Phase II, the project team selected structural materials and developed statistical material property data for future implementation efforts, evaluated surface preparation techniques and repair geometry effects, developed several advanced cold sprayed materials and testing methods, optimized the cold spray material through the development of high temperature stabilization techniques, designed, implemented and verified equipment modifications to enable in- situ repair within the LWR facility, and established working relationships with a LWR manufacturer, a DOE National Laboratory, and a large owner/operator, resulting in the identification of transition applications and demonstration of a cold spray repair on a LWR component. The phase IIA project will continue development of structural materials and transition cold spray by qualifying a repair in an in-situ application. VRC will work with our owner/operator contacts to develop in-situ cold spray repair, mockup demonstration, and code justification for cold spray in these applications. The team will develop novel material systems for LWR application, along with equipment augmentations and portable robotics for in-situ structural repair. This effort advances the state of the art in cold spray repair and develops the foundation for ASME code consideration, directly in line with the DOE’s need for in situ mitigation and repair of corrosion damage in LWR’s, offering owners/operators a cost-effective means of plant sustainment and reducing the overall maintenance burden of aging reactor components. This repair approach also improves the safety of LWR facilities, which provides both a benefit to the plant owner/operator, as well as the general public.