STP1046V2: Evaluation of the Fracture Toughness of Irradiated Stainless Steel Using Short Rod Specimens

    Clarke, W. L.
    Principal engineer, General Electric Co., Pleasanton, CA

    White, M. A.
    General Electric Co., San Jose, CA

    Ranganath, S.
    Manager, General Electric Co., San Jose, CA

    Pages: 17    Published: Jan 1990


    Abstract

    Assessment of the fracture margin of irradiated Light Water Reactor (LWR) austenitic stainless steel components requires knowledge of the fracture toughness as a function of neutron fluence. Since toughness strongly depends on irradiation conditions, particularly flux spectrum and temperature, it is important that fracture toughness test specimens be obtained from samples that have experienced actual LWR irradiation. This paper presents the results of an investigation of the fracture toughness of irradiated Type 304 stainless steel and evaluates the applicability of the relatively new short-rod fracture toughness test to remote testing. The test samples were obtained from instrumentation removed from an operating LWR. The accumulated fluence was 1.5×1021n/cm2 (E>1MeV) at an irradiation temperature of 288°C. The plane-strain fracture toughness was obtained using chevron-notched short-rod specimens, providing valid results from small samples and eliminating the need for fatigue precracking. A fracture toughness value of 55 MPa · m1/2 (50 ksi · in.1/2) was obtained at 288°C. Miniature tensile specimens were also fabricated and tested to determine the yield and ultimate strengths at room temperature and 288°C. The tensile test results demonstrated that a significant degree of ductility still exists at this fluence level. This ductility indicates a potential for increased toughness with stable crack extension, which the short-rod test is unable to reveal. However, the simplicity of the short-rod test lends itself to remote testing in a hot cell facility.

    Keywords:

    fracture toughness, stainless steel, irradiated material, light water reactors, short rod method, FRACJACK


    Paper ID: STP49468S

    Committee/Subcommittee: E10.07

    DOI: 10.1520/STP49468S


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