Geological setting of the Morsleben radioactive waste repository, with emphasis on hydrogeological modelling

The Morsleben radioactive waste repository is situated in the abandoned Bartensleben salt mine in the Allertal salt diapir, which is located in the Allertal fault zone. The radioactive waste repository was established on the fourth main level, 506 in below ground. It was licensed by the authorities of the former GDR. The permit for disposal of radioactive wastes with low content of actinides is valid until 30 June 2000. According to the nuclear materials law of the Federal Republic of Germany, an application must be made for a new license authorizing utilization after this date. The obligatory safety analysis will include determinations of possible transport paths and calculations of migration rates of radionuclides from the repository into the biosphere via the groundwater. This paper describes the Mesozoic to Quaternary sediments overlying and surrounding the diapir; a hydrogeological model of these strata has been developed as a basis for numerical water-movement calculations. The main hydrographic feature of this fault zone is the Aller River itself. Drilling and testing will end in October 1995 and the final results will be available in the middle of 1996. Since the numerical data with which the preliminary calculations were made may be considerably modified as a result of these investigations, the hydrogeological features will only be described qualitatively in this paper