Experimental study on gas permeability and radon control performance of red clay covering layer on uranium mill tailings pond

Abstract

The decommissioning of uranium mill tailings pond generally employs covering layer to diminish radon exhalation, with soil permeability, thickness, and moisture content being essential considerations in assessing the efficacy of radon reduction. This research uses a proprietary multi-field coupled seepage testing apparatus and a simulated covering layer radon exhalation device to evaluate samples’ permeability and radon control effectiveness across different covering layer thicknesses, pressure gradients, and moisture content levels. The findings demonstrate that gas permeability diminishes with increasing covering layer thickness, exhibiting a more pronounced decline at pressures below 0.35 MPa. Moreover, both moisture content and covering layer thickness significantly influence the radon exhalation rate, which decreases nonlinearly with the rise of both variables. A positive link exists between the radon exhalation rate and permeability, aligning with a natural exponential function model.