STP1423

    Quantitative Assessment of Irradiation Effect on Creep and Corrosion Properties of Zr-Base Alloys

    Published: Jan 2002


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    Abstract

    In order to qualify the properties of alternative zirconium-base alloys as fuel cladding material in PWRs, the segmented fuel rod irradiation program is being performed. In this program, segmented fuel rods were irradiated in Vandellos-2 to have burn-ups of 25 to 60 GWd/t, and more than 40 rods were examined by profilometry and/or eddy-current oxide measurement in hot cells at Studsvik. In parallel to the irradiation test, out-of-pile creep and corrosion tests were carried out on the archive claddings.

    One segmented fuel rod consists of seven segments axially connected, and it therefore has a unique feature, existence of plenums in the middle of the fuel stack region (in-flux plenum). Since evaluation of the temperature at plenums during operation is easier than at fuel regions, direct comparisons of the creep and corrosion behaviors with and without irradiation were able to be done.

    The irradiation effect on the corrosion properties were determined to accelerate the corrosion rate by a factor of 2 to 3 as increasing exposure time in the reactor irrespective of the cladding variants. On the other hand, evaluations of the creep-down behavior at plenums have shown that niobium-bearing zirconium alloys (MDA: 0.8Sn-0.2Fe-0.1Cr-0.5Nb, ZIRLO™: 1Sn-0.1Fe-1Nb) had an irradiation creep rate of 1/2 to 2/3 compared to that of Zircaloy-4, whereas conventional tin and low tin Zircaloy-4s showed little difference. This restraining effect of niobium is comparable to the influence of niobium on the axial length change of the rods.

    Keywords:

    zirconium alloys, corrosion, creep, radiation effects, fuel cladding, pressurized water reactors


    Author Information:

    Kido, T
    Senior engineer, Nuclear Development Corp., Ibaraki,

    Senda, Y
    Senior engineer, Mitsubishi Heavy Industries, Ltd., Kobe,

    Tukuta, Y
    General manager, senior manager, and chief engineer, Nuclear Power Engineering Corp., Tokyo,

    Hayashi, H
    General manager, senior manager, and chief engineer, Nuclear Power Engineering Corp., Tokyo,

    Murai, K
    General manager, senior manager, and chief engineer, Nuclear Power Engineering Corp., Tokyo,


    Paper ID: STP11416S

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP11416S


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