FABRICATION-INDUCED WELD RESIDUAL STRESSES IN AUSTENITIC STAINLESS STEEL DRY CASK STORAGE SYSTEM CANISTERS SUSCEPTIBLE TO CHLORIDE-INDUCED STRESS CORROSION CRACKING

摘要

Several in-service Dry Cask Storage System (DCSS) designs in the United States utilize an austenitic stainless steel canister to confine spent nuclear fuel (SNF). These canisters are stored within concrete shielding structures that have vents which allow for convective cooling and, consequently, expose the canister surface to any chlorides present in the atmosphere. Chloride salts that deposit on the canister surface can deliquesce in specific environments, resulting in the aqueous solution necessary to initiate chloride-induced stress corrosion cracking (SCC) if tensile stresses are present. While tensile stresses are thought to be present on the canister surface due to forming and welding operations, the magnitude of these stresses has not been quantified. This paper documents the results of a sequentially coupled thermal-structural finite element analysis for a generic canister configuration, including a discussion of analytical methods, assumptions, potential implications, uncertainties, and further potential research areas.