• Title/Summary/Keyword: Eddy Current Testing(ECT)

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Performance improvement of Classification of Steam Generator Tube Defects in Nuclear Power Plant Using Neural Network (신경회로망을 이용한 원전SG 세관 결함패턴 분류성능 향상기법)

  • Jo, Nam-Hoon;Han, Ki-Won;Song, Sung-Jin;Lee, Hyang-Beom
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.7
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    • pp.1224-1230
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    • 2007
  • In this paper, we study the classification of defects at steam generator tube in nuclear power plant using eddy current testing (ECT). We consider 4 defect patterns of SG tube: I-In type, I-Out type, V-In type, and V-Out type. Through numerical analysis program based on finite element modeling, 400 ECT signals are generated by varying width and depth of each defect type. In order to improve the classification performance, we propose new feature extraction technique. After extracting new features from the generated ECT signals, multi-layer perceptron is used to classify the defect patterns. Through the computer simulation study, it is shown that the proposed method achieves 100% classification success rate while the previous method yields 91% success rate.

Characteristic Analysis of Eddy Current Array Probe Signal in Combo Calibration Standard Tube Using Electromagnetic Numerical Analysis (전자기 수치해석을 이용한 표준보정시험편의 배열형 와전류 탐촉자 신호 특성 해석)

  • Kim, Ji-Ho;Lee, Hyang-Beom
    • Journal of the Korean Society for Nondestructive Testing
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    • v.30 no.4
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    • pp.330-337
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    • 2010
  • In this paper, 3-dimensional electromagnetic numerical analysis is performed about the eddy current(EC) array probe characteristic which is the next generation probe for accurate diagnosis of steam generator(SG) in nuclear power plants(NPPs). ASME(American Society of Mechanical Engineers) Standard and X-probe combo calibration standard tube are selected for acquisition of eddy current testing(ECT) signals and this result of compared with the real test signals for reasonability of result. Based on the analysis result of calibration standard tube, ECT signals that are about the defects of pitting, stress corrosion cracking(SCC), multiple SCC and wear is obtained. Material of specimen was Inconel 600 which is usually used for SG tubes in NPPs. The operation frequency of 300 kHz were used. The signal characteristics could be observed according to the various defects. The results in this paper can be helpful when the ECT signals from EC array probe are evaluated and analyzed.

A Study on the Design of RFECT System for Ferromagnetic Pipelines (강자성체 배관 탐상용 RFECT System의 설계에 관한 연구)

  • Lee, Yu Ki;Kim, Hui Min;Park, Gwan Soo
    • Journal of the Korean Magnetics Society
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    • v.24 no.6
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    • pp.171-178
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    • 2014
  • Remote Field Eddy Current Testing (RFECT), one of the ways which is a nondestructive testing using electromagnetic fields, can make up for Magnetic Flux Leakage (MFL) weaknesses and general Eddy Current Testing (ECT) weaknesses which is an occurrence of a huge friction force or disadvantage of detecting defects on the outer wall. So many of institutes and laboratories have studied on RFECT for the past 50 years. But There is a lack of discussion about a study on eddy current and magnetic field distributions in a pipe wall and designing of RFECT exciter coil. In this paper, eddy current and magnetic field distributions in a pipe wall and influence of altering variables are analyzed. Also, the optimal design algorithm about the RFECT Exciter coil are proposed, and influence on defect signals caused by alteration of its shape is analyzed.

Prediction of Defect Size of Steam Generator Tube in Nuclear Power Plant Using Neural Network (신경회로망을 이용한 원전SG 세관 결함크기 예측)

  • Han, Ki-Won;Jo, Nam-Hoon;Lee, Hyang-Beom
    • Journal of the Korean Society for Nondestructive Testing
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    • v.27 no.5
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    • pp.383-392
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    • 2007
  • In this paper, we study the prediction of depth and width of a defect in steam generator tube in nuclear power plant using neural network. To this end, we first generate eddy current testing (ECT) signals for 4 defect patterns of SG tube: I-In type, I-Out type, V-In type, and V-Out type. In particular, we generate 400 ECT signals for various widths and depths for each defect type by the numerical analysis program based on finite element modeling. From those generated ECT signals, we extract new feature vectors for the prediction of defect size, which include the angle between the two points where the maximum impedance and half the maximum impedance are achieved. Using the extracted feature vector, multi-layer perceptron with one hidden layer is used to predict the size of defects. Through the computer simulation study, it is shown that the proposed method achieves decent prediction performance in terms of maximum error and mean absolute percentage error (MAPE).

