Immobilization of 137Cs and 60Co in concrete matrix

To assess the safety for disposal of radioactive waste-cement-bentonite composition, the leaching of Cs-137 and Co-60, from a waste composite into a surrounding fluid has been studied [Burns, R.H. Atomic Energy Rev. 9 (1971) 547; Hashimoto, I., Deshpande, K.B. & Thomas, S.H. I & EC Fundamentals 3 (1964) 213]. Leaching tests were carried out in accordance with a method recommended by IAEA [Atomic Energy Rev. 9 (1971) 195]. Determination of retardation factors, K-F and coefficients of distribution, k(d), 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. 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 storage center. (C) 2003 Elsevier Ltd. All rights reserved.