Edgar Buck

Profile Information
Name
Dr. Edgar Buck
Institution
Pacific Northwest National Laboratory
Position
Staff Scientist V
h-Index
33
ORCID
0000-0001-5101-9084
Biography

Dr. Edgar C. Buck has been staff scientist in the Radiochemical Processing Laboratory at Pacific Northwest National Laboratory (PNNL) since 2000. Prior to this he was at Argonne National Laboratory for nearly 10 years.  He managed several projects within PNNL’s Nuclear Processing Science Initiative to develop new advanced microscopy tools, including in-situ liquid cell and cryoEM for nuclear sciences.  He has been the Program Manager for a DOE-NE project supporting research for geologic disposal since 2009 and is Principal Investigator for a Counter-Weapons of Mass Destruction (CWMD) project on signature development, as well as several other smaller projects.  He has over 70 publications and co-authored the Chapter on Uranium for the 3rd edition of the Chemistry of the Actinide and Transactinide Elements.  He has held other scientific leadership roles over time, including actinide migration and the waste form corrosion projects. 

Dr. Buck is knowledgeable in the interaction of electron beams with matter, electron and x-ray instrumentation, and materials science with an emphasis on radioactive materials.  He has expertise in the long-term behavior of nuclear materials, including spent nuclear fuels, borosilicate glass, radio-colloids, and post-irradiation examination of reactor components.

He was part of a team that was awarded the DOE Secretary of Energy Honor Award for work conducted on the WIPP accident in 2014 and was the lead author on the Waste Form and In-drift Colloids-Associated Radionuclide Concentrations: Abstraction and Summary, for the Yucca Mountain Repository License Application. 

He has taught a graduate level course in electron microscopy at Washington State University (WSU) Tri-Cities and is currently an adjunct professor at WSU.  He has mentored several postdocs, students, and junior staff over the past ten years.  He is the Specialty Chief Editor on nuclear materials for a new Frontiers in Nuclear Technology journal and is leading a special issue on novel nuclear materials for the journal Materials.  

Expertise
Actinide, LWR, Material Characterization, SEM, STEM
Publications:
"Performance evaluation and post-irradiation examination of a novel LWR fuel composed of U0.17ZrH1.6 fuel pellets bonded to Zircaloy-2 cladding by lead bismuth eutectic" Mehdi Balooch, Edgar Buck, Andy Casella, Peter Hosemann, Donald Olander, Dave Senor, Kurt Terrani, Journal of Nuclear Materials Vol. 486 2017 391-401 Link
A novel light water reactor fuel has been designed and fabricated at the University of California, Berkeley; irradiated at the Massachusetts Institute of Technology Reactor; and examined within the Radiochemical Processing Laboratory at the Pacific Northwest National Laboratory. This fuel consists of U0.17ZrH1.6 fuel pellets core-drilled from TRIGA reactor fuel elements that are clad in Zircaloy-2 and bonded with lead-bismuth eutectic. The performance evaluation and post irradiation examination of this fuel are presented here.
Presentations:
" Microanalysis of Irradiated Metallic Hydride Nuclear fuel (U0.17 ZrH1.6) Fuels" Mehdi Balooch, Edgar Buck, Andy Casella, 2017 ANS Annual Meeting [unknown]
Additional Publications:
"Filtration of Hanford Tank 241-AW-105 Supernatant at 16 °C" , Christian Alvarez, Austin Bachman, Edgar Buck, Carolyn Burns, Richard Daniel, Jarrod Turner, Reid Peterson, , Jarrod Allred, [2025] · DOI: 10.2172/2571593
"Editorial: Plutonium legacy storage and degradation" Robin Taylor, Edgar Buck, [2024] Frontiers in Nuclear Engineering · DOI: 10.3389/fnuen.2024.1447819 · ISSN: 2813-3412
"Filtration of Hanford Tank 241-AN-107 Supernatant at 16 °C" Christian Alvarez, Edgar Buck, Carolyn Burns, Richard Daniel, Jarrod Turner, Amy Westesen, Reid Peterson, Jarrod Allred, [2024] · DOI: 10.2172/2426527
"Investigation of the thermal decomposition of Pu(IV) oxalate: a transmission electron microscopy study" Dallas D. Reilly, Luke E. Sweet, Aaron D. Nicholas, Forrest D. Heller, Gabriel B. Hall, Richard A. Clark, Amanda J. Casella, Edgar C. Buck, [2024] Frontiers in Nuclear Engineering · DOI: 10.3389/fnuen.2024.1380137 · ISSN: 2813-3412

The degradation of the internal structure of plutonium (IV) oxalate during calcination was investigated with Transmission Electron Microscopy (TEM), electron diffraction, Electron Energy-Loss Spectroscopy (EELS), and 4D Scanning TEM (STEM). TEM lift-outs were prepared from samples that had been calcined at 300°C, 450°C, 650°C and 950°C. The resulting phase at all calcination temperatures was identified as PuO2 with electron diffraction. The grain size range was obtained with high-resolution TEM. In addition, 4D STEM images were analyzed to provide grain size distributions. In the 300°C calcined sample, the grains were <10 nm in diameter, at 650°C, the grains ranged from 10 to 20 nm, and by 950°C, the grains were 95–175 nm across. Using the Kolmogorov-Smirnov (K-S) two sample test, it was shown that morphological measurements obtained from 4D-STEM provided statistically significant distributions to distinguish samples at the different calcination conditions. Using STEM-EELS, carbon was shown to be present in the low temperature calcined samples associated with oxalate but had formed carbon (possibly graphite) deposits in the 950°C calcined sample. This work highlights the new methods of STEM-EELS and 4D-STEM for studying the internal structure of special nuclear materials (SNM).

"Robust nanoporous NiMn oxide electrocatalysts for the oxygen evolution reaction through defect engineering" Ambrish Kumar, Ram K. Sharma, Edgar C. Buck, Bharat Gwalani, Meha Bhogra, Harpreet Singh Arora, Arpit Thomas, [2024] Journal of Materials Chemistry A · DOI: 10.1039/d4ta02679a

Excellent catalytic performance of oxygen vacancy enriched, nano-porous Mn3O4/Ni/NiMnO3 architecture.

"Expanding the Transuranic Metal–Organic Framework Portfolio: The Optical Properties of Americium(III) MOF-76" Aaron D. Nicholas, Michael A. Sinnwell, Bruce K. McNamara, Edgar C. Buck, Robert G. Surbella, Ana Arteaga, [2023] Inorganic Chemistry · DOI: 10.1021/acs.inorgchem.3c02742
"FY 23 Filtration of Hanford Tank 241-SY-101 Supernatant at 16 °C" Christian Alvarez, Edgar Buck, Carolyn Burns, Richard Daniel, John Geeting, Amy Westesen, Reid Peterson, Jarrod Allred, [2023] · DOI: 10.2172/1998619
"Insight into the Structural and Emissive Behavior of a Three‐Dimensional Americium(III) Formate Coordination Polymer" Ana Arteaga, Lucas C. Ducati, Edgar C. Buck, Jochen Autschbach, Robert G. Surbella, Aaron D. Nicholas, [2023] Chemistry – A European Journal · DOI: 10.1002/chem.202300077
Abstract

We report the structural, vibrational, and optical properties of americium formate (Am(CHO2)3) crystals synthesized via the in situ hydrolysis of dimethylformamide (DMF). The coordination polymer features Am3+ ions linked by formate ligands into a three‐dimensional network that is isomorphous to several lanthanide analogs, (e. g., Eu3+, Nd3+, Tb3+). Structure determination revealed a nine‐coordinate Am3+ metal center that features a unique local C3v symmetry. The metal–ligand bonding interactions were investigated by vibrational spectroscopy, natural localized molecular orbital calculations, and the quantum theory of atoms in molecules. The results paint a predominantly ionic bond picture and suggest the metal‐oxygen bonds increase in strength from Nd−O<Eu−O<Am−O. The optical properties were probed using diffuse reflectance and photoluminescence spectroscopies. Notably, the rarely reported 5D1′7F0′ emission band is observed and dominates the emission spectrum. This behavior is unusual and is attributed to the C3v coordination environment of the metal center.

"Insight into the Structural and Emissive Behavior of a Three-Dimensional Americium(III) Formate Coordination Polymer" Ana Arteaga, Lucas C. Ducati, Edgar C. Buck, Jochen Autschbach, Robert G. Surbella, Aaron D. Nicholas, [2023] Chemistry - A European Journal · DOI: 10.1002/chem.202300077
Abstract

We report the structural, vibrational, and optical properties of americium formate (Am(CHO2)3) crystals synthesized via the in situ hydrolysis of dimethylformamide (DMF). The coordination polymer features Am3+ ions linked by formate ligands into a three‐dimensional network that is isomorphous to several lanthanide analogs, (e. g., Eu3+, Nd3+, Tb3+). Structure determination revealed a nine‐coordinate Am3+ metal center that features a unique local C3v symmetry. The metal–ligand bonding interactions were investigated by vibrational spectroscopy, natural localized molecular orbital calculations, and the quantum theory of atoms in molecules. The results paint a predominantly ionic bond picture and suggest the metal‐oxygen bonds increase in strength from Nd−O<Eu−O<Am−O. The optical properties were probed using diffuse reflectance and photoluminescence spectroscopies. Notably, the rarely reported 5D1′7F0′ emission band is observed and dominates the emission spectrum. This behavior is unusual and is attributed to the C3v coordination environment of the metal center.

"Advancing radioactive material research method: the development of a novel in situ particle-attached microfluidic electrochemical cell" Shalini Tripathi, Bruce K. McNamara, Nabajit Lahiri, Shawn L. Riechers, Sayandev Chatterjee, Dallas D. Reilly, Eugene S. Ilton, Edgar C. Buck, Jennifer Yao, [2023] Frontiers in Nuclear Engineering · DOI: 10.3389/fnuen.2023.1206110 · ISSN: 2813-3412

Introduction: This study aims to develop a microgram-scale microfluidic electrochemical cell (E-cell) for investigating the redox behavior of uranium oxide (UO2). The traditional bulk electrochemical methods may require shielded facilities to investigate the hazardous materials, e.g., spent nuclear fuel, due to high radiation levels. Microfluidic E-cells offer advantages such as reduced radiation exposure, control over fluid flow rates, and high-throughput capabilities.

Methods: The design of the E-cell considers electrode morphology, adhesion to a thin membrane, electrode configuration, and vacuum compatibility. Three techniques, including FIB-SEM lift-out, Au coating, and polyvinylidene fluoride (PVDF) binder, are explored for fabricating and attaching microgram quantities of UO2 as working electrodes. The PVDF binder method proves to be the most effective, enabling the creation of a vacuum-compatible microfluidic E-cell.

Results and discussion: The PVDF binder method demonstrates successful electrochemical responses and allows for real-time monitoring of UO2 electrode behavior at the microscale. It offers chemical imaging capabilities using in situ SEM/EDS analysis. The technique provides consistent redox outcomes similar to bulk electrochemical analysis.

Conclusion: The development of a microgram-scale microfluidic electrochemical cell using the PVDF binder technique enables the investigation of UO2 redox behavior. It offers a low-risk approach with reduced radiation exposure and high-throughput capabilities. The technique provides real-time monitoring and chemical imaging capabilities, making it valuable for studying spent nuclear fuel systems and material characterization.

"Fiscal Year 2023 Filtration of Hanford Tank 241-AP-105 Supernatant at 16 °C" Christian Alvarez, Edgar Buck, Carolyn AM Burns, Richard Daniel, John GH Geeting, Amy Westesen, Reid Peterson, Jarrod Allred, [2023] · DOI: 10.2172/1998872
"Oxygen-Vacancy Abundant Nanoporous Ni/NiMnO3/MnO2@NiMn Electrodes with Ultrahigh Capacitance and Energy Density for Supercapacitors" Ambrish Kumar, Gopinath Perumal, Ram Kumar Sharma, Vignesh Manivasagam, Ketul Popat, Aditya Ayyagari, Anqi Yu, Shalini Tripathi, Edgar Buck, Bharat Gwalani, Meha Bhogra, Harpreet Singh Arora, Arpit Thomas, [2023] ACS Applied Materials & Interfaces · DOI: 10.1021/acsami.2c16818
"Oxygen-Vacancy Abundant Nanoporous Ni/NiMnO3/MnO2@NiMn Electrodes with Ultrahigh Capacitance and Energy Density for Supercapacitors" Ambrish Kumar, Gopinath Perumal, Ram Kumar Sharma, Vignesh Manivasagam, Ketul Popat, Aditya Ayyagari, Anqi Yu, Shalini Tripathi, Edgar Buck, Bharat Gwalani, Meha Bhogra, Harpreet Singh Arora, Arpit Thomas, [2023] ACS Applied Materials & Interfaces · DOI: 10.1021/acsami.2c16818
"Evaluation of the Radioactive Material Release in the Harborview Research and Training Building and Implications for Emergency Response" [2023] Health Physics
"Solubility controls on plutonium and americium release in subsurface environments exposed to acidic processing wastes" Sergey I. Sinkov, Carolyn I. Pearce, Kirk J. Cantrell, Calvin H. Delegard, Michelle M.V. Snyder, May-Lin Thomas, Dallas D. Reilly, Edgar C. Buck, Lucas E. Sweet, Amanda J. Casella, Jennifer C. Carter, Jordan F. Corbey, Ian J. Schwerdt, Richard Clark, Forrest D. Heller, David Meier, Mavrik Zavarin, Annie B. Kersting, Vicky L. Freedman, Hilary P. Emerson, [2023] Applied Geochemistry · DOI: 10.1016/j.apgeochem.2022.105241
"In-Situ Liquid Cell Transmission Electron Microscopy of Nanoparticles from Spent Nuclear Fuel" Bruce McNamara, Edgar Buck, Jaeyoung Heo, [2022] · DOI: 10.2172/1908677
"Corrosion of U233-Doped Uranium Oxide using Microfluidics Methods" Shalini Tripathi, Eugene Ilton, Bruce McNamara, Nabajit Lahiri, Matthew O'Hara, Shawn Riechers, Edgar Buck, Jennifer Yao, [2022] · DOI: 10.2172/1908674
"Grand challenges in nuclear materials new insights into nuclear materials using ion irradiation, CryoEM, and in-situ liquid cell microscopy" Edgar C. Buck, [2022] Frontiers in Nuclear Engineering · DOI: 10.3389/fnuen.2022.975132 · ISSN: 2813-3412
"Fiscal Year 2022. Filtration of Hanford Tank 241-AP-101 Supernatant at 16 °C" Edgar Buck, Carolyn Burns, Richard Daniel, John Geeting, Zechariah Webb, Amy Westesen, Reid Peterson, Jarrod Allred, [2022] · DOI: 10.2172/1874369
"A Review of Bismuth(III)-Based Materials for Remediation of Contaminated Sites" Nikolla P. Qafoku, Mark E. Bowden, R. Matthew Asmussen, Edgar C. Buck, Vicky L. Freedman, Carolyn I. Pearce, Tatiana G. Levitskaia, [2022] ACS Earth and Space Chemistry · DOI: 10.1021/acsearthspacechem.1c00114
"A microfluidic electrochemical cell for studying the corrosion of uranium dioxide (UO2)" Nabajit Lahiri, Shalini Tripathi, Shawn L. Riechers, Eugene S. Ilton, Sayandev Chatterjee, Edgar C. Buck, Jennifer Yao, [2022] RSC Advances · DOI: 10.1039/d2ra02501a

Highlight of the multimodal characterization of corrosion behaviour of microgram quantities of UO2, enabled by a novel particle-attached microfluidic electrochemical cell.

