Development Of The Gamma Ray Spectrum Measurement System For Radionuclides In Air

In recent years,nuclear terrorism,nuclear tests and nuclear power plants around the country by the damage caused by a nuclear accident,radioactive pollution caused by air environment,affect the national security and people's health,highlighting the radioactive pollution monitoring,nuclear safety,nuclear pollution,air.Although some of the advanced countries in the world have established a gamma radiation monitoring system,they do not carry out the large flow of air sampling,enrich the radionuclides in the air,resulting in low detection sensitivity,slow response.The radioactive air pollutants(such as I-131,Cs-134,Cs-137,Xe-133 etc.)the gamma spectrometry analysis method,designed and completed a large flow of air automatic sampling device,automatic sampling device,gamma spectrum acquisition electronics circuit,the gamma energy spectrum analysis algorithm,spectrum stabilization algorithm,real time the monitoring software and other related work,the main research results include the following aspects:1.In order to monitor the real time gamma ray spectrum of continuous monitoring,this paper adopts the method of filtering to collect and enrich the radionuclides in air.Therefore,this paper designs and implements a large flow of air sampling device,automatic sample preparation device,to achieve the enrichment of radionuclides in the air,the gamma ray spectrum analysis to provide sample materials.2,using 3 inches lanthanum bromide scintillator with a photomultiplier tube as a radiation detector,and the design of the preamplifier,the bias voltage,the digital multi-channel pulse amplitude analyzer and gamma spectrum acquisition electronics system,realize the gamma lanthanum bromide detector energy spectrum detection system based on.3,according to the high energy resolution,lanthanum bromide detector is its high radioactive background characteristics,and characteristics of radionuclides in air samples,this paper designed to optimize the linear background subtraction algorithm of smooth spectrum analysis algorithm,derivative method,spectral peak search method combined with the least squares method of 5 dots and the moving average method,the qualitative and quantitative analysis,identification and radioactivity of radionuclides in air calculation.4,the lanthanum bromide scintillation detector,pre amplifier,bias voltage and other hardware devices are sensitive to temperature,and the measuring time is long in the measurement process,leading to the measured spectrum spectrum drift problem is serious,poor energy resolution.In this paper,we design and implement a hybrid spectrum stabilization method,which is based on the combination of PID hardware stability spectrum and the reference peak energy inversion method.5,for the long time,continuous,real-time,automatic monitoring requirements,based on the Windows operating system,using the Microsoft foundation class(MFC),energy spectrum analysis software design of real-time monitoring,real-time monitoring of radioactive contaminants in the air,and the pipeline communication mechanism of gamma ray spectrum analysis software total data output to the monitoring system,realize the energy spectrum analysis software and real-time monitoring software for independent operation.In this paper,through theoretical research,design,implementation,completion of the radionuclide gamma spectrum analysis in the air traffic system sampling device,automatic sampling device,lanthanum bromide scintillator gamma spectrum acquisition electronics system,gamma ray spectrum analysis algorithm and gamma analysis software based on real time spectrum monitoring and performance.Parameters of the spectra acquisition electronics system were tested and analyzed.Because of the temperature sensitivity of lanthanum bromide scintillator detector,the performance parameters of the system are tested and analyzed in the laboratory environment.In order to verify the reliability of the gamma ray spectrum analysis algorithm,the system is applied to the actual field environment for testing and analysis.In addition,the system can test the performance of I/O,such as CPU usage,memory usage,and data exchange speed.