Session: 01-05: Nuclear Plant Operation, Modification, Life Extension, Maintenance and Life Cycle - V

Paper Number: 135066

135066 - Research on the Localization Method of Loose Components in Nuclear Power Plants Based on Hilbert-Huang Signal Processing 

Abstract: 

As an important part of clean energy, nuclear power plants must pay attention to potential loose parts in order to ensure their stable operation. Due to aging wear, construction modification, irradiation and other factors during the service cycle, loose parts may be produced, which has a potential impact on the safety and efficiency of nuclear power plants. Loose parts are transferred along the primary coolant flow, 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 the possible presence of loose parts in the reactor primary circuit. Detecting and identifying the impact signal of the loose part and accurately locating the location of the loose part are the primary tasks of this system. In order to realize the above functions, locate, identify and track the trajectory of the loose part in the system and facilitate subsequent maintenance and troubleshooting, this paper applies Hilbert-Huang transform to extract the main frequency of the impact signal. Empirical mode decomposition (EMD) is used to overcome the non-adaptive defect of wavelet transform in processing such shock signals, due to the unique advantages of its nonlinear and adaptive signal decomposition method, it can separate the alimetic 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. Compared with the traditional Hilbert transform method, this method reduces the time difference and optimizes the group velocity acquisition of bending waves. Based on the triangulation method, the time difference of the sensors obtained can accurately locate the impact location. In order to verify the effectiveness of the proposed method, the algorithm is validated on a small model, through the simulation of steel ball, the loose parts hit the metal plate through free fall at different test points to generate vibration signals and locate, the results show that the proposed location method based on Hilbert-Huang transform has a remarkable effect on the location of impact signals, and can realize rapid location. This provides a feasible solution for the detection of loose parts in the operation of nuclear power plants in the future, and is expected to be popularized in practical applications. This research provides strong support for the improvement of safety and operation and maintenance of nuclear power plants.

Presenting Author: Yu Liu North China Electric Power University

Presenting Author Biography: Mainly engaged in reactor structural mechanics and thermal hydraulics and other scientific research work.

Authors:

Jiming Jiang North China Electric Power University
Yu Liu North China Electric Power University
Daogang Lu North China Electric Power University