"Formation and growth of cerium (III) oxalate nanocrystals by liquid-cell transmission electron microscopy" Karen Kruska, Gabriel B. Hall, Richard A. Clark, David E. Meier, Edgar C. Buck, Lili Liu, [2022] Scripta Materialia · DOI: 10.1016/j.scriptamat.2022.114856
"Interfacial Engineering with a Nanoparticle-Decorated Porous Carbon Structure on β"-Alumina Solid-State Electrolytes for Molten Sodium Batteries" Shalini Tripathi, Evgueni Polikarpov, Nathan L. Canfield, Kee Sung Han, J. Mark Weller, Edgar C. Buck, Mark H. Engelhard, David M. Reed, Vincent L. Sprenkle, Guosheng Li, Minyuan M. Li, [2022] ACS Applied Materials & Interfaces · DOI: 10.1021/acsami.2c05245
"Studying Corrosion Using Miniaturized Particle Attached Working Electrodes and the Nafion Membrane" Edgar C. Buck, Shawn L. Riechers, Shalini Tripathi, Lyndi E. Strange, Mark H. Engelhard, Xiao-Ying Yu, Jiyoung Son, [2021] Micromachines · DOI: 10.3390/mi12111414

We developed a new approach to attach particles onto a conductive layer as a working electrode (WE) in a microfluidic electrochemical cell with three electrodes. Nafion, an efficient proton transfer molecule, is used to form a thin protection layer to secure particle electrodes. Spin coating is used to develop a thin and even layer of Nafion membrane. The effects of Nafion (5 wt% 20 wt%) and spinning rates were evaluated using multiple sets of replicates. The electrochemical performance of various devices was demonstrated. Additionally, the electrochemical performance of the devices is used to select and optimize fabrication conditions. The results show that a higher spinning rate and a lower Nafion concentration (5 wt%) induce a better performance, using cerium oxide (CeO2) particles as a testing model. The WE surfaces were characterized using atomic force microscopy (AFM), scanning electron microscopy-focused ion beam (SEM-FIB), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and X-ray photoelectron spectroscopy (XPS). The comparison between the pristine and corroded WE surfaces shows that Nafion is redistributed after potential is applied. Our results verify that Nafion membrane offers a reliable means to secure particles onto electrodes. Furthermore, the electrochemical performance is reliable and reproducible. Thus, this approach provides a new way to study more complex and challenging particles, such as uranium oxide, in the future.

"Stamping Nanoparticles onto the Electrode for Rapid Electrochemical Analysis in Microfluidics" Edgar C. Buck, Shawn L. Riechers, Xiao-Ying Yu, Jiyoung Son, [2021] Micromachines · DOI: 10.3390/mi12010060

Electrochemical analysis is an efficient way to study various materials. However, nanoparticles are challenging due to the difficulty in fabricating a uniform electrode containing nanoparticles. We developed novel approaches to incorporate nanoparticles as a working electrode (WE) in a three-electrode microfluidic electrochemical cell. Specifically, conductive epoxy was used as a medium for direct application of nanoparticles onto the electrode surface. Three approaches in this work were illustrated, including sequence stamping, mix stamping, and droplet stamping. Shadow masking was used to form the conductive structure in the WE surface on a thin silicon nitride (SiN) membrane. Two types of nanomaterials, namely cerium oxide (CeO2) and graphite, were chosen as representative nanoparticles. The as-fabricated electrodes with attached particles were characterized using atomic force microscopy (AFM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Electrochemical analysis was performed to verify the feasibility of these nanoparticles as electrodes. Nanomaterials can be quickly assessed for their electrochemical properties using these new electrode fabrication methods in a microfluidic cell, offering a passport for rapid nanomaterial electrochemical analysis in the future.

"Formation of pyrophosphates across grain boundaries induces the formation of mismatched but oriented interfaces in silver phosphate polypods" Zexi Lu, Miao Song, Lingmei Liu, Bin Wang, Nini Wei, Mark E. Bowden, Mark G. Wirth, Daniel E. Perea, Daliang Zhang, Edgar C. Buck, Yu Han, Peter V. Sushko, Dongsheng Li, Peng Ren, [2021] Applied Surface Science · DOI: 10.1016/j.apsusc.2021.149980
"Neutron irradiation induced changes in isotopic abundance of 6Li and 3D nanoscale distribution of tritium in LiAlO2 pellets analyzed by atom probe tomography" Bethany Matthews, Bruce Arey, Larry Bagaasen, Edgar Buck, Gary Sevigny, David Senor, Arun Devaraj, [2021] Materials Characterization · DOI: 10.1016/j.matchar.2021.111095
"Thermal properties of U-Mo alloys irradiated under high fission power density" Ian J. Schwerdt, Tanja K. Huber, Harald Breitkreutz, Christian Reiter, Winfried Petry, Jason L. Schulthess, Andrew M. Casella, Amanda J. Casella, Edgar C. Buck, Karl N. Pool, Paul J. MacFarlan, Matthew K. Edwards, Frances N. Smith, Douglas E. Burkes, [2021] Journal of Nuclear Materials · DOI: 10.1016/j.jnucmat.2021.152823
"Towards data-driven next-generation transmission electron microscopy" Colin Ophus, Lewys Jones, Amanda Petford-Long, Sergei V. Kalinin, Matthew J. Olszta, Rafal E. Dunin-Borkowski, Norman Salmon, Khalid Hattar, Wei-Chang D. Yang, Renu Sharma, Yingge Du, Ann Chiaramonti, Haimei Zheng, Edgar C. Buck, Libor Kovarik, R. Lee Penn, Dongsheng Li, Xin Zhang, Mitsuhiro Murayama, Mitra L. Taheri, Steven R. Spurgeon, [2021] Nature Materials · DOI: 10.1038/s41563-020-00833-z
"Fiscal Year 2020 Filtration of Hanford Tank Waste 241-AP-105" John Geeting, Amy Westesen, Edgar Buck, Reid Peterson, Jarrod Allred, [2020] · DOI: 10.2172/1699392
"Independent Technical Review of INL Aluminum-Clad Spent Nuclear Fuel (ASNF) Oxide Layer Radiolytic Gas Generation Resolution: Task 2" Richard Wittman, Brady Hanson, Edgar Buck, [2020] · DOI: 10.2172/1987652
"Spontaneous redox continuum reveals sequestered technetium clusters and retarded mineral transformation of iron" Jennifer A. Soltis, Ravi K. Kukkadapu, Yingge Du, Lucas E. Sweet, Vanessa E. Holfeltz, Gabriel B. Hall, Edgar C. Buck, Carlo U. Segre, Hilary P. Emerson, Yelena Katsenovich, Tatiana G. Levitskaia, Daria Boglaienko, [2020] Communications Chemistry · DOI: 10.1038/s42004-020-0334-x
Abstract

The sequestration of metal ions into the crystal structure of minerals is common in nature. To date, the incorporation of technetium(IV) into iron minerals has been studied predominantly for systems under carefully controlled anaerobic conditions. Mechanisms of the transformation of iron phases leading to incorporation of technetium(IV) under aerobic conditions remain poorly understood. Here we investigate granular metallic iron for reductive sequestration of technetium(VII) at elevated concentrations under ambient conditions. We report the retarded transformation of ferrihydrite to magnetite in the presence of technetium. We observe that quantitative reduction of pertechnetate with a fraction of technetium(IV) structurally incorporated into non-stoichiometric magnetite benefits from concomitant zero valent iron oxidative transformation. An in-depth profile of iron oxide reveals clusters of the incorporated technetium(IV), which account for 32% of the total retained technetium estimated via X-ray absorption and X-ray photoelectron spectroscopies. This corresponds to 1.86 wt.% technetium in magnetite, providing the experimental evidence to theoretical postulations on thermodynamically stable technetium(IV) being incorporated into magnetite under spontaneous aerobic redox conditions.

"Author Correction: Distribution of metallic fission-product particles in the cladding liner of spent nuclear fuel" Michele A. Conroy, Timothy G. Lach, Edgar C. Buck, Kristi L. Pellegrini, Bruce K. McNamara, Jon M. Schwantes, Richard A. Clark, [2020] npj Materials Degradation · DOI: 10.1038/s41529-020-0113-2

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

"Distribution of metallic fission-product particles in the cladding liner of spent nuclear fuel (vol 17, pg 861, 2020)" Michele A. Conroy, Timothy G. Lach, Edgar C. Buck, Kristi L. Pellegrini, Bruce K. McNamara, Jon M. Schwantes, Richard A. Clark, [2020] Npj Materials Degradation · DOI: 10.1038/s41529-020-0113-2

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

"Distribution of metallic fission-product particles in the cladding liner of spent nuclear fuel" Michele A. Conroy, Timothy G. Lach, Edgar C. Buck, Kristi L. Pellegrini, Bruce K. McNamara, Jon M. Schwantes, Richard A. Clark, [2020] npj Materials Degradation · DOI: 10.1038/s41529-019-0107-0
Abstract

We have made observations of noble metal phase fission-product agglomerates and gaseous xenon within the fuel-cladding interaction (FCI) zone of a high-burnup UO2 fuel. The FCI is the boundary between the UO2 pellet outer surface and the inner wall of the oxidized Zr-liner/cladding of the fuel rod. These fission-product agglomerates are well known to occur within the spent fuel matrix, and although radionuclides have been reported by others, we reveal aspects of their speciation and morphology. That they occur as discrete particles in the oxidized Zr liner, suggests the occurrence of hitherto unknown processes in the FCI zone during reactor operation, and this may have implications for the long-term storage and disposal of these types of materials. As expected, the particle agglomerates, which ranged in size from the nanometer scale to the micrometer scale, contained mainly Mo, Ru, Tc, Rh, and Pd; however, we also found significant quantities of Te associated with Pd. Indeed, we found nanometer scale separation of the distinct Pd/Te phase from the other fission products within the particles. Often associated with the particles was concentrations of uranium, sometimes appearing as a “cloud” with a tail emanating from the fuel into the oxidized cladding liner. Many of the noble metal phase particles appeared as fractured clusters separated by Xe-gas-filled voids. Possible mechanisms of formation or transport in the cladding liner are presented.

"A new non-diffusional gas bubble production route in used nuclear fuel: implications for fission gas release, cladding corrosion, and next generation fuel design" Jacob L. Bair, Edgar C. Buck, Ram Devanathan, Sean H. Kessler, Timothy G. Lach, Jason M. Lonergan, Bruce K. McNamara, Camille J. Palmer, Richard A. Clark, Jon M. Schwantes, [2020] Physical Chemistry Chemical Physics · DOI: 10.1039/c9cp05363h

“Phase” map showing Noble metal phase particle (orange) and U fuel fragments (green and yellow) ejected into Zr cladding (red and blue) as a result of Xe bubble rupture.

