Abstract: Radioactive waste may be stored in storage containers that are suitable for long-term disposal, but do not provide adequate shielding. By assembling an overpack from metal plates, the metal plates each being substantially flat, and the overpack providing sufficient shielding for the radioactive waste, and enclosing the storage container that contains radioactive waste in the overpack, the storage container can then be stored safely in a weatherproof enclosure. The enclosure does not need to provide radiation shielding. The plates can be stored as a flat-pack, and assembled into the overpack when required.