(GRS 163) Einfluß netzwerkartiger Strukturen der Grubenhohlräume auf die Langzeitsicherheit eines Endlagers im Salinar

Jürgen Brenner, Dieter Buhmann, Thomas Kühle

The long-term safety of a repository with radioactive waste in salt highly depends on the performance of the near field within the salt dome. In this report, the differences in modelling the open voids of the near field as a tree-like structure or as a network structure are investigated. Furthermore, the consequences of a gas production in the emplacement sites have been investigated, and the location of the brine intrusion into the near field has been varied to demonstrate its influence on the calculated consequences. The repository was assumed to be for direct disposal of spent fuel elements from light water reactors. The results of the calculations for tree-like structure show small differences to the results for network structure, which can be mainly attributed to differences in the numerical procedures of the respective computer codes. The computer code LOPOS is used for network structures. It turned out to be more flexible for complex near field structures than the computer code REPOS for tree-like structures. In deterministic calculations, the location of the brine intrusion turned out to be of high importance to the calculated doses. This was supported by a probabilistic calculation using Monte-Carlo techniques.The gas production in the near field turned out to be of minor influence on the doses for the given repository. All the calculated doses are below the limit of the German radiation protection law.