Ceramic Materials for Nuclear Energy Research and Applications: Microstructure and Properties - Experiments and Modeling
Sponsored by: TMS Extraction and Processing Division, TMS Structural Materials Division, TMS Light Metals Division, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Energy Committee, TMS: Nuclear Materials Committee
Program Organizers: Xian-Ming Bai, Virginia Polytechnic Institute and State University; Yongfeng Zhang, University of Wisconsin; Larry Aagesen, Idaho National Laboratory; Vincenzo Rondinella, Jrc-Ec
Wednesday 2:00 PM
March 17, 2021
Room: RM 51
Location: TMS2021 Virtual
Session Chair: Marat Khafizov, Ohio State University
2:00 PM Invited
Exotic Magneto-elastic Properties in Uranium Dioxide: Krzysztof Gofryk1; 1Idaho National Laboratory
The magneto-elastic properties of nuclear materials remain an unsolved puzzle resulting from the lack of a thorough understanding of the strong coupling between magnetism and lattice vibrations. During the talk, we will show the results of our recent detailed thermodynamic and structural measurements on uranium dioxide, main nuclear fuel. We will present how these studies can be used to examine magneto-structural properties in this nuclear material. Understanding the magneto-elastic coupling in UO2 is important since it may affect its thermal transport, so critical in nuclear technology. The unusually strong correlations between the magnetic moments in U-atoms and lattice distortions are also a direct consequence of the non-collinear symmetry of the magnetic state, reduction of its thermal conductivity, and appearance of piezomagnetism at low temperatures. We will discuss the implications of these results in the context of the thermal properties of UO2.
2:30 PM Invited
Towards a Model of Coupled Irradiation and Corrosion: Amitava Banerjee1; Aaron Kohnert1; Edward Holby1; Laurent Capolungo1; Blas Uberuaga1; 1Los Alamos National Laboratory
Materials in reactors are exposed to multiple extreme environments simultaneously. Two of these environments – irradiation and corrosion – can lead to extensive changes in the materials properties. However, while there have been a number of empirical observations of their combined effects, there is still much unknown at a fundamental level regarding the synergies between these two extremes. Here, we present the foundations of a model of coupled irradiation and corrosion. Using Fe-Fe2O3 as a model system, density functional theory (DFT) calculations at the hybrid level are used to characterize the thermodynamics and kinetics of radiation-induced point defects. These are then used to parameterize a cluster dynamics model that accounts for the radiation-induced defect supersaturations on the corrosive response of the material. This model, while based on a number of assumptions, reveals that, based on conditions, radiation damage can have a dramatic effect on corrosion.
3:00 PM
Impact of Dislocation Loops on Thermal Conductivity of CeO2: Marat Khafizov1; Lingfeng He2; Miaomiao Jin2; David Hurley2; 1Ohio State University; 2Idaho National Laboratory
Dislocation loops are formed when ceramic materials are irradiated with energetic particles. They influence microstructure evolution and impact a number of physical properties determining physical behavior of ceramics in nuclear energy systems. Experimental measurement of thermal conductivity in proton irradiated ceria suggest that (111) faulted loops have a dramatic impact on thermal conductivity. Phonon mediated thermal transport analysis shows that the impact of individual interstitials making up the faulted loop on thermal conductivity is smaller than when they are a part of a faulted loop. This is in contrast to a general understanding that defect clustering leads to a recovery of thermal conductivity as the scattering strength of phonons by larger clusters is weaker. This effect was attributed to a long-range strain field around the faulted loops. Molecular dynamics simulations are performed to analyze the impact of (110) perfect and (111) faulted loops in fluorite structure using Green-Kubo approach.
3:20 PM
Microstructural Analysis and Micro-mechanical Testing on Xenon-irradiated Uranium Dioxide: Mack Cullison1; Fei Teng2; David Fraser2; Boopathy Kombaiah2; Kun Mo3; Jie Lian4; Tianyi Chen1; Fabiola Cappia2; 1Oregon State University; 2Idaho National Laboratory; 3Argonne National Laboratory; 4Rensselaer Polytechnic Institute
Spark plasma sintered UO2 with initial grain sizes of 10 and 70 µm were irradiated by 84 MeV Xenon ions up to about 1400 peak displacements per atom (dpa) at 350 to 500ºC. Ion-implantation is used to induce microstructure modifications that mimic in-reactor damage occurring at high burnup. Transmission electron microscope (TEM) characterization shows strong depth dependency in irradiated microstructure. 1-20 nanometer sized bubbles were observed near the peak dpa region while grain refinement was observed near the irradiated surface. Micro-mechanical testing will be applied to samples receiving different damage levels to determine the fracture behavior, strength, toughness and elastic local UO2 properties as a function of microstructural development under irradiation. Micromechanical properties in high-dpa irradiated UO2 will be useful for fuel development.
