Calvert Cliffs Stainless Steel Dry Storage Canister Inspection

Stress corrosion cracking (SCC) of welded stainless steel dry storage canisters may potentially impact systems exposed to corrosive atmospheric elements, such as those occurring near salt water bodies. Conditions important for atmospheric-related SCC include concentration and chemical species of the contaminants, temperature, and humidity. Calvert Cliffs Nuclear Power Plant conducted this historically important first inspection of spent fuel canisters to collect data for an SCC evaluation as part of the EPRI-led Extended Storage Collaboration Program (ESCP).

With no clear path for its ultimate disposition, spent fuel will remain in dry storage containers for an extended period of time, likely well beyond the current license period of 60 years. To ensure the integrity of stainless steel spent fuel containers in long-term dry storage, degradation mechanisms such as SCC must be evaluated. Several studies have shown that the materials used for dry storage canisters can in fact undergo SCC under the right conditions. By collecting data on the actual in-service conditions of stainless steel canisters—and combining that data with information on the conditions required for SCC—it will be possible to identify which, if any, dry storage canisters may be susceptible to SCC and when they may become susceptible.