Behaviour of sintered glasses containing simulated high level wastes under repository conditions

Within the framework of an IAEA-CNEA Research Contract established in 1992, we have studied the vitrification of simulated high level wastes (HLW) from reprocessed PHWR fuel on a laboratory scale by the alternative method of powder glass sintering. The HLW was added in a proportion of 10 wt% to alumino-borosilicate glass powder. The powder mixture was treated using the procedure of cold pressing and subsequent sintering at about 1000K. The microstructures of the sintered samples were analyzed by optical microscopy and SEM. Water corrosion tests were done in different aqueous media. Devitrification studies were conducted by heat-treating the samples at 950, 1000, 1050 and 1100K for 3, 30, 300 and 3000 h. Values of the corrosion resistance of the studied glasses, were similar to those found in the literature for waste forms produced by melting technology. We have obtained promising results indicating that the glass sintering method could be an interesting alternative for immobilization for not only high level wastes but intermediate level wastes. (author)