Preferential sorption of radionuclides on different mineral phases typical for host rocks at the site of the future Russian high level waste repository

The sorption behaviour of 137Cs, 226Ra, 232,238U, 237,239Np, 239,240Pu, 241,243Am onto rock samples was analysed using image processing of digital autoradiography and scanning electron microscopy results. The rock samples were collected from deep well R12, located within the proposed site of future Russian high level radioactive waste disposal (the exocontact zone of the Nizhnekansky granitoid massif), at depths of 166–476 m. Sorption experiments were performed under conditions similar to those of the disposal near-field (atmospheric conditions, and composition, pH, and Eh of simulated groundwater solutions). The combination of digital autoradiography and scanning electron microscopy allowed the characterisation of the diverse relative sorption properties of different mineral phases of the specific rock samples. The sorption properties of minerals were expressed in terms of relative sorption efficiency.