A comparison of the behavior of vitrified HLW in repositories in salt, clay and granite. I: Experimental

Laboratories from 11 countries participated in a round robin comparative test exercise using the European Commission's Repository Systems Simulation Test. The compulsory core part of this exercise involved testing an inactive simulant of the French high-level waste glass (SON68) in containers in which the conditions were similar to those that might occur after disposal of vitrified waste in a future repository. There were three options for the test, representing repositories in clay, granite and salt. Fifteen laboratories, mostly from within the European Community, but including laboratories from USA, Canada and Japan took part in the round robin. The HLW (high-level radioactive waste) borosilicate glass SON68 (R7T7), to be returned to and eventually disposed of in various geological repositories by Cogema's reprocessing customers, was tested in a stainless steel autoclave developed and provided by CEA, Marcoule. The glass was prepared and delivered by CEA; together with crushed granite, sand, smectite and groundwater for the granite option. SCK-Mol provided the clay, smectite, sand and the recipe for claywater, HMI-Berlin the recipe for the rock salt composition. The analytical method was the only variable to be chosen by the participants. After termination of the experiments (duration 14-364d, temperature 90C), the concentrations of the glass constituents Si, B, Mo, Li, in solution had to be determined. The data base was used to evaluate the test procedure and to identify analytical problems