Method for the conditioning of high level radioactive wastes for their safe storage and disposal

A method is described for the treatment of solidified high level radioactive wastes to enable them to be safely stored or disposed of in an approved manner. The solidified waste is embedded in a matrix of pure metals or metal alloys. The metals may be Pb, Pb/Sb alloys, Pb/Sn alloys, Pb/Bi alloys, Pb/Zn alloys, or mixtures of these, or Al, Al/Si alloys, Al/Mg alloys, Al/Cu alloys, or mixtures. The matrix is clad with non-corrosive material, selected from stainless steel, Ti, Pb, Pb alloys, Al, Al alloys, or mixtures of same. A non-corrosive container is filled with the solidified waste and is heated to above the melting temperature of the metallic matrix material used to embed the waste. The matrix material is then added and the container is cooled. The container may then be degassed. The solidified waste feed may be in the form of a vitreous material containing the high level waste; this vitreous material may consist of a lead borosilicate or a mixture of non-lead borosilicates and phosphate glasses, and the method of preparing it is described. (U.K.)