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.

流动加速腐蚀 (FAC) 是一种管道腐蚀，其中管道厚度根据流体流动条件而减小。在核电站中，FAC 主要发生在二次系统的碳钢管中。然而，由于二次系统管道的温度超过150°C，使用传统的超声波无损检测方法进行现场监测很困难。在我们之前的研究中，我们开发了一种波导超声厚度测量系统。在这项研究中，我们应用波导超声测厚系统根据 pH 值的变化监测管道的变薄。

韩国原子能研究所安装了防 FAC 设施，能够监测内部流体流动条件，这些条件固定约 1000 小时以分析 pH 值的影响。测量系统无故障运行约 3000 小时，发现与 pH 7 相比，在 pH 9 时管道厚度减少了 ~10%。实验后使用显微镜测量管道厚度，可靠性确认系统的误差小于 1%。该技术有望应用于其他高温材料的减薄监测。