Investigation of colloid-facilitated effects on the radionuclides migration in the fractured rock with a kinetic solubility-limited dissolution model

Nuclides can move with the groundwater either as solutes or colloids, where the latter mechanism generally results in much shorter traveling time as they interact strongly with solid phases, such as actinides. It is therefore essential to assess the relative importance of these two transport mechanisms for different nuclides. The relative importance of colloids depends on the nature and concentration of colloids in groundwater. Plutonium (Pu), neptunium (Np), uranium (U) and americium (Am) are four nuclides of concern for long-term emplacement of nuclear wastes at potential repository sites. If attached to iron oxide, clay or silica colloids in groundwater. Strong sorption of the actinides by colloids in groundwater may facilitate transport of these nuclides along potential flow paths. Solubility-limited dissolution model models can be used to determine the release of the safety assessment for nuclear waste in geological disposal sites. The present study investigates the effect of colloid on the transport of solubility limited nuclide under the kinetic solubility limited dissolution (KSLD) boundary condition in fractured media. The release rate of nuclide would proportional to the difference between the saturation concentration and the inlet aqueous concentration of nuclide. The presence of colloids could decrease the aqueous concentration of nuclide and thus could increase the release flux of nuclide from the waste form. (author)