A borosilicate glass for the Italian high level waste. Characterization and behaviour

The objective of this work was the selection of a borosilicate glass composition suitable for the solidification of the HLW stream coming from the treatment of all the high level wastes stored in Italy (MTR, CANDU and ELK RIVER). This work was part of an Italian research project named 'ULISSE Project'; its main concept is to carry out a pre-treatment of the wastes, in order to concentrate the HLW fraction and to simplify the vitrification process, separating the most part of the inert salts. Many glass compositions were tested and the glass named BAZ was finally selected. A complete characterization of this glass was carried out and the same characterization programme was applied to the BAZ glass produced in the IVET plant. A comparison between the two glasses and a critical evaluation of their performance with respect to other nuclear waste glasses durability was performed. (author) 14 figs., 8 tabs., 21 refs