Utilization of bentonite and zeolite in cementation of dry radioactive evaporator concentrate

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 sorbents (bentonite and zeolite) on 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, under 300 days. From the leaching data the apparent diffusivity of cobalt, cesium and strontium in cement–bentonite matrix with a waste load of 701 kg/m3 evaporator concentrate was measured. The uniaxial compressive strength of 11 mortar samples is determined following the ASTM standards. These results are part of a 30-year mortar and concrete testing project which will influence the design of radioactive waste management for a future Serbian radioactive waste disposal center.