Leaching behavior of 60Co and 137Cs from spent ion exchange resins in cement–bentonite clay matrix

Abstract The leach rate of 60 Co and 137 Cs 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 60 Co: (4.2–7.3) × 10 −5 cm/d, and for 137 Cs: (3.2–6.6) × 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 60 Co: (1.0–4.0) × 10 −6 cm 2 /d and for 137 Cs: (0.5–2.6) × 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.