High accuracy determination of235U in nondestructive assay standards by gamma spectrometry

Autor: B. S. Carpenter, Robert R. Greenberg
Rok vydání: 1987
Předmět:
Zdroj: Journal of Radioanalytical and Nuclear Chemistry Articles. 111:177-197
ISSN: 1588-2780
0236-5731
Popis: High precision gamma spectrometry measurements have been made on five sets of uranium isotope abundance reference materials for nondestructive assay (NDA). These sets are intended for international safeguards use as primary reference materials for the determination of the235U abundance in homogeneous uranium bulk material by gamma spectrometry. The measurements were made to determine the count rate uniformity of the235U 185.7 keV gamma-ray as well as the235U isotope abundance for each sample. Since the samples were packaged such that the U3O8 is infinitely thick for the 185.7 keV gamma-ray, the measured count rate was not dependent on the material density. In addition, the activity observed by the detector was collimated to simulate calibration conditions used to measure bulk material in the field. The sample-to-sample variations observed within the 5 sets of samples ranged between 0.005–0.11% (1s) with standard deviations of the mean ranging from 0.01–0.02%. This observed variation appears to be due predominantly to counting statistics and not to material inhomogeneity and/or packaging. The results of this study indicate that accuracy of235U determinations via gamma spectrometry, in the range of few hundredths of a percent (2σ), is achievable. The main requirement for achieving this level of accuracy is a set of standards whose235U isotope abundances are known to within 0.01% (2σ).
Databáze: OpenAIRE
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