Study On Spectrum Correction Algorithm Of HPGe-LaBr₃ Double Detector System Under Radiation Conditions

China's nuclear power industry is in a stage of rapid development. Higher requirements are put forward to China's nuclear safety work. The study of nuclear accident emergency monitoring method is particularly important. At present, the airborne radioactive monitoring device has been widely used to measure the nuclide information in the nuclear emergency. However, there is larger development space on obtaining about the fast and accurate information of radioactive nuclides. In this paper, a new spectrum correction algorithm is proposed for the double detector system in airborne radioactive monitoring equipment NH-UAV, which can realize the fast and accurate measurement of fixed-point radionuclide information about the system.The main research contents and research results are as follows:1) A new spectrum correction algorithm is proposed for the airborne radioactive monitoring equipment NH-UAV. According to the difference of detection region between the HPGe detector and LaBr₃ detector, detection spectra of the HPGe detector are set to the standard spectra, and the detection data of the LaBr₃ detector are corrected based on the data of the HPGe detector. Spectra correction coefficients are calculated and corresponding spectra correction curves are fitted using relative software. The theoretical basis and its preliminary verification of the method was discussed for the energy spectra correction algorithm. The spectra of the HPGe detector and the LaBr₃ detector were obtained using the Monte Carlo simulation. During MCNP simulation, Russia Roulette and mandatory collision were used to reduce the variance. A kind of secondary sources variance reduction technique was proposed here. The applicability of the method under different probe location and different size were studied. The results showed that there was a good linear relationship between the correction factor and energy. The maximum relative deviation from the actual value reduced from 1.65 to 0.035 after amending. The method was verified as feasible.2) According to the different stages of nuclear accident, the feasibility and applicability of the spectrum correction algorithm about the NH-UAV airborne radioactive monitoring system under different complex radiation environments were explored. These conditions included the beginning of the nuclear accident different nuclear accidents, the mid-term of nuclear accident, and late nuclear accident, different altitude and detecting the position and size of different source term. Research results showed that the energy spectrum correction method was applicable to different radiation environment, and there was a good linear relationship between the corresponding energy and energy spectrum correction coefficient. Within a certain error range, energy spectrum correction algorithm has nothing to do with the flying height. But the probe location and the size of the source term has a great influence on the result of the energy spectrum correction.3) The G?E? function of the LaBr₃ detector was studied using least square method. Energy spectrums of several energies were obtained using Monte Carlo technique. The G?E? function equation of the LaBr₃ detector was obtained. The function equation was proved to be feasible.The research work done in this study can provide the effective proof to data processing in the process of detection. And it also can help to realize the function of accurate radionuclides measurement in real time and in a fixed place.