Dependence of Na + leakage on intrinsic properties of cation exchange resin in simulated secondary environment for nuclear power plants

Material corrosion in nuclear power plant (NPP) is not controlled only by amine injection but also by ion exchange (IX) which is the best option to remove trace Na+. This study was conducted to understand the Na+ leakage characteristics of IX beds packed with ethanolamine-form (ETAH-form) and hydrogen-form (H-form) resins in the simulated water-steam cycle in terms of intrinsic behaviors of four kinds of cation-exchange resins through ASTM test and Vanselow mass action modeling. Na+ was inappreciably escaped throughout the channel created in resin layer. Na+ leakage from IX bed was non-linearly raised because of its decreasing selectivity with increasing Na+ capture and with increasing the fraction of ETAH-form resin. Na+ did not reach the breakthrough earlier than ETAH+ and NH4+ due to the increased selectivity of Na+ to the cation-exchange resin (H+ < ETAH+ < NH4+ ≪ Na+) at the feed composition. Na+ leakage from the resin bed filled with small particles was decreased due to the enhanced dynamic IX processes, regardless of its low selectivity. Thus, the particle size is a predominant factor among intrinsic properties of IX resin to reduce Na+ leakage from the condensate polishing plant (CPP) in NPPs.