Immobilization of radioactive evaporator concentrate in mortar matrix

Traditional methods of processing evaporator concentrates from NPP are evaporation and cementation. These methods allow the transformation of a liquid radioactive waste into an inert form, suitable for a final disposal. To assess the safety for disposal of radioactive mortar-waste composition, the leaching of 137Cs from immobilized radioactive evaporator concentrate into a surrounding fluid has been studied. Leaching tests were carried out in accordance with a method recommended by IAEA. Determination of retardation factors, KF, and coefficients of distribution, kd, using a simplified mathematical model for analyzing the migration of radionuclides, has been developed. In our experiment we have achieved the lowest leaching values after 60 days in samples. Results presented in this paper are examples of results obtained in a 20 year mortar and concrete testing project, which will influence the design of the engineered trenches system for a future central Serbian radioactive waste disposal center