"An Atomic-Scale Understanding of UO2 Surface Evolution during Anoxic Dissolution" Steven R. Spurgeon, Bethany Matthews, Matthew J. Olszta, Beng Thye Tan, Thomas Gouder, Rachel Eloirdi, Edgar C. Buck, Ian Farnan, Aleksej J. Popel, [2020] ACS Applied Materials & Interfaces · DOI: 10.1021/acsami.0c09611
"Focused ion beam for improved spatially-resolved mass spectrometry and analysis of radioactive materials for uranium isotopic analysis" Chelsie L. Beck, Edgar C. Buck, John B. Cliff, Andrew M. Duffin, Timothy G. Lach, Martin Liezers, Kellen WE. Springer, Stephanie J. Tedrow, Mindy M. Zimmer, Dallas D. Reilly, [2020] Talanta · DOI: 10.1016/j.talanta.2020.120720
"In situ liquid SIMS analysis of uranium oxide" Jennifer Yao, Edgar C. Buck, Zihua Zhu, Xiao‐Ying Yu, [2020] Surface and Interface Analysis · DOI: 10.1002/sia.6799

Trace analysis of nuclear materials in solid particles collected in the environment or particles in liquid slurry generated in nuclear material manufacturing processes can pinpoint elemental, organic, and isotopic signatures of nuclear fuel cycle activities and processes. Such information can support nuclear safeguards programs by increasing our ability to detect undeclared nuclear materials, routine activities for safeguarding at declared facilities, and illicit activities. However, trace radioactive material analysis in liquids and slurries is challenging using bulk approaches. For example, one drawback of sensitive analysis such as inductively coupled plasma mass spectrometry (ICP‐MS) is that sample is consumed or destroyed as a result of the technical approach. We developed a vacuum compatible microfluidic interface to enable surface analysis of liquids and solid–liquid interactions using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). In this work, we illustrate the initial results from the analysis of liquid uranium oxide standard solutions using in situ liquid SIMS. Because the liquid SIMS analysis is almost nondestructive, the same sample can then be analyzed by other analytical techniques or saved for future reference. Consequently, multimodal analysis is possible. Our results demonstrate that in situ liquid SIMS can be used as a new approach to analyze radioactive materials in liquid and slurry forms of relevance to diverse applications.

"Targeted uranium recovery from complex alloys using fluoride volatility" A.M. Casella, E.C. Buck, R.A. Clark, I.J. Schwerdt, R.G. Surbella III, K.M. McCoy, B.K. McNamara, [2020] Journal of Fluorine Chemistry · DOI: 10.1016/j.jfluchem.2020.109539
"Scanning Transmission Electron Microscopy of Plutonium Particles in Hanford Tanks 241-TX-118 and 241-SY-102" Sergey Sinkov, Dallas Reilly, Timothy Lach, Eugene Ilton, Edgar Buck, [2019] · DOI: 10.2172/1646991
"Plutonium Particles in Samples Extracted from Hanford Tank Waste TX-118 and SY-102 (Interim Report)" Sergey Sinkov, Eugene Ilton, Trevor Scott, David Blanchard, Dallas Reilly, Timothy Lach, Bruce McNamara, Gregg Lumetta, Edgar Buck, [2019] · DOI: 10.2172/2205519
"In Situ Electrochemical Testing of Uranium Dioxide under Anoxic Conditions (FY19 Report)" Xiao-Ying Yu, Jenn Yao, Dallas Reilly, Jiyoung Son, Sayandev Chatterjee, Bruce McNamara, Cyrena Parker, Eugene Ilton, Edgar Buck, [2019] · DOI: 10.2172/1987564
"Nanoscale oxygen defect gradients in UO 2+ x surfaces" Michel Sassi, Colin Ophus, Joanne E. Stubbs, Eugene S. Ilton, Edgar C. Buck, Steven R. Spurgeon, [2019] Proceedings of the National Academy of Sciences · DOI: 10.1073/pnas.1905056116

Oxygen defects govern the behavior of a range of materials spanning catalysis, quantum computing, and nuclear energy. Understanding and controlling these defects is particularly important for the safe use, storage, and disposal of actinide oxides in the nuclear fuel cycle, since their oxidation state influences fuel lifetimes, stability, and the contamination of groundwater. However, poorly understood nanoscale fluctuations in these systems can lead to significant deviations from bulk oxidation behavior. Here we describe the use of aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy to resolve changes in the local oxygen defect environment in U O 2 + x surfaces. We observe large image contrast and spectral changes that reflect the presence of sizable gradients in interstitial oxygen content at the nanoscale, which we quantify through first-principles calculations and image simulations. These findings reveal an unprecedented level of excess oxygen incorporated in a complex near-surface spatial distribution, offering additional insight into defect formation pathways and kinetics during U O 2 surface oxidation.

"Nanoscale oxygen defect gradients in UO2+x surfaces" Michel Sassi, Colin Ophus, Joanne E. Stubbs, Eugene S. Ilton, Edgar C. Buck, Steven R. Spurgeon, [2019] Proceedings of the National Academy of Sciences · DOI: 10.1073/pnas.1905056116

Oxygen defects govern the behavior of a range of materials spanning catalysis, quantum computing, and nuclear energy. Understanding and controlling these defects is particularly important for the safe use, storage, and disposal of actinide oxides in the nuclear fuel cycle, since their oxidation state influences fuel lifetimes, stability, and the contamination of groundwater. However, poorly understood nanoscale fluctuations in these systems can lead to significant deviations from bulk oxidation behavior. Here we describe the use of aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy to resolve changes in the local oxygen defect environment in U O 2 + x surfaces. We observe large image contrast and spectral changes that reflect the presence of sizable gradients in interstitial oxygen content at the nanoscale, which we quantify through first-principles calculations and image simulations. These findings reveal an unprecedented level of excess oxygen incorporated in a complex near-surface spatial distribution, offering additional insight into defect formation pathways and kinetics during U O 2 surface oxidation.

"Cesium Removal from Tank Waste Simulants Using Crystalline Silicotitanate at 12% and 100% TSCR Bed Heights" Amy Rovira, Jarrod Allred, Heather Colburn, Margaret Smoot, Andrew Carney, Truc Trang-Le, Michael Cantaloub, Edgar Buck, Reid Peterson, Sandra Fiskum, [2019] · DOI: 10.2172/1556114
"In-situ Electrochemical Testing of Uranium Oxide Alteration under Anoxic Conditions" Xiao-Ying Yu, Jenn Yao, Sayandev Chatterjee, Edgar Buck, [2019] · DOI: 10.2172/1647008
"An electrochemical technique for controlled dissolution of zirconium based components of light water reactors" Meghan S. Fujimoto, Nathan L. Canfield, Monte R. Elmore, Devin W. Olson, Edgar C. Buck, Michele A. Conroy, Tamas Varga, David J. Senor, Sayandev Chatterjee, [2019] RSC Advances · DOI: 10.1039/c8ra08693a

This work demonstrates a controlled potential electrochemistry with correlative microscopy for insight into the radial H-distribution into TPBAR components of light water reactors.

"Chemical and Isotopic Characterization of Noble Metal Phase from Commercial UO2 Fuel" Chuck Z. Soderquist, Steve D. Shen, Eirik J. Krogstad, Camille J. Palmer, Kyzer R. Gerez, Edgar C. Buck, Timothy G. Lach, Jon M. Schwantes, Richard A. Clark, Kristi L. Pellegrini, [2019] Analytical Chemistry · DOI: 10.1021/acs.analchem.8b05549
"Fission recoil-induced microstructural evolution of the fuel-cladding interface [FCI] in high burnup BWR fuel" Danny J. Edwards, Edgar C. Buck, Bruce K. McNamara, Jon M. Schwantes, Richard A. Clark, Timothy G. Lach, [2019] Journal of Nuclear Materials · DOI: 10.1016/j.jnucmat.2019.04.044
"Multiscale microscopy study of plutonium(III)-oxalate crystal growth" [2019] Abstracts of Papers of the American Chemical Society
"Revisiting the Growth Mechanism of Hierarchical Semiconductor Nanostructures: The Role of Secondary Nucleation in Branch Formation" Maria L. Sushko, Edgar C. Buck, Xin Zhang, Libor Kovarik, Zhizhang Shen, Jinhui Tao, Elias Nakouzi, Jun Liu, James J. De Yoreo, Lili Liu, [2019] Journal of Physical Chemistry Letters · DOI: 10.1021/acs.jpclett.9b02110
"Determination of the degree of grain refinement in irradiated U-Mo fuels" Douglas E. Burkes, Paul J. MacFarlan, Edgar C. Buck, Andrew M. Casella, [2018] Heliyon · DOI: 10.1016/j.heliyon.2018.e00920
"Getters for improved technetium containment in cementitious waste forms" Carolyn I. Pearce, Brian W. Miller, Amanda R. Lawter, James J. Neeway, Wayne W. Lukens, Mark E. Bowden, Micah A. Miller, Edgar C. Buck, R. Jeffery Serne, Nikolla P. Qafoku, R. Matthew Asmussen, [2018] Journal of Hazardous Materials · DOI: 10.1016/j.jhazmat.2017.07.055
"Imaging crystal growth from nanometers to microns: In situ microscopy across scales for the study of europium oxalate growth" [2018] Abstracts of Papers of the American Chemical Society
"In situ microscopy across scales for the characterization of crystal growth mechanisms: the case of europium oxalate" William C. Isley, Michele Conroy, Shawn M. Kathmann, Edgar C. Buck, Gregg J. Lumetta, Jennifer A. Soltis, [2018] CrystEngComm · DOI: 10.1039/c7ce01450c

The development of targeted syntheses requires a better understanding of how production pathways affect the final product, but many ex situ techniques used for studying nanoparticle growth are unsuitable as standalone methods for identifying and characterizing growth mechanisms.

"Lead and uranium distribution in particles from the Pena Blanca site using Cs-corrected STEM" [2018] Abstracts of Papers of the American Chemical Society
"Monitoring bromide effect on radiolytic yields using in situ observations of uranyl oxide precipitation in the electron microscope" Richard S. Wittman, Chuck. Z. Soderquist, Bruce K. McNamara, Edgar C. Buck, [2018] RSC Advances · DOI: 10.1039/c8ra01706a

During electron microscopy observations of uranium-bearing phases and solutions in a liquid cell, the electron beam induced radiolysis causes changes in the chemistry of the system.

"Observation and characterization of Pd-Te compounds within noble metal inclusions in spent nuclear fuel" [2018] Abstracts of Papers of the American Chemical Society
"Plutonium phases in Hanford-derived wastes" [2018] Abstracts of Papers of the American Chemical Society
"Review of the Scientific Understanding of Radioactive Waste at the US DOE Hanford Site" Edgar C. Buck, Jaehun Chun, Richard C. Daniel, Daniel L. Herting, Eugene S. Ilton, Gregg J. Lumetta, Sue B. Clark, Reid A. Peterson, [2018] Environmental Science & Technology · DOI: 10.1021/acs.est.7b04077
"Electron Microscopy Characterization of Suspended Solids from Hanford Tank 241-AP-105 Direct Feed Waste" Edgar Buck, [2017] · DOI: 10.2172/1598866
"Effects of hydrated lime on radionuclides stabilization of Hanford tank residual waste" Wooyong Um, Kirk J. Cantrell, Michelle M.V. Snyder, Mark E. Bowden, Mark B. Triplett, Edgar C. Buck, Guohui Wang, [2017] Chemosphere · DOI: 10.1016/j.chemosphere.2017.06.103
"Effect of Iodide on Radiolytic Hydrogen Peroxide Generation" Richard Wittman, Edgar Buck, [2017] · DOI: 10.2172/1598817
"Characterization of fission gas bubbles in irradiated U-10Mo fuel" Douglas E. Burkes, Paul J. MacFarlan, Edgar C. Buck, Andrew M. Casella, [2017] Materials Characterization · DOI: 10.1016/j.matchar.2017.06.007
"Effect of processing conditions on lanthanide and actinide oxalate crystal growth mechanisms: Insights from in situ characterization and computational modeling" [2017] Abstracts of Papers of the American Chemical Society
"Fate of trace metals during aluminum oxyhydroxide phase transitions: Implications for reactivity" [2017] Abstracts of Papers of the American Chemical Society
"Importance of interlayer H bonding structure to the stability of layered minerals" Jennifer A. Soltis, Rick S. Wittman, Frances N. Smith, Sayandev Chatterjee, Xin Zhang, Eugene S. Ilton, Edgar C. Buck, Michele Conroy, [2017] Scientific Reports · DOI: 10.1038/s41598-017-13452-7
Abstract

Layered (oxy) hydroxide minerals often possess out-of-plane hydrogen atoms that form hydrogen bonding networks which stabilize the layered structure. However, less is known about how the ordering of these bonds affects the structural stability and solubility of these minerals. Here, we report a new strategy that uses the focused electron beam to probe the effect of differences in hydrogen bonding networks on mineral solubility. In this regard, the dissolution behavior of boehmite (γ-AlOOH) and gibbsite (γ-Al(OH)3) were compared and contrasted in real time via liquid cell electron microscopy. Under identical such conditions, 2D-nanosheets of boehmite (γ-AlOOH) exfoliated from the bulk and then rapidly dissolved, whereas gibbsite was stable. Further, substitution of only 1% Fe(III) for Al(III) in the structure of boehmite inhibited delamination and dissolution. Factors such as pH, radiolytic species, and knock on damage were systematically studied and eliminated as proximal causes for boehmite dissolution. Instead, the creation of electron/hole pairs was considered to be the mechanism that drove dissolution. The widely disparate behaviors of boehmite, gibbsite, and Fe-doped boehmite are discussed in the context of differences in the OH bond strengths, hydrogen bonding networks, and the presence or absence of electron/hole recombination centers.

