Study on the leachable behavior of cation exchange resins

Abstract

The amount of total organic carbon (TOC) leached from cation exchange resins (CERs) in condensate demineralizers are related to the quality of reactor water in nuclear power plants (NPPs). In the recent years, quality problems of CERs used by ChinShan and KuoSheng NPPs have been identified. Prior to use, TOC and sulfate concentrations must be reduced to meet the criteria; however, this involves an extended purification process and heavy use of water resources. Even in cases where resin can be used, the quality of the water in the reactor remains poor. This study, therefore, investigated the leachates of resins from these NPPs in order to establish a reference for the quality of deep bed CERs. Gel permeation chromatography and ion-pair chromatography were used to identify molecular peaks in the CER leachates in order to elucidate the molecular distributions. We also sought to determine TOC and sulfate concentrations of post-UV treatment using long-term soaking tests, in which the solutions used to soak resins were drained off for analysis on a daily basis. Hydrogen peroxide is employed to accelerate the aging process associated with decomposition in soaking tests to determine the stabilities of the resins.