Handling and final storage of unreprocessed spent nuclear fuel

The following stages in the handling of the fuel on its way to final storage are proposed in this report. 1) The spent fuel is stored at the nuclear power plant for at least six months. 2) The fuel is then transported to a central storage facility for spent nuclear fuel, where it is stored for 40 hears. 3) The fuel is transported to an encapsulation station located above ground in connection with the final repository. Here the fuel rods are separated from the other parts of the fuel assemblies. The fuel rods are enclosed in copper canisters and the cavities are filled up with lead. Other radioactive material is embedded in concrete cubes. 4) The copper canisters are taken to a final repository which is built at a depth of approximately 500 metres in the bedrock. The copper canisters are surrounded by blocks of highly compacted bentonite - a clay which possesses very low permeability and which swells considerably upon absorbing water. 5) The facility can be kept open as long as surveillance is deemed desirable. It is then sealed by filling all tunnels and shafts with a mixture of quartz sand and bentonite. 6) The concrete cubes containing the metal components of the fuel assemblies are deposited in a separate repository at a depth of 300 metres in the bedrock. This repository is sealed with concrete, sand and bentonite. (author)