(GRS 500) Smart Kd-Concept for Long-term Safety Assessments - Extension towards more Complex Applications

U. Noseck, V. Brendler, S. Britz, M. Stockmann, J. Fricke, C. Richter, M. Lampe, A. Gehrke, J. Flügge

A key component of long-term safety assessment for radioactive waste repositories in deep geological formations is the simulation of fluid and contaminant transport through the repository system, i. e. through large model areas over very long time frames. To describe the migration of radionuclides impacted by geochemical changes as realistic as possible a first version of the smart Kd-concept was developed and implemented into the transport program for long-term safety assessment recently. In the frame of the research project WEIMAR which is presented here, this approach was further developed based on methodological / conceptual developments as well as on a comprehensive experimental program. The approach for implementing geochemical changes and their quantitative impact on radionuclide sorption has been further developed and the geometrical model for flow and transport calculations further refined. This was based on a systematic review of potential scenarios at the reference site, on verification calculations with the geochemically coupled transport code PHAST and on a comprehensive evaluation of the hydrochemical data from the reference site. Moreover, updated probabilistic uncertainty and sensitivity analyses have been performed and the respective software package has been further developed. 

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