Co在某极低放废物填埋场土壤中的迁移行为初步研究

选择某拟建填埋场土壤为研究对象,研究Co在土壤中的静态分配试验和动态迁移,以评价场址的安全性。结果表明:初始质量浓度为5 mg/L时,Co的Kd值为753 mL/g,土壤对Co的吸附模式符合Freundlich模式;核素初始质量浓度的升高导致静态试验Kd值增大;静态试验与动态试验的相互印证说明,可以通过动态试验较好地预测核素在极低放填埋场中的迁移速度;Co在该土壤中的迁移速度小于0.24 m/a,Co在进入地表水前已经衰变至非常低的水平,不会对生物圈造成污染。

Preliminary study of the migration behavior of Co in the landfill soil of the extremely low-level radioactive waste

The article is mainly concerned about the results of our primary study of the migration behavior of Co in the landfill soil of the extremely low-level radioactive waste.Our investigation has been done by choosing the landfill sites with the technical supports in hoping to investigate the migration situation of radionuclides in the polluted soil.The soil chosen for our study has been investigated to evaluate the security of the landfill by making both dynamic and static experiments for their distribution in the soil.The results show that the adsorption of Co in the soil can be made to reach the equilibrium completely in 7 days from the bath experiments,with the Kd for Co being 753 mL/g when S/L rate was 1:50 and when the adsorption on Co for soil fits the Freundlich model.Higher initial concentration of the initial radionuclides proves to be likely to lead to the increase of the Kd values by the bath experiment.Besides,the results of bath experiment and the distribution experiment about Co also prove to be in conformity with each other perfectly.Furthermore,we have done experiment to forecast the migration speed of the radionuclide in the sites for the radioactive waste,from which we have found that though the flowing rate of water in the distribution experiment is not slow enough,the adsorption of Co on the soil remains unable to reach the full equilibrium.And this in turn makes the Kd from the distribution experiment remain smaller than those from the bath experiments,which lead to the slowing down of the migrating speed of Co in this soil both from theoretical calculation and in actual distribution tests.Practically speaking,the migration speed for Co in the waste soil proves to be less than 0.24 m/a,with the concentration of Co getting very low by the decay before Co got into surface water of the earth,in spite of the fact that the biosphere won’t be contaminated.