Signal Denoising Method For Neutron Flux Measurement System Based On Sparse Decomposition

As a weak signal processing system,the neutron flux measurement system is susceptible to different types of interference noise,resulting in signal anomalies.For the pool core measurement system of the pool type sodium-cooled fast reactor,it has a more harsh operating environment and the electromagnetic environment is more complicated.For the pool core measurement system,the signal-to-noise ratio is low during the field debugging process,and the nuclear pulse is difficult to detect.In this paper,a signal denoising method for nuclear measurement systems based on sparse decomposition method is proposed.The research content of this paper mainly includes the following parts:From the pool-type sodium-cooled fast reactor pool core measurement system debugging process,the electromagnetic interference is serious,the neutron signal is overwhelmed by noise,and the problem cannot be detected.The methods and measures for solving the electromagnetic interference of the nuclear measurement system were proposed.A digital signal processing method based on sparse decomposition is used to filter out electromagnetic interference and system noise existing in the output signal of the nuclear measurement system.The basic ideas of sparse decomposition,basic mathematical models,typical sparse decomposition algorithms,and the construction of overcompleted dictionaries are introduced in detail.Based on the theory of signal sparse decomposition method,this paper proposes a sparse representation method based on Gabor dictionary and Chirplet dictionary design for nuclear signal.Analyze the nuclear signal and influence the interference noise generation mechanism and its influence on the nuclear signal,and construct the mathematical model of the output nuclear pulse signal of the pool core measurement system.The characteristics of nuclear signals are analyzed,and the mechanism of interference noise and its influence on nuclear pulse signals are studied.The mathematical model of output nuclear pulse signal of pool core measurement system is constructed.Based on the mathematical model of signal characteristics,a nuclear signal simulation test platform based on MATLAB is designed.It provides the necessary tools for the research of nuclear signal sparse decomposition algorithms.A nuclear measurement system is built under experimental conditions for verification based on measured nuclear signals.The results of simulation and measured signal denoising experiments show that the denoising results of this method can effectively improve the signal-to-noise ratio of the output signal of the system,and the amplitude error and waveform distortion are smaller than the traditional wavelet threshold method.In summary,this paper develops a nuclear signal denoising method,which has the ability to detect nuclear signals with low signal-to-noise ratio under complex electromagnetic environment.The feasibility and accuracy of the method are verified by numerical simulation and experimental tests under laboratory conditions,which has the potential for further application research.