Cask

A heavily shielded container used for the dry storage or shipment (or both) of radioactive materials such as spent nuclear fuel or other high-level radioactive waste. Casks are often made from lead, concrete, or steel. Casks must meet regulatory requirements and are not intended for long-term disposal in a repository. For additional detail, see Dry Cask Storage and Dry Spent Fuel Storage Designs: NRC Approved for General Use.