A Study of Frequency Mixing Approaches for Eddy Current Testing of Steam Generator Tubes

  • Jung, Hee-Jun;Song, Sung-Jin;Kim, Chang-Hwan;Kim, Dea-Kwang
    • Journal of the Korean Society for Nondestructive Testing
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    • v.29 no.6
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    • pp.579-585
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    • 2009
  • The multifrequency eddy current testing(ECT) have been proposed various frequency mixing algorithms. In this study, we compare these approaches to frequency mixing of ECT signals from steam generator tubes; time-domain optimization, discrete cosine transform-domain optimization. Specifically, in this study, two different frequency mixing algorithms, a time-domain optimization method and a discrete cosine transform(DCT) optimization method, are investigated using the experimental signals captured from the ASME standard tube. The DCT domain optimization method is computationally fast but produces larger amount of residue.

Development of New Low Frequency ECT Sensor to Detect Inner Defects(I) - Characteristic of Loss of Induced Electromotive Force - (내부결함 검출 가능한 저주파 ECT 센서개발(I) - 전자기 유도기전력 손실량의 특성-)

  • Park, Jeong-Ung;Jang, Mun-Seok;Gim, Guk-Ju;Kim, Beom-Ki
    • Journal of Welding and Joining
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    • v.33 no.4
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    • pp.57-62
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    • 2015
  • Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing(ECT) is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. The New ECT sensor which can detect inner defects was developed regardless the condition of surface. This sensor is verified to do experiment which measure the loss of induced electromotive force. The loss of induced electromotive force was measured in 5.4% and this low frequency ECT device can detect internal defects at depth 20 mm.

Development of New Low Frequency ECT Sensor to Detect Inner Defects(II) - Application to Welding Specimens Included Defects - (내부결함 검출 가능한 저주파 ECT 센서개발(II) - 결함을 가진 소형 용접시험편에 적용 -)

  • Park, Jeong-Ung;Jang, Mun-Seok;Gim, Guk-Ju;Kim, Beom-Ki
    • Journal of Welding and Joining
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    • v.33 no.4
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    • pp.63-67
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    • 2015
  • Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing(ECT) is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. The New ECT sensor which can detect inner defects was developed regardless the condition of surface. This sensor is verified to do experiment which measure the loss of induced electromotive force. The loss of induced electromotive force was measured in 5.4% and this low frequency ECT device can detect internal defects at depth 20 mm.

와전류탐상과 유한요소해석을 이용한 Carbon/epoxy 튜브의 결함 평가

  • Kim, Chul-Woong;Lee, Jung-Soon;Um, Tae-Gun;Song, Il;Gu, Sang-Mo
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.05a
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    • pp.75-75
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    • 2004
  • Carbon/epoxy는 기존의 금속재료에 비해 피로강도 및 기계적 특성이 매우 우수하다. 따라서 최근 튜브형태의 Carbon/epoxy 활용방안이 부각되고 있다. 그러나 Carbon/epoxy는 탄소재료의 특성상 고압, 충격 및 부식에 매우 취약하다. 또한, 장기간 고압피로 및 크리프에 노출될 경우, 금속재료에서는 관찰할 수 없는 층간분리(delamination)가 발생된다. 이러한 층간분리는 섬유방향과 평행하게 진전될 때 급격한 파손을 야기하므로 층간분리에 대한 메커니즘을 이해하고 그 방지책을 강구하는 것은 매우 중요하다.(중략)

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Parametric Study of Rectangular Coil for Eddy Current Testing of Lamination

  • Wang, Pengfei;Zeng, Zhiwei
    • Journal of the Korean Society for Nondestructive Testing
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    • v.36 no.2
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    • pp.155-159
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    • 2016
  • Eddy current testing (ECT) is an important nondestructive testing technology for the inspection of flaws in conductive materials. However, this widely used technology is not suitable for inspecting lamination when a conventional pancake coil is used because the eddy current (EC) generated by the pancake coil is parallel to the lamination and will not be perturbed. A new method using a rectangular coil placed vertical to the work piece is proposed for lamination detection. The vertical sections of the rectangular coil induce ECs that are vertical to the lamination and can be perturbed by the lamination. A parametric study of a rectangular coil by finite element analysis was performed in order to examine the capability of generating vertical EC.