核素在非饱和黄土介质中迁移的环境模拟试验结果的拟合与分析  

FITTING AND ANALYSES OF SIMULATION EXPERIMENT RESULTS FOR RADIONUCLIDE MIGRATION IN UNSATURATED LOESS MEDIUM

作　　者：王志明[1] 杨月娥[1] 赵英杰[1] 倪世伟[1] 

机构地区：[1]中国辐射防护研究院

出　　处：《辐射防护》1998年第1期11-17,共7页Radiation Protection

摘　　要：本文简要介绍了核素６０Ｃｏ、８５Ｓｒ和１３７Ｃｓ在非饱和黄土介质中迁移的环境模拟试验结果。文中简述了试验的模拟装置和方法；给出了主要的试验结果，包括２号土柱与４号土柱黄土中８５Ｓｒ比活度垂直分布的直接测量结果和４号柱黄土中６０Ｃｏ和１３７Ｃｓ比活度垂直分布的取样测量结果。对模拟试验测量数据进行了拟合与分析，得到了８５Ｓｒ比活度垂直分布的质心坐标ｚ０（ｔ）随试验时间ｔ的变化关系；给出了２号和４号土柱中８５Ｓｒ比活度垂直分布方差σ２（ｔ）（ｃｍ２）随ｔ（ｄ）变化的拟合公式，其分别为幂函数σ２（ｔ）＝０．２１８ｔ０．７１６和σ２（ｔ）＝０．０３３４ｔ０．９６２；根据ｔ＝３６５ｄ时４号土柱的取样测量结果，用二次矩方法计算了６０Ｃｏ和１３７Ｃｓ的比活度分布方差，其值均为σ２（ｔ＝３６５ｄ）＝０．２０ｃｍ２；还估算了土柱中的水流速度ｕ、８５Ｓｒ的平均迁移速度ｖ和延迟系数Ｒｄ。The simulation experiment results for 60 Co, 85 Sr and 137 Cs migration in unsaturated loess medium are briefly introduced in this paper. Simulation experiment equipment and method are also described. The main results, including vertical distribution of specific activities of 85 Sr in loess in columns No.2 and No.4 by direct measurement as well as that of 60 Co and 137 Cs in column No.4 by sampling method, are shown here. The relationship of centers of mass, z 0(t) of vertical distribution of specific activities of 85 Sr and time, t, are obtained on the basis of fitting and analyses of the simulation experiment data. The fitted equations of variance, σ 2(t)(cm 2), of vertical distribution of specific activities of 85 Sr and time, t(d), are given, that is, σ 2(t)= 0.218 t 0.716  (for column No.2) and σ 2(t)= 0.0334 t 0.962  (for column No.4). The variances of specific activities of 60 Co and 137 Cs in colunm No.4 are calculated by quadratic moment method according to the results obtained at t= 365 d by sampling method. Their values are σ 2(t= 365 d)= 0.20 cm 2 . Also water flow velocity, u, and the average migration velocity, v, and retardation coefficient, R d, for 85 Sr in the columns are evaluated. The results are of great value to safety assessment of disposal of low and intermediate level radioactive wastes.

关 键 词：环境 核素迁移 模拟试验 非饱和带 黄土介质 

分 类 号：TL942.1[核科学技术—辐射防护及环境保护] X591[环境科学与工程—环境工程]