摘要
基于多孔介质模型及CFD方法,数值模拟了铀尾矿库滩面析出氡在覆土中的竖向运移及分布特性。结果表明:影响覆土中流体速度的主要因素是铀尾矿库滩面氡析出通量,覆土中氡通量随覆土高度增加呈指数规律降低;对于同一铀尾矿库滩面氡析出通量(10Bq/(m2·s)),低氡扩散系数(0.5×10-6m2/s)覆土中氡通量要远小于高扩散系数(3×10-6m2/s)覆土中氡通量,达到退役铀尾矿库氡析出通量的限定值0.74 Bq/(m2·s)所需的覆土高度前者为1.27 m,后者为3.45 m,前者仅为后者的36.8%;当覆土氡扩散系数为2×10-6m2/s、铀尾矿库滩面氡析出通量分别为2 Bq/(m2·s)和20 Bq/(m2·s)时,达到退役铀尾矿库氡析出通量的限定值0.74 Bq/(m2·s)所需的覆土高度分别为0.97 m和3.54 m,前者仅为后者的27.4%。
Based on the computational fluid dynamics and the porous medium model, the present article intends to analyze the radon migration and distribution in the cover soils upon the uranium tailings of the impoundment beach surface. The results of our study show that the main influential factor that affects the fluid velocity in the cover soils is the radon flux of the uranium tailing beach surface though the diffusivity of radon has little impact on the fluid velocity in the cover soil. However, the distribution of radon flux in the cover soils tends to decrease exponentially with the deepening thickness of the cover soils. For example, for the same uranium tailings impoundment （10 Bq/（m^2 ·s））, the low radon diffusivity （0.5×10^-6 m^2 /s） tends to have a much lower radon diffusion flux exponent of the cover soils （3×10^-6 m^2 /s）, which can be so low as the minimum value of the flux of 0.74 Bq/（m^2 ·s）. For that limit, the thickness of cover soils for the former is only 36.8% of that of the latter. That is to say, the thickness of cover soils for the former is 1.27 m whereas the radon flux of the uranium tailings impoundment beach surface of latter is 3.45 m. It implies that the flux of the former is merely 27.4% of that of the latter. However, when the radon diffusion coefficient of the cover soils is equal to 2×10^-6 m^2 /s, the radon flux of uranium tailings impoundment beach surface should be 2 Bq/（m^2 ·s）, only 0.97 m of the thickness of cover soils would be necessary to reach the minimum radon flux of 0.74 Bq/（m^2 ·s） in the decommissioning uranium tailings impoundment. What is more, when the radon flux of uranium tailings impoundment beach surface reaches 2 Bq/（m^2 ·s） and 20 Bq/（m^2 ·s）, respectively, it would be necessary for the thickness of cover soils of 3.54 m to reach the minimum value of decommissioning uranium tailings impoundment, the thickness of the cover soils for the former is only equal to 27.4 % of the latter in the final analysis.
出处
《安全与环境学报》
CAS
CSCD
北大核心
2014年第3期176-179,共4页
Journal of Safety and Environment
基金
国家自然科学基金项目(11075072)
关键词
辐射防护技术
铀尾矿库
数值模拟
氡扩散系数
氡通量
radiation protection technology
uranium tailings impoundment
numerical simulation
radon diffusivity
radon flux
