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

Abstract

The leach rate of Co-60 and Cs-137 from two different ion exchange resins: (a) spent cation exchange resins and (b) spent mix bead ion 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 leach rates from the cement-bentonite matrix as Co-60: (4.2-7.3) x 10(-5) cm/d, and for Cs-137: (3.2-6.6) x 10-5 cm/d, after 245 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 as Co-60: (1.0-4.0) x 10(-6) cm(2)/d and for Cs-137: (0.5-2.6) x 10(-4) cm(2)/d after 245 days. These results are part of a 20-year mortar and concrete testing project which will influence the design of radioactive waste management for a future Serbian radioactive waste disposal center. (C) 2004 Elsevier B.V. All rights reserved.