Below is a drawing of a partial view of the interior cavity of the Holtec HI-STORM 100 carbon steel lined concrete storage cask. This model is stored above ground at numerous U.S. nuclear facilities, such as Indian Point.
As each Holtec thin-wall (1/2″ thick) stainless steel canister (about 50 tons) is loaded into a concrete storage cask, the canister walls are scrape against the carbon steel vertical MPC [canister] guide channels — the entire length of the canisters.
Carbon particles are also embedded in the canister walls, which is a trigger for galvanic corrosion.
Once cracks start in these stainless steel thin-wall pressure vessels, cracks continue to grow through the walls.
ASME pressure vessel codes require a type of inspection that can determine if the defects are such that the canister should not be put into service. The NRC knows these canisters cannot be inspected for defects, let alone repaired, but continue to approve them.
See link below for details and references on this issue.
See also new evidence from NRC Senior inspector that canister walls are impossible to inspect for defects, let alone repair.
Anyone claiming thin-wall welded canisters filled with nuclear fuel waste have or can be “inspected” is ignorant or deceptive.
For more information on Holtec issues for storage or transport go to the Nuclear Waste Holtec webpage below.
Inventory of US dry storage systems (DOE June 2013) 2-page
Other countries use thick-wall casks that don’t have these issues.