Advanced Characterization and Modeling of Nuclear Fuels: Microstructure, Thermo-physical Properties: Nuclear Fuels Microstructure-Experimental
Sponsored by: TMS Structural Materials Division, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Energy Committee, TMS: Nanomechanical Materials Behavior Committee, TMS: Nuclear Materials Committee
Program Organizers: David Frazer, Idaho National Laboratory; Fabiola Cappia, Idaho National Laboratory; Tsvetoslav Pavlov, Idaho National Laboratory; Peter Hosemann

Tuesday 8:00 AM
March 1, 2022
Room: 202B
Location: Anaheim Convention Center

Session Chair: Fabiola Cappia, Idaho National Laboratory

8:00 AM  Invited
Pulsed Neutron Characterization of Irradiated Fuels at LANSCE: Sven Vogel1; Thilo Balke1; Charles A. Bouman2; Luca Capriotti3; Jason M. Harp4; Alexander M. Long1; Danielle C. Schaper1; Anton S. Tremsin5; Brendt E. 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; 5University of California 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.

8:30 AM  
On the Phases Observed in Irradiated U-19Pu-14Zr Fuels: Assel Aitkaliyeva1; Thaddeus Rahn1; Karen Wright2; Luca Capriotti2; 1University of Florida; 2Idaho National Laboratory
    In this contribution, systematic radial microstructural examination of irradiated U-19Pu-14Zr fuels was performed using electron probe microanalyzer (EPMA), focused ion beam (FIB), and transmission electron microscope (TEM). The crystal structure of observed phases was determined using selective area electron diffraction (SAED) in TEM and compositions using EPMA. The conducted microstructural characterization is significant because the structure of metal fuels 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. Therefore, the conducted analysis provides a significant insight into metal fuel performance.

8:50 AM  
Perspectives on Synchrotron Micro-computed Tomography and Serial Sectioning Applied to Metallic Nuclear Fuels: Maria Okuniewski1; Alejandro Figueroa Bengoa1; Jonova Thomas2; 1Purdue University; 2Argonne National Laboratory
    Metallic nuclear fuels are utilized in a wide variety of applications from advanced reactor fuels to research and test reactor fuels. In order to predict the behavior of any fuel subjected to irradiation, a comprehensive three-dimensional (3-D) understanding of the microstructure is required. Both serial sectioning combined with energy dispersive spectroscopy within a scanning electron microscope and synchrotron micro-computed tomography techniques enable this 3-D perspective. However, each technique possesses its own attributes and challenges. This study presents a synopsis of these techniques, along with the benefits, challenges, and mitigations, applied to metallic fuel systems.

9:10 AM  
Thermophysical Properties of Liquid Chlorides from 600-1600 K: Stephen Parker1; 1Los Alamos National Laboratory
    Melt point, enthalpy of fusion, heat capacity, and volumetric expansion of single- and multi-component liquid chlorides {NaCl, KCl, LiCl, MgCl2, CaCl2, UCl3} were measured experimentally. These properties and materials are relevant in applications such as heat transfer, liquid nuclear fuel, and pyrochemical processing. A novel method for density measurement by neutron radiography was shown to produce high-quality data, consistent with reference literature where available. Measurements of the melt point, enthalpy of fusion, and heat capacity of these ionic liquids were achieved by differential scanning calorimetry. All results are presented within the context of a comprehensive review of the available published data. Models for the prediction of the density and heat capacity of mixtures of liquid chlorides are proposed and demonstrated within a case study of the {NaCl + x mol% UCl3} system.