放射性核素在饱和浙江红粘土中的迁移

Radioactive Nuclide Migration Experiment in Saturated Zhejiang Red Clay

用分层土柱法研究放射性核素在浙江红粘土介质中的迁移规律．通过为期２８ｄ 的饱和土柱动态吸附－解吸实验，测定了１３７Ｃｓ、８５Ｓｒ、６０Ｃｏ、１４４Ｃｅ、１５５Ｅｕ 和２３７Ｎｐ ６种放射性核素在浙江红粘土样品中的垂直剖面浓度分布及其迁移速度．为便于根据实际场址的入渗水通量确定这些核素的滞留因子，进行了氚弥散实验，测定了土壤有效孔隙率和土壤中水运移速度．根据土柱装填密度、有效孔隙率和土壤中水运移速度，计算出上述核素在红粘土中的吸附分配系数和滞留因子．结果表明：浙江红粘土对１３７Ｃｓ、８５Ｓｒ、６０Ｃｏ、１４４Ｃｅ、１５５Ｅｕ 和２３７Ｎｐ ６种核素均有较大的吸附分配系数和滞留因子；对１３７Ｃｓ的吸附分配系数和滞留因子分别为２３８８ｍ ｌ·ｇ－ １和７７３２，对８５Ｓｒ的吸附分配系数和滞留因子分别为１４３２ｍ ｌ·ｇ－ １和４６４５．

This paper probes into the radioactive nuclide migration mechanism in the red clay by layered clay column method.The vertical section concentration distribution and their migration velocity of six kinds of radioactive nuclides,such as 137 Cs, 85 Sr, 60 Co, 144 Ce, 155 Eu and 237 Np,were measured by 28 days saturated clay column dynamic adsorption desorption experiment.In order to calculate the retardation factor of these nuclides according to the water infiltration flux in site the diffusion experiment was conducted,and the flow velocity and the soil coefficient porosity were also measured.And the retardation factor and adsorption distribution coefficient of these nuclides in red clay were calculated by clay column loading density,effective porosity,and flow velocity in soil.The results showed that Zhejiang red clay has high adsorption distribution coefficients and retardation factors to 137 Cs, 85 Sr, 60 Co, 144 Ce, 155 Eu and 237 Np.The adsorption distribution coefficients and retardation factor to 137 Cs are 2388 ml·g -1 and 7732 respectively,and the adsorption distribution coefficients and retardation factor to 85 Sr are 1432 ml·g -1 and 4645 respectively.