Woodruff School of Mechanical Engineering

NRE 8011/8012 and MP 6011/6012 Seminar

Nuclear & Radiological Engineering and Medical Physics Programs


Quantifying Morphological and Oxygen Isotopic Signatures of UO2 Based on Production History


Dr. Luther McDonald


Assistant Director, University of Utah Department of Civil and Environmental Engineering - Nuclear Engineering Program


Thursday, March 1, 2018 at 11:00:00 AM


Boggs Building, Room 3-47


Steve Biegalski


Oxygen isotope ratios of uranium oxides are known to correlate with those of the fluids from which they precipitated. The variety of processing routes utilized in the nuclear fuel cycle, from ore concentration through enrichment, will contribute to a wide variation in δ18O values encountered among uranium oxides. Application of this information for nuclear forensics purposes requires an understanding of the oxygen isotopic fractionation induced through each processing condition. The initial focus of this study is an interrogation of changes in the 18O/16O ratio along each step of commonly employed synthetic routes, with variation in the chemical compositions of starting materials. Beginning with a uranyl nitrate starting material depleted in 18O, uranium oxide intermediate products: α-UO3, am-UO3, and α-U3O8, were synthesized from aqueous solutions enriched in 18O using the uranyl peroxide route. Each of these compounds was then calcined to a final product of uranium dioxide. Identification of each uranium species was confirmed using powder X-ray diffraction, while oxygen isotope ratios of the starting materials, intermediated U-oxides, and the final UO2 were measured using a High Vacuum Fluorination System (HVFS) coupled with Isotope Ratio Mass Spectrometry (IRMS). Scanning electron microscopy (SEM) was used to quantify any morphological differences in the UO2 relative to the intermediate U-oxides. Results of oxygen isotope fractionation arising from variation in processing methods will be discussed, along with their implications for future nuclear forensic investigations.


Prof. McDonald joined the UU in January 2014 as an assistant professor in the Department of Civil and Environmental Engineering serving as the Assistant Director of the Nuclear Engineering Program. At Utah, he has led the development of a nuclear and radiochemistry research laboratory, mentoring over thirty students. McDonald also serves as the University Director of the Department of Homeland Security’s Nuclear Forensics Undergraduate Summer School. Prior to joining the UU, McDonald performed a post-doctoral fellowship at Pacific Northwest National Laboratory, worked as a visiting scientist at the Commissariat à l’énergie atomique in Saclay, France, and completed his Ph.D. at Washington State University in Radiochemistry. He served at the elected Secretary of the American Chemical Society’s Division of Nuclear Chemistry and Technology from 2013 – 2016 and was named one of Forbes 30 under 30 in Science in 2017.


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