Abstract: A unitarily cast receptacle for the storage of radioactive wastes consists of cast iron, especially spherolitic cast iron, or cast steel, and has upright walls defining a chamber in which the radioactive waste is stored above a base unitary with these walls. A cover is recessed in the receptacle and, according to the invention, is overlain by a safety cover which fits within an annular recess defined by a welding lip formed unitarily on the receptacle and defined at the upper end thereof by an upwardly open annular groove. The safety cover, which overlies the shielding cover which can be of the plug type, may have a counterlip which is likewise defined by an upwardly open annular groove.