HI-STORM UMAX (Holtec International Storage Module Underground Maximum Security), licensed by the NRC under Docket
Number 72-1040, stores the canister containing the spent fuel or high level waste entirely below-ground providing a clear, unobstructed view of the entire Independent Spent Fuel Storage Installation (ISFSI) from any location. Each below-ground storage location is engineered and sized to accommodate all currently licensed dry spent fuel storage system canisters, making it
possible to store all U.S. commercial fuel in a common storage system. The stored canisters are arrayed vertically inside heavy walled steel containers, which are engineered to provide an essentially rigid and structurally impregnable housing for the canister. The heat produced inside the canister is rejected to the ambient environment by an internal ventilation system that is hardened against external loads and is configured to block the release of radiation to the environment.