Monte Carlo Simulation Of The Response Function And Impact Analysis Of Transuranic Nuclide

High-level radioactive waste has always been the focus and difficulty of radioactive waste treatment and disposal.It usually comes from the spent fuel produced by the combustion of fuel rods in nuclear islands,accounting for about 3% of the total weight of spent fuel,but the high activity of high-level radioactive waste is high.The long decay cycle has always been the difficulty and focus of nuclear waste treatment and disposal.Representative transuranic ?-nuclides include Pu,U,Am,Cm,and Np.Effective alpha particle measurement data can be used not only to calculate the radioactivity of the parent nuclide,to identify the type of alpha nuclide,but also to provide a basis for the monitoring of alpha nuclide in the deep geological repository of high-level radioactive waste.Spectral measurement methods for the detection of long half-life transuranic nuclides are a fundamental and very important task.In the alpha spectrum measurement process,the alpha spectrum is easily affected by various factors.The influence of various factors on the measurement results in the process of alpha spectrum measurement is experimentally analyzed and is limited by the instrument conditions and performance.The feasibility is poor.In this paper,the Monte Carlo method is used to simulate the alpha spectrum response function,and the various influencing factors in the energy spectrum measurement process are analyzed one by one,and the main influencing factors of spectrometer detection efficiency in the alpha spectrum measurement process are defined.The MC model was established based on the actual parameters of the detector,and the model was calibrated by comparing the experimental results with the simulation results.Based on this,the ?-spectral response function was simulated and the influencing factors on the detection efficiency of the ?-spectrometer were studied.In this paper,SRIM software is used to simulate the range and concentration distribution of alpha particles in the air and in the detector dead layer.The effect of chamber pressure and dead layer thickness on the detection efficiency of the spectrometer is analyzed.MCNPX was used to simulate the effect of source detector distance and detector intrinsic detection efficiency on the detection efficiency of the spectrometer.The intrinsic detection efficiency of the spectrometer for the three sources was calculated through experimental and simulated data.The influence of axis center distance and placement angle of the radiation source on the detection efficiency of the spectrometer was analyzed through the Monte Carlo simulation of the ?-spectral response function.The experimental and simulation results show that the Monte Carlo method used in this paper can be used for ?-spectral response function simulation.The factors affecting the detection efficiency of the alpha spectrometer include: source detector distance,intrinsic detection efficiency,axis center distance,and radioactive source placement angle.The results of the study indicate that the axis center distance of the source should be less than 4cm during the alpha spectrum measurement,the placement angle should be less than 39.8°,and the deflectable interval should be [50.2°,129.8°].The research work done in this paper can not only be used for ?-spectral response function simulation,but also can provide guidance for the accurate measurement of ?-spectrum data and provide basis for the formulation of experimental schemes.At the same time,the Monte carlo model established in this paper can also be used for the simulation of single-energy ?-spectral response function,which can provide help for the study of single-energy ?-particle energy spectrum.