Gamma Radiation Induced Degradation and Leaching Behavior of Ion Exchange Resin

Objectives : The objectives of this study were to investigate gamma radiation induced degradation and leaching behavior of nuclide and/or organic complexing agent adsorbed ion exchange resin.Methods : Cation exchange resin (IRN 77) and anion exchange resin (IRN 78) widely used in nuclear power plants were purchased. Cobalt ion and EDTA were used to represent nuclide and organic complexing agent adsorbed to ion exchange resins. Cation and anion exchange resin adsorbed cobalt ion and/or EDTA were radiated by 60Co nuclide. The radiation dose rate was 10 kGy/hr and total doses were 0, 300, 500, and 700 kGy.Results and Discussion : The sulfone and quaternary ammonium functional groups of gamma radiated ion exchange resin were degraded, indicating nuclide/organic complexing agent would be leached from ion exchange resin. It was shown that degradation of anion exchange resin was worse than that of cation exchange resin. While the high concentrations of cobalt ion and organic matter were observed in leachate from anion exchange resin, those in leachate from cation exchange resin were very low. For mixed cation and anion exchange resin, the leaching behavior of mixed resin was improved. This shows that disposal in the form of a mixed ion exchange resin was evaluated as a safer method than that of a cation or anion exchange resin alone.Conclusion : The adsorbed nuclide and organic complexing agent were leached from ion exchange resin by gamma irradiation. The leaching behavior of cation and anion exchange resin was improved by using mixed ion exchange resin.