Radionuclide Transport on the Host-Rock Scale: Coupled Physics and Safety Assessment

The APaRat-project investigates radionuclide transport through geological barriers over the one-million-year timescale, with the goal of supporting long-term safety assessments for deep geological repositories (DGRs). It aims to define conservative yet realistic scenarios in transport of uranium and iodine on the host-rock scale, defining benchmarks to be computed for safety analysis of geological barriers. To this end, specific models are set up for clay-, crystalline- and salt-rock, exhibiting unfavorable geological conditions and evolutions, which reflect possible long-term developments of the repository system and are used to quantify the transport of radionuclides as well as their potential release from the containment-providing rock zone. Focusing on the host rock and on processes induced by the repository itself, relevant physical couplings affecting radionuclide transport as well as the key geochemical parameters affecting radionuclide mobility should be identified. The approach emphasizes the importance of material parameter variations, model sensitivity, conceptual simplifications, dimensionality reduction, and the influence of fractures and disturbance zones. A central aspect is the application of containment indicators according to the German regulation, which are used to assess potential radionuclide release through the geological barrier. Numerical simulations are implemented using OpenGeoSys supported by automated software workflows. Preliminary results from benchmark studies and model setup workflows will be presented.

 

Acknowledgment

This work has been funded by the German Federal Office for the Safety of Nuclear Waste Management. Project APaRat: „Auswirkungen von Parametervariationen auf den Radionuklidtransport“ (“Effects of Parameter Variations on Radionuclide Transport”) (BASE research contract 4724F10301)