K-Edge Measurement Technology Simulation Model Design

Abstract

The K-edge technique is a nondestructive analysis (NDA) method that provides key data for nuclear material accountancy, mainly for the measurement of U and Pu concentrations in spent fuel reprocessing processes, with an analytical accuracy close to that of chemical analytical techniques. By analyzing the transmission spectrum of the light source absorbed by the sample, there is a distinct K-edge absorption jump in the spectrum at relatively high U concentrations, the intensity of which correlates with the U elemental concentration. The accuracy of the K-edge analysis technique is mainly affected by the K-edge absorption distance, the resolution of the detector, the intensity of the light source, and other parameters. Based on the principle of K-edge technology and particle transport theory, the article establishes the calculation model of K-edge measurement technology, which includes key components such as the continuous X-ray light source, high-purity germanium detector, cylindrical sample, collimator, and so on. In terms of light source setting, the light source function was obtained by linear interpolation method according to the X-ray light source model formula; in terms of K-edge absorption distance, the average K-edge absorption distance calculation method was adopted to improve the concentration calculation formula. The calibration factor was obtained under the experimental conditions with 8 mm diameter sample bottles. Under identical experimental conditions, the validation was tested out using samples with concentrations of 150 g/L. The reconstructed uranium concentrations were 148.5 g/L, with deviations of 1% between the initial values. To validate the average absorption distance calculation approach, a series of solutions with uranium concentrations ranging from 20 to 170 g/L were configured, and the calibration factors were computed. To further validate the correctness of the modified concentration calculation formula, the diameters of the sample bottles were altered to 6 mm and 10 mm, and the corresponding calibration factors were obtained, respectively. Verification experiments were subsequently carried out using solutions with concentrations of 150 g/L. The simulation outcomes validate the accuracy of the model and the modified concentration calculation formula. The calculation model constructed in the article combines with actual application scenarios to provide preliminary technical assurance for the expansion and optimization of K-edge measurement technology.