Systems analysis 'Mischkonzept': Analysis of the long-term safety of repository design concepts for heat generating radioactive wastes

The long-term safety analyses for the systems analysis 'Mischkonzept' were performed taking as a basis three selected repository design concepts with two different disposal conditions each, and a further design concept with only one disposal condition. The analyses refer to the mine workings as used in the SAM plans, to the cap rock and biosphere models as used for evaluations of the Gorleben site. The radioactive waste types considered by the safety studies are high-level radioactive wastes, spent fuel elements, and heat generating medium-level radioactive wastes. For every design concept, deterministic long-term safety analyses were carried out assuming the input parameters to be best estimate values. For two concepts, i.e. disposal in boreholes only or disposal in boreholes and mine roadways, Monte-Carlo simulations were performed in order to take into account uncertainties in the input parameter values. (orig.)