Structure and Reactivity of X-ray Amorphous Uranyl Peroxide, U ₂ O ₇

Journal Article · Mon Mar 14 00:00:00 EDT 2016 · Inorganic Chemistry

DOI:https://doi.org/10.1021/acs.inorgchem.6b00017· OSTI ID:1241447

Odoh, Samuel O. ^[1]; Shamblin, Jacob ^[2]; Colla, Christopher A. ^[3]; Hickam, Sarah ^[4]; Lobeck, Haylie L. ^[4]; Lopez, Rachel A. K. ^[4]; Olds, Travis ^[4]; Szymanowski, Jennifer E. S. ^[4]; Sigmon, Ginger E. ^[4]; Neuefeind, Joerg ^[5]; Casey, William H. ^[3]; Lang, Maik ^[2]; Gagliardi, Laura ^[1]; Burns, Peter C. ^[6]

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1. University of Minnesota, Department of Chemistry, Minnesota Supercomputing Institute, Minneapolis, Minnesota 55455, United States
2. Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennesee 37996, United States
3. Department of Earth and Planetary Sciences, Department of Chemistry, University of California, Davis, California 95616, United States
4. Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana 46556, United States
5. Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
6. Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana 46556, United States, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States

Recent accidents resulting in worker injury and radioactive contamination occurred due to pressurization of uranium yellowcake drums produced in the western USA. The drums contained an unexpected X-ray amorphous reactive form of uranium oxide, U₂O7. Heating hydrated uranyl peroxides produced during in situ mining unintentionally produced U₂O₇. It is a hygroscopic anhydrous uranyl peroxide that reacts rapidly with water to release O₂ gas and form metaschoepite, a uranyl-oxide hydrate. Quantum chemical calculations indicate that the most stable U₂O₇ conformer consists of two bent (UO₂)²⁺ uranyl ions bridged by a peroxide group bidentate and parallel to each uranyl ion, and a μ2-O atom, resulting in charge neutrality. A pair distribution function from neutron total scattering supports this structural model. The reactivity of U₂O₇ in water and with water in air is much higher than other uranium oxides, and this can be both hazardous and potentially advantageous in the nuclear fuel cycle.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Energy Frontier Research Centers (EFRC) (United States). Materials Science of Actinides (MSA)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0001089; AC05-00OR22725
• OSTI ID: 1241447
• Alternate ID(s): OSTI ID: 1334422
• Journal Information: Inorganic Chemistry, Journal Name: Inorganic Chemistry Vol. 55 Journal Issue: 7; ISSN 0020-1669
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY