STP824

    Effect of Lithium Hydroxide on the Corrosion Behavior of Zircaloy-4

    Published: Jan 1984


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    Abstract

    Post-transition corrosion data were obtained on Zircaloy-4 tubing at temperatures of 589, 616, and 633 K, and in lithium hydroxide (LiOH) concentrations that ranged from 0.001 to 0.1 molal. Following the corrosion exposures, the oxide films of selected specimens were analyzed to determine the quantity of lithium that had been absorbed as a function of corrosion temperature and LiOH concentration. Analyses of the weight gain versus exposure time data yielded several conclusions. First, LiOH concentrations as low as 0.01 molal (70-ppm lithium) can lead to significantly increased corrosion rates, particularly at high temperatures (633 K). Second, at moderate concentrations, 0.01 to 0.06 molal (70 to 420 ppm lithium), there is an intermediate post-transition region where the corrosion rate is only slightly greater than that typical of pure water exposures. Ultimately, however, there is a transition to a more accelerated corrosion rate. Third, there is a synergistic effect between corrosion temperature and LiOH concentration in that the cooperative effect of these two parameters on post-transition corrosion rate is greater than their independent sum. These synergistic effects can be described by an empirical Arrhenius-type equation where both the frequency factor and activation energy are functions of the LiOH concentration. Data obtained from the lithium analyses performed on the various oxides suggest that accelerated corrosion begins when the lithium concentration in the oxide reaches a critical value.

    Keywords:

    zirconium, Zircaloy, lithium hydroxide, corrosion, pressurized water reactor


    Author Information:

    McDonald, SG
    Westinghouse Research and Development Center, Pittsburgh, Pa.

    Sabol, GP
    Westinghouse Research and Development Center, Pittsburgh, Pa.

    Sheppard, KD
    Westinghouse Nuclear Fuel Division, Monroeville, Pa.


    Paper ID: STP34490S

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP34490S


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