Seaborg Institutes: Emerging Topics in Actinide Materials and Science: Fuels
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
Wednesday 8:30 AM
March 22, 2023
Room: 28A
Location: SDCC
Session Chair: Assel Aitkaliyeva, University of Florida
8:30 AM Invited
Microstructural and Mechanical Characterization of High Burnup UO2 Fuel: Fabiola Cappia1; David Frazer1; Kaustubh Bawane1; Colby Jensen1; Dan Wachs1; 1Idaho National Laboratory
Safety and transient testing are essential pillars for both the development of Accident Tolerant Fuels and the optimization of fuel economics beyond current burnups. The successful interpretation of the transient testing results relies upon the knowledge of the initial microstructure of fuel and cladding, as it plays into the response of the system during the test. One example is the phenomenon of fine fragmentation that occurs in light-water reactor fuel at high burnup. The lack of information regarding the initial conditions of the fuel microstructure has hindered the development of a fully mechanistic fragmentation criterion and the determination of the conditions under which pulverization is predominant. The better knowledge of irradiation-induced phenomena could help the prediction of its performance. In this context, we applied many advanced techniques to determine properties relevant for safety and performance. The results are interpreted in the context of engineering scale post-irradiation examinations and irradiation conditions
9:00 AM Cancelled
Alpha-damage Studies of Mixed Oxides Fuels for Fast Reactors: Thierry Wiss1; 1European Commission - Jrc
Fast Reactors oxide fuels will be withstanding the most extreme irradiation and temperature conditions. A deep understanding of the behaviour of MOX fuels is hence one of the key aspects towards the licensing process of the reactors. The high alpha-activity due to the plutonium content in the fuel leads to the formation of large amount of defects, which will appear even before irradiation in the reactor leading to some properties degradation. At the back end of the fuel cycle, the microstructure evolution of spent nuclear fuel will be mainly due to the alpha-decaying minor actinides including plutonium and americium. Over the medium term, they will also contribute significantly to damage the fuel matrix. Experimental observations obtained by TEM, Thermal diffusivity, XRD, Thermal Desorption Spectroscopy, RAMAN, DSC of the self-irradiation alpha-damage effects on fresh and irradiated Uranium-Plutonium MOX fuel samples with a variety of Plutonium content will be reported
9:30 AM
Oh, My Darling Clementine: A Contemporary Investigation of the Los Alamos Plutonium Fast Reactor: Hannah Patenaude1; Vedant Mehta2; Franz Freibert2; 1University of Nevada, Las Vegas; 2Los Alamos National Laboratory
At the end of WWII, a group of Los Alamos pioneering researchers led by Jane and David Hall designed and built the world’s first fast reactor nicknamed “Clementine”. This reactor was unique in many aspects as a critically important high intensity fission-neutron source, novel platform to prove the adaptability of plutonium as a metallic reactor fuel, and utilized a first-of-a-kind heavy metal coolant in the form of liquid mercury. Clementine’s Pu alloy core fissioned on the fast neutron spectrum and was used to acquire a variety of neutron cross sections. Furthermore, Clementine provided information about fast reactors, including control characteristics and nuclear breeding properties of thorium and uranium required for production of commercial power and generation of fissile materials. With the aid of well-archived design information and experimental data, we are conducting a modern reactor analysis of Clementine to further explore and characterize this singularly unique experimental device. LA-UR-22-25668.
9:50 AM
U3O8 and UO2 Microspheres Synthesized Utilizing Sol-gel Chemistry and Microfluidics for Use as Next Generation Nuclear Fuels: James Kurley1; Rodney Hunt1; Jake McMurray1; Andrew Nelson1; 1Oak Ridge National Laboratory
Sol-gel chemistry has been utilized to synthesize UO2 microspheres with a wide range of sizes for decades. Standard methods have difficulties in the generation of wet uranium gel spheres with diameters below 600µm and with a narrow size distribution. Microfluidics has the capability to generate monodisperse droplets with diameters below 10µm with ease. However, microfluidics suffers from a lower throughput and necessitates longer synthesis times to generate the same amount of material. To accommodate the longer synthesis times, the broth feedstock required modification to increase broth longevity at room temperature without inhibiting gelation. The modified broth successfully lasted 5 hours and produced ~0.5 grams of air-dried 75μm UO3•nH2O•mNH3 microspheres. The air-dried microspheres were converted to U3O8 and UO2 microspheres with diameters of ~50 and ~40µm, respectively. The smaller microspheres with narrower size distribution could expand the nuclear fuel design space while reducing conservatisms in fuel performance calculations.
