Criteria for evaluation of the long-term safety of underground waste disposal sites in evaporite bodies. The distribution of bromide and rubidium in carnallite rocks. Final report

The study reports theoretical and experimental work for determination of the relative distribution of bromide and rubidium in carnallite rocks. The derived theoretical models together with existing models are taken as baseline data for an interpretation of the constituent materials and substances in primary and secondary carnallite rocks. The evaluation criteria derived are explained with an example using specimens from the Gorleben salt dome. The results and data established by this study are a representative example of a scientific approach for an assessment of materials data of evaporite bodies and evaluation with regard to the long-term safety of such formations in their capacity as ultimate waste disposal sites, and are an example that can be cited in response to assertions that there are 'fissured zones' in the Gorleben salt stock which might involve the penetration of aqueous solutions from the roof rock down to depths of 800 or even 1000 m. The study yielded data on the long-term safety of a repository in the Gorleben salt stock that can be considered reliable and specific geoscientific data with general applicability, obtained at comparatively reasonable cost. The study's approach and results for a geochemical evaluation of the primary and secondary carnallite rocks of an evaporite formation can be applied to other Zechstein deposits as well. The evaluation procedure and the results derived can be applied to the assessment of planned geologic repositories at an early stage of the exploration work. (orig.)