Research on the Localization Method of Loose Components in Nuclear Power Plants Based on Hilbert-Huang Signal Processing

Abstract During the service cycle of the nuclear power plant, due to factors such as construction renovation, irradiation, and other factors, loose parts may transfer along the flow of coolant in the primary circuit, which may lead to the failure of the RCP system and even cause the failure of the primary circuit containment state. The Loose Part Monitoring System (LPMS) is used to detect, locate, and estimate possible loose parts in the reactor primary circuit. To accurately locate the position of loose components, identify and track their trajectory within the system, and facilitate subsequent maintenance and troubleshooting, this paper applies the Hilbert Huang transform to extract the main frequency of the impact signal to achieve accurate measurement of the signal arrival time. Due to the unique advantages of its nonlinear and adaptive signal decomposition method, it can separate the amorphous vibration waveforms in the signal with the highest confidence. By determining the peak time of the first envelope curve after Hilbert transformation, the accurate measurement of signal arrival time can be realized conveniently. Based on the triangulation method, the time difference of the sensors obtained can accurately locate the impact location. To verify the effectiveness of the method, the algorithm validation is carried out on a small model, and the results show that the proposed localization method based on Hilbert’s yellow transform achieves significant results in the localization of impact signals, and can achieve fast localization. Finally, a digital twin system is proposed based on simulation to assist the LPMS system for fast localization by iteratively obtaining a collision moment lookup table.