STP681

    Out-of-Pile Testing of Iodine Stress Corrosion Cracking in Zircaloy Tubing in Relation to the Pellet-Cladding Interaction Phenomenon

    Published: Jan 1979


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    Abstract

    To investigate iodine stress corrosion cracking on the behavior of Zircaloy tubing, a standard test procedure with internally pressurized creep specimens (I-SCC standard test) and a split-ring test (I-SCC laboratory test) were developed. The threshold value for brittle cracking in iodine is 10-6 g iodine per square centimetre. The uniform elongation shows a clear minimum in its dependence on strain rate. Basal pole orientations in the range of ±50 to ±70 deg relative to the radial direction are the most I-SCC sensitive textures. The I-SCC process occurs in several stages; incubation, crack nucleation, and propagation. A thermodynamic evaluation indicates that I-SCC only occurs when zirconium iodides condense on the Zircaloy surface. Results show that comparisons of the I-SCC susceptibility of tubing manufactured in different manners should be made at the same point on the strain rate versus uniform elongation curves; for example, at the strain rate with the minimum of uniform elongation.

    Keywords:

    Zircaloy, iodine stress corrosion cracking, iodine threshold concentration, influence of stress, strain rate, texture, test procedures


    Author Information:

    Peehs, M
    Physicists and engineer, Research and Development Reactor Group, Kraftwerk Union AG, Erlangen,

    Stehle, H
    Physicists and engineer, Research and Development Reactor Group, Kraftwerk Union AG, Erlangen,

    Steinberg, E
    Physicists and engineer, Research and Development Reactor Group, Kraftwerk Union AG, Erlangen,


    Paper ID: STP36684S

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP36684S


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