Abstract: Method for preventing malfunctions in the solidification of radioactive wastes contained in an aqueous waste solution in a glass, glass ceramic or glass ceramic-like matrix wherein the wastes are spray-dried and calcinated. Diatomaceous earth or diatomaceous earth-like substances in solid form are added to the aqueous waste solution before the spray drying step in quantities of 45g/l to 70g/l and in grain sizes of which more than 85 percent by weight of the grain size distribution are grain sizes from 6 to 75.mu..

Abstract: Highly radioactive liquid wastes are permanently stored in a solidification matrix containing the components of a known borosilicate glass together with nucleation agents selected from the group consisting of oxides of Li, K, Mg, Mo and Cr, fluorides of those metals and of Al, and pure noble metals in the elemental form with particles with sizes smaller than 0.1 .mu.m in diameter, and up to 35% by weight of waste fission and corrosion products or waste fission and corrosion products and gadolinium oxide. The product is produced by denitrating and calcining the radioactive waste solution, melting the calcined waste product together with a borosilicate frit containing nucleation agents at a temperature of between 1,050.degree. and 1,200.degree.