A Comparison of the Behaviour of Vitrified HLW in Repositories in Salt, Clay and Granite: Part II: Results
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A COMPARISON OF THE BEHAVIOUR OF VITRIFIED HLW IN REPOSITORIES IN SALT, CLAY AND GRANITE: PART II: RESULTS J.A.C. MARPLESa, W. LUTZEb, M. KAWANISHIc and P. van ISEGHEMd aarwell Laboratory, Didcot, Oxon OXI ORA, UK. Hahn-Meitner Institut, Glienicker Strasse 100, D1000 BERLIN 39, FRG. CAbico Research Laboratory, Abico, Chiba-pre, 270-11, JAPAN. dSCK/CEN, B-2400, Mol, BELGIUM
ABSTRACT A 'Round Robin' test of the European Commission's "Repository Systems Simulation Test" has been undertaken. This involved testing an inactive simulant of the French high-level waste glass SON68 (RTT7) in containers which also held backfill, geological materials and water. Ten laboratories undertook the granite option, six salt and three clay. The test procedure was closely specified and is given in detail in a companion paper [1]. Experiments with glass powder and (optionally) solid specimens in contact with aqueous solutions were run for periods of up to one year at 90 0 C and the solutions were analysed for Si, B, Li and Mo (compulsory) and other constituents of the corroded glass (optional). The analytical results are used to compare the performance of the glass under conditions representing those that might occur in future repositories in the three media. INTRODUCTION Fifteen laboratories, representing 11 countries, from the European Community and elsewhere have participated in a "Round Robin" test of the European Commission's Repository Systems Simulation Test (RSST). The objectives were (a) to evaluate the test and (b) to compare the performance of the glass SON68 (R7T7) in simulated salt, clay and granite repository environments. The laboratories are listed in Table I. Ten undertook the granite option, six salt and three clay: some laboratories did more than one option. The vessels, shown schematically in [13, and the materials for the test were provided by the European Commission (EC) and the procedure was specified and is described in a companion paper [l]. The vessels had a volume of 250mi. The lower 200ml was filled with "repository components", whilst a steel grid and mesh defined a separate 50mi specimen chamber at the top. Water of an appropriate composition filled the interstices of the geological material and backfill ("interstitial water") and the specimen chamber ("supernatant water"). Elements in solution could diffuse from the specimen chamber to the interstitial water or vice-versa but the solids were separated by the mesh. The glass used was an inactive simulant of SON68, which is to be used to solidify the HLW at the Cap de la Hague plant in France. After a one week equilibration period at 900C, glass powder (125 - 250pm) and, in some cases, a glass coupon for mass-loss leach-rate measurements were added to the specimen chamber. The SA/V ratio was about 240m-2 if the volume of all the water in the system was used or 700m- 1 if only that in the specimen chamber was considered. The vessels were then sealed and held at 900 C for periods of 14, 28, 56, 91, 182 and 365 days before being opened and the supernatant and i
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