Abstract: A storage element for use in the recovery of heat originating from the cooling of radioactive wastes including a first element for the storage of radioactive waste having a first closed shell including the wastes, and disposed within a second closed shell, both shells being of generally spherical shape, the second shell bristling with externally projecting radial points or spines, the value between the two shells being filled with a non-contaminatable fluid, promoting the transfer of heat originating from the cooling of the wastes from the first towards the second shell, of which the points or spines serve as radiators in relation to the external medium.