Scenario analysis of radon attenuation efficacy of earthen cover for uranium mill tailings impoundment driven by dry and wet cycles

The stability and reliability of earthen cover (EC) are crucial for radon treatment of uranium mill tailings (UMTs), and radon attenuation efficacy (RAE) typically serves as the key parameter for performance evolution analysis of the EC. The EC is generally exposed to a periodic meteorological environment with the characteristic of significant dry-wet cycles, therefore the evolution of RAE exhibits apparent uncertainty and unpredictability. In this study, the method of scenario analysis, on the basis of previous research findings and logical reasoning, was utilized to assess the RAE of EC evolution of a typical UMTs impoundment in China. Specifically, a scenario-based degradation model for RAE was developed by defining three core dimensions: dry and wet meteorological environments, intrinsic characteristics of EC, management practices of UMTs impoundment. The critical factors influencing the RAE were identified, and the scenario model was further validated via indoor accelerated degradation experiments. This study can provide a scientific foundation for the optimal design of EC for UMTs impoundment, as well as ensure the UMTs impoundment within effective and long-term radon attenuation performance.