Comparing Metrological Characteristics of Methodologies for Determining Uranium Enrichment Using NaI and LEGe Detectors

Abstract

The purpose of this work was to compare metrological characteristics of methodologies for determining uranium enrichment using different types of detectors and the IMCA software. This software includes several programs (applications), two of which were used in this work: IMCN was used for NaI detector, and IMCG was used for LEGe detector. The principle of enrichment measurement is that the uranium enrichment is directly proportional to the count rate at the 185.7 keV peak resulting from decay of 235U, provided that the sample’s thickness is sufficient (“infinite thickness” method). Based on the results of repeated measurements of samples with known enrichment, metrological characteristics of methodologies for different count times were calculated and compared. Analysis of the results led us to the following conclusions: reproducibility of results when performing measurements using LEGe detector is just as good as when using NaI detector; at that, uncertainty reported by the IMCG program is almost the same as the reproducibility estimate, while the IMCN program reports uncertainties that are several times smaller than the estimated reproducibility.