1
|
Kurtyka N, van Devener B, Chung BW, McDonald LW. In Situ Liquid Cell Transmission Electron Microscopy Study of Studtite Particle Formation and Growth via Electron Beam Radiolysis. ACS OMEGA 2023; 8:48336-48343. [PMID: 38144047 PMCID: PMC10733958 DOI: 10.1021/acsomega.3c07743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 11/10/2023] [Accepted: 11/15/2023] [Indexed: 12/26/2023]
Abstract
This study presents in situ observations of studtite (UO2O2(H2O)2·2H2O) crystal growth utilizing liquid phase transmission electron microscopy (LP-TEM). Studtite was precipitated from a uranyl nitrate hexahydrate solution using hydrogen peroxide formed by the radiolysis of water in the TEM electron beam. The hydrogen peroxide (H2O2) concentration, directly controlled by the electron beam current, was varied to create local environments of low and high concentrations to compare the impact of the supersaturation ratio on the nucleation and growth mechanisms of studtite particles. The subsequent growth mechanisms were observed in real time by TEM and scanning TEM imaging. After the initial precipitation reaction, a post-mortem TEM analysis was performed on the samples to obtain high-resolution TEM images and selected area electron diffraction patterns to investigate crystallinity as well as energy-dispersive X-ray spectroscopy spectra to ensure that studtite was produced. The results reveal that studtite particles form through various mechanisms based on the concentration ratio of uranyl to H2O2 and that studtite is initially produced through an amorphous intermediary prior to formation of the crystalline material commonly reported in the literature.
Collapse
Affiliation(s)
- Nick Kurtyka
- Department
of Nuclear Engineering, University of Utah, 110 Central Campus Dr., Suite 2000, Salt Lake City, Utah 84112, United States
| | - Brian van Devener
- Electron
Microscopy and Surface Analysis Laboratory, University of Utah, Salt Lake
City, Utah 84112, United States
| | - Brandon W. Chung
- Lawrence
Livermore National Laboratory, 7000 East Ave., Livermore, California 94550, United States
| | - Luther W. McDonald
- Department
of Nuclear Engineering, University of Utah, 110 Central Campus Dr., Suite 2000, Salt Lake City, Utah 84112, United States
| |
Collapse
|
2
|
Pandelus SB, Kennedy BJ, Murphy G, Brand HE, Keegan E, Pring A, Popelka-Filcoff RS. Phase Analysis of Australian Uranium Ore Concentrates Determined by Variable Temperature Synchrotron Powder X-ray Diffraction. Inorg Chem 2021; 60:11569-11578. [PMID: 34293259 DOI: 10.1021/acs.inorgchem.1c01562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The chemical speciation of uranium oxides is sensitive to the provenance of the samples and their storage conditions. Here, we use diffraction methods to characterize the phases found in three aged (>10 years) uranium ore concentrates of different origins as well as in situ analysis of the thermally induced structural transitions of these materials. The structures of the crystalline phases found in the three samples have been refined, using high-resolution synchrotron X-ray diffraction data. Rietveld analysis of the samples from the Olympic Dam and Ranger uranium mines has revealed the presence of crystalline α-UO2(OH)2, together with metaschoepite (UO2)4O(OH)6·5H2O, in the aged U3O8 samples, and it is speculated that this forms as a consequence of the corrosion of U3O8 in the presence of metaschoepite. The third sample, from the Beverley uranium mine, contains the peroxide [UO2(η2-O2)(H2O)2] (metastudtite) together with α-UO2(OH)2 and metaschoepite. A core-shell model is proposed to account for the broadening of the diffraction peaks of the U3O8 evident in the samples.
Collapse
Affiliation(s)
- Samantha B Pandelus
- College of Science and Engineering, Flinders University, Adelaide, South Australia 5001, Australia
| | - Brendan J Kennedy
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Gabriel Murphy
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia.,ANSTO, Lucas Heights, Sydney, New South Wales 2234, Australia
| | - Helen E Brand
- Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | | | - Allan Pring
- College of Science and Engineering, Flinders University, Adelaide, South Australia 5001, Australia.,School of Physical Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Rachel S Popelka-Filcoff
- College of Science and Engineering, Flinders University, Adelaide, South Australia 5001, Australia.,School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Parkville, Victoria 3010, Australia
| |
Collapse
|
3
|
Hanson A, Nizinski CA, McDonald LW. Effect of Diel Cycling Temperature, Relative Humidity, and Synthetic Route on the Surface Morphology and Hydrolysis of α-U 3O 8. ACS OMEGA 2021; 6:18426-18433. [PMID: 34308073 PMCID: PMC8296549 DOI: 10.1021/acsomega.1c02487] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 06/22/2021] [Indexed: 06/13/2023]
Abstract
The speciation and morphological changes of α-U3O8 following aging under diel cycling temperature and relative humidity (RH) have been examined. This work advances the knowledge of U-oxide hydration as a result of synthetic route and environmental conditions, ultimately giving novel insight into nuclear material provenance. α-U3O8 was synthesized via the washed uranyl peroxide (UO4) and ammonium uranyl carbonate (AUC) synthetic routes to produce unaged starting materials with different morphologies. α-U3O8 from UO4 is comprised of subrounded particles, while α-U3O8 from AUC contains blocky, porous particles approximately an order of magnitude larger than particles from UO4. For aging, a humidity chamber was programmed for continuous daily cycles of 12 "high" hours of 45 °C and 90% RH, and 12 "low" hours of 25 °C and 20% RH. Samples were analyzed at varying intervals of 14, 24, 36, 43, and 54 days. At each aging interval, crystallographic changes were measured via powder X-ray diffraction coupled with whole pattern fitting for quantitative analysis. Morphologic effects were studied via scanning electron microscopy and 12-way classification via machine learning. While all samples were found to have distinguishing morphologic characteristics (93.2% classification accuracy), α-U3O8 from UO4 had more apparent change with increasing aging time. Nonetheless, α-U3O8 from AUC was found to hydrate more quickly than α-U3O8 from UO4, which can likely be attributed to its larger surface area and porous starting material morphology.
