Characterization of Water as a Media of Nuclide Migration in a Buffer Material for Geological Disposal

在高放废物处置的安全评价中，需要对缓冲材料进行性能评价。在处理后，缓冲材料被地下水饱和。当玻璃废物形式与地下水接触时，所含的放射性核素逐渐释放，并在缓冲材料中的地下水中迁移。1.压实蒙脱石中水行为的热力学研究(已发表)2.氚和离子在压实蒙脱石中的扩散及其与温度的关系，以阐明水在膨润土中的动力学行为(已发表的文献除外)3.粘土中的有机物与裂变产物和辐系元素形成络合物，并可能影响核素的迁移。因此，测定了天然有机物腐植酸与裂变产物锶(II)、Eu(III)以及榄系元素Np(V)的络合生成常数。研究了腐植酸存在下蒙脱石对这些元素的吸附系数。

In the safety assessment of high-level radioactive waste disposal, performance assessment of a buffer materials is needed. The buffer materials are saturated with ground water, after the disposal. When the glass waste form is in contact with the ground water, the radionuclides contained are released gradually and migrate in the ground water in the buffer materials. Therefore, the following studies were carried out :1. Thermodynamic study on the behavior of the water in compacted montmorillonite, which is a major mineral of bentonite as a buffer material (published)2. Diffusion and its temperature dependence of tritium and ions in compacted montmorillonite to clarify kinetic dehavior of water in bentonite (published except for tritium)3. Organic matters occuring in clay form complex with fission products and actinides and may affects the nuclide migration. Therefore, complex formation constant of humic acid, a natural organic matter, with the fission products Sr(II) and Eu(III), and the actinide Np(V) were determined. The sorption coefficients of the elements on montmorillonite in the presence of humic acid were studied.