"Life cycle of Boehmite nano-particles in high level nuclear waste tanks: An electron microscopy study of their growth, aggregation and dissolution" [2017] Abstracts of Papers of the American Chemical Society
"Performance evaluation and post-irradiation examination of a novel LWR fuel composed of U0.17ZrH1.6 fuel pellets bonded to Zircaloy-2 cladding by lead bismuth eutectic" Donald R. Olander, Kurt A. Terrani, Peter Hosemann, Andrew M. Casella, David J. Senor, Edgar C. Buck, Mehdi Balooch, [2017] Journal of Nuclear Materials · DOI: 10.1016/j.jnucmat.2016.08.020
"Quantitative morphological analysis of actinide materials" [2017] Abstracts of Papers of the American Chemical Society
"Uranium uptake and redistribution in the transformation of ferrihydrite to goethite" [2017] Abstracts of Papers of the American Chemical Society
"Sequestration of radioactive iodine in silver-palladium phases in commercial spent nuclear fuel" Edward J. Mausolf, Bruce K. McNamara, Chuck Z. Soderquist, Jon M. Schwantes, Edgar C. Buck, [2016] Journal of Nuclear Materials · DOI: 10.1016/j.jnucmat.2016.10.029
"Effect of Iron on Radiolytic Hydrogen Peroxide Generation" Richard Wittman, Edgar Buck, [2016] · DOI: 10.2172/1598836
"Addition of Bromide to Radiolysis Model Formulation for Integration with the Mixed Potential Model" Richard Wittman, Edgar Buck, [2016] · DOI: 10.2172/1592703
"Can Cr(iii) substitute for Al(iii) in the structure of boehmite?" Michele A. Conroy, Frances N. Smith, Hee-Joon Jung, Zheming Wang, Reid A. Peterson, Ashfia Huq, David G. Burtt, Eugene S. Ilton, Edgar C. Buck, Sayandev Chatterjee, [2016] RSC Advances · DOI: 10.1039/c6ra20234a

Cr(iii) is observed to prefer (near-)surface sites in boehmite, as opposed to the bulk.

"Formation of Technetium Salts in Hanford Low-Activity Waste Glass" Edgar C. Buck, John S. McCloy, Mike J. Schweiger, Albert A. Kruger, Chuck Z. Soderquist, [2016] Journal of the American Ceramic Society · DOI: 10.1111/jace.14442

The distribution and physical form of technetium in a Hanford low‐activity waste (LAW) glass was examined with scanning electron microscopy (SEM) and X‐ray diffraction (XRD). A simulated Hanford LAW glass was spiked with varying amounts of potassium pertechnetate and melted at 1000°C. The glass was melted in a sealed quartz ampoule with the air pumped out, so that volatile material could leave the glass but would not be lost from the system. Previous studies have shown that technetium remains in the glass up to about 2000 ppm, but rises to the top of the melt as a separate salt phase above this concentration. Examination by SEM shows that crystals of technetium compounds appear to grow out of the hot glass, which implies that the hot glass was supersaturated in technetium salts. Some of the technetium compound crystals had apparently melted, but other crystals had obviously not melted and must have formed after the glass had partially cooled. The technetium compounds in the salt layer are KTcO4 and NaTcO4, according to SEM and XRD. No TcO2 was found in the salt phase, even though Tc(IV) has been previously reported in the glass.

"Identification of Uranyl Minerals Using Oxygen K-Edge X-Ray Absorption Spectroscopy" Mark Bowden, C. Tom Resch, Steven Smith, Bruce K. McNamara, Edgar C. Buck, Gregory C. Eiden, Andrew M. Duffin, Jesse D. Ward, [2016] Geostandards and Geoanalytical Research · DOI: 10.1111/j.1751-908x.2015.00337.x

Although most of the world's uranium exists as pitchblende or uraninite, this mineral can be weathered to a great variety of secondary uranium minerals, most containing the uranyl cation. Anthropogenic uranium compounds can also react in the environment, leading to spatial–chemical alterations that could be useful for nuclear forensics analyses. Soft X‐ray absorption spectroscopy (XAS) has the advantages of being non‐destructive, element‐specific and sensitive to electronic and physical structure. The soft X‐ray probe can also be focused to a spot size on the order of tens of nanometres, providing chemical information with high spatial resolution. However, before XAS can be applied at high spatial resolution, it is necessary to find spectroscopic signatures for a variety of uranium compounds in the soft X‐ray spectral region. To that end, we collected the near edge X‐ray absorption fine structure (NEXAFS) spectra of a variety of common uranyl‐bearing minerals, including uranyl carbonates, oxyhydroxides, phosphates and silicates. We find that uranyl compounds can be distinguished by class (carbonate, oxyhydroxide, phosphate or silicate) based on their oxygen K‐edge absorption spectra. This work establishes a database of reference spectra for future spatially resolved analyses. We proceed to show scanning X‐ray transmission microscopy (STXM) data from a schoepite particle in the presence of an unknown contaminant.

"Synthesis and preservation of graphene-supported uranium dioxide nanocrystals" Haitao Wang, Peter C. Burns, Bruce K. McNamara, Edgar C. Buck, Chongzheng Na, Hanyu Ma, [2016] Journal of Nuclear Materials · DOI: 10.1016/j.jnucmat.2016.03.027
"Dehydration of uranyl nitrate hexahydrate to uranyl nitrate trihydrate under ambient conditions as observed via dynamic infrared reflectance spectroscopy" Timothy J. Johnson, Lucas E. Sweet, David E. Meier, Edward J. Mausolf, Eunja Kim, Philippe F. Weck, Edgar C. Buck, Bruce K. McNamara, [2015] Chemical, Biological, Radiological, Nuclear, and Explosives (cbrne) Sensing Xvi · DOI: 10.1117/12.2179704
"Nanostructure of metallic particles in light water reactor used nuclear fuel" Edward J. Mausolf, Bruce K. McNamara, Chuck Z. Soderquist, Jon M. Schwantes, Edgar C. Buck, [2015] Journal of Nuclear Materials · DOI: 10.1016/j.jnucmat.2015.03.001
"On the mechanical stability of uranyl peroxide hydrates: implications for nuclear fuel degradation" Eunja Kim, Edgar C. Buck, Philippe F. Weck, [2015] RSC Advances · DOI: 10.1039/c5ra16111h

The mechanical properties and stability of studtite, (UO2)(O2)(H2O)2·2H2O, and metastudtite, (UO2)(O2)(H2O)2, were investigated using density functional perturbation theory.

"Spatially resolved characterization techniques for next generation nuclear forensics signature development" [2015] Abstracts of Papers of the American Chemical Society
"Thermal properties of U–Mo alloys irradiated to moderate burnup and power" Andrew M. Casella, Amanda J. Casella, Edgar C. Buck, Karl N. Pool, Paul J. MacFarlan, Matthew K. Edwards, Frances N. Smith, Douglas E. Burkes, [2015] Journal of Nuclear Materials · DOI: 10.1016/j.jnucmat.2015.04.040
"Time-Resolved Infrared Reflectance Studies of the Dehydration-Induced Transformation of Uranyl Nitrate Hexahydrate to the Trihydrate Form" Lucas E. Sweet, David E. Meier, Edward J. Mausolf, Eunja Kim, Philippe F. Weck, Edgar C. Buck, Bruce K. McNamara, Timothy J. Johnson, [2015] The Journal of Physical Chemistry A · DOI: 10.1021/acs.jpca.5b06365
"Chemical stabilization of Hanford tank residual waste" Wooyong Um, Benjamin D. Williams, Mark E. Bowden, Brandy Gartman, Wayne W. Lukens, Edgar C. Buck, Edward J. Mausolf, Kirk J. Cantrell, [2014] Journal of Nuclear Materials · DOI: 10.1016/j.jnucmat.2013.10.060
"Conditions for Critical Effects in the Mass Action Kinetics Equations for Water Radiolysis" Edgar C. Buck, Edward J. Mausolf, Bruce K. McNamara, Frances N. Smith, Chuck Z. Soderquist, Richard S. Wittman, [2014] The Journal of Physical Chemistry A · DOI: 10.1021/jp509856g
"Corrigendum to “Single-pass flow-through test elucidation of weathering behavior and evaluation of contaminant release models for Hanford tank residual radioactive waste” [Appl. Geochem. 28 (2013) 119–127]" Kenneth C. Carroll, Edgar C. Buck, Doinita Neiner, Keith N. Geiszler, Kirk J. Cantrell, [2014] Applied Geochemistry · DOI: 10.1016/j.apgeochem.2014.08.007
"Development and Validation of Capabilities to Measure Thermal Properties of Layered Monolithic U-Mo Alloy Plate-Type Fuel" Andrew M. Casella, Edgar C. Buck, Amanda J. Casella, Matthew K. Edwards, Paul J. MacFarlan, Karl N. Pool, Frances N. Smith, Franciska H. Steen, Douglas E. Burkes, [2014] International Journal of Thermophysics · DOI: 10.1007/s10765-014-1683-4
"Examination and reactivity studies of the metallic residues of a high burn-up BWR fuel" [2014] Abstracts of Papers of the American Chemical Society
"Nature of nano-sized plutonium particles in soils at the Hanford Site" Dean A. Moore, Kenneth R. Czerwinski, Steven D. Conradson, Olga N. Batuk, Andrew R. Felmy, Edgar C. Buck, [2014] Radiochimica Acta · DOI: 10.1515/ract-2013-2103
Abstract

The occurrence of plutonium dioxide (PuO2) either from direct deposition or from the precipitation of plutonium-bearing solutions in contaminated soils and sediments is well described, particularly for the Hanford site in Washington State. However, past research has suggested that plutonium at the Hanford site may exist in chemical forms in addition to PuO2. Although the majority of the plutonium is present as oxide, we present evidence for the formation of nano-sized mixed plutonium- iron phosphate hydroxide structurally related to the rhabdophane group minerals in 216-Z9 crib sediments from Hanford using both transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAS). The iron-plutonium phosphate formation may depend on the local microenvironment in the sediments, availability of phosphate, and hence the distribution of these minerals may control long-term migration of plutonium in the soil.

"Separation of metallic residues from the dissolution of a high-burnup BWR fuel using nitrogen trifluoride" Edgar C. Buck, Chuck Z. Soderquist, Frances N. Smith, Edward J. Mausolf, Randall D. Scheele, Bruce K. McNamara, [2014] Journal of Fluorine Chemistry · DOI: 10.1016/j.jfluchem.2014.02.010
"The solubility of (PuO2)-Pu-242 in the presence of aqueous Fe(II): the impact of precipitate preparation" Dean A. Moore, Edgar Buck, Steven D. Conradson, Ravi Kukkadapu, Lucas Sweet, David Abrecht, Eugene S. Ilton, Andrew R. Felmy, [2014] Radiochimica Acta · DOI: 10.1515/ract-2013-2187
Abstract

The solubility of different forms of precipitated 242PuO2(am) were examined in solutions containing aqueous Fe(II) over a range of pH values. The first series of 242PuO2(am) suspensions were prepared from a 242Pu(IV) stock that had been treated with thenoyltrifluoroacetone (TTA) to remove the 241Am originating from the decay of 241Pu. These 242PuO2(am) suspensions showed much higher solubilities at the same pH value and Fe(II) concentration than previous studies using 239PuO2(am). X-ray absorption fine structure (XAFS) spectroscopy of the precipitates showed a substantially reduced Pu–Pu backscatter over that previously observed in 239PuO2(am) precipitates, indicating that the 242PuO2(am) precipitates purified using TTA lacked the long range order previously found in239PuO2(am) precipitates. The Pu(IV) stock solution was subsequently repurified using an ion exchange resin and an additional series of 242PuO2(am) precipitates prepared. These suspensions showed higher redox potentials and total aqueous Pu concentrations than the TTA purified stock solution. The higher redox potential and aqueous Pu concentrations were in general agreement with previous studies on 242PuO2(am) precipitates, presumably due to the removal of possible organic compounds originally present in the TTA purified stock. 242PuO2(am) suspensions prepared with both stock solutions showed almost identical solubilities in Fe(II) containing solutions even though the initial aqueous Pu concentrations before the addition of Fe(II) were orders of magnitude different. By examining the solubility of 242PuO2(am) prepared from both stocks in this way we have essentially approached equilibrium from both the undersaturated and oversaturated conditions. The final aqueous Pu concentrations are predictable using a chemical equilibrium model which includes the formation of a nanometer sized Fe(III) reaction product, identified in the 242PuO2(am) suspension both by use of 57Fe Mössbauer spectroscopy and transmission electron microscopy (TEM) analysis.

"Formation of Tc metal in 12 M HCl using Zn as a reductant" Erik Johnstone, Frederic Poineau, Suzanne Nguyen, Steven Jones, Thomas Hartmann, Edgar Buck, Kenneth Czerwinski, Edward Mausolf, [2013] Journal of Radioanalytical and Nuclear Chemistry · DOI: 10.1007/s10967-013-2453-7
"Formation of Tc metal in 12 M HCl using Zn as a reductant" Erik Johnstone, Frederic Poineau, Suzanne Nguyen, Steven Jones, Thomas Hartmann, Edgar Buck, Kenneth Czerwinski, Edward Mausolf, [2013] Journal of Radioanalytical and Nuclear Chemistry · DOI: 10.1007/s10967-013-2453-7
"Heterogeneous reduction of (PuO2)-Pu-239 by aqueous Fe(II) in the presence of hematite" D. A. Moore, O. Qafoku, E. Buck, S. D. Conradson, E. S. Ilton, A. R. Felmy, [2013] Radiochimica Acta · DOI: 10.1524/ract.2013.2091
Abstract

The reduction of PuO2(am) by Fe(II) in the presence and absence of hematite was studied over a range of pH values and oxidation/reduction potentials. In contrast to thermodynamic predictions, the presence of hematite did not have a major effect on the overall reduction of PuO2(am) to aqueous Pu(III). Instead the aqueous Pu(III) concentrations at longer time frames were accurately predicted using the measured Fe(II) concentration and existing thermodynamic data for the reaction: H2O + H++ Fe2++ PuO2(am) ⇌ Pu3++ Fe(OH)3(am) with log K =− 0.6. The accuracy of this approach in all solutions containing aqueous Fe(II), coupled with the apparent lack of oxidation of Fe(II) by O2(g), suggests that the Fe(OH)3(am) is formed by the oxidation of Fe(II) to Fe(III) by radiolysis. The continued generation of reactive amorphous iron hydroxide by radiolysis prevents thermodynamic equilibrium from being reached with more stable ferric oxide compounds, except possibly under acidic conditions where amorphous ferric hydroxide is soluble. The use of measured pe values, instead of aqueous Fe(II) measurements, also yields reasonable predictions of the final Pu(III) concentrations although the predictions are more uncertain.

