^(90)Sr、^(237)Np、^(238)Pu和^(241)Am 在水平土柱中迁移的实验场示踪研究

Experimental Field Tracer Migration Test of ^(90)Sr,^(237)Np,^(238)Pu and ^(241)Am in Horizontal Column

将装有示踪剂和含水层未扰动土的水平土柱,通过竖井壁水平插入含水层,天然地下水通过与含水层介质紧密相连的一端流过土柱,在另一端接取水样;通过测量实验期间采集的水样和实验结束后切割的土壤样品中示踪剂的浓度,得到核素的迁移数据。实验结果表明,所用核素中迁移最快的90Sr的延迟系数>290,说明黄土对实验所用的90Sr、237Np、238Pu和241Am都有较强或很强的吸附能力;有腐殖酸的3号和8号土柱中90Sr的延迟系数大于无腐殖酸的2号土柱的延迟系数,说明腐殖酸延缓了90Sr的迁移;无腐殖酸的2号水平土柱中90Sr的延迟系数与实验室模拟土柱的延迟系数基本相同。

The horizontal columns, in which tracers and undisturbed soil collected from the aquifer are filled, are inserted into the aquifer through the experimental shaft wall. Natural underground water flowing through the horizontal columns is collected in sample bottles. The tracer concentrations in both water and soil samples are obtained. The retardation coefficient of 90Sr, which migrates at fastest velocity among tracers, is more than 290, so loess has stronger capacity to sorbs the nuclides of 90Sr, 237Np, 238Pu and 241Am; retardation coefficient of 90Sr in the horizontal columns 3 and 8 with humus are larger than those in the horizontal column 2 without humus. It shows that humus may retard migration of 90Sr. And retardation coefficient of 90Sr in the horizontal column 2 without humus is basically same with simulation experiment results in vertical column.