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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Synchrotron Microdiffraction Study of Heavy-Ion-Irradiated Uranium-Molybdenum Dispersion Fuel

There has been an ongoing effort by the Department of Energy Office of Material Management and Minimization to convert research and test reactors from high-enriched to low-enriched uranium fuels. Uranium-molybdenum alloy fuel dispersed in an aluminum matrix (UMo-Al dispersion fuel) has emerged as the leading candidate fuel for converting the remaining high-power research reactors in Europe. One of the primary barriers to using this fuel type is the deleterious reaction of UMo with Al. Depending on the operating temperature of the reactor, this interaction layer can be amorphous under irradiation and allows for the accumulation of fission gas products in large bubbles, leading to unacceptable swelling of the fuel. Therefore, detailed characterization of the phases that form within the fuel and in the interaction layer is critical to understanding, and controlling, UMo-Al dispersion fuel behavior under irradiation. Furthermore, the phase stability of the UMo fuel is of great importance, as the alpha-UMo phase has undesirable swelling compared to the metastable gamma-UMo phase. Heavy ion irradiation was used to reproduce the interaction layer that develops in-reactor. Samples of both the fuel and interaction layer formed under ion irradiation were examined using the high-energy x-ray microdiffraction technique at the Advanced Photon Source (APS) at Argonne National Laboratory to examine the microstructure of the interaction layer. The high-resolution phase information obtained in this experiment provides a valuable basis for understanding the evolution of UMo-Al dispersion fuel under irradiation and as input for computational studies to improve predictive capabilities. Phase information for in-pile fuels can currently be determined from TEM samples (limited sample volume, limiting statistics), or by extrapolation from SEMEDS analysis. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Small-angle X-ray microdiffraction from fibrils embedded in tissue thin sections

Small-angle X-ray scattering (SAXS) from fibrils embedded in a fixed, thin section of tissue includes contributions from the fibrils, the polymeric matrix surrounding the fibrils, other constituents of the tissue, and cross-terms due to the spatial correlation between fibrils and neighboring molecules. This complex mixture severely limits the amount of information that can be extracted from scattering studies. However, availability of micro- and nano-beams has made the measurement of scattering from very small volumes possible, which, in some cases, may be dominated by a single fibrillar constituent. In such cases, information about the predominant species may be accessible. Nevertheless, even in these cases, the correlations between the positions of fibrils and other constituents have a significant impact on the observed scattering. Here, strategies are proposed to extract partial information about fibril structure and tissue organization on the basis of SAXS from samples of this type. It is shown that the spatial correlation function of the fibril in the direction perpendicular to the fibril axis can be computed and contains information about the predominant fibril structure and the organization of the surrounding tissue matrix. This has significant advantages over approaches based on techniques developed for X-ray solution scattering. Examples of correlation calculations in different types of samples are given to demonstrate the information that can be obtained from these measurements.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Investigation of plastic yielding in near-micrometer grain size aluminum using synchrotron microdiffraction

The onset of plastic yielding has been studied in samples of aluminum with nearmicrometer average grain size using in situ tensile loading combined with synchrotron radiation. A white-beam Laue 3D micro-diffraction technique was used allowing the collection of diffraction signal from a volume with a resolution of 1 μm in all three dimensions. The orientation data obtained from the micro-diffraction are used to estimate the local variation in geometrically necessary dislocation density, and correction factors are suggested for voxels where neighbors are missing in either one or two dimensions. The results demonstrate a considerable heterogeneity in deformation in the early stages of plastic deformation.

Zhang, C L↗
DOE OSTI2023

Demonstrating Cross-Facility Data Processing at Scale with Laue Microdiffraction

In February and April 2023 live, at-scale data processing demonstrations were conducted between the Advanced Photon Source (APS), a synchrotron light source, and the Argonne Leadership Computing Facility (ALCF). These tests were run as part of a novel beamline technique: coded aperture laue micro-diffraction. This technique requires a significant amount of compute to decode appeture patterns embedded in the detector stream. An autonomous system was able to send data to ALCF during an experiment, utilize 50 nodes of the Polaris supercomputer to process 6-12 hour scans, and return the data back to the APS within 12-15 minutes behind the detector. With scan points arriving every 72 seconds, the system kept up with the beamline, potentially enabling in-experiment analysis. The data processing system utilizes Globus infrastructure and an on-demand queue to dynamically acquire nodes on Polaris. The underlying reconstruction algorithms were parallelized via MPI and accelerated with custom CUDA kernels.

Prince, Michael↗