The life expectancy of the stainless-steel canister, which is the primary containment of the spent nuclear fuel, varies based on the environment. However, conservative estimates put the life expectancy of the canister at hundreds of years given the system is both robust and has no active components.
Initially, the NRC licenses each system for a 20-year period with the ability, based on aging management program and inspection, to renew the license for an additional 40 years. This renewal process goes through extensive review and inspection.