The condensate demineralizer (CD) is installed to keep the reactor water quality in high purity. The CD should keep enough ion removal efficiency at all times to take proper countermeasures against the main condenser cooling water leakage. The reactor water sulfate ion should be kept as low as possible to mitigate the possibility of IGSCC. The IGSCC is induced and accelerated by sulfate ion. One of the major sources of sulfate ion is leachables from strong acid type cation exchange resin (CER). On the other hand, it has appeared that anion exchange resin (AER) kinetics is interfaced by total organic carbon (TOC) leached from the CER. It is very important to use high stability CERs against oxidized degradation to keep not only the reactor water sulfate ion in low level but also enough kinetics of the AER. This paper describes phenomena of the AER kinetics degradation and reactor water sulfate ion increase occurred at the same time and the CER stability measurements against oxidized degradation.
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