Passive Non-Destructive Assay based on gamma-ray spectrometry to verify UO₂ samples in the form of powder and pellet

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• 作者：M. Tohamy^a ; S. Abd El-Ghany^b ; S.M. El-Minyawi^b ; M. Fayez-Hassan^a ; Elham H. El-hakim^c ; Sayed A. El-Mongy^d ; M.N.H. Comsan^a ;
• 关键词：Passive Non-Destructive Assay ; Nuclear material verification ; Natural uranium ; Low enriched uranium ; Intrinsic self-calibration ; Isotopic activity ratio
• 刊名：Annals of Nuclear Energy
• 出版年：2016
• 出版时间：January 2016
• 年：2016
• 卷：87
• 期：part_P2
• 页码：186-191
• 全文大小：1020 K

文摘

Passive Non-Destructive Assay (PNDA) gamma-spectroscopic method is employed for nuclear material verification. The investigated materials are natural (NU) and low enriched uranium (LEU) in the form of uranium dioxide (UO₂) pellets and powder, respectively. A high-resolution gamma-ray spectrometer based on HPGe detector and associated electronics is used for the measurement. The spectrometer efficiency was measured experimentally using the intrinsic self-calibration method taking into account the necessary correction factors.

Sample isotopic fractions were obtained using two methods; that based on the measurement of the count rate of 185.7 keV gamma line of ²³⁵U and 1001 keV gamma line of ^234mPa (²³⁸U) employing the intrinsic self-calibration technique to calculate the activity ratio of ²³⁵U/²³⁸U. The other method is based on uranium activity ratio measurements without efficiency corrections by choosing two gamma-rays close enough in energy, one related to ²³⁵U (84.2 keV gamma line of ²³¹Th) and the other to ²³⁸U (63.3 keV gamma line of ²³⁴Th).

Samples were characterized by calculating uranium isotopic mass, uranium isotopic activity ratio, total uranium content and enrichment. Special attention was given at calculating absolute error of the measured quantities, as well as the statistical behavior of the measured data in terms of the well known statistical quantities. The experimental results showed good agreement with calculated data.