(GRS 183) Two-Phase-Flow Experiment in the Fractured Rock of the HRL Äspö

H. Kull, P. Bastian, R. Helmig, H. Jakobs, N. Jockwer, K.-P. Kröhn, J. Mönig, V. Reichenberger, U. Zimmer

Gas is expected to be generated in repositories for LLW and ILW wastes by anaerobic corrosion of canisters, radiolysis, and microbial degradation of organic substances. For that reason overpressures could be built up in disposal rooms and affect the integrity of geotechnical barriers. To assess the importance of this scenario in repositories in granite formations two-phase-flow models are needed which enable numerical simulation of gas migration through water-saturated fractures.In 1995, the Swedish Nuclear Fuel and Waste Management Company (SKB) and the German Federal Ministry of Education, Science, Research and Technology (BMBF) therefore signed a co-operation agreement in view of the performance of a German Two-Phase-Flow Experiment the Äspö Hard Rock Laboratory (HRL) in Sweden. The project involved field investigations and theoretical studies in order to provide the needed calibrated models. The project was performed by GRS1 and BGR2, while PTE3 co-ordinated the co-operation with SKB. This report describes the work performed by GRS and its subcontractor CAB4 in the years 1997 through 1999. A summary report of the German Two-Phase-Flow-Experiment including the work of BGR as well as of GRS is in preparation and will be published as SKB report.