实验室尺度三维含水层核素迁移模型试验
Experiment on Nuclide Migration of Aquifer by Three-Dimensional Model in Laboratory Scale
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摘要: 为了准确模拟和预测核素在含水层中的分布、累积情况，借助物理模型试验与核素迁移模式客观反映其迁移、转化规律是不可或缺的手段。以山西第四系粉质壤土潜水层地下水为研究对象，建立实验室尺度下的核素迁移三维模型试验，示踪核素90Sr以点源形式布设在断面中心位置，通水量为375 mL/d。结果表明，260 d后中心点处90Sr浓度峰值沿轴向迁移了3.9 cm，峰值活度浓度为1.04×104 Bq/cm3；随着与轴线距离的增加，径向上、下对称6个区域的峰值浓度逐渐减小，上半部活度浓度为1.02×103～8.03×103 Bq/cm3，峰值迁移距离约为2.7～3.6 cm，下半部活度浓度为1.86×103～9.80×103 Bq/cm3，峰值迁移距离约为3.3～3.6 cm。结合试验体中90Sr的浓度分布，建立Hydrus-3D核素迁移三维数值模型，拟合得到了90Sr在粉质壤土中的吸附分配系数为79.0 mL/g，纵向弥散度为0.7 cm，横向弥散度为0.8 cm。Abstract: In order to accurately simulate and predict the distribution of nuclides in the aquifer, the physical experiment and numerical model are used to reflect its migration and transformation. As quaternary silty loam of aquifer in Shanxi Province for example, a three dimensional model of nuclide migration in laboratory scale was established and the tracer 90Sr was located at the center of the section by point source. After 260 d injection water by 375 mL/d, the results show that 90Sr peak concentration migrates 3.9 cm along the direction of water flow and the peak activity concentration is 1.04×104 Bq/cm3. With the increase in distance to axis, the peak activity concentration of the six regions in radial by symmetry decreases gradually. The activity concentration of upper half part is 1.02×103-8.03×103 Bq/cm3 and peak migration distance is about 2.7-3.6 cm. The activity concentration of lower half part is 1.86×103-9.80×103 Bq/cm3 and peak migration distance is about 3.3-3.6 cm. According to the concentration distribution of 90Sr, a three-dimensional numerical model of Hydrus-3d nuclide migration was established. The distribution coefficient of strontium in silty loam is 79.0 mL/g, the longitudinal dispersion is 0.7 cm and transverse dispersion is 0.8 cm.
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Keywords:
- nuclide migration /
- three-dimensional model /
- Hydrus-3D /
- 90Sr
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