Electron microscopy characterization of an as-fabricated research reactor fuel plate comprised of U-7Mo particles dispersed in an Al-2Si alloy matrix

Journal Article · Mon Nov 15 00:00:00 EST 2010 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2010.07.010· OSTI ID:22066238

Gan, J; Jue, J F ^[1]; Miller, B D ^[2]; Clark, C R ^[1]

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1. Idaho National Laboratory, P. O. Box 1625, Scoville, ID 83415-6188 (United States)
2. University of Wisconsin, Madison, WI 53706 (United States)

To understand the microstructural development of nuclear fuel plates during irradiation, it is imperative to know the microstructure of a fuel plate after all the fabrication steps have been completed and before it is inserted into the reactor. To this end, a U-7 wt.% Mo alloy research reactor dispersion fuel plate with Al-2 wt.% Si matrix was destructively examined using scanning and transmission electron microscopy to characterize the developed microstructure after fabrication. Of particular interest for this study was how the Si that was added to the fuel matrix partitioned between the various fuel plate phases during fabrication. Si was added to the matrix so that the microstructure that developed during fuel fabrication would exhibit good irradiation behavior. SEM analysis was used to identify the representative microstructure, the compositions of the various phases, and the partitioning behavior of the fuel and matrix constituents. TEM analysis was employed to definitively identify the phases in the U-7Mo alloy and the phases that formed due to diffusional interactions between the fuel particles and matrix during fuel plate fabrication. The TEM results are the first reported for an as-fabricated U-7 wt.% Mo dispersion fuel plate with an Al alloy matrix. SEM results showed that a significant portion of the original {gamma}-(U-Mo) fuel particles had transformed to a lamellar microstructure, comprised of {alpha}-U and either {gamma} or {gamma}' phases, and the fuel/matrix interaction layers were enriched in Si. TEM analysis identified an ordered fcc (U-Mo)(Al-Si){sub 3} type of phase, which formed at the decomposed U-7Mo/matrix interface and extended into the lamellar microstructure. Some regions of the U-7Mo particles retained the single-phase {gamma}-(U-Mo). Small precipitate phases were observed in the fuel meat matrix that contained Fe, Al, and Si. The Si that is added to the matrix of a U-Mo dispersion fuel plate to improve irradiation performance appears to result in the creation of a Si-rich (U-Mo)(Al-Si){sub 3} type of fuel/matrix interaction layer during fabrication that appears to exhibit favorable behavior during irradiation compared to the behavior of the layers that form in U-Mo dispersion fuel plates without Si in the matrix. - Research Highlights: {yields}Si seems to positively affect the microstructure of an as-fabricated fuel plate. {yields}Si modifications to the fuel plate exhibit favorable performance during irradiation. {yields}Si interdiffuses faster than Al.

• OSTI ID: 22066238
• Journal Information: Materials Characterization, Vol. 61, Issue 11; Other Information: Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
ALUMINIUM ALLOYS
FABRICATION
FCC LATTICES
FUEL PARTICLES
FUEL PLATES
INTERFACES
IRRADIATION
MICROSTRUCTURE
MOLYBDENUM
NUCLEAR FUELS
PLATES
PRECIPITATION
RESEARCH REACTORS
SCANNING ELECTRON MICROSCOPY
SILICON ALLOYS
TRANSMISSION ELECTRON MICROSCOPY
URANIUM-ALPHA