Guaranteeing the security of the steam generator tubes of the pressurized water reactor (PWR) in the nuclear power plants is a key factor in their safe exploitation. Accordingly the eddy current testing is used for the reason of high accuracy and high spend because the test must be done in a limited period. We developed a multi probe that can detect cracks with distinction between axial and circumferential cracks. The probe is composed with two kinds of excitation coils of axial and circumferential windings and 32 pickup coils. The excitation coil of this probe is able to generate uniform eddy current distribution on a wide area compared with the detection area of the pickup cods. Therefore the probe can ignore the influence of the shape of excitation current source on detecting cracks, and numerical analysis for this probe is handled simply by devising boundary condition. From measurement results, the probe is confirmed to be able to measure direction of cracks with high sensitivity and high speed.
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