"Single-pass flow-through test elucidation of weathering behavior and evaluation of contaminant release models for Hanford tank residual radioactive waste" Kenneth C. Carroll, Edgar C. Buck, Doinita Neiner, Keith N. Geiszler, Kirk J. Cantrell, [2013] Applied Geochemistry · DOI: 10.1016/j.apgeochem.2012.09.004
"Spectroscopic Studies of the Several Isomers of UO3" Dallas D. Reilly, David G. Abrecht, Edgar C. Buck, David E. Meier, Yin-Fong Su, Carolyn S. Brauer, Jon M. Schwantes, Russell G. Tonkyn, James E. Szecsody, Thomas A. Blake, Timothy J. Johnson, Lucas E. Sweet, [2013] Proceedings of SPIE - The International Society for Optical Engineering · DOI: 10.1117/12.2029408
"Characterization of a Plutonium-Bearing Zirconolite-Rich Synroc" B. Ebbinghaus, A. J. Bakel, J. K. Bates, E. C. Buck, [2012] MRS Proceedings · DOI: 10.1557/proc-465-1259
ABSTRACT

A titanate-based ceramic waste form, rich in phases structurally related to zirconolite (CaZrTi2O7), is being developed as a possible method for immobilizing excess plutonium from dismantled nuclear weapons. As part of this program, Lawrence Livermore National Laboratory (LLNL) produced several ceramics that were then characterized at Argonne National Laboratory (ANL). The plutonium-loaded ceramic was found to contain a Pu-Gd zirconolite phase but also contained plutonium titanates, Gd-polymignyte, and a series of other phases. In addition, much of the Pu was remained as PuO2-x. The Pu oxidation state in the zirconolite was determined to be mainly Pu4+, although some Pu3+was believed to be present.

"Controls on soluble Pu concentrations in PuO2/magnetite suspensions" Dean A. Moore, Carolyn I. Pearce, Steven D. Conradson, Odeta Qafoku, Edgar C. Buck, Kevin M. Rosso, Eugene S. Ilton, Andrew R. Felmy, [2012] Environmental Science and Technology · DOI: 10.1021/es3028956
"Controls on Soluble Pu Concentrations in PuO2/Magnetite Suspensions" Dean A. Moore, Carolyn I. Pearce, Steven D. Conradson, Odeta Qafoku, Edgar C. Buck, Kevin M. Rosso, Eugene S. Ilton, Andrew R. Felmy, [2012] Environmental Science & Technology · DOI: 10.1021/es3028956
"Grain Boundary Corrosion and Alteration Phase Formation During the Oxidative Dissolution of UO2 Pellets" Edgar C. Buck, John K. Bates, David J. Wronkiewicz, [2012] MRS Proceedings · DOI: 10.1557/proc-465-519
ABSTRACT

The alteration behavior of UO2 pellets following their reaction under unsaturated drip-test conditions, at 90°C, for time periods of up to 10 years has been examined by solid phase and leachate analyses. Sample reactions were characterized by preferential dissolution of grain boundaries between the original press-sintered UO2 granules comprising the samples, development of a polygonal network of open channels along the intergrain boundaries, and spallation of surface granules that had undergone severe grain boundary corrosion. The development of a dense mat of alteration phases after two years of reaction trapped loose granules, resulting in reduced rates of particulate uranium release. The paragenetic sequence of alteration phases that formed on the present samples was similar to that observed in surficial weathering zones of natural uraninite (UO2) deposits, with alkali and alkaline earth uranyl silicates representing the long-term solubility-limiting phases for uranium in both systems.

"Investigations into the polymorphs and hydration products of UO3" Edgar C. Buck, Charles H. Henager, Shenyang Hu, David E. Meier, Shane M. Peper, Jon M. Schwantes, Yin-Fong Su, Robert L. Sams, Thomas A. Blake, Timothy J. Johnson, Thomas J. Kulp, Ricky L. Sommers, Joshua D. Sugar, Jeffrey D. Chames, Lucas E. Sweet, [2012] Proceedings of SPIE - The International Society for Optical Engineering · DOI: 10.1117/12.919706
"Investigations into the Polymorphs and Hydration Products of UO3" Edgar C. Buck, Charles H. Henager, Shenyang Hu, David E. Meier, Shane M. Peper, Jon M. Schwantes, Yin-Fong Su, Robert L. Sams, Thomas A. Blake, Timothy J. Johnson, Thomas J. Kulp, Ricky L. Sommers, Joshua D. Sugar, Jeffrey D. Chames, Lucas E. Sweet, [2012] Proceedings of SPIE - The International Society for Optical Engineering · DOI: 10.1117/12.919706
"Sensitivity of UO2 stability in a reducing environment on radiolysis model parameters" Edgar C. Buck, Richard S. Wittman, [2012] Materials Research Society Symposium Proceedings · DOI: 10.1557/opl.2012.1449
ABSTRACT

Results for a radiolysis model sensitivity study of radiolytically produced H2O2 are presented as they relate to Spent (or Used) Light Water Reactor uranium oxide (UO2) nuclear fuel (UNF) oxidation in a low oxygen environment. The model builds on previous reaction kinetic studies to represent the radiolytic processes occurring at the nuclear fuel surface. Hydrogen peroxide (H2O2) is the dominant oxidant for spent nuclear fuel in an O2-depleted water environment. The most sensitive parameters have been identified with respect to predictions under typical conditions. As compared with the full model with about 100 reactions, it was found that only 30 to 40 of the reactions are required to determine [H2O2] to one part in 10–5 and to preserve most of the predictions for major species. This allows a systematic approach for model simplification and offers guidance in designing experiments for validation.

"Solution-Borne Colloids from Drip Tests using actinide-Doped and Fully-Radioactive Waste Glasses" Stephen F. Wolf, Edgar C. Buck, Carol J. Mertz, John K. Bates, Jeffrey A. Fortner, [2012] MRS Proceedings · DOI: 10.1557/proc-465-165
ABSTRACT

Drip tests designed to replicate the synergistic interactions between waste glass, repository groundwater, water vapor, and sensitized 304L stainless steel in the potential Yucca Mountain Repository have been ongoing in our laboratory for over ten years. Results will be presented from three sets of these drip tests: two with actinide-doped glasses, and one with a fully-radioactive glass. Periodic sampling of these tests have revealed trends in actinide release behavior that are consistent with their entrainment in colloidal material when as-cast glass is reacted. Results from vapor hydrated glass show that initially the actinides are completely dissolved in solution, but as the reaction proceeds, the actinides become suspended in solution. Sequential filtering and alpha spectroscopy of colloid-bearing leachate solutions indicate that more than 80% of the plutonium and americium are bound to particles that are captured by a 0.1 μm filter, while less than 10% of the neptunium is stopped by a 0.1 μm filter. Analytical transmission electron microscopy has been used to examine particles from leachate solutions and to identify several actinide-bearing phases which are responsible for the majority of actinide release during glass corrosion.

"Technetium containing waste forms - An innovator's perspective, invited" [2012] Transactions of the American Nuclear Society · EID: 2-s2.0-84876548707
"A Radiochemical Analyses of Metastudtite and Leachates from Spent Fuel" Brady Hanson, Edgar Buck, Chuck Soderquist, Bruce McNamara, [2011] MRS Proceedings · DOI: 10.1557/proc-824-cc9.4
Abstract

We have characterized considerable amounts of the two known uranyl peroxide phases that formed under static immersion conditions on commercial spent nuclear fuel (CSNF) samples. Milligrams of corroded fuel aggregates were observed at the air-water interface in each sample. The bulk fuel and the interfacial solids were examined by SEM, EDX, and XRD and were found to contain studtite and metastudtite, respectively. The reason for the partitioning of the two phases is not clear at this time. The unique occurrence of the floating phase prompted a radiochemical analysis of these solids. The analysis indicated that 90Sr, 137Cs, 99Tc, and to a lesser extent of 238,239Pu and 237Np, had partitioned with the air-water interface aggregates. The concentration of 241Am in the interfacial solids was two orders of magnitude lower than the inventory in the fuel prior to contact with water. The radiochemical analyses of two fuel leachate samples are compared to reported leaching data of a similar fuel which did not result in the formation of studtite.

"Accelerated Glass Reaction Under PCT Conditions" J. K. Bates, E. C. Buck, C. R. Bradley, W. L. Ebert, [2011] MRS Proceedings · DOI: 10.1557/proc-294-569
ABSTRACT

Static leach tests similar to the PCT were performed for times up to two years to assess the long-term reaction behavior of high-level nuclear waste glasses similar to those expected to be produced at the Defense Waste Processing Facility. These tests show the reaction rate to decrease with the reaction time from an initially high rate to a low rate, but then to accelerate to a higher rate after reaction times of about one year, depending on the glass surface area/leachant volume ratio (SAN) used. The solution concentrations of soluble glass components increase as the reaction is accelerated, while the release of other glass components into solution is controlled by secondary phases which form during the reaction. The net result is that the transformation of glass to stable phases is accelerated while the solution becomes enriched in soluble components that are not effectively contained in secondary phases. The rate becomes linear in time after the acceleration and may be similar to the initial forward rate. A current model of glass reaction predicts that the glass reaction will be accelerated upon the formation of secondary phases which lower the silicic acid solution concentration. These tests show the total silicon concentration to increase upon acceleration of the reaction, however, which may be due to the slightly higher pH that is attained with the acceleration. The sudden change in the reaction rate is likely due to secondary phase formation.

"Characterization of a Cerium-Rich Pyrochlore-Based Ceramic Nuclear Waste Form" S. Segvich, E. C. BUCK, R. Gieré, [2011] MRS Proceedings · DOI: 10.1557/proc-757-ii6.4
ABSTRACT

Titanate ceramics have been proposed as candidate materials for immobilizing excess weapons plutonium. This study focuses on the characterization of a titanate-based ceramic through X-ray diffraction (XRD), electron probe microanalysis, and electron energy-loss spectroscopy (EELS). Three distinct phases have been identified, and their volume fraction was determined from element distribution maps using Scionimage-NIH Analysis software. This analysis revealed that the pyrochlore-group phase betafite (A2Ti2O7) forms the matrix of the ceramic and occupies 90.4% of the volume. Uniformly distributed in this matrix are perovskite (A2Ti2O6) and Hf-enriched rutile (TiO2), which account for 6.4 vol% and 3.1 vol%, respectively. The studied ceramic exhibits a very low porosity (0.3 vol%), which is characterized by small (<6 μm), rounded and isolated voids. In the studied ceramic, A-site cations are represented by Ca, rare earth elements, and Hf. The powder XRD pattern of the ceramic allowed refining the unit cell parameters for the cubic betafite, which is characterized by a cell edge of 10.132±0.003Å. The EELS data indicate that Ce is present as both Ce3+ and Ce4+ in betafite, whereas in perovskite, all Ce is trivalent.

"Corrosion Mechanisms of Spent Fuel Under Oxidizing Conditions" R. Finch, E. Buck, J. Bates, P. A. Finn, [2011] MRS Proceedings · DOI: 10.1557/proc-506-123
ABSTRACT

The release of99Tc can be used as a reliable marker for the extent of spent oxide fuel reaction under unsaturated high-drip-rate conditions at 90°C. Evidence from leachate data and from scanning and transmission electron microscopy (SEM and TEM) examination of reacted fuel samples is presented for radionuclide release, potential reaction pathways, and the formation of alteration products. In the ATM-103 fuel, 0.03 of the total inventory of99Tc is released in 3.7 years under unsaturated and oxidizing conditions. Two reaction pathways that have been identified from SEM are 1) through-grain dissolution with subsequent formation of uranyl alteration products, and 2) grain-boundary dissolution. The major alteration product identified by X-ray diffraction (XRD) and SEM, is Na-boltwoodite, Na[(UO2)(SiO3OH)]H20, which is formed from sodium and silicon in the water leachant.

"Element Partitioning in a Pyrochlore-Based Ceramic Nuclear Waste form" C. Hatcher, E. Reusser, E. C. Buck, R. Gieré, [2011] MRS Proceedings · DOI: 10.1557/proc-713-jj2.4
ABSTRACT

Pyrochlore-rich ceramics containing additional zirconolite, brannerite and rutile have been developed for immobilizing excess weapons plutonium. This study reports data for a ceramic containing small amounts of Al and Mo in addition to the major oxide components of Ti, U, Ca, Hf, Gd and Ce. Hafnium and Gd are added as neutron absorbers, Al and Mo represent impurities. Quantitative electron microprobe data demonstrate that UO2 is strongly partitioned into brannerite (45 wt%), which is present as euhedral crystals with inclusions of unreacted UO2. Pyrochlore forms the groundmass and has an average UO2 content of 28 wt%. Zirconolite contains only 15 wt% UO2, but is significantly more effective in accommodating Hf and Gd than both brannerite and pyrochlore. Zirconolite incorporates U together with Hf and Ce in one structural site, whereas brannerite and pyrochlore accommodate U with Gd in a site that is distinct from that occupied by Hf. Incorporation of Gd into zirconolite takes place via a coupled substitution involving Al, thus explaining the high Al2O3 contents (3 wt%). Molybdenum was not detected in the major oxides, and it might be present in the accessory rutile. Although the studied waste form was designed to incorporate Pu, the present dataset is also valuable because immobilization of highly fissile U (e.g., U-233) might need to be considered in the future.

