SYMPOSIA PAPER Published: 01 January 1999
STP13891S

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

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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.

Author Information

Maeda, N
University of Tokyo, Tokyo, Japan
Yamaguchi, A
AGE Project, Tsurumi Research and Development Center, Japan Power Engineering & Inspection Corporation, Yokohama, Kanagawa, Japan
Sugibayashi, T
AGE Project, Tsurumi Research and Development Center, Japan Power Engineering & Inspection Corporation, Yokohama, Kanagawa, Japan
Kohno, K
AGE Project, Tsurumi Research and Development Center, Japan Power Engineering & Inspection Corporation, Yokohama, Kanagawa, Japan
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Details
Developed by Committee: E10
Pages: 601–615
DOI: 10.1520/STP13891S
ISBN-EB: 978-0-8031-5395-0
ISBN-13: 978-0-8031-2614-5