| dc.description.abstract | The final disposal method for high-level waste is Deep Geological Disposal. This is where nuclear waste is buried in geological formations at depths greater than 300 meters, and canister and buffer materials are used to cover and secure it. By the principles of isolation and retardation, the waste decays harmlessly, isolating it from the biosphere and ensuring human health and environmental safety. However, after hundreds of years of disposal, gas may be generated due to the corrosion of metallic materials under anoxic conditions, the radiolysis of water or microbial degradation. With continuous gas pressure accumulation, the stress on buffer materials can no longer withstand it, leading to pathway dilation and fractures, allowing gas to escape. As gas degrades the barrier′s capability, endangering the safety of the repository. Therefore, buffer materials play a crucial role in the repository, bentonite is commonly chosen as the buffer materials. In practical situations, bentonite exhibits different particle arrangements, porosity, and permeability, presenting heterogeneous distributions. This heterogeneity may lead to the formation of preferential pathways, particularly in regions with high porosity and loose particle arrangements, making gas flow more accessible and consequently influencing the gas migration behavior. Therefore, this study successfully utilized the THMC7.1 numerical model to demonstrate the changes in gas pressure accumulation. Simulations with heterogeneous bentonite confirmed that the preferential pathways created by heterogeneous distribution significantly affect gas velocity. | en_US |