"Evidence for Neptunium Incorporation into Uranium (VI) Phases" Brady D. Hanson, Judah I. Friese, Matt Douglas, Bruce K. McNamara, Edgar C. Buck, [2011] MRS Proceedings · DOI: 10.1557/proc-824-cc9.3
Abstract

This paper examines the ability of electron energy-loss spectroscopy (EELS) combined with transmission electron microscopy (TEM) to detect both low concentrations of Np in a U matrix and to provide evidence for incorporation of Np in U(VI) phases. The case for U(VI) secondary minerals acting as solubility-controlling phases for Np in repository performance assessment models has not been fully established. Direct evidence for incorporation, rather than sorption, continues to be difficult to obtain. Detection of Np with TEM-EELS is hampered by the occurrence of a plural (multiple) scattering event from the more abundant U atoms (U-M5 + U- O4,5), that results in severe overlap on the Np-M5 edge at ∼3665 eV. By examining the energy âgap' between the Np-M5 and Np-M4 edges (184 eV), a method for observing Np independently of the plural scattering event has been established. Clear evidence of Np incorporation into synthetic studtite {(UO2)(O2)(H2O)2](H2O)2} and uranophane {Ca(UO2)2(SiO3OH)2(H2O)5} has been found with TEM-EELS. The EELS technique continues to remain an important tool for examining the potential for transuranic behavior in nuclear waste materials.

"Heterogeneous reduction of PuO 2 with Fe(II): Importance of the Fe(III) reaction product" Dean A. Moore, Kevin M. Rosso, Odeta Qafoku, Dhanpat Rai, Edgar C. Buck, Eugene S. Ilton, Andrew R. Felmy, [2011] Environmental Science and Technology · DOI: 10.1021/es104212g
"Heterogeneous Reduction of PuO2 with Fe(II): Importance of the Fe(III) Reaction Product" Dean A. Moore, Kevin M. Rosso, Odeta Qafoku, Dhanpat Rai, Edgar C. Buck, Eugene S. Ilton, Andrew R. Felmy, [2011] Environmental Science & Technology · DOI: 10.1021/es104212g
"Imaging hydrated microbial extracellular polymers: Comparative analysis by electron microscopy" Matthew J. Marshall, Bruce W. Arey, Kenneth H. Williams, Edgar C. Buck, James K. Fredrickson, Alice C. Dohnalkova, [2011] Applied and Environmental Microbiology · DOI: 10.1128/aem.02001-10
ABSTRACT

Microbe-mineral and -metal interactions represent a major intersection between the biosphere and geosphere but require high-resolution imaging and analytical tools for investigation of microscale associations. Electron microscopy has been used extensively for geomicrobial investigations, and although usedbona fide, the traditional methods of sample preparation do not preserve the native morphology of microbiological components, especially extracellular polymers. Herein, we present a direct comparative analysis of microbial interactions by conventional electron microscopy approaches with imaging at room temperature and a suite of cryogenic electron microscopy methods providing imaging in the close-to-natural hydrated state.In situ, we observed an irreversible transformation of the hydrated bacterial extracellular polymers during the traditional dehydration-based sample preparation that resulted in their collapse into filamentous structures. Dehydration-induced polymer collapse can lead to inaccurate spatial relationships and hence could subsequently affect conclusions regarding the nature of interactions between microbial extracellular polymers and their environment.

"Immobilization of 99-technetium (VII) by Fe(II)-goethite and limited reoxidation" Hyun-Shik Chang, Jonathan P. Icenhower, Wayne W. Lukens, R. Jeffrey Serne, Nikolla P. Qafoku, Joseph H. Westsik, Edgar C. Buck, Steven C. Smith, Wooyong Um, [2011] Environmental Science and Technology · DOI: 10.1021/es104343p
"Incorporation of Cerium and Neodymium in a Uranyl Hydroxide Solid" D.J. Wronkiewicz, R.J. Finch, E.C. Buck, C.W. Kim, [2011] MRS Proceedings · DOI: 10.1557/proc-713-jj11.66
ABSTRACT

The migration behavior of radionuclides in a nuclear-waste repository will be influenced, in part, by their equilibrium solubilities in the presence of radionuclide-bearing solids and/or adsorption affinities as trace components onto the surfaces of solid host phases. Uranium phases that precipitate on the surface of altered spent nuclear fuel may thus influence the mobility of radionuclides released in the near-field environment, since by proximity, these will be the first phases that the radionuclides encounter following their release from the spent fuel matrix.

We have evaluated the potential for incorporating radionuclides into crystalline compounds by precipitating uranyl phases from aqueous solutions containing dissolved rare earth elements (REE; 2.1 ppm Ce4+, 4.6 ppm Ce4+, or 286 ppm Nd3+). Rare earth elements serve both as monitors for evaluating the potential behavior of REE radionuclides and as surrogate elements for the actinides (e.g., Ce4+ and Nd3+ for Pu4+ and Am3+, respectively). Although the crystalline compound that formed in the present set of experiments has not been positively identified, x-ray diffraction profiles suggest the presence of a uranyl hydroxide (UO2(OH)2) as the principal reaction product. An analysis of the crystalline products indicate a progressive decrease in concentration of cerium; from 26, to 20, and finally 11 ppm for crystals produced in 7-, 35-, and 190-day tests, respectively (Kd = 14, 11, 3, respectively). Results with neodymium display a similar trend, with concentrations in the solid decreasing from 1240 to 922 ppm between 7 and 35 days of reaction (Kd = 14 and 11, respectively). The decreasing concentration of REEs in the uranyl crystals can be correlated with both a coarsening in crystal size and a decrease in the concentration of dissolved uranium over time. Thus, REE incorporation in the crystalline solids decreases in conjunction with a decrease in the ratio of surface area/volume of the crystals, a decrease in the rate of crystal growth as uranium concentrations are lowered, or both. These data also suggest that adsorption of REE (and by analogy, actinides) onto crystal surfaces and subsequent trapping by crystal overgrowth processes may play key roles in the limiting the mobility of radionuclides in a nuclear waste repository.

"Intergrowth Structures in Synthetic Pyrochlores: Implications for Radiation Damage Effects and Waste Form Formulation" D. B. Chamberlain, R. Gieré, E. C. Buck, [2011] MRS Proceedings · DOI: 10.1557/proc-556-19
Abstract

Titanate-based ceramic waste forms are currently under development for the immobilization of excess weapons plutonium. Both Hf and Gd are added to the ceramic formulation as neutron absorbers in order to satisfy a defense-in-depth concept for the waste form. The introduction of significant amounts of hafnium may be responsible for the presence of zirconolite-2M crystals in pyrochlore-based ceramics and the formation of zirconolite lamellae within pyrochlore. The zirconolite grows epitaxially on { 111 }planes of pyrochlore. Although the zirconolite lamellae within pyrochlore are non-cubic, any volume expansion due to radiation damage in the pyrochlore should still be isotropic; in addition, the presence of these intergrowths may allow some stress relief in the ceramic.

"Neptunium Incorporation into Uranium(Vi) Compounds formed During Aqueous Corrosion of Neptunium-Bearing Uranium Oxides" Jeffery A. Fortner, Edgar C. Buck, Stephen F. Wol, Robert J. Finch, [2011] MRS Proceedings · DOI: 10.1557/proc-713-jj11.63
ABSTRACT

We report results of experimental studies on the behavior of Np during aqueous corrosion of unirradiated Np-bearing U oxides. Np-doped U oxides were reacted in humid air at 90°C and 150°C for several weeks within sealed stainless-steel vessels. Reacted solids were examined by scanning and transmission electron microscopies (SEM and TEM), electron energy-loss spectroscopy (EELS), and X-ray powder diffraction (XRD). Dehydrated schoepite, (UO2)O0.25-z(OH)1.5+2z (0 ≤z ≤0.15), is the predominant U(VI) compound formed in these experiments. Preliminary EELS analysis on crushed grains verify that dehydrated schoepite formed at 150°C contains up to approximately 2 wt.% Np, corresponding to a maximum Np:U molar ratio of approximately 1:40. These are maximum values because the degree to which surface-sorbed Np is present on the grains analyzed is not yet known. Crystalline NpO2 also precipitated during these experiments, and the concentration of Np in dehydrated schoepite may represent the maximum amount of Np that can be incorporated into dehydrated schoepite under the experimental conditions.

"Observation of Studtite and Metastudtite on Spent Fuel" Edgar Buck, Brady Hanson, Bruce McNamara, [2011] MRS Proceedings · DOI: 10.1557/proc-757-ii9.7
ABSTRACT

We have characterized uranyl peroxide phases on commercial spent nuclear fuel (SNF) samples formed under immersion conditions. At short times, crystallites of metaschoepite were observed on the hydrated fuel particles. Over a two-year period, all evidences of metaschoepite disappeared and in many samples, the fuel particles appeared to be coated by a new alteration phase. Additionally, milligrams of corroded fuel aggregates were observed at the sample air-water interface in each sample. The corrosion phases on bulk fuel and on the suspended materials were examined by SEM, EDX, and XRD and were identified as studtite (UO4·4H20) and metastudtite (UO4·2H20), respectively. The reason for the partitioning of the two phases is unclear at this time. SEM micrographs of the bulk powders indicated extensive surface corrosion and fragmentation of particles.

"Oxidative Corrosion of Spent uo2 Fuel in Vapor and Dripping Groundwater at 90°C" Edgar C. Buck, Patricia A. Finn, John K. Bates, Robert J. Finch, [2011] MRS Proceedings · DOI: 10.1557/proc-556-431
Abstract

Oxidative dissolution of spent UO2 fuel in vapor and dripping groundwater at 90°C occurs via general corrosion at fragment surfaces. Dissolution along fuel-grain boundaries is also evident in samples contacted by the largest volumes of groundwater, and corroded grain boundaries extend at least 20 or 30 grains deep (> 200 μm), possibly throughout mm-sized fragments. Apparent dissolution of fuel along defects that intersect grain boundaries has produced 50 to 200 nm-diameter dissolution pits that penetrate 1–2 μm into each grain, giving rise to a “worm-like” texture along fuel-grain boundaries. Sub-micrometer-sized fuel shards are common between fuel grains and may contribute to the reactive surface area of fuel exposed to groundwater. Outer surfaces of reacted fuel fragments develop a fmne-grained layer of corrosion products adjacent to the fuel (5–15 μm thick). A more coarsely crystalline layer of corrosion products commonly covers the fine-grained layer, the thickness of which varies considerably among samples (from less than 5 μm to greater than 40 μm). The thickest and most porous corrosion layers develop on fuel fragments exposed to the largest volumes of groundwater. Corrosion-layer compositions depend strongly on water flux, with uranyl oxy-hydroxides predominating in vapor experiments, and alkali and alkaline earth uranyl silicates predominating in high drip-rate experiments. Low drip-rate experiments exhibit a complex assemblage of corrosion products, including phases identified in vapor and high drip-rate experiments.

"Retention of Neptunium in Uranyl Alteration Phases Formed During Spent Fuel Corrosion" R. J. Finch, P. A. Finn, J. K. Bates, E. C. Buck, [2011] MRS Proceedings · DOI: 10.1557/proc-506-87
ABSTRACT

Uranyl oxide hydrate phases are known to form during contact of oxide spent nuclear fuel with water under oxidizing conditions; however, less is known about the fate of fission and neutron capture products during this alteration. We describe, for the first time, evidence that neptunium can become incorporated into the uranyl secondary phase, dehydrated schoepite (UO3•0.8H2O). Based on the long-term durability of natural schoepite, the retention of neptunium in this alteration phase may be significant during spent fuel corrosion in an unsaturated geologic repository.

"Spectroscopic characterization of actinide materials" E. C. Buck, D. L. Clark, G. van der Laan, R. Caciuffo, [2011] MRS Bulletin · DOI: 10.1557/mrs2010.716

Advanced spectroscopic techniques provide new and unique tools for unraveling the nature of the electronic structure of actinide materials. Inelastic neutron scattering experiments, which address temporal aspects of lattice and magnetic fluctuations, probe electromagnetic multipole interactions and the coupling between electronic and vibrational degrees of freedom. Nuclear magnetic resonance clearly demonstrates different magnetic ground states at low temperature. Photoemission spectroscopy provides information on the occupied part of the electronic density of states and has been used to investigate the momentum-resolved electronic structure and the topology of the Fermi surface in a variety of actinide compounds. Furthermore, x-ray absorption and electron energy-loss spectroscopy have been used to probe the relativistic nature, occupation number, and degree of localization of 5f electrons across the actinide series. More recently, element- and edge-specific resonant and non-resonant inelastic x-ray scattering experiments have provided the opportunity of measuring elementary electronic excitations with higher resolution than traditional absorption techniques. Here, we will discuss results from these spectroscopic techniques and what they tell us of the electronic and magnetic properties of selected actinide materials.

"Waste Glass Weathering" Edgar C. Buck, John K. Bates, [2011] MRS Proceedings · DOI: 10.1557/proc-333-41
ABSTRACT

The weathering of glass is reviewed by examining processes that affect the reaction of commercial, historical, natural, and nuclear waste glass under conditions of contact with humid air and slowly dripping water, which may lead to immersion in nearly static solution. Radionuclide release data from weathered glass under conditions that may exist in an unsaturated environment are presented and compared to release under standard leaching conditions. While the comparison between the release under weathering and leaching conditions is not exact, due to variability of reaction in humid air, evidence is presented of radionuclide release under a variety of conditions. These results suggest that both the amount and form of radionuclide release can be affected by the weathering of glass.

