Validating Fracture Networks for Radioactive Waste Repositories: A DFN Modeling Approach for Crystalline Rock

Numerical subsurface models are essential tools for understanding fluid behavior in geological formations, which are understood to provide feasible long-term repositories for nuclear waste. This study focuses on the role of discrete fracture network (DFN) modeling in evaluating the potential of crystalline rock formations as high-level radioactive waste (HLW) repositories. Crystalline rocks, despite their risk of secondary permeability due to fractures, have been identified as promising sites for HLW storage. However, fracture geometry and connectivity significantly impact fluid flow behavior in these settings, necessitating detailed modeling approaches.

In this study, a comprehensive DFN modeling workflow is developed using photogrammetric data from the Odenwald Crystalline Complex in Germany. A three-dimensional digital model of the outcrop surface is generated and utilized to extract statistical fracture data. These data are then applied to construct DFN models through fracture generation approaches. Specific attention is given to topology and its impact on flow. The generated models undergo rigorous quality control before being proposed for the flow simulations used in the evaluation of the potential of crystalline rock bodies for nuclear waste storage.