317 / 2024-03-15 15:04:57

Modelling the reactive transport of hydrogen in clay-water system of engineered barriers

gas flow, bentonite buffer, geological disposal, hydrogen, reactive transport

3、深地工程与能源利用 > 3、深部资源与地下空间利用

Understanding the transport and fate of hydrogen is important for performance assessment of geological disposal concepts for higher activity waste.  Hydrogen gas can be generated due to the corrosion of steel canisters and flow through the engineered barrier system. Hydrogen gas can be dissolved into the pore water of the clay barrier (compacted bentonite) and interacts within the clay-water system of compacted bentonite through multiple and complex geochemical reactions including dissolution and precipitation of minerals and ion exchange reactions. In this paper, we will study a scenario where the compacted clay is partially and heterogeneously saturated when hydrogen gas generation happen. We will present the results of modelling the reactive transport hydrogen within an unsaturated compacted bentonite by considering multiple homogeneous and heterogeneous reactions that occur within the clay-gas-water system. In this paper, we will revisit the geochemical modelling of the problem by incorporating a more accurate description of the state of water (here under suction) in geochemical modelling of the problem. The results provide new insights into the transport and fate of hydrogen in the clay barrier and highlight the importance of the buffering capacity of the clay-water system in the overall assessment process.