高温配管肉厚連続モニタリング装置を用いたＰＷＲ二次系水質改善によるＦＡＣ抑制効果の検証

抄録

Flow Accelerated Corrosion (FAC) of carbon steel (CS) piping is one of main issues in secondary system of Pressurized Water Reactor (PWR) nuclear power plant. Therefore, Oxygenated Water Chemistry (OWC) as a new approach to FAC suppression for PWR secondary system was applied to condensate system of Tsuruga-2 (1160 MWe PWR, commercial operation started in 1987) in Jan. 2011. To evaluate the FAC mitigation effect of OWC, wall thickness of actual condensate piping in Tsuruga-2 after OWC application was measured by continuous monitoring system, using high-temperature and high-resolution ultrasonic probe. As a result, it was demonstrated that FAC was mitigated by more than 5ppb of oxygen under Low-AVT (pH9.3) condition, and FAC was almost stopped even in 2ppb of oxygen under High-AVT (pH9.8) condition.