STP633

    Deformation and Rupture Behavior of Zircaloy Cladding under Simulated Loss-of-Coolant Accident Conditions

    Published: Jan 1977


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    Abstract

    Information on the diametral expansion and rupture characteristics of Zircaloy-4 cladding has been obtained in a vacuum environment over a wide range of internal pressures at several heating rates. The effect of axial constraint of the cladding, exerted by a mandrel that simulated the pellets in a fuel rod, on the relationship between the maximum circumferential strain and the burst temperature also was investigated. The circumferential strain for unconstrained cladding was significantly larger than for axially constrained tubes, particularly for burst temperatures below ∼850°C, in which cladding remains essentially in the α-phase. Three superplastic strain peaks have been identified, namely, at rupture temperatures of ∼850, ∼1050, and ∼1220°C. In the case of complete axial restraint, the failure strains were not dependent on heating rate for burst temperatures above ∼920°C; however the low-temperature (∼850°C) strain peak increases and moves to lower temperatures as the heating rate decreases. The deformation data in this investigation also have been used to evaluate instability criteria proposed for thin-wall tubes under a biaxial stress state. The onset of plastic instability or local ballooning in the cladding has been defined in terms of the effective stress and strain during transient-heating conditions.

    Keywords:

    zirconium, zirconium alloys, deformation, rupture, stresses, strains, instability, superplasticity


    Author Information:

    Chung, HM
    Assistant metallurgist, assistant metallurgist, and senior metallurgist, Argonne National Laboratory, Argonne, Ill

    Garde, AM
    Assistant metallurgist, assistant metallurgist, and senior metallurgist, Argonne National Laboratory, Argonne, Ill

    Kassner, TF
    Assistant metallurgist, assistant metallurgist, and senior metallurgist, Argonne National Laboratory, Argonne, Ill


    Paper ID: STP35566S

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP35566S


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