Influence of bentonite and zeolite in cementation of dry radioactive evaporator concentrates

To assess the safety for disposal of radioactive mortar-waste composition, the leaching of 137Cs, 60Co and 85Sr from immobilized radioactive evaporator concentrate, into a surrounding fluid has been studied. This paper also presents results from studies made to determine the influence of natural adsorbents (bentonite and zeolite) in immobilization of evaporator concentrate in cement matrix, by measuring leachability of 137Cs, 60Co, and 85Sr. Leaching tests were carried out in accordance with a method recommended by IAEA during 300 days. From the leaching data the apparent diffusivity of cobalt, cesium, and strontium in the cement-bentonite matrix was measured. The uniaxial compressive strength of eleven mortar samples was determined following the ASTM standards. These results are part of a 30-year mortar and concrete testing project which will contribute to the design of radioactive waste management for a future Serbian radioactive waste disposal center.