3:40 PM Invited
Comprehensive Treatment of Thermal Transport Under Irradiation in ThO2: David Hurley1; Marat Khafizov2; Cody Dennett1; Amey Khanolkar1; Zilong Hua1; Lingfeng He1; Jian Gan1; Anter ElAzab3; Maneieha Salaken3; Chao Jiang1; Miaomiao Jin1; Ryan Deskins3; Bawane Kausubh1; Chris Marianettii4; Matthew Mann5; 1Idaho National Laboratory; 2Ohio State University; 3Purdue University; 4Columbia University; 5AFRL
We report on a thermal transport study of thorium dioxide exposed to proton irradiation. This comprehensive treatment includes molecular dynamic modeling coupled with cluster dynamics to understand defect evolution. Models of defect evolution are compared/validated by transmission electron microscopy, Raman spectroscopy, ellipsometry, and x-ray diffraction measurements. Thermal transport properties of the thin damage layer are measured using modulated thermal reflectance and compared directly to a Boltzmann transport model of phonon mediated thermal transport in the presence of defects. The Boltzmann transport as well as the molecular dynamic and cluster dynamic models are informed from first principles models of defect formation and migration energies, phonon scattering cross-sections and phonon dispersion and lifetime in perfect, defect free materials. This comprehensive treatment of thermal transport demonstrates the level of detail made possible by combining elements of condensed matter physics, irradiation materials science, and mesoscale thermal transport studies.
4:10 PM
TEM Characterization of Dislocation Loops in Ion-irradiated Single Crystal ThO2: Kaustubh Bawane1; Xiang Liu1; Tiankai Yao1; Marat Khafizov2; Aaron French3; Matthew Mann4; Lin Shao3; Jian Gan1; David Hurley1; Lingfeng He1; 1Idaho National Laboratory; 2Ohio State University; 3Texas A&M University; 4Air Force Research Laboratory
This work focuses on the full characterization of dislocation loops in single-crystal ThO2 irradiated with proton and Kr ions at various temperatures and energies. Transmission electron microscopy (TEM) characterization was performed on a large number of dislocation loops. Burgers vector director analyzed using standard g.b=0 invisibility criterion showed <111> and <110> type loops for Kr irradiation and <111> type loops for proton irradiation. Loop density and loop growth behavior were discussed based on kinetic rate theory. TEM analysis of edge-on dislocation loops were used to determine habit planes for <111> type loops as {111} type. The nature of dislocation loops was revealed using the inside-outside contrast method as interstitial type. The interstitial loop of 1/3<111>{111} has also been confirmed using rel-rod dark field imaging and atomic-resolution scanning transmission electron microscopy imaging techniques.
4:30 PM
Hydrothermal Corrosion of Silicon Carbide: Jianqi Xi1; Dane Morgan1; Izabela Szlufarska1; 1University of Wisconsin-Madison
Due to its excellent physico-chemical properties, silicon carbide (SiC) has been recognized for its potential as a structural material in nuclear reactor applications. One of the remaining issues that can limit usability of this material is corrosion. In this talk, I will discuss our recent theoretical studies revealing corrosion mechanisms of SiC exposed to the hydrothermal water environment. I will first discuss, from the thermodynamic point of view, the open question of which corrosion products form, i.e., the formation of SiO2 vs Si(OH)4. Secondly, I will discuss the elementary interfacial reactions driving corrosion, including a discovery of the unexpected hydrogen scission reaction that plays a key role in surface degradation. Our kinetic studies reveal that SiC is dissolved directly into the water without forming the silica layer, although the reactions are analogous to those observed during dissolution of silica. Finally, I will discuss the surface orientation effect on SiC corrosion.
4:50 PM
TMIST-3A Post-irradiation Examination: Mark Lanza1; Walter Luscher1; David Senor1; Gary Hoggard2; 1Pacific Northwest National Laboratory; 2Idaho National Laboratory
Gamma-lithium aluminate (γ-LiAlO2) pellets with engineered microstructures were irradiated in the Advanced Test Reactor between September 2016 and January 2019 for a total of 350EFPD at 23MWth. Tritium speciation was studied by placing the pellets in individual capsules and surrounding them with components that preferentially react with either T2 or T2O. Post irradiation examination (PIE) is expected to reveal the fractionation between T2 and T2O released during irradiation. In addition to engineered microstructures with varying porosity and grain size, an alternate pellet design consisting of ~30μm γ-LiAlO2 granules dispersed with volume fractions (0.1-0.4) in a zirconium matrix was irradiated. Comparison between standard LiAlO2 and LiAlO2/Zr designs is expected to reveal the effects of encapsulating LiAlO2 granules in a Zr matrix on tritium release and speciation. This presentation will provide an overview of the experiment and anticipated PIE campaign as well as recently obtained measurement data from ongoing PIE activities.