Characterization of leakage jet flow field and wall vibration of steam generator pipes

• Analyzed the generation mechanism of leaked signals. • Obtained the time–frequency characteristics of the leaked signals. • Obtained the relationship between the leaked signal and the leak hole diameter. • Obtained the relationship between the leaked signal and the pipeline internal pressure. • Analyzed the influence of leakage on the stress and strain of the pipe wall. Leaks in steam generator piping at nuclear power plants can lead to reactor shutdowns and cause environmental contamination. When a pipeline ruptures, timely detection of the failure and rapid localization of the leak source can reduce damage and mitigate contamination. The closed state and complex working environment of steam generators increase the error and difficulty of leak detection. To improve the accuracy of pipeline leakage detection and localization results based on the characteristics of accelerometer signals. This paper establishes a three-dimensional numerical calculation model to simulate the leakage behavior of small holes in steam generator heat transfer tubes in nuclear power plants. Obtained the flow field distribution law and pipe wall vibration law caused by pipeline leakage, and analyzed the generation mechanism of leakage signals. Finally, the time–frequency characteristics of leakage acceleration signals in the initial and sustained leakage stages were studied through experimental research. The results indicate that within the range of 1000–4500 Hz, the leakage signal exhibits four distinct peaks. Compared with the acceleration signal in the continuous leakage stage, the pulse wave signal in the initial leakage stage is less affected by background noise, which is more conducive to the detection and localization of low-pressure and small leaks.