Modelling the effects of fault heterogeneity and fault movement on radionuclide transport

Evaluations of regional flow fields, and predictions of radionuclide migration rates and paths through the geosphere, require an understanding of fluid flow paths along faults as well as the effects of fault movement. The European Commission is supporting a project aimed at evaluating the level of detail at which fault hydrogeology and the hydrodynamics of fault movement should be included in performance assessments of radioactive waste disposal systems. The project has involved the development of a detailed three-dimensional model of fluid flow and radionuclide transport within a fault zone, incorporating a range of hydrogeological structures identified through a review of observations of fault hydrogeology. Also, a model of rock deformation and associated fluid pressure perturbations has been developed in order to evaluate the changes in groundwater flow associated with fault reactivation. (author)