A Comparison of the Behaviour of Vitrified HLW in Repositories in Salt, Clay and Granite. I: Experimental
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A COMPARISON OF THE BEHAVIOUR OF VITRIFIED HLW IN REPOSITORIES IN SALT, CLAY AND GRANITE. I: EXPERIMENTAL. L. A. Mertens, W. Lutze, Hahn-Meitner-Institut, Glienicker Strasse 100, 1000 Berlin 39, FRG., J. A. C. Marples, AERE Harwell, Oxfordshire, OXIl ORA, UK., P. van Iseghem, SCK/CEN, Boeretang 200, 2400 Mol, Belgium, and E. Vernaz, CEA Valrho, Marcoule BP 171, 30205 Bagnols sur C~ze, France. 1. Introduction Laboratories from 11 countries participated in a 'Round Robin' comparative test excercise using the European Commission's Repository Systems Simulation Test [1,5). 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. Most of the laboratories only covered one option: clay, 3, granite, 10, and salt 6. The test procedure was closely specified by the European Communities. This contribution and a companion paper (2] summarize the acquired information. The HLW 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 90'C), 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. 2.
Experimental section
Though the various laboratories followed the test procedure closely, minor deviations have been reported in some cases. Therefore, the details reported here are representative but not necessarily exactly the same as those applied in every participating laboratory. 2.1 Test equipment: The autoclave (Fig. 1) was fabricated from stainless steel AISI309 (NS 24),which is the steel into which the glass is to be cast by Cogema. Surface area ratio of the steel and the glass is approximately that which will occur in practice. It comprised: - the pot and a lid with outlet and ethylene-propylene O-ring seal. - a specimen holder (NS 24) comprising a grill with 3 pins welded into it at right angles using some of the holes; defining a volume 3 of 40 cm free from environmental materials. Two stainless steel meshes of
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