STP1325

    Detection of Irradiation Embrittlement of Low-Alloy Steel for Nuclear Reactor Pressure Vessels Using a Probe Type Eddy Current Sensor

    Published: Jan 1999


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    Abstract

    This report describes the results of studies made for the purpose of detecting the irradiation embrittlement of low-alloy steel used for nuclear reactor pressure vessels. For the method of using eddy current to detect material degradation, the device and the sensor employed are light in weight and compact in size, allowing testing without contact. In this study the frequency of input current to the excitation coil is changed in steps of 1 kHz. The output signal is processed by phase detection method, and displayed on a complex plane. It depicts a trajectory as the frequency is changed. To extract features of the trajectories, averaged radius and averaged phase angle are defined and plotted as function of neutron fluence or ductile-brittle transition temperature. Experiment shows that the averaged phase angle and transition temperature decrease as the neutron fluence is increased. Behavior of the averaged phase angle is interpreted employing magnetic permeability and electric conductivity of the test specimens. It becomes clear that electric conductivity decreases as the neutron fluence is increased.

    Keywords:

    nondestructive evaluation, neutron irradiation, nuclear pressure vessel, degradation, eddy current


    Author Information:

    Maeda, N
    Former DirectorPresent Visiting Professor, R&D Center, Japan Power Engineering & Inspection CorporationUniversity of Tokyo, TokyoTokyo,

    Yamaguchi, A
    Assistant Director, AGE Project, Tsurumi Research and Development Center, Japan Power Engineering & Inspection Corporation, Yokohama, Kanagawa

    Sugibayashi, T
    Assistant Manager, AGE Project, Tsurumi Research and Development Center, Japan Power Engineering & Inspection Corporation, Yokohama, Kanagawa

    Kohno, K
    Assistant Manager, AGE Project, Tsurumi Research and Development Center, Japan Power Engineering & Inspection Corporation, Yokohama, Kanagawa


    Paper ID: STP13891S

    Committee/Subcommittee: E10.07

    DOI: 10.1520/STP13891S


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