Uranium enrichment measurements using the intensity ratios of self-fluorescence X-rays to 92* keV gamma ray in UXKα spectral region

In this paper, the known multigroup γ-ray analysis method for uranium (MGAU) as one of the non-destructive γ-ray spectrometry methods has been applied to certified reference nuclear materials (depleted, natural and enriched uranium) containing 235U isotope in the range of 0.32–4.51% atom 235U. Its analysis gives incorrect results for the low component 235U in depleted and natural uranium samples where the build-up of the decay products begins to interfere with the analysis. The results reveal that the build-up of decay products seems to be significant and thus the algorithms for the presence of decay products should be improved to resulting in the correct enrichment value. For instance, for the case of 235U analysis in depleted uranium or natural ore samples, self-induced X-rays such as 94.6 keV and 98.4 keV lying in UXKα spectral region used by MGAU can be excluded from the calculation. Because the significant increases have been observed in the intensities of uranium self-induced X-rays due to γ-ray emissions with above 100 keV energy arising from decay products of 238U and 235U and these parents. Instead, the use of calibration curve to be made between the intensity ratios of self-fluorescence X-rays to 92* keV γ-ray and the certified 235U abundances is suggested for the determination of 235U when higher amounts of decay products are detected in the γ-ray spectrum acquired for the MGAU analysis.