WTZ Granit

Prediction of heterogeneous radionuclide sorption on fracture and fault surfaces in granitic rocks: parameterization and validation of improved reactive transport processes

BMWK Project, grant 02 E 11911B

Duration:  01.05.2021 to 30.04.2024

Project lead: Prof. Thorsten Schäfer

Personnell in charge: Annemie Kusturica, Dr. Sarah Hupfer, Dr. Neele van Laaten

Cooperation:  Helmholtz-Zentrum Dresden Rossendorf, Department of Reactive Transport (Leipzig)
Project coordination: PD Dr. Cornelius Fischer, Associated PhD: Wenyu Zhou

Description:

Deep geological repositories are an internationally recognized solution for the long-term disposal of high-level nuclear waste. Crystalline rocks such as granites or gneisses are one potential host rock. The safety analysis and optimization of the concept for the final disposal of highly radioactive and long-lived waste in granitoid formations is part of current research projects.

The overall question in this project deals with the improvement of the predictability of radionuclide migration and retention in fractured crystalline rocks. A generalizable parameterization of reactive transport models should enable the quantitative influence of micrometer and submicrometer roughness of fracture and fault surfaces in crystalline host rocks to be considered in reactive transport models. The focus of this collaborative project is on numerically based predictability of radionuclide migration and, in particular, reactive transport modeling.

Three work packages have been defined to achieve the objectives. The first work package deals with characterization of fracture and fault surfaces of a selection of regional crystalline host rocks, e.g. from the Lusatia and the Ore mountains. The segmentation of computed tomographic data (µCT/XRM) of the fracture and fault surfaces with variable spatial resolution serves as the basis for the simulation calculations. Subsequently, comparative work will be carried out using samples from the Russian project partner, e.g. from Krasnoyarsk. In the second work package, heterogeneous surface reactivity is investigated in experimental and numerical studies of sorption efficiency. Following sorption experiments, spatially resolved sorption data will be determined and scale-dependent reactivity contrasts will be parameterized and validated. The final step is the parameterization and validation of the reactive transport models. Transport behavior is analyzed using quantitative visualization of flow field distribution and heterogeneity. Data sets with different spatial resolution and field of view are blended in the transport simulation. The goal of combining the updated transport and reactivity simulation is a supra-regionally applicable reactive transport model that accounts for the dominant mechanisms to the quantitative and mechanistic aspects at the pore scale.

The BMBF-funded research project is perceived as Scientific and Technical Cooperation between Germany and the Russian Federation in form of the cooperation between the Department of Reactive Transport (Leipzig Branch) of the Institute of Resource Ecology of the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the Radiochemical Department of the Lomonosov Moscow University (MSU) and the Institute of Geosciences, Applied Geology Group of the University of Jena.

Preliminary results:

PhD topic Annemie Kusturica: The influence fracture surface mineralogical heterogeneity in crystalline rock on sorption

Due to the current political situation, the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) is suspending its institutional cooperation activities with Russia for the time being. The DFG is aware of the consequences of these measures and at the same time deeply regrets them from an academic perspective. However, the DFG remains available as a reliable contact partner for researchers of both countries.