This title appears in the Scientific Report :
2019
Application of High Performance Computing to evaluate effects of system heterogeneity in coupled reactive transport simulations at various scales
Application of High Performance Computing to evaluate effects of system heterogeneity in coupled reactive transport simulations at various scales
Deep geological disposal facilities (GDF) for high-level nuclear waste are based on multi-barrier concepts, combining an engineered barrier system with a suitable repository host rock. The migration of radionuclides from a GDF into the geo-/biosphere occurs mainly via the water pathway, after the wa...
Saved in:
Personal Name(s): | Deissmann, Guido (Corresponding author) |
---|---|
Trinchero, Paolo / Molinero, Jorge / Iraola, Aitor / Puigdomenech, Ignasi / Gylling, Björn / Bosbach, Dirk | |
Contributing Institute: |
Nukleare Entsorgung; IEK-6 |
Imprint: |
2019
|
Conference: | GeoMünster 2019, Münster (Germany), 2019-09-22 - 2019-09-25 |
Document Type: |
Poster |
Research Program: |
Nuclear Waste Management |
Publikationsportal JuSER |
Deep geological disposal facilities (GDF) for high-level nuclear waste are based on multi-barrier concepts, combining an engineered barrier system with a suitable repository host rock. The migration of radionuclides from a GDF into the geo-/biosphere occurs mainly via the water pathway, after the waste comes into contact with groundwater, subsequent to failure of the waste canisters. The long-term evolution of the geochemical conditions in a geological repository system, the release of radionuclides from the emplaced wastes, and the radionuclide migration behaviour in the repository near- and far-field are governed by various strongly coupled thermo-hydraulical-mechanical-chemical-biological (THMCB) processes. The radionuclide and solute transport driven either by diffusion and/or advection involves multi-phase flow phenomena under hydraulic and geochemical gradients. The transport phenomena are affected by various complex reactions including dissolution, (co)precipitation and adsorption, or redox processes, which are partly induced and catalysed by microbial activity. For rigorous comparative analyses of geological repository systems, an in-depth understanding and close to reality description of the coupled THMCB processes that affect the radionuclide transport on different time and length scales is required, including an understanding of effects introduced by process couplings and system heterogeneity.In-situ and laboratory investigations provided manifold evidence of the highly heterogeneous nature of crystalline rocks on various scales, for example, with respect to microstructure, distribution of available (reactive) mineral surfaces, or fracture networks. In this presentation, we discuss the application of reactive transport simulations using (micro-)continuum models to analyse the effects of heterogeneities in crystalline rocks on processes affecting subsurface radionuclide migration, from the (sub-millimetre) grain scale to the repository scale. Radionuclide retardation by sorption processes or solid solution formation, and redox buffering by Fe(II)-bearing minerals against the ingress of oxygenated glacial meltwaters are used as examples. Due to the high computational demands, these simulations were performed on the supercomputers JUQUEEN and JURECA at the Jülich Supercomputing Centre, using the massively parallel reactive transport code PFLOTRAN. The results of these simulations contribute to a refined understanding of the effects of system heterogeneities on key processes controlling the geochemical evolution and radionuclide migration in the subsurface. Moreover, they may serve as a starting point for the development of approaches to represent system heterogeneity on multiple scales and for upscaling strategies for larger-scale reactive transport models, thus providing a more realistic view on the evolution of repository systems. |