Seaborg Institutes: Emerging Topics in Actinide Materials and Science: Characterization/Separation II
Sponsored by: TMS Structural Materials Division, TMS: Nuclear Materials Committee
Program Organizers: J. Rory Kennedy, Idaho National Laboratory; Taylor Jacobs, Helion Energy; Krzysztof Gofryk, Idaho National Laboratory; Assel Aitkaliyeva, University of Florida; Don Wood, Idaho National Laboratory
Tuesday 8:00 AM
March 21, 2023
Room: 28A
Location: SDCC
Session Chair: Jean-Christophe Griveau, ITU Karlsruhe; Don Wood, INL
8:00 AM Invited
How to Figure Out Local Order Against Average Order in UO2?: Lionel Desgranges1; Gianguido Baldinozzi2; 1CEA; 2CNRS
Recent results, using different experimental methods, evidenced a shortening of UO distance in UO2 PDF, while the average unit cell is expanding with increasing temperature. This shortened UO distance induces a change in the uranium coordination polyhedron, going from cubic in the regular Fm-3m to octahedral with shorter UO distances. Different interpretations were given for this change of coordination polyhedron, amongst which static multi-domains, dynamic domains or coexisting phases. Whatever its origin, this change in uranium coordination polyhedron might have consequences on UO2 behavior at low and high temperature. At high temperature, the existence of a local octahedral environment could be a reason why UO2 can incorporate so many fission products, because this environment is more favorable for fission products. At low temperature, the PDF uranium coordination polyhedron is very close to the one in Pa-3 symmetry, which is the symmetry of UO2 under Neel transition.
8:30 AM Invited
Thermochemical Behavior and Microstructural Characterization of Advanced Fuels in Oxidizing and Reducing Atmospheres: Elizabeth Sooby1; 1University of Texas at San Antonio
Commercial fuel vendors are considering higher uranium density fuels to enhance fuel economy and better accommodate accident tolerant cladding, and the leading designs for small modular reactors are looking toward complex, particle fuel architectures. There exist several gaps in our scientific understanding of how f-electron systems behave in both oxidizing and reducing atmospheres. With the terminal oxidation product for uranium in low oxidant partial pressures being UO2, we would expect breakaway oxidation kinetics at temperatures relevant to fuel during irradiation. However, depending on the bonding cation we observed varied oxidation kinetics. For some fuel compounds this has been linked to hydridization. Furthermore, for advanced cladding materials such as silicon carbide, thermochemical driven destabilization can occur at T~1200°C. Presented will be the characterization of these materials following exposure to high temperature oxidizing and reducing atmospheres along with the experimentally observed thermochemistry governing the dynamic response of nuclear materials to extreme environments.
9:00 AM
A 69Ga NMR Study of Aging in 7 at.% Ga Stabilized δ-Plutonium: Seth Blackwell1; Filip Ronning1; Michihiro Hirata1; Eric Bauer1; Joe Thompson1; Jeremy Mitchell1; Paul Tobash1; Tomas Martinez1; Carlos Archuleta1; Mike Ramos1; 1Los Alamos National Laboratory
Nuclear magnetic resonance (NMR) spectroscopy was used to study aging in a 7 at.% Ga ä-Pu sample via the 69Ga resonance. The 69Ga NMR was explored under swept-field and fixed-field conditions. The 69Ga data reveals self-irradiation damage manifesting in intrinsic local site disorder seen in field-swept spectra. Subsequent data from spin-relaxation measurements shows a spread of relaxation values across the resonance. Lastly, high-resolution spectra of the narrow component details radiation damage in-growth over ~1 month of storage at 5 K.
