• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.5
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• pp.526-531
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• 2001

The flow of remote field eddy current energy is studied at nonmagnetic coaxial tubes by using both experiments and finite element calculations based on commercial software package. The results showed that remote field eddy current energy at coaxial tubes flow along over the outer surface of external tube, not through the gap between internal and external tubes. This means that the through wall transmission characteristic of remote field eddy current testing (RFECT) is still valid at tube in tube configurations and the RFECT could be potential nondestructive technique for crack detection, spacer location and gap sizing at the coaxial CANDU fuel channel tubes.

• Journal of Sensor Science and Technology
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• v.7 no.3
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• pp.203-210
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• 1998

An experimental study of an eddy current nondestructive testing system to measure dimensions of cylindrical metallic rods, such as cross-sectional area or diameter, is presented. Impedance characteristics of a solenoid sensor, which are generally based on Maxwell's equations in electromagnetic field, are briefly discussed for inspecting geometrical parameters of the coil sensor and testing materials. A measurement system for detecting the diameter of the metallic rod is implemented. This instrument has capabilities for detecting the sensor output signals and estimating demensions of the testing material, continuously. As a result, it was shown that the eddy current sensor with an encircling coil could estimate the diameter of metallic rod. The implemented measurement system gives accurate information for inspecting the dimension of conducting rod with good sensitivity.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.5
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• pp.561-564
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• 2001

The cladding area of HANARO Research Reactor fuel rods should be checked not to have any defects larger than the size required at QA documents by using eddy torrent testing method doting fabrication process. To apply eddy current testing inspection to the fuel rods, encircling differential probes and standard specimen were designed and fabricated. The impedance of the fabricated probes was measured with impedance analyzer in order to cheek that the probe has a suitable impedance for the inspection frequency, and with this probe and MIZ-40A eddy current equipment, the detectability of this probes was investigated. The developed probes could detect artificial notch with 2mm length 10% depth of cladding thickness in cladding area. In addition, the probe was successfully applied to detect the defects in cladding area doting fabrication of the research reactor rods.

• Journal of the Korean Society for Nondestructive Testing
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• v.11 no.1
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• pp.38-43
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• 1991

The relationship between eddy current response and case hardening depth has been studied on SM40C(KS D-3752) and SCM440(KS D-3711) steels which were surface hardened by high frequency induction hardening. The results obtained in this study were as follows ; 1) Case hardening depth was successfully measured by observing the eddy current impedance changes of each steel. The impedance decreased linearly with increasing case hardening depth. 2) For large impedance gradient between the hardened surface and core metal, the eddy current response was more sensitive to case hardening depth than for low impedance gradient.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.5
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• pp.348-354
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• 1989

The metallurgical transformation ratios of metals have been evaluated by the eddy current method. Eddy current probes have been designed and applied to various standard samples. The equivalent impedance estimated from the eddy current measurement is closely related to the variation of transformation ratios in metals. It has been found that the variation of the impedance is relatively large in the samples where the transformation ratios of the samples are small. Both reactance and resistance increase when the transformation ratio is large. Sensitivities of eddy current test is increased with increasing frequencies and by inserting ferrite core the solenoid eddy probe. Our results have shown the implementation of eddy current measurement to the one-line nondestructive testing of metals.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.748-750
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• 2001

This paper describes numerical analysis of eddy current testing for tube with axi-symmetric defect using boundary element method. In this ECT(Eddy Current Testing) numerical analysis. BEM and FEM are used to compare their characteristics and results of ECT, respectively BEM is easier than FEM to design geometrically complex domain because in case of BEM, domain is divided into segments or elements, but in case of FEM, domain is divided into small finite triangular or quadrilateral elements. For this reason asymmetry defect is used for this BE numerical analysis. As a result, the similar result can be obtained through both numerical analyses, and BEM can be applied to the numerical analysis of ECT.

• Journal of the Korean Society for Nondestructive Testing
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• v.4 no.2
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• pp.7-14
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• 1985

An experiment to investigate the rate of change of phase angle of eddy current output signal caused by outer surface defect of nonferromagnetic tube by variation of standard depth of penetration and variation of percent of tube wall penetration was carried out. The results of the experiment show that the phase angle of defect signal is increased with decreasing the standard depth of penetration or the depth of defect. The results also show that the phase angle is decreased with increasing the skin effect of eddy current, and that the resolution is decreased with decreasing the depth of defect.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.102-104
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• 2001

This paper presents a numerical analysis of the eddy current testing for pipe with axi-symmetric defect according to frequency changes using the finite element method(FEM). The defects used in this analysis are inner and outer axi-symmetric type. In order to obtain the behaviors of the signals by changing the frequency, the defects with different depths are modeled and analyzed using FEM. It is important to choose proper frequency because of the effect of skin depth in eddy current testing. This paper describes signal characteristics of each defects as frequency is changed.

• Proceedings of the KIEE Conference
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• summer
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• pp.965-967
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• 2004

In this paper, characteristic analysis of PC(Pancake Coil) probe with the size variation is presented for eddy current testing. Characteristics of probe are numerically calculated by using the finite element method. From the numerical analysis, the optimum frequency and groups for an experiment are selected. Probes are made and experiment is performed. From the experimental results, the probe shows maximum sensitivity when the size of defect is equal to the size of probe and when the inside diameter is similar to the width of probe and when the height is low. The result can be helpful to the standard of design of PC probe for eddy current testing.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.6
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• pp.519-523
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• 2013

A steam generator (SG) tube is an important component of a nuclear power plant (NPP). It works as a pressure boundary between the primary and secondary systems. The integrity of a SG tube can be assessed by an eddy current test every outage. The eddy current technique(adopting a bobbin probe) is currently the main technique used to assess the integrity of the tubing of a steam generator. An eddy current signal analyst for steam generator tubes continuously analyzes data over a given period of time. However, there are possibilities that the analyst conducting the test may get tired and cause mistakes, such as: missing indications or not being able to separate a true defect signal from one that is more complicated. This error could lead to confusion and an improper interpretation of the signal analysis. In order to avoid these possibilities, many countries of opted for automated analyses. Axial ODSCC (outside diameter stress corrosion cracking) defects on the tubes of OPR1000 steam generators have been found on the tube that are in contract with tube support plates. In this study, automated analysis software called CDS (computer data screening) made by Zetec was used. This paper will discuss the results of introducing an automated analysis system for an axial ODSCC on the tubes of an OPR1000 steam generator.