Feasibility evaluation on using the ORP to better monitor generator internal cooling water system

Inadequate monitoring of generator internal cooling water (GICW) system is one of the root causes for the system failure in nuclear, thermal and hydraulic power plants. The feasibility of using the oxidation-reduction potential (ORP) of GICW to better monitor the system statuses, GICW slight-alkalization and typical system abnormalities, were evaluated on our dynamic simulation test device. During the process of GICW slight-alkalization, the ORP decreases linearly as the pH value increases with high correlation R-2 of 0.9996, which is far more sensitive than the open-circuit potential (OCP) proposed in previous studies. This sensitive indication is attributed to the chemical inertness of the electrode in GICW, thus ensuring its stable surface characteristic. Meanwhile, two most common system abnormalities, CO2 leakage and DO decrease, were simulated. The results demonstrate that the ORP can keenly diagnose these two abnormalities, from their occurrences to their handlings. Further, a more comprehensive specification of GICW oxidation property characterized as the ORP was obtained for guiding the field operation. In conclusion, it is feasible to use the ORP to better monitor GICW system statuses. This study proposes a promising parameter that can be used to improve current inadequate GICW system monitoring.