STP1354: Studies of Zirconium Alloy Corrosion and Hydrogen Uptake During Irradiation

    McDougall, GM
    Scientist, AECL, Chalk River Laboratories, Chalk River, Ontario

    Urbanic, VF
    Branch manager, AECL, Chalk River Laboratories, Chalk River, Ontario

    Aarrestad, O
    Division head, Halden,

    Pages: 17    Published: Jan 2000


    Abstract

    The in-reactor corrosion and hydrogen pickup of Zircaloy-2 and Zr-2.5Nb pressure tube materials are being studied in two test loops: a light water loop in the NRU research reactor, and a new heavy water loop in the Halden reactor. The complimentary test programs examine the corrosion behavior of small specimens as a function of fast neutron flux and fluence, temperature, water chemistry, and specimen pre-oxidation.

    In NRU tests conducted over a range of reducing conditions (20 to 60 cm3 H2 · kg-1) at 568 K, Zr-2.5Nb specimens bearing “thin” prefilm oxides (⩽6 ηm) experience a reduction in oxidation rate influx. However, samples with thick prefilm oxides exhibit higher rates, suggesting that, like Zircaloy-2, rates for Zr-2.5Nb may increase as the oxide film continues to thicken.

    Initial results from the Halden program (5 to 7 cm3 D2 · kg-1) show that prefilmed specimens from tubes made of β-quenched material exhibit lower oxidation and deuterium pickup rates than tubes made from non-β-quenched materials. Prefilmed tubes made from β-quenched material also pickup a lower percentage of the D generated by the corrosion reaction. At high flux levels, prefilmed specimens from tube made of both materials exhibit a narrow range of percentage pickup values (4 to 5%), irrespective of temperature. A preliminary examination of activation energies over the range 523 to 598 K suggests significant differences in the temperature dependencies for oxidation and deuterium pickup of prefilmed specimens of tubes made from β and non-β-quenched Zr-2.5Nb. The differences are correlated with fast flux level.

    Keywords:

    corrosion, irradiation, temperature, water chemistry, pre-oxidation, Zircaloy-2, Zr-2.5Nb, zirconium oxide, β quenching, deuterium pickup


    Paper ID: STP14326S

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP14326S


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