9:20 AM
High Energy X-Ray Characterization of Microstructure at Macroscopic Depths in Pu Alloys: Dale Carver1; Donald Brown1; Taylor Jacobs1; Alice Smith1; Peter Kenesei1; Jun-Sang Park1; 1Los Alamos National Laboratory
Plutonium is often alloyed with tri-valent elements, such as Aluminum or Gallium, to stabilize the more ductile -phase at room temperature. As Pu alloys accumulate defects with time naturally through fission events, the phase transformation behavior, as well as mechanical properties) of Pu alloys evolves with age. The advent of 3rd generation synchrotron X-ray sources with beamlines optimized for high energy (70-130 keV) X-rays is a game changer for the study of the phase transformations of Pu and its alloys. We will show first of their kind bulk transmission x-ray micro-tomography (CT) and high energy X-ray (HEXRD) diffraction measurements on four Pu alloy samples with thickness of order 0.5 mm. The four samples had 2 distinct alloy contents and different histories (age and deformation). Measurements at ambient conditions provide texture, dislocation density, and phase information prior to in-situ measurements collected during cooling to 10K and back to room temperature.
9:40 AM Break
10:00 AM Invited
Clarifying the Electronic Phase Space for U-based Materials with the ThCr2Si2-type Structure: Ryan Baumbach1; 1National High Magnetic Field Laboratory
Quantum materials are at the nexus of ongoing efforts to produce novel states of matter. However, especially for strongly correlated f-electron systems, progress is hampered by a lack of clarity regarding how to uncover new examples with enhanced properties. This is largely because (i) the relative strengths of interactions (e.g., Kondo and RKKY) vary widely between different materials, (ii) unusual states often emerge as a result of finely balanced or cumulative interactions, and (iii) first principles calculations often have limited success. In order to address this, we have aggregated information about the families of strongly correlated electron materials with the UT2X2 composition, where useful trends emerge [1]. We will discuss the utility of this approach in studying the hidden order compound URu2Si2 and related actinide materials.[1] Y. Lai et al., “Electronic landscape of the f-electron intermetallics with the ThCr2Si2 structure,” Science Advances in press (2022).
10:30 AM Cancelled
The Use of Capillary Electrophoresis assisted by Ligand Complexation for Efficient Separation of Actinides and Lanthanides: Thibaut Lecrivain1; Chloe Tolbert1; Robert Fox1; 1Idaho National Laboratory
Since the discovery of yttria in 1787, chemists still face a fascinating challenge, the separation of f-elements. Due to their similar chemical properties, f-elements remain difficult to separate using conventional techniques. The development of ion-exchange chromatography was arguably the first major advance in the separation of high-purity macroquantities of f-elements. The subsequent development of f-element separation methods has since continued to be one of the most exciting and successful areas of study for separation sciences, with numerous practical application (hydrometallurgy, forensics, nuclear, radiopharmaceutical, etc.). It has been approximately four decades since Jorgenson and Lukacs presented capillary-electrophoresis (CE). Since then, method developments and subsequential use of CE has been almost exclusively focused on the separation of biological-organic agents. This presentation will describe the use of CE methods for actinides and Lanthanides separation and its applications, coupled with metal-ligand chemistry to enhance the separation factor between adjacent f-elements.
11:00 AM
Comparison of the Electronic Transport of UN and ThN versus ThC: Barbara Szpunar1; Jayangani Ranasinghe1; Jerzy Szpunar1; 1University of Saskatchewan
We compare the electronic heat capacity and thermal conductivity of non-magnetic UN and ThN against ThC. We used Quantum Espresso and EPW codes based on density-functional theory to evaluate the electron density of states, the electronic heat capacity coefficient, the electron phonon coupling strength, the averaged over the temperature range 300 K – 1000 K, number of mobility electrons, and the electronic heat conductivity [1-3]. We confirmed that while the electronic heat capacity coefficient was linearly dependent on the electron density of states at Fermi energy, such a simple relation could not be used to determine the electronic heat conductivity, which was the highest for ThN. References: 1) B. Szpunar, J.I. Ranasinghe, L. Malakkal, and J.A. Szpunar, J. Alloys Compd., 879 (2021) 160467; 2) B. Szpunar, J.I. Ranasinghe, et al, J. Phys. and Chem. Solids, 165 (2022) 110647;3) B. Szpunar, Nucl. Mater. Energy, 32 (2022) 101212, pp. 5.