A SGS efficiency calibration method for measuring the radioactive waste drum based on Monte Carlo simulation and function model

Abstract

This work presents a Segmented Gamma Scanning (SGS) efficiency calibration method based on Monte Carlo simulation and function model, to calculate the efficiency matrix and reconstruct the radioactivity of the radioactive waste drum. The middle- or low-energy gamma rays emitted by the transmission source ¹⁵²Eu, cannot transmit the high-density waste drum in the Segmented Gamma Scanning of the radioactive waste drum. Therefore, the accurate attenuation correction cannot be achieved through efficiency calibration, for the middle- or low-energy gamma rays emitted from the drum, which affects the accuracy of the reconstructed radioactivity. High-energy gamma rays have been employed to transmit the waste drum to determine the density of segment, and then the efficiency of segment is determined from the density of segment and the energy of gamma rays emitted from the waste drum. When the point source ¹³⁷Cs is distributed in segments with varying densities in the waste drum sample, the relative deviations of reconstructed radioactivity fall in − 90.69% ~ 22.33%. The method is convenient and effective for the SGS efficiency calibration while measuring the high-density waste drum, and the relative deviations of reconstructed activity are acceptable on this basis. Compared with alternative methods, the process outlined in this method is more simple, operational, and practical. Further, it provides the user with a practical method in SGS efficiency calibration and the activity reconstruction of the waste drum.