Measurement of uranium-236 in particles by secondary ion mass spectrometry. Issue 2 (13th January 2017)

• Record Type: Journal Article
• Authors: Simons, David S.; Fassett, John D.
• Is Part Of: Journal of analytical atomic spectrometry. Volume 32:Issue 2(2017)
• Page Start: 393
• Page End: 401
• Publication Date: 2017-01-13
• Subjects: Atomic spectra -- Periodicals; Atomic absorption spectroscopy -- Periodicals; 543.0858
• DOI: 10.1039/c6ja00402d
• Languages: English
• ISSNs: 0267-9477

Abstract

Abstract : The determination of the relative isotopic abundance by secondary ion mass spectrometry of 236 U in uranium-containing material is complicated by the presence of 235 U 1 H + ions at the same nominal mass as the uranium isotopic peak. Abstract : The determination of the relative isotopic abundance by secondary ion mass spectrometry of 236 U in uranium-containing material is complicated by the presence of 235 U 1 H + ions at the same nominal mass as the uranium isotopic peak. The net intensity of the 236 U signal is usually determined by a peak-stripping procedure, whereby the 235 U 1 H + contribution is obtained by applying the 238 U 1 H + / 238 U + ratio to the 235 U + signal. The subtraction of one signal from another has consequences for the uncertainty of the final 236 U abundance determination that may be especially significant when the amount of sample is limited, as is the case with small uranium particles that are of great interest for nuclear safeguards. We have developed a model based on Poisson counting statistics to determine the effects of various parameters on the uncertainty of the 236 U abundance, including uranium enrichment level, hydride-to-parent ratio, uranium mass consumed during analysis, single versus multichannel counting, and sample substrate composition. The model predictions have been successfully tested against experimental measurements of uranium oxide particles of both 3% and 90% enrichment in 235 U.