基于广义积分变换法的放射性核素迁移计算

摘要

针对我国某铀矿尾库的风险评估需求,根据具体场地的水文地质条件,建立了包气带及饱和带中核素迁移的数学模型.在理论建模基础上,基于广义积分变换法对核素迁移方程进行求解,分析了铀尾矿库中238U、234U、230Th、226Ra、210Pb在4种情景下的迁移规律.结果表明:广义积分变换法对于评估相对较复杂的地下污染物运移问题效果较好,尤其对于长时间尺度和污染物浓度非常小的情况,结果准确.进一步验证了较厚的包气带不仅能最低程度上减小核素在饱和带的迁移速率,而且浓度也低.吸附性能越强的介质,对核素迁移的阻滞作用越大.%According to the demand of risk assessment of a uranium tailing in China,the mathematical model of radionuclide migration in the vadose zone and saturation zone was established according to the hydrogeological conditions of the specific site.On the basis of theoretical model,the migration equation was solved based on the generalized integral transform technique,and the migration rules of 238U,234U,230Th,226Ra and 210Pb in the uranium tailing were analyzed in four scenarios.The results show that the generalized integral transform technique for evaluating relatively complex underground pollutant migration issues is very effective,and especially for small contaminant concentration and long time scale,the result is very accurate.The thicker vadose zone not only can reduce the rate of nuclide migration in saturation at the lowest extent,but also the concentration is low.The stronger adsorption performance of the medium is,the greater the role of the retardation of radionuclide migration is.