Speciation of actinides and fission products at smectite rich natural clay-water interface

Speciation of actinides (Am(lll), Pu(lV), Np(V)) and long lived fission products, (Cs(l), Sr(II), Tc(VII)) at the interface between smectite rich clay and water has been studied by batch sorption experiments under different experimental conditions of pH, ionic strength and metal ion concentration. Modeling of the sorption data have been used to delineate the mechanism of the sorption of the metal ions on the clay. The study revealed different mechanisms (surface complexation, ion exchange) operating under different pH conditions and for different metal ions. Studies have been extended to diffusion of these radionuclides in the compacted clay to obtain the diffusion coefficient in saturated clay