Introduction to OECD/NEA Sorption Project Phase III

Deep or near-surface underground repositories are being considered for the safe long-term storage and/or final disposal of radioactive wastes in many countries. A key safety feature is to prevent or sufficient retard radionuclide migration to the biosphere. Radionuclide sorption is one of the most important processes which provide this safety feature. Sorption is generally characterized by equilibrium distribution coefficients (Kd values) for performance assessment (PA) of a repository. The NEA Sorption Project was established to reduce uncertainty in Kd and to increase confidence in PA. The overall objective of the NEA Sorption Project is to clarify and demonstrate how the use of thermodynamic sorption models (TSMs) can serve to improve confidence in the Kd values used to represent radionuclide sorption in most PA models