Abstract: An underground repository for the storage of radioactive material. The repository consists of an inner cavity surrounded by a shell of rock. The shell of rock is surrounded by a shell of clay, and the body formed by the shells of rock and clay is enclosed in an outer underground cavity. A hollow cylindrical member is placed in an upright position inside the inner cavity. The space inside and outside the cylindrical member is filled with spherical bodies of concrete which are provided with through-going openings. Radioactive material formed into rods is accommodated in the openings in those spherical bodies which are placed in the lower part of the interior of the cylindrical member.