STP551

    Assessment of Fracture Studies on Zircaloy-2 Pressure Tubes

    Published: Jan 1974


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    Abstract

    It is shown that, to initiate an unstable fast fracture during operation of Zircaloy-2 pressure tubes used in the Steam Generating Heavy Water Reactor, a defect more than 4 in. long and having a depth 80 percent through the wall has to be present. The effect of hydrides oriented in both the circumferential and radial directions is discussed, and it is concluded that the hydrogen absorbed during a 30 year life should have no significant effect on the critical defect size. Similarly, it is shown that fast neutron damage will not have a deleterious effect on the critical defect size. The growth of partial thickness defects due to pressure cycling is discussed in relation to the types of defects which could be present in pressure tube or could form during operation. Overpressure tests before and during the operational life of the reactor are analysed, and the use of periodic cold pressure tests is considered as a means of demonstrating pressure tube integrity.

    Keywords:

    Zircaloy, embrittlement, irradiation, defects, fractures (materials), defect growth rates, pressure measurement, zirconium alloys


    Author Information:

    Pickles, BW
    Senior scientific officer, principal scientific officer, and scientific officer, United Kingdom Atomic Energy Authority, Risley Engineering and Materials Lab., Risley, Warrington, Lanes,

    Cowan, A
    Senior scientific officer, principal scientific officer, and scientific officer, United Kingdom Atomic Energy Authority, Risley Engineering and Materials Lab., Risley, Warrington, Lanes,

    Johnson, ER
    Senior scientific officer, principal scientific officer, and scientific officer, United Kingdom Atomic Energy Authority, Risley Engineering and Materials Lab., Risley, Warrington, Lanes,


    Paper ID: STP32127S

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP32127S


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