The central climate change scenario: SKI's SITE-94 project to evaluate the future behaviour of a deep repository for spent-fuel

Part of the SITE-94 project currently being performed by the Swedish Nuclear Power Inspectorate (SKI) involves the construction of scenarios to assist in the evaluation of the future behaviour of a deep repository for spent-fuel. The project uses real data from the Aspoe site, and assumes that a hypothetical repository (reduced in size to approximately 10 %) is situated at about 500 m depth in granitic bedrock in this coastal area of SE Sweden. A Central Scenario, involving prediction of the climate and consequent surface and subsurface environments at the site for the next. 120,000 years, lies at the heart of the scenario definition work. The Central Climate Change Scenario has been based on the climate models ACLIN (Astronomical climate index), Imbrie and Imbrie (1980) and the PCM model by Berger et al. (1989). These models suggest glacial maxima at c. 5000, 20,000, 60,000 and 100,000 years from now. The Aspoe region is predicted to be significantly affected by the latter three glacial episodes, with the ice sheet reaching and covering the area during the latter two episodes (by up to c. 2200 m and 1200 m thickness of ice respectively). The objective of this work is to provide a first indicator of the physical and hydrogeological conditions below and at the front of the advancing and retreating ice sheet, with the aim of identifying critical aspects for modelling impacts of future glaciations on far-field groundwater flow, rock stress and groundwater chemistry. The output of this study is a time-dependent description of the properties of the site, coupled to predictions of key parameter values at different times in the future, for input into performance assessment modelling. (authors). 30 refs., 4 figs