Materials in Nuclear Energy Systems (MiNES) 2021: Fuels and Actinide Materials- Metallic Fuels II
Program Organizers: Todd Allen, University of Michigan; Clarissa Yablinsky, Los Alamos National Laboratory; Anne Campbell, Oak Ridge National Laboratory

Wednesday 10:30 AM
November 10, 2021
Room: Grand Ballroom
Location: Omni William Penn Hotel

Session Chair: Erofili Kardoulaki, Los Alamos National Laboratory


10:30 AM  Invited
The Challenges of α-uranium: Fundamental Understanding of a Past and Future Nuclear Fuel Material: Andrea Jokisaari1; Benjamin Beeler2; Michael Tonks3; Fidelma di Lemma1; Khadija Mahbuba2; Aashique Rezwan4; Yuhao Wang5; Tiankai Yao1; 1Idaho National Laboratory; 2North Carolina State University; 3University of Florida; 4University of Wisconsin; 5University of Michigan
    Metallic uranium is one of the first materials ever used as nuclear fuel; yet it displays complex irradiation behaviors that are still not well understood today. These complex behaviors make the material challenging to use in modern metallic nuclear fuels, but provides a rich arena to investigate the fundamental, multi-scale mechanisms of irradiation damage. Most open research into the irradiation behavior of uranium ceased during the 1960s, while experimental and computational techniques have continued to progress. We apply modern investigation techniques, such as molecular dynamics, phase field modeling, crystal plasticity, and in-situ TEM experiments, to study the fundamental behaviors of α-uranium with and without irradiation. We investigate the properties of point defects, their collection into extended defects and interaction with microstructural sinks as well as mesoscale phenomena such as grain growth, irradiation growth, and plasticity. Recently gained insights also highlight potential avenues of future work.

11:10 AM  
Impact of Zirconium Concentration Variation on Metal Fuel Constituent Redistribution: Thaddeus Rahn1; Fidelma Di Lemma2; Tammy Trowbridge2; Luca Capriotti2; Assel Aitkaliyeva1; 1University of Florida; 2Idaho National Laboratory
    Constituent redistribution in metal U-Pu-Zr fuels is a complex process driven by gradients in temperature and chemical potential, which produce radially-distributed phase fields, each with different material properties and behaviors. The location and composition of the phase fields evolve dynamically as swelling, fission gas release, and sodium infiltration alter the thermal conductivity of the fuel. Gaps in understanding of these processes limit our ability to model higher-level behaviors such as fuel-cladding chemical interaction and perform design and safety analyses with confidence. To study constituent redistribution in metal fuels, we selected three U-Pu-Zr fuel pin with varying Zr compositions (6-14 wt%) from X441 experiment for postirradiation examination (PIE), which included both non-destructive and destructive analyses. In this contribution, we discuss the results from optical metallography and scanning electron microscopy and compare new PIE results to historical data.

11:30 AM  
Electron Probe Microanalysis of Fuel from EBR-II Experiment X441A: Effects of Varying U:Pu:Zr Elemental Ratios: Karen Wright1; Thaddeus Rahn2; Luca Capriotti1; Assel Aitkaliyeva2; 1Idaho National Laboratory; 2University of Florida
    Three samples from the EBR-II X441A experiment were selected for electron probe microanalysis (EPMA) to determine how varying U:Pu:Zr ratios affects constituent redistribution and fuel cladding chemical interaction (FCCI), and to provide a comprehensive, modern quantitative analysis for model development. The Na-bonded, D9-cladded, irradiated metallic fuel samples experienced burnup ranging from ~9-11.5% fissions per initial metal heavy atom and were all cut from the x/L = 0.65 section of the fuel rod. Samples A814 (U-19Pu-14Zr) and A812 (U-19Pu-10Zr) show similar radial elemental redistribution profiles; however, in the rod's center, A814's U concentration is about 20% lower and its Zr concentration approximately 20% higher than observed in A812. There is no significant Pu profile difference. Sample A814 shows non-uniform FCCI around the fuel periphery, with fuel and cladding constituents migrating further and at larger concentrations on one side compared to the opposite side. Results from all three samples will be presented.