ABSTRACT
China is also based on a multi-barrier system as other countries, which comprises the Natural Geological Barriers (NBS) and the Engineered Barriers (EBS). The design of high-level radioactive waste repositories in deep geological media includes the construction of a barrier around the waste containers constituted by a buffer/ backfilling material. The basic requirement for the buffer is to retard radionuclide migration by restricting groundwater movement, providing a high sorption capacity for dissolved nuclide and acting as a filter for radionuclide-bearing colloids. Bentonite has been chosen as the buffer/backfill material in most disposal concepts because of its low permeability, swelling capacity and retention properties, among other features. Therefore it is considered of important for the long-term behavior under the coupled THM conditions.
