摘要
在某铀尾矿库运行了 3 1年后 ,取库底下方的亚粘土样 ,测量了从库底迁移的U、Th和2 2 6 Ra的比活度分布。为研究其迁移规律 ,还测量了尾矿的颗粒分布、不同颗粒尾矿中核素的比活度和浸出因子、核素在亚粘土层的分配系数等参数 ,并采用一维对流弥散模式拟合得到核素在亚粘土层中比活度分布曲线。结果表明 ,矿泥是尾矿中的主要成分 ,其中的核素比活度高于矿砂 ;而浸出因子则低于矿砂。库底下方天然的和建库时人工铺垫的亚粘土层对三种核素具有较强的吸附滞留能力 ,从而有效地减少了核素的垂向迁移 ;U、Th和2 2 6 Ra在亚粘土中的分配系数分别为 62、1 .3× 1 0 3和 9.8× 1 0 2 mL/g,在库底下方核素比活度降到本底水平的距离 ,U为 1 .2m ,Th和2 2 6 Ra为 0 .2m。
After 31 years operation of an uranium tailings impoundment, sub-clayey samples beneath its bottom were taken for determining concentration distribution of U, Th and 226Ra migration from the impoundment. For study of nuclide migration, parameters were measured such as particle size of tailings, nuclide specific activities and leaching factors of tailings, and distribution coefficients of nuclides in sub-clay. One dimensional convection-dispersion model of nuclide migration was applied for fitting nuclide distribution in sub-clay. The result indicates that the sludge is the main component of tailings, and possess higher specific activities and 1ower leaching factor than coarse tailings. Sub-clay has a strong adsorption ability to nuclides, and the natural and man-made sub-clay layers beneath the impoundment bottom can effectively reduce nuclides seepage and vertical migration distance. Distribution coefficients of U, Th and 226Ra are 62, 1.3×10 3 and 9 8×10 2 mL/g, respectively. The vertical migration distances at which the concentrations of nuclides reduce to background level are 1.2 m for U and 0.2 m for Th and 226Ra.
出处
《辐射防护》
CAS
CSCD
北大核心
2005年第1期24-30,共7页
Radiation Protection
关键词
核素比活度
比活度
人工
本底
滞留
天然
迁移
尾矿
分配系数
亚粘土
Uranium Tailings Impoundment, U, Th, 226Ra, Sub-clay, Distribution Coefficient, Nuclide Migration
