STP681

    Evaluation Models of Zircaloy Oxidation in Light of Recent Experiments

    Published: Jan 1979


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    Abstract

    Measurements of Zircaloy-steam oxidation kinetics on as-received and preoxidized cladding are reported, as are measurements of the inside to outside diameter oxygen ratio following rupture of simulated fuel rods. The kinetics data confirm the conservative nature of the Baker-Just equation and suggest that preoxidation effects would provide an additional element of conservatism in regard to the amount of oxidation that would be expected if a fuel rod were subjected to a pressurized water reactor (PWR)-type temperature transient. Although a great deal of scatter was found in the measured inside-outside diameter oxygen ratios, the average value even at the rupture position was less than unity. The strongest trends showed a decreasing inside-outside diameter oxygen ratio with decreasing test time and increasing distance from the rupture site.

    It was found that differences in values of published oxidation kinetics parameters can be reconciled if the procedure used to heat the test specimens is taken into account. A regression analysis of data reported from seven recent investigations showed that the activation energy for the oxidation process was about 7.6 kcal/mole less in experiments using internally heated specimens than in experiments using externally heated specimens. Similar effects are also seen in inside-outside diameter oxygen ratio data; values from externally heated specimens are larger than those from internally heated specimens.

    Keywords:

    zirconium alloys, oxidation, reaction kinetics


    Author Information:

    Ocken, H
    Project manager, Electric Power Research Institute, Palo Alto, Calif.

    Biederman, RR
    Professor, Worcester Polytechnic Institute, Worcester, Mass.

    Hann, CR
    Manager, Fuels Design and Development, and staff scientist, Battelle, Pacific Northwest Laboratories, Richland, Wash.

    Westerman, RE
    Manager, Fuels Design and Development, and staff scientist, Battelle, Pacific Northwest Laboratories, Richland, Wash.


    Paper ID: STP36699S

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP36699S


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