Leaching of 60Co and 137CS from spent ion exchange resins in cement-bentonite clay matrix

The leaching rate of Co-60 and Cs-137 from the spent cation exchange resins in cement-bentonite matrix has been studied. The solidification matrix was a standard Portland cement mixed with 290-350 (kg/m(3)) spent cation exchange resins, with or without 2-5% of bentonite clay. The leaching rates from the cement-bentonite matrix for Co-60: (4,2-7,0) x 10(-5) (cm/d) and Cs-137: (3,2-6,6) x 10(-4) (cm/d), after 125 days were measured. From the leaching data the apparent diffusivity of cobalt and cesium in cement-bentonite clay matrix with a waste load of 290-350 (kg/m(3)) spent cation exchange resins, was measured for Co-60: (1,14,0) x 10(-6) (cm(2)/d) and Cs-137 :(0,5-2,6) x 10(-4) (cm(2)/d), after 125 days. The results presented in this paper are part of the results obtained in a 20-year mortar and concrete testing project which will influence the design of radioactive waste management for a future Serbian radioactive waste disposal centre.