In-situ measurement via the flow-through method and numerical simulations for radon exhalation during measurements of the radon exhalation rate  

作　　者：Ming Xia Yong-Jun Ye Shan-Wei Shang Ting Yu Dai-Jia Chen 

机构地区：[1]School of Resources Environment and Safety Engineering,University of South China,Hengyang,421001,China [2]Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy,University of South China,Hengyang,421001,China

出　　处：《Nuclear Science and Techniques》2024年第7期192-207,共16页核技术（英文）

基　　金：National Natural Science Foundation of China(No.11575080);Hunan Provincial Natural Science Foundation of China(No.2022JJ30482);Hunan Provincial Innovation Foundation for Postgraduate(No.QL20220206).

摘　　要：Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two methods.An abnormal radon exhalation behavior was observed,leading to computational fluid dynamics(CFD)-based simulations in which dynamic radon migration in a porous medium and accumulation chamber was considered.Based on the in-situ experimental and numerical simulation results,variations in the radon exhalation rate subject to permeability,flow rate,and insertion depth were quantified and analyzed.The in-situ radon exhalation rates measured using the flow-through method were higher than those measured using the closed-loop method,which could be explained by the negative pressure difference between the inside and outside of the chamber during the measurements.The consistency of the variations in the radon exhalation rate between the experiments and simulations suggests the reliability of CFD-based techniques in obtaining the dynamic evolution of transient radon exhalation rates for diffusion and convection at the porous medium-air interface.The synergistic effects of the three factors(insertion depth,flow rate,and permeability)on the negative pressure difference and measured exhalation rate were quantified,and multivariate regression models were established,with positive correlations in most cases;the exhalation rate decreased with increasing insertion depth at a permeability of 1×10^(−11) m^(2).CFD-based simulations can provide theoretical guidance for improving the flow-through method and thus achieve accurate measurements.

关 键 词：Radon exhalation FLOW-THROUGH Numerical simulation Accumulation chamber Multivariate regression 

分 类 号：X837[环境科学与工程—环境工程] X753