镅的器壁吸附及其对扩散池实验的影响

Sorption of Americium on Container Wall and Its Influence on Through-Diffusion Cell Tests

针对北山地下水介质中镅(Am)在花岗岩内的扩散池实验中出现的Am在器壁上的吸附现象进行研究和分析。对扩散池实验的监测结果表明,母液内Am活度随时间显著降低。通过对可能产生该现象的几种原因进行分析和实验验证,确定了Am在器壁上的吸附损失是导致母液内Am活度降低的首要原因。Am在器壁上的吸附行为主要由Am的赋存形态决定。由于Am的赋存形态常随pH变化而改变,因此,pH对Am的器壁吸附行为影响很大。通过对可能降低Am器壁吸附损失的措施进行分析和探索,结果表明,对于像Am一样的强吸附性核素,不宜选择扩散池法研究其扩散行为。

The sorption of americium （Am） on container wall, which occurred in the through-diffusion cell tests using groundwater and granite from Beishan, Gansu Province, China, was investigated. It is shown from the through-diffusion cell tests that the concentrations of Am in the source reservoirs decrease notably with time increase. The prime one of some possible reasons for this decrease is the sorption of Am on the container wall. The sorption behavior of Am is dominated by its chemical speciation. The chemical speciation of Am often varies with the pH of the solution, which results in that the pH has significant influence on the sorption behavior of Am. The failure of attempts to lower the sorption loss of Am suggests that the through-diffusion cell test is not practicable for strongly sorbed nuclides such as Am.