Collapse
|
4
|
Hanson A, Schwerdt IJ, Nizinski CA, Lee RN, Mecham NJ, Abbott EC, Heffernan S, Olsen A, Klosterman MR, Martinson S, Brenkmann A, McDonald LW. Impact of Controlled Storage Conditions on the Hydrolysis and Surface Morphology of Amorphous-UO 3. ACS OMEGA 2021; 6:8605-8615. [PMID: 33817521 PMCID: PMC8015116 DOI: 10.1021/acsomega.1c00435] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 03/02/2021] [Indexed: 06/12/2023]
Abstract
The hydration and morphological effects of amorphous (A)-UO3 following storage under varying temperature and relative humidity have been investigated. This study provides valuable insight into U-oxide speciation following aging, the U-oxide quantitative morphological data set, and, overall, the characterization of nuclear material provenance. A-UO3 was synthesized via the washed uranyl peroxide synthetic route and aged based on a 3-factor circumscribed central composite design of experiment. Target aging times include 2.57, 7.00, 14.0, 21.0, and 25.4 days, temperatures of 5.51, 15.0, 30.0, 45.0, and 54.5 °C, and relative humidities of 14.2, 30.0, 55.0, 80.0, and 95.8% were examined. Following aging, crystallographic changes were quantified via powder X-ray diffraction and an internal standard Rietveld refinement method was used to confirm the hydration of A-UO3 to crystalline schoepite phases. The particle morphology from scanning electron microscopy images was quantified using both the Morphological Analysis of MAterials software and machine learning. Results from the machine learning were processed via agglomerative hierarchical clustering analysis to distinguish trends in morphological attributes from the aging study. Significantly hydrated samples were found to have a much larger, plate-like morphology in comparison to the unaged controls. Predictive modeling via a response surface methodology determined that while aging time, temperature, and relative humidity all have a quantifiable effect on A-UO3 crystallographic and morphological changes, relative humidity has the most significant impact.
Collapse
|
5
|
Pastoor KJ, Kemp RS, Jensen MP, Shafer JC. Progress in Uranium Chemistry: Driving Advances in Front-End Nuclear Fuel Cycle Forensics. Inorg Chem 2021; 60:8347-8367. [PMID: 33619961 DOI: 10.1021/acs.inorgchem.0c03390] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The front-end of the nuclear fuel cycle encompasses several chemical and physical processes used to acquire and prepare uranium for use in a nuclear reactor. These same processes can also be used for weapons or nefarious purposes, necessitating the need for technical means to help detect, investigate, and prevent the nefarious use of nuclear material and nuclear fuel cycle technology. Over the past decade, a significant research effort has investigated uranium compounds associated with the front-end of the nuclear fuel cycle, including uranium ore concentrates (UOCs), UF4, UF6, and UO2F2. These efforts have furthered uranium chemistry with an aim to expand and improve the field of nuclear forensics. Focus has been given to the morphology of various uranium compounds, trace elemental and chemical impurities in process samples of uranium compounds, the degradation of uranium compounds, particularly under environmental conditions, and the development of improved or new techniques for analysis of uranium compounds. Overall, this research effort has identified relevant chemical and physical characteristics of uranium compounds that can be used to help discern the origin, process history, and postproduction history for a sample of uranium material. This effort has also identified analytical techniques that could be brought to bear for nuclear forensics purposes. Continued research into these uranium compounds should yield additional relevant chemical and physical characteristics and analytical approaches to further advance front-end nuclear fuel cycle forensics capabilities.
Collapse
Affiliation(s)
- Kevin J Pastoor
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - R Scott Kemp
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Mark P Jensen
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States.,Nuclear Science and Engineering Program, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Jenifer C Shafer
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States.,Nuclear Science and Engineering Program, Colorado School of Mines, Golden, Colorado 80401, United States
| |
Collapse
|
6
|
Schwantes JM, Conroy M, Lach TG, Lonergan JM, Pellegrini KL, Robertson JD, Clark RA. Changing the rules of the game: used fuel studies outside of a remote handling facility. J Radioanal Nucl Chem 2019. [DOI: 10.1007/s10967-019-06921-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|