Analysis of pipe thickness reduction according to pH in FAC facility with In situ ultrasonic measurement real time monitoring

• Published in: Nuclear engineering and technology 2022, 54(1), , pp.186-192
• Main Authors: Oh, Se-Beom, Kim, Jongbeom, Lee, Jong-Yeon, Kim, Dong-Jin, Kim, Kyung-Mo
• Format: Article
• Language: English
• Subjects: Flow accelerated corrosion (FAC); High-temperature pipe; Thickness monitoring; Waveguide; 원자력공학
• ISSN: 1738-5733; 2234-358X
• DOI: 10.1016/j.net.2021.07.048

Flow accelerated corrosion (FAC) is a type of pipe corrosion in which the pipe thickness decreases depending on the fluid flow conditions. In nuclear power plants, FAC mainly occurs in the carbon steel pipes of a secondary system. However, because the temperature of a secondary system pipe is over 150 °C, in situ monitoring using a conventional ultrasonic non-destructive testing method is difficult. In our previous study, we developed a waveguide ultrasonic thickness measurement system. In this study, we applied a waveguide ultrasonic thickness measurement system to monitor the thinning of the pipe according to the change in pH. The Korea Atomic Energy Research Institute installed FAC-proof facilities, enabling the monitoring of internal fluid flow conditions, which were fixed for ~1000 h to analyze the effect of the pH. The measurement system operated without failure for ~3000 h and the pipe thickness was found to be reduced by ~10% at pH 9 compared to that at pH 7. The thickness of the pipe was measured using a microscope after the experiment, and the reliability of the system was confirmed with less than 1% error. This technology is expected to also be applicable to the thickness-reduction monitoring of other high-temperature materials.