TRANSFER PhD Colleg

Project title: 

TRANSFER - Relevance of spatial and temporal heterogeneity to the retention of radionuclides in a final repository system using the example of Opalinus Clay

TRANSFER is a structured graduate programm jointly by five Helmholtz centers and five Universities.

Project description: 

Germany faces a major scientific challenge in finding a site for a final repository for radioactive waste. Opalinus Clay, already used as host rock in Switzerland, is being investigated for its transferability to Germany. The scientific concept of TRANSFER is to examine various aspects of the influence of spatial and temporal heterogeneities on the retention of radionuclides in Opalinus Clay retention of radionuclides, thereby enabling conclusions to be drawn about the transferability of findings in Switzerland to the Opalinus Clay in Germany. The overarching goal is to provide a quantitative systemic understanding of the final disposal of high-level radioactive waste in a multi-barrier repository.

The subproject of UFZ aims to further optimise the existing OpenGeoSys two-phase transport model. Since the repository will initially be sealed in an unsaturated state, the diffusive and advective transport of three gas components (H2O, H2 and N2) must be taken into account. The main objective of this sub-project is to improve the functionality of the numerical model OpenGeoSys for estimating the corrosion rate of the final repository container. Radioactive decay also increases the temperature and gas pressure in the near field. Since this has a significant impact on fluid transport, heat transport is also to be integrated into the OpenGeoSys software.

The second key task is to spatially resolve the Opalinus Clay in the model into The second central task is to spatially resolve the Opalinus Clay in the model into several layers in order to simulate, for example, a sandy facies with higher permeability. The results of the experimental investigations from the other doctoral theses can be incorporated as parameters in the modelling. A parameter study is intended to provide a more precise understanding of the hydraulic processes on the one hand and to enable better quantitative estimates of the maximum pressures in different areas of the near field on the other.