In Situ Stress Corrosion Crack Repair and Prevention for Nuclear Waste Canisters

The U.S. depends on its fleet of nuclear facilities for the clean and reliable generation of electricity. With much uncertainty facing long term, geologic storage facilities, long duration on-site waste storage is being considered. One potential problem facing the existing fleet of nuclear waste storage canisters is chlorine assisted stress corrosion cracking (CISCC) of austenitic stainless steel. While there have been no failures or evidence of failure of any storage systems in use, needed is a cost-effective plan to repair and mitigate CISCC that can be performed in situ and results in a long term and reliable solution. VRC Metal Systems, in collaboration with our academic research partner, SDSM&T, our robotics system developer, Robotic Technologies of Tennessee, propose to apply cold spray technology to mitigate and repair SCC in 304 stainless steel. Cold spray has been shown to arrest crack growth, protect from further corrosion damage, and fully restore the hermetic seal. The small form-factor of the cold spray applicator will allow for the delivery of the cold spray applicator within the canister overpack, eliminating the need to disturb the canister and remove it from the overpack and greatly increase the safety in a potential repair situation. Mitigation of CISCC is both a safety and economic priority for utilities across the country and around the world. It is anticipated that the proposed mitigation method will completely obviate CISCC concerns for new canisters and provide a technologically sound and safe repair solution should evidence of CISCC or corrosion be detected in the existing fleet of dry storage canisters, providing assurance to the plant owner / operator as well as the public. Additionally, the development of robotic cold spray repair of stainless steel tanks could find applications in other energy sectors, such as fossil fuel storage and chemical processing tanks, thereby increasing the potential market for such a technology. VRC Metal Systems has a proven track record of success transitioning advanced technologies to DOD customers and prime contractors. We will use our quality program management system to coordinate the multidisciplinary team and ensure a successful phase I and transition to phase II and beyond.