Molecular dynamics (MD) simulations were performed to study the diffusion and adsorption behaviors of aqueous uranyl species in interlayer space of clay minerals, which are key processes in the safety assessment for geological disposal of radioactive waste. The diffusion behaviors of UO2 2+, K+, CO3 2- and Cl- and H2O were evaluated for the aqueous solution system. The diffusion coefficients of these species decreased with increasing solutes concentration, and that of UO2 2+ was much smaller than others. In the aqueous solution with higher concentration of carbonate ions, uranyl carbonate complexes such as UO2CO3 and UO2(CO3)2 2- could be observed. For the clay-aqueous solution system (clay: montmorillonite or illite), the adsorption and diffusion behaviors of UO2 2+ and K+ were evaluated by MD calculations. The distribution coefficients (K D) of these solutes increased with the layer charge of clay, and the K D value of UO2 2+ might be smaller than that of K+. Further, the diffusion coefficients in the adsorption layer on the basal plane were relatively small and decreased with increasing the layer charge of clay.
- Layer charge
- Molecular dynamics simulation
ASJC Scopus subject areas
- Energy Engineering and Power Technology
- Nuclear Energy and Engineering
- Waste Management and Disposal
- Safety, Risk, Reliability and Quality