The process of stabilizing radioactive waste by melting it into glass material. It is usually used for residual waste from spent fuel reprocessing, but it can be used for any other waste. The liquid or crushed solid waste is mixed with glass-forming material and melted at 1,200 °C to make silicone or borosilicate glass. The result is an insoluble, stable substance. In this form, the waste can be safely stored in, for example, a final geological repository.