Effects of heat treatment on U–Mo fuel foils with a zirconium diffusion barrier

Journal Article · Fri May 01 00:00:00 EDT 2015 · Journal of Nuclear Materials

DOI:https://doi.org/10.1016/j.jnucmat.2015.02.017· OSTI ID:1177668

Jue, Jan-Fong ^[1]; Trowbridge, Tammy L. ^[1]; Breckenridge, Cynthia R. ^[1]; Moore, Glenn A. ^[1]; Meyer, Mitchell K. ^[1]; Keiser, Dennis D. ^[1]

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1. Idaho National Lab. (INL), Idaho Falls, ID (United States)

A monolith fuel design based on U–Mo alloy has been selected as the fuel type for conversion of the United States’ high performance research reactors (HPRRs) from highly enriched uranium (HEU) to low-enriched uranium (LEU). In this fuel design, a thin layer of zirconium is used to eliminate the direct interaction between the U–Mo fuel meat and the aluminum-alloy cladding during irradiation. The co-rolling process used to bond the Zr barrier layer to the U–Mo foil during fabrication alters the microstructure of both the U–10Mo fuel meat and the U–Mo/Zr interface. This work studied the effects of post-rolling annealing treatment on the microstructure of the co-rolled U–Mo fuel meat and the U–Mo/Zr interaction layer. Microscopic characterization shows that the grain size of U–Mo fuel meat increases with the annealing temperature, as expected. The grain sizes were ~9, ~13, and ~20 μm for annealing temperature of 650, 750, and 850 °C, respectively. No abnormal grain growth was observed. The U–Mo/Zr interaction-layer thickness increased with the annealing temperature with an Arrhenius constant for growth of 184 kJ/mole, consistent with a previous diffusion-couple study. The interaction layer thickness was 3.2 ± 0.5 μm, 11.1 ± 2.1 μm, 27.1 ± 0.9 μm for annealing temperature of 650, 750, to 850 °C, respectively. The homogeneity of Mo improves with post rolling annealing temperature and with U–Mo coupon homogenization. The phases in the Zr/U–Mo interaction layer produced by co-rolling, however, differ from those reported in the previous diffusion couple studies.

• Research Organization: Idaho National Lab. (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• DOE Contract Number: AC07-05ID14517
• OSTI ID: 1177668
• Report Number(s): INL/JOU-14-33179; TRN: US1500187
• Journal Information: Journal of Nuclear Materials, Vol. 460, Issue C; ISSN 0022-3115
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
SLIGHTLY ENRICHED URANIUM
ROLLING
ANNEALING
GRAIN SIZE
ZIRCONIUM
ALUMINIUM ALLOYS
NUCLEAR FUELS
RESEARCH REACTORS
THICKNESS
FOILS
THIN FILMS
DESIGN
GRAIN GROWTH
CONVERSION
INTERFACES
PERFORMANCE
URANIUM BASE ALLOYS
MOLYBDENUM ALLOYS
BINARY ALLOY SYSTEMS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
DIFFUSION BARRIER
MICROSTRUCTURE
MONOLITHIC
U-MO