OpenWorkFlow - Reproducible Near-Field Multiphysics Simulations of Radioactive Waste Repositories

Reliable safety assessments of deep geological repositories require transparent, reproducible exploration of a wide range of processes, design options, and site conditions. To address this need, we developed a fully automated simulation workflow for coupled thermo-hydro-mechanical (and chemical) processes using the open-source code OpenGeoSys (OGS), within the scope of the OpenWorkFlow research project.

The workflow integrates newly developed tools within the OGSTools package and builds on OGS’s transparent modelling framework to support reproducible simulations: automated generation of simulation-ready meshes from CAD geometries with symbolic identifiers for repository components; consistent assignment of thermo-hydro-mechanical-chemical material properties from a dedicated database into OGS input files; and standardized post-processing routines for multiphysics result evaluation. This approach enables script-based model creation and simulation with minimal manual effort.

We focus on near-field analyses of vertical sections through generic repository prototypes, allowing evaluation at arbitrary positions. Multiple process couplings (HM, THM, TH2M, etc.) are supported, and large ensembles of model variants can be generated, facilitating systematic variation of design parameters, material data, or boundary conditions, and enabling both sensitivity and uncertainty analyses.

The workflow has been applied to repository configurations in the Northern Lägern site region. Automated simulations reproduced system behaviour reported in previous studies and showed consistency with results from other modelling groups, demonstrating both the validity of the workflow and its applicability to safety-relevant assessments.

Overall, this study illustrates the potential of open-source, automated multiphysics workflows to enhance transparency, reproducibility, and efficiency in repository performance evaluation, and to provide a versatile platform for comparing design alternatives across host rocks and site conditions.