EVALUATION OF AUSTENITIC STAINLESS STEEL DRY STORAGE CASK STRESS CORROSION CRACKING SUSCEPTIBILITY

摘要

Many nuclear plants are now storing spent nuclear waste in NRC licensed onsite dry storage facilities, because of limited remaining space in spent fuel pools. Some of these plants are located close to the coast and are in chloride-rich environments. Because most dry storage containers are manufactured from austenitic stainless steel, a potential concern is the susceptibility of the cask materials to chloride induced stress corrosion cracking. The objective of this work was to evaluate the atmospheric chloride stress corrosion cracking susceptibility of austenitic type 304, 304L, and 316L stainless steels. U-bend samples of these alloys were assembled, placed in an environmental chamber heated to various temperatures to simulate decay heat from the spent fuel, and subjected to an accelerated exposure test involving dry deposition of sea salt and cyclic humidity exposure. To date, stress corrosion cracking accompanied by pitting corrosion was observed on all three alloys exposed under conditions where partial deliquescence of the deposited salt occurred.