HI-STORM UMAX (Holtec International Storage Module Underground MAXimum Capacity) is an underground Vertical Ventilated Module (VVM) dry spent fuel storage system engineered to be fully compatible with all presently certified multi-purpose canisters (MPCs) under USNRC CoC 72-1014 (HI-STORM 100 dry cask storage system) and CoC 72-1032 (HI-STORM FW dry cask storage system).


HI-STORM FW (Holtec International Storage Module Flood and Wind) is Holtec International’s highest capacity Multi-Purpose Canister (MPC) system for the dry storage of used nuclear fuel. HI-STORM FW is designed to provide physical protection of the used fuel, radiation shielding, and passive heat removal during interim storage.



HI-STORM 100U is the underground counterpart of the presently licensed above-ground models. The underground HI-STORM vertical ventilated module is the latest to join the HI-STAR/HI-STORM family of HLW storage systems. Licensed under USNRC CoC 72-1014 (HI-STORM 100 dry cask storage system) the HI-STORM 100U stores the spent nuclear fuel completely below grade taking full advantage of the shielding offered by the surrounding soil and concrete.


The HI-STORM 100 System is designed to accommodate a wide variety of spent nuclear fuel assemblies and other radioactive materials in a single overpack by utilizing different MPCs. The HI-STORM 100 System utilizes the HI-TRAC Transfer Cask for transporting the MPC from the spent fuel pool and for inter-cask MPC transfer required for on-site storage and off-site transport.