STP1423

    Effects of Alpha-Beta Transformation on High Temperature (LOCA) Creep behavior of Zr-Alloys

    Published: Jan 2002


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    Abstract

    The Zircaloy material models used for evaluation of the cladding behavior during a hypothetical LOCA are usually based on creep rupture tests at constant temperature and constant heat-up rates. Tests with a more realistic thermal history, including a first temperature peak, show under certain conditions significant higher creep resistance and longer time-to-rupture. To find the cause of this phenomenon, different examinations were performed. Synchrotron radiation was used to investigate the alpha to beta phase transformation kinetic. This technique allows examination of the bulk material without any preparation. In these tests, diffraction patterns were evaluated during constant heat-up rates (up to 10 K/s) and under stepped temperature changes. Phase transition was found to be delayed at fast heat-up rates. Structural changes and oxidation were examined by metallography. Changes in microstructure were seen at temperatures greater than 850°C. Significant oxidation was found at temperatures above 1000°C.

    Keywords:

    PWR, Zr alloy, Zircaloy, LOCA, creep, creep rupture behavior, phase transitions


    Author Information:

    Sell, HJ
    Framatome ANP GmbH, Erlangen,

    Ortlieb, E
    Framatome ANP GmbH, Erlangen,


    Paper ID: STP11410S

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP11410S


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