Research On The Abundance Detection Method Of Spherical Uranium Parts Of The Same Mass Based On Spectral Analysis

Since the birth of nuclear weapons,people have been fully aware of the dangers of nuclear proliferation,but they also feared the threat of nuclear weapons.In order to limit the development trend of nuclear proliferation,the international community has done a lot of work,of which the establishment of the International Atomic Energy Agency is one of the landmark achievements.As a permanent member of the United Nations and a nuclear power,China should contribute to nuclear non-proliferation and security.In addition to international environmental factors,there are also high technical requirements for solving nuclear non-proliferation and nuclear arms control problems.Because 235U of uranium components has weak ability of spontaneous fission,it is particularly difficult to detect uranium components.The United States,Russia and other countries have achieved phased results in the research of uranium component detection methods.Among many detection methods,"time correlation coincidence method" is currently recognized as a possible method to solve the problem of uranium component quality abundance detection.But the relevant research needs to be improved,and there is no breakthrough has yet been seen in China.This thesis traces the frontiers of this field abroad.The research object and scenario are simulated by GEANT4 software based on the principle of "time correlation coincidence method".Based on the physical process of neutron-induced uranium component fission,the method of uranium component abundance detection based on cross-correlation function,cross-power spectral density function and bispectrum function is studied by using spectral analysis technology.At the same time,a fast cross-correlation function algorithm(OFC algorithm)is designed to ensure the real-time detection of the system.The main research results and conclusions are as follows:1.Based on the time correlation coincidence method,the research model and scenario are designed,and the simulation system of uranium component abundance detection is designed by using open source software GEANT4.Using this system,simulation data can be generated by setting parameters,which is in line with the actual situation,and can be used for subsequent research.2.Based on the data scale of the research object and the sparse characteristic of the data itself,a fast correlation function algorithm(OFC)for ultra-long sparse data is designed.This method can be used in the uranium component abundance detection,and the basic data calculation and analysis can be completed in 20 minutes.It solves the problem of poor real-time performance of detection system in current research and application.3.Using cross-correlation analysis,cross-power spectral density analysis,bispectrum analysis and other spectral analysis methods,the "inversion" of the detection data of the time correlation coincidence system is studied.Four explicit abundances solving methods,namely,cross-correlation function attenuation coefficient method,cross-correlation function attenuation integral method,cross-power spectrum transition frequency method,cross-power spectrum low-frequency mean method,and the method based on bispectrum characteristics,are given respectively.The methods given are compared and analyzed at last.