10:10 AM Break
10:30 AM Invited
Phase Decomposition in Uranium-Molybdenum Fuels Subjected to Low Neutron Fluences
: Maria Okuniewski1; Gyuchul Park1; Mehmet Topsakal2; Simerjeet Gill2; Lynne Ecker2; Daniel Murray3; Eric Dooryhee2; 1Purdue University; 2Brookhaven National Laboratory; 3Idaho National Laboratory
Low-enriched uranium molybdenum (U-Mo) monolithic fuel is the primary candidate for research and test reactors to replace high-enriched uranium fuel to minimize proliferation concerns. Low fluence neutron irradiations (< 1 dpa) were carried out in the Advanced Test Reactor at temperatures ranging from 150oC to 350oC to understand the early stages of microstructural evolution in U-10 wt.%Mo fuel. Synchrotron X-ray scattering and electron microscopy techniques were used to characterize the phase evolution, phase fractions, ordering, and microchemical changes as a function of neutron dose, temperature, and fabrication technique. Particular attention was paid to the phase decomposition of the as-fabricated γ- U-10 wt.%Mo fuel to the α-U and γ’-U2Mo phases.
11:00 AM Cancelled
Understanding the Role of Fission Products on the Formation and Collapse of the Gas Bubble Superlattice in U-Mo Fuel: Charlyne Smith1; Mukesh Bachhav1; Dennis Keiser1; 1Idaho National Laboratory
Self-organization of defect superlattices in far-from-equilibrium systems present a promising way to mitigate swelling concerns in nuclear materials. The gas bubble superlattice (GBS) is a highly ordered, complex defect structure that can retain fission gases Uranium-Molybdenum fuels. The elucidation of the GBS formation and collapse mechanisms can contribute to improving the stability and lifetime of the GBS such that fission gases could more effectively be stored. Studies have been performed to characterize the fission gas bubble sizes, bubble spacing, and thermal stability of the GBS. However, little is known about the distribution of fission products in the GBS and how they may contribute to the stability and ordering mechanism(s) in the GBS. This study combines transmission electron microscopy, atom probe tomography, and image analysis to isolate the fission product distribution and behavior at different crystallographic planes in irradiated U-Mo fuel.
11:30 AM
Pulsed Neutron Characterization of Irradiated Fuels at LANSCE: Sven Vogel1; Thilo Balke1; Charles A. Bouman2; Luca Capriotti3; Jason M. Harp4; Alexander M. Long1; Anton S. Tremsin5; Brendt Wohlberg1; Eric J. Larson1; Aaron E. Craft3; Brian J. Gross3; D. Travis Carver1; James R. Angell3; Vedant K. Mehta1; 1Los Alamos National Laboratory; 2Purdue University; 3Idaho National Laboratory; 4Oak Ridge National Laboratory; 5UC Berkeley
Neutrons offer bulk, non-destructive characterization of irradiated materials for which other bulk methods, e.g. X-ray diffraction or tomography, are not suitable due to the immense gamma background emitted from the samples. In particular, pulsed neutrons provide information from the ability to resolve the neutron energy or wavelength using their time-of-flight. This enables the potential to utilize neutron absorption resonance spectroscopy to characterize the spatial distribution of isotopes, so-called energy-resolved neutron imaging or neutron resonance imaging. Here, we report on characterization of an irradiated U-10Zr-1Pd fuel (6mm diameter, <2mm thick, 3R/hr dose rate) at LANSCE as well as our efforts to develop a cask enabling pulsed neutron characterization of entire irradiation capsules (<12mm diameter, <20cm length, 900R/hr dose rate), the so-call SHERMAN (Sample Handling Environment for Radioactive Material Analysis using Neutrons) cask.