Patent Number: 047972327
Section: abstract

The invention relates to a process for the preparation of a borosilicate glass containing nuclear waste.. In this process, an inactive borosilicate matrix is prepared in an aqueous medium by mixing the following:. a silica-based gel precursor, PA0 a concentrated aqueous solution of a boron compound, and PA0 a concentrated aqeuous solution of the vitrification adjuvant,. in proportions corresponding to the composition of the final glass minus the waste, with stirring at a high rate of shear, at a temperature of between 20.degree. C. and 80.degree. C., preferably at 65.degree.-70.degree. C., at an acid pH, preferably a pH of between 2.5 and 3.5, so as to form a gelled solution, and the said matrix is heat-treated and the nuclear waste is added at any stage during the said treatment to form, by melting, the final borosilicate glass containing the said waste.. The process according to the invention is applied to the treatment of nuclear waste, especially to solutions of fission products.