Materials in Nuclear Energy Systems (MiNES) 2021: Fuels and Actinide Materials- Metallic Fuels I
Program Organizers: Todd Allen, University of Michigan; Clarissa Yablinsky, Los Alamos National Laboratory; Anne Campbell, Oak Ridge National Laboratory
Wednesday 8:00 AM
November 10, 2021
Room: Grand Ballroom
Location: Omni William Penn Hotel
Session Chair: Benjamin Beeler, North Carolina State University
8:00 AM Invited
3D-reconstruction via Genetic Algorithms: Application to Metallic Fuel: Riccardo Genoni1; Davide Pizzocri1; Federico Antonello1; Tommaso Barani1; Lelio Luzzi1; Fabiola Cappia2; 1Politecnico di Milano; 2Idaho National Laboratory
Advanced microscopy for nuclear fuels has increased over the last years supporting the understanding of nuclear material irradiation effects. Focused ion beam/scanning electron microscopy (FIB-SEM) serial reconstruction or X-ray tomography are used to determine three-dimensional (3D) microstructure features. These techniques provide fundamental 3D information, but they present some limitations in applications to nuclear fuels, as both techniques can investigate only small amount of material. A cost-effective approach is the reconstruction of the 3D multi-phase material from two-dimensional images. Such approach, despite intrinsically ill-posed, is of great value and applied in many fields. Here we study the fission gas bubbles of irradiated metallic fuels with a combination of image analysis and an optimization technique based on genetic algorithm (GA). The aim is to provide quantitative information regarding the porosity in 3D in U-Pu-Zr fuel with minor actinides and to obtain a correlation between the 3D properties and the measurable 2D quantities.
8:40 AM
Identifying Crystalline Phases in Irradiated U-Pu-Zr Fuels Using TEM: Assel Aitkaliyeva1; Thaddeus Rahn1; Luca Capriotti2; 1University of Florida; 2Idaho National Laboratory
The structure of metal fuel used in fast reactors is a complex function of composition, porosity, sodium content, texture, defect concentration, and crystalline phases. Of these, crystalline phases are arguably the most important in determining thermal, mechanical, and chemical behaviors of the fuel, and thus dominate the response of the fuel to a given set of operational conditions. This contribution will report on the crystalline phases observed in irradiated U-Pu-Zr fuels, which have been identified using selective area electron diffraction (SAED). In the past, phase identification in both fresh and irradiated fuels was done sporadically using less reliable methods. In this contribution, we report on the systematic radial microstructural examination of irradiated U-Pu-Zr fuels performed using SEM, focused ion beam (FIB) instrument, and transmission electron microscope (TEM). The crystalline phases in irradiated fuels were conclusively identified and the results compared to unirradiated fuels.
9:00 AM
Does the Fuel Fabrication Method Have an Impact on the Fuel Performance Microstructure in Uranium-molybdenum?: Maria Okuniewski1; Gyuchul Park1; Lynne Ecker2; Simerjeet Gill2; Daniel Murray3; 1Purdue University; 2Brookhaven National Laboratory; 3Idaho National Laboratory
Uranium-molybdenum (U-Mo) fuels have applications within both research and test reactor fuels, as well as fast reactor fuels. Each of these reactor types requires differing fabrication methodologies, thus resulting in varied microstructures prior to reactor insertion. Specifically, U-Mo fuels are cast and then rolled to produce a monolithic foil, whereas fast reactor U-Mo fuels are simply cast to produce a fuel rod. Therefore, it is of interest to understand how fabrication influences irradiation performance. This research explored low fluence neutron irradiation effects on rolled and cast U–10 wt.%Mo microstructures as a function of dose and temperature. The evolution of phase fractions, lattice parameters, and strain, was determined with synchrotron X-ray diffraction. Electron microscopy was utilized to complement the phase identification, identify decomposition regions, and characterize defects.
9:20 AM Cancelled
Zirconium Redistribution in a High Burnup U-10Zr Metallic Fuel: Tiankai Yao1; Michael Benson1; Luca Capriotti1; 1Idaho National Laboratory
Zirconium (Zr) redistribution inside an irradiated U-10Zr (weight %) metallic fuel can significantly change fuel performance and reactor safety margin. Inside a reactor, with increase of burnup, concentric zones form inside U-10Zr fuel with presumably different U matrix phases. Following the temperature gradient from center to rim, the matrix phase changes from gamma to beta and to alpha phase. Gamma phase has the highest Zr content whereas beta phase has the lowest Zr content. The mechanism of Zr redistribution is often attributed to the low solubility of Zr inside beta U phase. This work investigates a U-10Zr fuel irradiated to a local burnup of ~12.4 % atomic percent at the Fast Flux Test Facility. Transmission electron microscopy reveals a nanoscale Zr rich phase redistribution in different zones for the first time to support a better understanding of Zr redistribution in irradiated metallic fuel.
9:40 AM Break