"Influence of dynamical conditions on the reduction of UVI at the magnetite-solution interface" Jean-François Boily, Edgar C. Buck, Frances N. Skomurski, Kevin M. Rosso, Christopher L. Cahill, John R. Bargar, Andrew R. Felmy, Eugene S. Ilton, [2010] Environmental Science and Technology · DOI: 10.1021/es9014597
"Influence of Dynamical Conditions on the Reduction of UVI at the Magnetite-Solution Interface" Jean-François Boily, Edgar C. Buck, Frances N. Skomurski, Kevin M. Rosso, Christopher L. Cahill, John R. Bargar, Andrew R. Felmy, Eugene S. Ilton, [2010] Environmental Science & Technology · DOI: 10.1021/es9014597
"Verifying the presence of low levels of neptunium in a uranium matrix with electron energy-loss spectroscopy" Matt Douglas, Rick S. Wittman, Edgar C. Buck, [2010] Micron · DOI: 10.1016/j.micron.2009.08.007
"Characterization of high phosphate radioactive tank waste and simulant development" Bruce K. McNamara, Edgar C. Buck, Sandra K. Fiskum, Lanée A. Snow, Gregg J. Lumetta, [2009] Environmental Science and Technology · DOI: 10.1021/es9013745
"The Formation and Modeling of Colloids from the Corrosion of Nuclear Waste Forms" Rick S. Wittman, Edgar Buck, [2009] Materials Research Society Symposium Proceedings · DOI: 10.1557/proc-1124-q11-01
"Radiation damage effects in candidate titanates for Pu disposition: Zirconolite" R.D. Scheele, E.C. Buck, A.E. Kozelisky, R.L. Sell, R.J. Elovich, W.C. Buchmiller, D.M. Strachan, [2008] Journal of Nuclear Materials · DOI: 10.1016/j.jnucmat.2007.01.278
"Radiolytic microscale power generation based on single chamber fuel cell operation" Brian K Paul, Todd Palmer, Qiao Wu, William Jost, Chih-Heng T Tseng, Santosh Tiwari, Gertrude Patello, Edgar C Buck, Jamelyn D Holladay, Rick Shimskey, Paul Humble, Paul MacFarlan, Jesse Wainright, Richard B Peterson, [2007] Journal of Micromechanics and Microengineering · DOI: 10.1088/0960-1317/17/9/s07
"Incorporation of cerium and neodymium in uranyl phases" David J. Wronkiewicz, Robert J. Finch, Edgar C. Buck, Cheol-Woon Kim, [2006] Journal of Nuclear Materials · DOI: 10.1016/j.jnucmat.2006.02.087
"Observation of aqueous Cm(III)/Eu(III) and UO2 2+ nanoparticulates at concentrations approaching solubility limit by laser-induced fluorescence spectroscopy" Andrew R. Felmy, Yuanxian Xia, Edgar C. Buck, Zheming Wang, [2006] Journal of Alloys and Compounds · DOI: 10.1016/j.jallcom.2005.07.080
"Observation of aqueous Cm(III)/Eu(III) and UO22+ nanoparticulates at concentrations approaching solubility limit by laser-induced fluorescence spectroscopy" Andrew R. Felmy, Yuanxian Xia, Edgar C. Buck, Zheming Wang, [2006] Journal of Alloys and Compounds · DOI: 10.1016/j.jallcom.2005.07.080
"Comment on 'extended electron energy loss fine structure simulation of the local boron environment in sodium aluminosilicate glasses containing gadolinium' by M. Qian, H. Li, L. Li and D.M. Strachan [J. Non-Cryst. Solids 328 (2003) 90]" J.C.H. Spence, N. Jiang, [2005] Journal of Non-Crystalline Solids · DOI: 10.1016/j.jnoncrysol.2004.07.052
"Corrosion of commercial spent nuclear fuel. 1. Formation of studtite and metastudtite" Bruce McNamara, Edgar C. Buck, Judah I. Friese, Evan Jenson, Kenneth Krupka, Bruce W. Arey, Brady D. Hanson, [2005] Radiochimica Acta · DOI: 10.1524/ract.93.3.159.61613
Summary

The contact of commercial spent nuclear fuel (CSNF) with water over a 2-year period led to an unexpected corrosion phase and morphology. At short hydration times, crystallites of metaschoepite [(UO2)8O2(OH)12](H2O)10 were observed on the hydrated CSNF particles. Over the 2-year contact period, all evidence of metaschoepite disappeared, and the fuel particles were coated by a new alteration phase. Additionally, films of the reacted fuel were observed at the sample air-water interface of each sample. The corrosion phases on fuel powders and on the suspended films were examined by scanning electron microscopy, energy-dispersive X-ray fluorescence, and X-ray diffraction and were identified as studtite [(UO2)(O2)(H2O)2](H2O)2 and metastudtite (UO4·2H2O), respectively. The reason for the partitioning of the latter phase to the sample air-water interface is unclear at this time but may be due to structural differences between the two phases. Scanning electron micrographs of the CSNF powders indicated surface corrosion along grain boundaries and fragmentation of the primary solid. The occurrence of studtite and metastudtite on CSNF could have implications for the potential attenuation of released radionuclides during oxidative corrosion of CSNF in a geologic repository.

"Corrosion of commercial spent nuclear fuel. 2. Radiochemical analyses of metastudtite and leachates" Brady D. Hanson, Edgar C. Buck, Chuck Soderquist, Bruce McNamara, [2005] Radiochimica Acta · DOI: 10.1524/ract.93.3.169.61615
Summary

Immersing commercial spent nuclear fuel (CSNF) in deionized water produced two corrosion products after a 2-year contact period. Suspensions of aggregates were observed to form at the air–water interface for each of five samples. These suspended aggregates were characterized by X-ray diffraction (XRD) to be metastudtite (UO4·2H2O), while the corrosion present on the surface of the fuel itself was determined to be studtite [(UO2)(O2)(H2O)2](H2O)2]. The presence of unreacted UO2matrix was below the limits of detection by XRD for the three samples examined. The result prompted a radiochemical analysis of the solids collected from the sample air–water interface. The analysis indicated that high concentrations of90Sr,137Cs, and99Tc, relative to the fuel inventory, had concentrated at the air–water interface along with the aggregates of metastudtite. Concentrations of241Am were at least two orders of magnitude lower than expected in these solids, and retention of237Np and239Pu into the corrosion product was observed. The combined radiochemical analyses of the air–water interface aggregates and leachate samples are a rare example of radionuclide partitioning to an alteration phase and may provide preliminary evidence for mechanisms that give rise to such noticeable departures from fuel-inventory values. The leachate radiochemical data are compared to existing data from hydration of the same CSNF.

"Determination of the uranium valence state in the brannerite structure using EELS, XPS, and EDX" G. R. Lumpkin, Z. Zhang, E. C. Buck, K. L. Smith, M. Colella, [2005] Physics and Chemistry of Minerals · DOI: 10.1007/s00269-004-0444-5
"Microscale characterization of uranium(VI) silicate solids and associated neptunium(V)" Sue B. Clark, Judah I. Friese, Bruce W. Arey, Edgar C. Buck, Brady D. Hanson, Satoshi Utsunomiya, Rodney C. Ewing, Matthew Douglas, [2005] Radiochimica Acta · DOI: 10.1524/ract.93.5.265.64281
Summary

The uranium(VI) silicate phases uranophane, Ca[(UO2)(SiO3OH)]2·5H2O, and sodium boltwoodite, Na[(UO2)(SiO3OH)]·1.5H2O, were synthesized in the presence of small, variable quantities (0.5–2.0 mol % relative to U) of pentavalent neptunium (Np(V), as NpO2 +), to investigate the nature of its association with these U(VI) solid phases. Solids were characterized by X-ray powder diffraction (XRD), gamma spectrometry (GS), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM) with electron energy-loss spectroscopy (EELS). Neptunium concentration was determined in the bulk solid phases by GS and was found to range from 780–15800 μg/g. In some cases, Np distributions between the aqueous and solid phases were monitored, and 78–97% of the initial Np was associated with the isolated solid. Characterization of individual crystallites by TEM/EELS suggests the Np is associated with the U(VI) phase. No discrete Np phases, such as Np oxides, were observed. Because the U(VI) silicates are believed to be important solubility-controlling solids on a geologic timescale, these results suggest that the partitioning of the minor actinides to these solids must be considered when assessing the performance of a waste repository for spent nuclear fuel.

"Neptunium(V) partitioning to uranium(VI) oxide and peroxide solids" Sue B. Clark, Judah I. Friese, Bruce W. Arey, Edgar C. Buck, Brady D. Hanson, Matthew Douglas, [2005] Environmental Science and Technology · DOI: 10.1021/es0405169
"Radiation damage effects in candidate titanates for Pu disposition: Pyrochlore" R.D. Scheele, E.C. Buck, J.P. Icenhower, A.E. Kozelisky, R.L. Sell, R.J. Elovich, W.C. Buchmiller, D.M. Strachan, [2005] Journal of Nuclear Materials · DOI: 10.1016/j.jnucmat.2005.04.064
"Reply to “Comment on ‘Extended electron energy loss fine structure simulation of the local boron environment in sodium aluminoborosilicate glasses containing gadolinium’ by M. Qian, H. Li, L. Li and D.M. Strachan [J. Non-Cryst. Solids 328 (2003) 90]”" Maoxu Qian, Edgar Buck, Denis M. Strachan, Hong Li, [2005] Journal of Non-Crystalline Solids · DOI: 10.1016/j.jnoncrysol.2004.07.090
"Electron energy-loss spectroscopy of anomalous plutonium behavior in nuclear waste materials" Patricia A Finn, John K Bates, Edgar C Buck, [2004] Micron · DOI: 10.1016/j.micron.2003.11.014
"Neptunium(V) incorporation/sorption with uranium(VI) alteration products" [2004] Materials Research Society Symposium Proceedings · EID: 2-s2.0-14944372477
"Precipitation of nitrate-cancrinite in Hanford tank sludge" B. K. McNamara, E. C. Buck, [2004] Environmental Science and Technology · DOI: 10.1021/es034943i
"Precipitation of nitrate - Cancrinite in Hanford tank sludge" B. K. McNamara, E. C. Buck, [2004] Environmental Science & Technology · DOI: 10.1021/es034943i
"The geochemical behaviour of Tc, Np and Pu in spent nuclear fuel in an oxidizing environment" Brady D. Hanson, Bruce K. McNamara, Edgar C. Buck, [2004] Geological Society Special Publication · DOI: 10.1144/gsl.sp.2004.236.01.05
Abstract

Spent fuel from commercial nuclear reactors consists mainly of uranium oxide. However, the changes that occur during reactor operations have a profound effect on chemical and physical properties of this material. Heat build-up in the fuel pellet during reactor operations can cause redistribution of fission products. The fission products may aggregate in one of three types of precipitates; gaseous, metallic, or oxide, depending on the burn-up and in-core treatment. Radiation damage and variations in fission and neutron capture yields across the fuel pellets lead to Pu enrichment and increased porosity with increasing burn-up. A more porous surface may make the fuel more susceptible to oxidative dissolution. As the level of actinides and fission products increases, the fuel may become more resistant to oxidation. These changes may limit the usefulness of natural uraninite (UO 2 ) analogues for predicting the geological behaviour of spent fuel disposed in a high-level waste (HLW) repository. In this Chapter, an overview of spent fuel microstructure, radiolytic effects, and alteration processes is presented. Evidence for Np incorporation into U 6+ phases, the nature of Pu surface precipitates on spent fuel, and evidence for the preferential removal of 4d-metals from ε-particles in corroded spent fuel is discussed. Understanding the potential mechanisms of radionuclide attenuation through sorption and/or incorporation requires techniques with both high spatial resolution and excellent elemental sensitivity.

"Synthesis, characterization, and manipulation of helical SiO2 nanosprings" Chong-Min Wang, Edgar C. Buck, Lai-Sheng Wang, Hai-Feng Zhang, [2003] Nano Letters · DOI: 10.1021/nl0341180
"Synthesis, characterization, and manipulation of helical SiO2 nanosprings" Chong-Min Wang, Edgar C. Buck, Lai-Sheng Wang, Hai-Feng Zhang, [2003] Nano Letters · DOI: 10.1021/nl0341180
"Investigation of the oxidation state of uranium in nuclear materials and their alteration products" [2002] Materials Research Society Symposium - Proceedings · EID: 2-s2.0-0036381284
"Lithium-Assisted Self-Assembly of Aluminum Carbide Nanowires and Nanoribbons" Alice C. Dohnalkova, Chong-Min Wang, James S. Young, Edgar C. Buck, Lai-Sheng Wang, Hai-Feng Zhang, [2002] Nano Letters · DOI: 10.1021/nl015656k
"Alteration of uranium-rich microlite" [2001] Materials Research Society Symposium - Proceedings · EID: 2-s2.0-0035783106
"EXAFS and XANES analysis of plutonium and cerium edges from titanate ceramics for fissile materials disposal" [2000] Materials Research Society Symposium - Proceedings · EID: 2-s2.0-0034509778
"Growth and alteration of uranium-rich microlite" [2000] Materials Research Society Symposium - Proceedings · EID: 2-s2.0-0034507767
"Potential incorporation of transuranics into uranium phases" [2000] Materials Research Society Symposium - Proceedings · EID: 2-s2.0-0034509775
"The behavior of silicon and boron in the surface of corroded nuclear waste glasses: An eftem study" [2000] Materials Research Society Symposium - Proceedings · EID: 2-s2.0-0034514878
"Corrosion behavior of pvrochlore-rich titanate ceramics for plutonium disposition; impurity effects" [1999] Materials Research Society Symposium - Proceedings · EID: 2-s2.0-0033308238
"Corrosion behavior of pyrochlore-rich titanate ceramics for plutonium disposition; Impurity effects" V. N. Zyryanov, C. J. Mertz, E. C. Buck, D. B. Chamberlain, A. J. Bakel, [1999] Scientific Basis for Nuclear Waste Management Xxii · DOI: 10.1557/proc-556-181
Abstract

Four titanate ceramics were characterized and tested. These ceramics were similar to those proposed for Pu disposition, with Ce as a surrogate for Pu. The baseline ceramic contained Ti, U, Ca, Hf, Gd, and Ce, and was made up of only four crystalline phases: pyrochlore, zirconolite, rutile, and brannerite. The three other ceramics contained different amounts of impurities that are expected in the feed. Impurities are defined as any element other than Ti, U, Ca, Hf, Gd, and Ce. The ceramics that contained impurities contained different phases than the baseline. The addition of impurities led to the absence of brannerite and the presence of amorphous silicate, Ca-Al-Ti, and perovskite phases. The results from 3 day, 90°C MCC-I tests with impurity ceramics were significantly different than the results from tests with the baseline ceramic. Overall, the addition of impurities to these titanate ceramics altered the phase assemblages, which in turn, affected the corrosion behavior.

