Roller Burnishing Process to Mitigate CISCC of Welded Canister for Spent Nuclear Fuel Storage

A roller burnishing process was employed to control the surface roughness and residual stress, offering a practical solution for mitigating chloride-induced stress corrosion cracking (CISCC) in the aging management of austenitic stainless-steel canisters. The surface roughness and residual stress before and after roller burnishing were evaluated using a flat welded plate and a scaled canister model. The surface roughness improved by 74.5% in the former model and 60% in the scaled canister model following roller burnishing. The flat welded plate exhibited compressive residual stress at the yield strength level of stainless steel after treatment. Similarly, the scaled canister model displayed compressive residual stress comparable to the yield strength of stainless steel. Thus, the roller burnishing process enhanced surface roughness and induced compressive residual stress, effectively eliminating tensile residual stress in the weld zone and heat-affected zone. This method is expected to reduce the number of crack initiation sites and prevent crack initiation from pits caused by localized corrosion, thereby improving the CISCC resistance of austenitic stainless steel.