Interdiffusion and reactions between U-Mo and Zr at 650 degrees C as a function of time

    Authors

    Y. Park; D. P. Keiser;Y. H. Sohn

    Comments

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    Abbreviated Journal Title

    J. Nucl. Mater.

    Keywords

    URANIUM-MOLYBDENUM ALLOY; MONOLITHIC FUEL PLATE; DIFFUSION BARRIER; DISPERSION FUEL; THERMODYNAMIC PROPERTIES; PHASE-DIAGRAMS; HIGH-DENSITY; TH-MO; Materials Science, Multidisciplinary; Nuclear Science & Technology; Mining & Mineral Processing

    Abstract

    Development of monolithic U-Mo alloy fuel (typically U-10 wt.%Mo) for the Reduced Enrichment for Research and Test Reactors (RERTR) program entails a use of Zr diffusion barrier to eliminate the interdiffusion-reactions between the fuel alloy and Al-alloy cladding. The application of Zr barrier to the U-Mo fuel system requires a co-rolling process that utilizes a soaking temperature of 650 degrees C, which represents the highest temperature the fuel system is exposed to during both fuel manufacturing and reactor application. Therefore, in this study, development of phase constituents, microstructure and diffusion kinetics of U-10 wt.%Mo and Zr was examined using solid-to-solid diffusion couples annealed at 650 degrees C for 240, 480 and 720 h. Phase constituents and microstructural development were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Concentration profiles were mapped as diffusion paths on the isothermal ternary phase diagram. Within the diffusion zone, single-phase layers of beta-Zr and beta-U were observed along with a discontinuous layer of Mo2Zr between the beta-Zr and beta-U layers. In the vicinity of Mo2Zr phase, islands of alpha-Zr phases were also found. In addition, acicular alpha-Zr and U6Zr3Mo phases were observed within the gamma-U(Mo) terminal alloy. Growth rate of the interdiffusion-reaction zone was determined to be 7.75 (+/- 5.84) x 10(-16) m(2)/s at 650 degrees C, however with an assumption of a certain incubation period. (C) 2014 Elsevier B.V. All rights reserved.

    Journal Title

    Journal of Nuclear Materials

    Volume

    456

    Publication Date

    1-1-2015

    Document Type

    Article

    Language

    English

    First Page

    351

    Last Page

    358

    WOS Identifier

    WOS:000347274500046

    ISSN

    0022-3115

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