"Microanalysis of colloids and suspended particles from nuclear waste glass alteration" John K Bates, Edgar C Buck, [1999] Applied Geochemistry · DOI: 10.1016/s0883-2927(98)00088-2
"Uranium Mineralogy and the Geologic Disposal of Spent Nuclear Fuel" [1999] REVIEWS IN MINERALOGY <D>
"Phase distribution in a zirconolite-rich ceramic for plutonium immobilization." [1998] Abstracts of Papers of the American Chemical Society
"The corrosion behavior of individual elements during the corrosion of Pu-titanate ceramics." [1998] Abstracts of Papers of the American Chemical Society
"A new uranyl oxide hydrate phase derived from spent fuel alteration" D.J. Wronkiewicz, P.A. Finn, J.K. Bates, E.C. Buck, [1997] Journal of Nuclear Materials · DOI: 10.1016/s0022-3115(97)00188-8
"Detecting low levels of transuranics with electron energy loss spectroscopy" J.A. Fortner, E.C. Buck, [1997] Ultramicroscopy · DOI: 10.1016/s0304-3991(96)00109-x
"EELS analysis of redox in glasses for plutonium immobilization" Edgar C. Buck, Adam J.G. Ellison, John K. Bates, Jeffrey A. Fortner, [1997] Ultramicroscopy · DOI: 10.1016/s0304-3991(96)00108-8
"Physical and chemical characterization of actinides in soil from Johnston Atoll" John K. Bates, Edgar C. Buck, Nancy L. Dietz, Jeffrey A. Fortner, Neil R. Brown, Stephen F. Wolf, [1997] Environmental Science and Technology · DOI: 10.1021/es960295+
"Spent fuel reaction: The behavior of the epsilon-phase over 3.1 years" J. C. Hoh, S. F. Wolf, M. T. Surchik, E. C. Buck, J. K. Bates, P. A. Finn, [1997] Scientific Basis for Nuclear Waste Management Xx · DOI: 10.1557/proc-465-527
ABSTRACT

The release fractions of the five elements in the ε-phase (99Tc, 97Mo, Ru, Rh, and Pd) as well as that of 238U are reported for the reaction of two oxide fuels (ATM-103 and ATM-106) in unsaturated tests under oxidizing conditions. The 99Tc release fractions provide a lower limit for the magnitude of the spent fuel reaction. The 99Tc release fractions indicate that a surface reaction might be the rate controlling mechanism for fuel reaction under unsaturated conditions and the oxidant is possibly H2O2, a product of alpha radiolysis of water.

"Spent fuel reaction: The behavior of the ε-phase over 3.1 years" [1997] Materials Research Society Symposium - Proceedings · EID: 2-s2.0-0030656004
"Contaminant uranium phases and leaching at the Fernald site in Ohio" Neil R. Brown, Nancy L. Dietz, Edgar C. Buck, [1996] Environmental Science and Technology · DOI: 10.1021/es9500825
"Ten-year results from unsaturated drip tests with UO2 at 90°C: Implications for the corrosion of spent nuclear fuel" John K. Bates, Stephen F. Wolf, Edgar C. Buck, David J. Wronkiewicz, [1996] Journal of Nuclear Materials · DOI: 10.1016/s0022-3115(96)00383-2
"The chemistry of the light rare-earth elements as determined by electron energy loss spectroscopy" E. C. Buck, J. A. Fortner, [1996] Applied Physics Letters · DOI: 10.1063/1.116627

The energy loss spectra of the rare earths are characterized by sharp M4,5 edges, the relative intensities of which are characteristic of the 4f-shell occupancy of the excited ion. For the light rare earths, the dependence of these relative peak heights on 4f-shell occupancy is quite pronounced. Thus they may be used to determine the oxidation state of the multivalent elements Ce and Pr. The second derivative of the spectrum is shown to be extremely sensitive to the chemical environment. Modern instrumentation and detection techniques allow the oxidation state of Ce and Pr to be determined even when they are present as only minor constituents.

"The chemistry of the light rare‐earth elements as determined by electron energy loss spectroscopy" E. C. Buck, J. A. Fortner, [1996] Applied Physics Letters · DOI: 10.1063/1.116627

The energy loss spectra of the rare earths are characterized by sharp M4,5 edges, the relative intensities of which are characteristic of the 4f-shell occupancy of the excited ion. For the light rare earths, the dependence of these relative peak heights on 4f-shell occupancy is quite pronounced. Thus they may be used to determine the oxidation state of the multivalent elements Ce and Pr. The second derivative of the spectrum is shown to be extremely sensitive to the chemical environment. Modern instrumentation and detection techniques allow the oxidation state of Ce and Pr to be determined even when they are present as only minor constituents.

"Alteration of spent fuel matrix under unsaturated water conditions" [1995] High Level Radioactive Waste Management - Proceedings of the Annual International Conference · EID: 2-s2.0-0029210646
"Disposition of plutonium and cerium in waste forms determined by electron energy loss spectroscopy" [1995] MICROBEAM ANALYSIS 1995
"Effects of electron irradiation of barium titanate" E. C. Buck, [1995] Radiation Effects and Defects in Solids · DOI: 10.1080/10420159508225752
"Effects of electron irradiation of rutile" E. C. Buck, [1995] Radiation Effects and Defects in Solids · DOI: 10.1080/10420159508220015
"Reactivity of plutonium-containing glasses for the immobilization of surplus fissile materials" [1995] High Level Radioactive Waste Management - Proceedings of the Annual International Conference · EID: 2-s2.0-0029222310
"Uranium-contaminated soils: Ultramicrotomy and electron beam analysis" Nancy L. Dietz, John K. Bates, Edgar C. Buck, [1995] Microscopy Research and Technique · DOI: 10.1002/jemt.1070310208
Abstract

Uranium‐contaminated soils from the U.S. Department of Energy (DOE) Fernald Site, Ohio, have been examined by a combination of backscattered electron imaging (BSE) and analytical electron microscopy with electron diffraction (AEM). The inhomogeneous distribution of particulate uranium phases in the soil required the development of a method for using ultramicrotomy to prepare transmission electron microscopy (TEM) thin sections from the SEM mounts. A water‐miscible resin was selected that allowed comparison between SEM and TEM images, permitting representative sampling of the soil. Uranium was found in iron oxides, silicates (soddyite), phosphates (autunites), and uraninite (UO2+x). No uranium was detected in association with phyllosilicates in the soil. © 1995 Wiley‐Liss, Inc.

"ANALYSIS OF REACTED NUCLEAR-WASTE GLASS USING ELECTRON BEAMS" [1994] Fifty-second Annual Meeting - Microscopy Society of America/twenty-ninth Annual Meeting - Microbeam Analysis Society, Proceedings
"ANALYTICAL ELECTRON-MICROSCOPY EXAMINATION OF SOLID REACTION-PRODUCTS IN LONG-TERM TESTS OF SRL-200 WASTE GLASSES" [1994] Materials Research Society Symposium - Proceedings
"Analytical electron microscopy examination of solid reaction products in long-term tests of SRL 200 waste glasses" [1994] Materials Research Society Symposium Proceedings · EID: 2-s2.0-0028255092
"COLLOIDAL PRODUCTS AND ACTINIDE SPECIES IN LEACHATE FROM SPENT NUCLEAR-FUEL" [1994] Radiochimica Acta
"Characteristics of colloids generated during the corrosion of nuclear waste glasses in groundwater" E.C. Buck, C. Mertz, J.K. Bates, J.C. Cunnane, D. Chaiko, X. Feng, [1994] Chemistry and Migration Behaviour of Actinides and Fission Products in the Geosphere · DOI: 10.2172/10196073
"Colloidal Products and Actinide Species in Leachate from Spent Nuclear Fuel" E. C. Buck, M. Gong, J. C. Hoh, J. W. Emery, L. D. Hafenrichter, J. K. Bates, P. A. Finn, [1994] Radiochimica Acta · DOI: 10.1524/ract.1994.6667.s1.189
"DISTRIBUTION OF URANIUM-BEARING PHASES IN SOILS FROM FERNALD" N. R. Brown, N. L. Dietz, E. C. Buck, [1994] Materials Research Society Symposium - Proceedings · DOI: 10.1557/proc-333-437
ABSTRACT

Electron beam techniques have been used to characterize uranium-contaminated soils at the Fernald Site, Ohio. Uranium particulates have been deposited on the soil through chemical spills and from the operation of an incinerator plant on the site. The major uranium phases have been identified by electron microscopy as uraninite, autunite, and uranium phosphite [U(PO3)4]. Some of the uranium has undergone weathering resulting in the redistribution of uranium within the soil.

"ELECTRON-BEAM MICROANALYSIS OF NUCLEAR WASTE GLASS" [1994] Abstracts of Papers of the American Chemical Society
"ELEMENTS PRESENT IN LEACH SOLUTIONS FROM UNSATURATED SPENT FUEL TESTS" J. K. Bates, J. C. Hoh, J. W. Emery, L D. Hafenrichter, E. C. Buck, M. Gong, P. A. Finn, [1994] Scientific Basis for Nuclear Waste Management Xvii · DOI: 10.1557/proc-333-399
ABSTRACT

Preliminary results for the composition of the leachate from unsaturated tests at 90°C with spent fuel for two successive periods of ~60 days each with pretreated J-13 groundwater are reported. The pH of the leachate solutions ranged from 4 to 7. The americium concentration was 104 to 105 greater than that reported for saturated spent fuel tests in which the leachate pH was 8. The major fraction of material in the leachate was present as colloids containing both americium and curium. The presence of actinides in a form not currently directly included in repository radionuclide transport models provides information that can be used in spent fuel reaction modeling, the performance assessment of the repository and the design of the engineering barrier system.

"Elements present in leach solutions from unsaturated spent fuels tests" [1994] Materials Research Society Symposium Proceedings · EID: 2-s2.0-0028196010
"Results of drip tests on sludge-based and actinide-doped glasses" [1994] High Level Radioactive Waste Management - Proceedings of the Annual International Conference · EID: 2-s2.0-0028591409
"ANALYTICAL ELECTRON-MICROSCOPY STUDY OF COLLOIDS FROM NUCLEAR WASTE GLASS REACTION" [1993] Materials Research Society Symposium - Proceedings
"Analytical electron microscopy. Study of colloids from nuclear waste glass reaction" [1993] Materials Research Society Symposium Proceedings · EID: 2-s2.0-0027309621
"DOES FULLY RADIOACTIVE GLASS BEHAVE DIFFERENTLY THAN SIMULATED WASTE GLASS" [1993] Materials Research Society Symposium - Proceedings
"Does fully radioactive glass behave differently than simulated waste glass?" [1993] Materials Research Society Symposium Proceedings · EID: 2-s2.0-0027262778
"LONG-TERM COMPARISON OF DISSOLUTION BEHAVIOR BETWEEN FULLY RADIOACTIVE AND SIMULATED NUCLEAR WASTE GLASSES" John K. Bates, Edgar C. Buck, Charles R. Bradley, Meiling Gong, Xiangdong Feng, [1993] Nuclear Technology · DOI: 10.13182/nt93-a34883
"Reaction of SRL 202 glass in J-13 and DIW" [1993] Materials Research Society Symposium Proceedings · EID: 2-s2.0-0027262780
"THE REACTION OF SRL 202 GLASS IN J-13 AND DIW" J. K. Bates, E. C. Buck, W. L. Ebert, [1993] Scientific Basis for Nuclear Waste Management Xvi · DOI: 10.1557/proc-294-137
ABSTRACT

Static leach tests were performed in both 304L stainless steel and Teflon vessels using a synthetic high-level waste glass with either deionized water (DIW) or a tuff groundwater solution as the leachant to assess the effects of the vessel and the initial leachant composition on the extent and nature of the glass reaction. The tests were performed using monolith samples at 340 m−1 and crushed samples at 2000 m−1 for times up to 1 year. The results show less silicon is released from the glass into the groundwater solution than into DIW at both high and low glass surface area/leachant volume ratios (SA/V), but the alkali metal and boron releases are not affected by the leachant used. Tests performed in a stainless steel vessel resulted in slightly lower leachate pH values, but similar reaction rates to those performed in a Teflon vessel, as measured by the boron release. Blank tests with DIW or EJ-13 in the vessels showed the Teflon vessels to release small amounts of fluoride (1 to 2 ppm) and to acidify the DIW slightly (4.0 < pH < 5.6). The pH values of blank tests with EJ-13 increased from 8.2 to about 8.6 in steel and to about 9.2 in Teflon vessels. The slightly higher pH values attained in Teflon vessels are attributed to outgassing of CO2 during the test.

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