The Morsleben repository has been in operation since 1971 as a repository for low- and intermediate-level radioactive waste. Until the end of the disposal phase in 1998 a waste volume of about 37,000 m(3) with a total activity of 4.5.10(14) Bq was disposed of. Currently, the German Federal Office for Radiation Protection (BfS) is applying for the licence to finally close the repository. Concerning the possible release of radionuclides to the biosphere, the repository is subject to German radiation protection regulations. Their fulfilment has to be proven by means of numerical calculations as a part of the safety case. A simplified repository model has been developed by GRS and used for calculating the consequences of different scenarios and variants, as well as for a probabilistic uncertainty and sensitivity analysis. The application for licensing is, among others, based on these results. In this paper the main features of the model and the underlying assumptions, as well as the most important calculation results are presented and explained.
