Numerical simulation of radionuclide particle tracking based on discrete fracture network
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摘要: 高放废物地质处置过程中涉及的核素在围岩裂隙地下水中的迁移问题已引起广泛关注，数值模拟是研究核素粒子运移的重要方法。目前裂隙介质中渗流模型主要是等效连续介质模型、双重介质模型和离散裂隙网络模型。对于岩体尺度裂隙地下水的流动，离散裂隙网络模型能充分表现裂隙介质的各向异性、不连续性等特征。因此，针对裂隙介质准确概化及核素迁移模拟等难点，文章结合Monte Carlo随机生成裂隙方法、裂隙渗流有限元算法和高放射性核素衰变方程等方法，依据花岗岩深钻孔裂隙统计数据，采用离散裂隙网络模型对内蒙古阿拉善高放废物地质处置预选区展开了核素粒子迁移数值模拟研究，并讨论了实例预测分析结果。结果显示：针对设定的地质模型，核素粒子从中心运移到边界的迁移路径长度平均为1293.35 m，粒子运移到边界耗费的时间平均为1.70E+11 d。Abstract: The migration of high-level radioactive waste in fracture media during geological disposal has caused widespread concern, and the numerical simulation of radionuclide particle transport is an important research methods. Current flow simulation methods of fractured media are mainly equivalent continuum model, the dual media model and the discrete fracture network model. For the rock scale studies, the first two models view the fracture media as a continuous medium, cannot adequately represent fractured anisotropic media and discontinuities features. Therefore, this study constructed numerical simulation method of radionuclide particle migration based on the discrete fracture network model, in combination with the Monte Carlo method, the finite element method and the radionuclide particle transport model. We carry out this study of alternative high-level nuclear waste site(Alax) and calculated radionuclide particle migration results. The results show that for the established numerical model, the pathway lengths of radionuclide particles in the model are averaged 1293.35 m, which spent an average time of 1.70×1011 days. Drilling data are used in this study to verify the reliability of the model, and the above results prove that the radionuclide particle simulation method we constructed can be used to predict the high-level radioactive migration in waste disposal site. This study can provide a reference for selecting the geological repository of high-level radioactive waste.
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Key words:
- discrete fracture network /
- fracture /
- nuclide /
- particle tracking /
- Alxa
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