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

Abstract

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