Safety cases for geological disposal facilities require a sound understanding of the interaction and evolution of waste packages with engineered barriers and the host rock, mediated by groundwater and any other fluids present or generated.
Quintessa has strength in depth regarding the development and application of conceptual and mathematical models for coupled thermal-hydrological-mechanical-chemical processes that cause disposal facilities to evolve towards equilibrium, including:
- thermal modelling of alternative designs of high-level waste and spent fuel facilities;
- resaturation following closure of a disposal facility followed by coupled groundwater flow and gas generation;
- conceptual modelling of the mechanical development of disposal facilities due to the evolution of voidage;
- geochemical evolution modelling for interactions between groundwater and combinations of cement, bentonite, metals and rock;
- evolution of gas from wastes and engineered materials coupled to two-phase flow of water and gas;
- multi-phase flow modelling coupled with mechanical deformation and geochemical evolution in clay;
- thermo-hydro-mechanical modelling of bentonite buffers;
- gas migration at the disposal cell and disposal module scales including the effect of interfaces;
- reactive geochemical transport modelling of engineered barriers for high-level waste disposal in clay, including pore clogging due to cement carbonation;
- generation of non-aqueous phase liquids (NAPLs) from waste degradation, and multi-phase flow from a disposal facility; and
- reactive geochemical transport modelling of cement hydration and the flow of hyper-alkaline fluids through fractured rock and mudstone.
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