The purpose of this study is to establish a computational procedure to support the optimization of an EMAT configuration. In this study, computer simulations were performed to obtain the propagation behavior of ultrasonic waves generated by an EMAT and the signals received with an EMAT. The simulation results were compared with the corresponding experimental results to validate the simulation method. The simulation results reasonably matched the corresponding experimental results....
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FEM simulation with consideration of electromagnetic interaction for transmitting and receiving ultrasonic waves with an EMAT

The authors have proposed a novel probe combining angle beam EMAT (Electro magnetic Acoustic Transducer) and EC (Eddy Current) Probe as a multi-probe with simple structure. In this paper, the structure of the above dual pro be is improved in order to increase sensitivity of the probe as EC probe....
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Proposal of EMAT-EC Dual Probe for Monitoring of Crack Propagation

This paper proposes backpropagation neural network models which are based on artificial intelligence technology to detect the defect signals and to discern the measurements of defects according to the eddy current testing (ECT) results even under the probe lift-off and probe wobble noise effects. In this paper, a stainless plate with three different depth slits is tested by ECT to collect defect signals. And during the scanning process, the noise which is mentioned above is added. All the collected data are...
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Detection and sizing of defects in eddy current testing using artificial neural network

Eddy current testing (ECT) has been widely used for the non-destructive testing of metal structures. ECT has high capability of detecting surface breaking cracks and length sizing in nuclear power plants. However, it is known there is the error in the evaluation of the depth of the crack. Martensitic phase occurs due to the stress of crack in the vicinity of the crack and oxide layer of crack surface can affect the evaluation of crack depth. In this study, we assess the influence that impact these fact...
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Influence of eddy current testing of martensitic phase and oxide fillings in fatigue cracks

The PIRT process was developed as a part of the systematic and documented means of demonstrating the validation of best estimate simulation codes in USNRC licensing of nuclear power plants. In this paper the PIRT process was applied for finding influential factors giving an impact on the accuracy of ultrasonic testing and eddy current testing and related problems required to improve the accuracy and also reports the results that the problems were ranked from the viewpoint of importance, knowledge and c...
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Accuracy of Non-destructive Examination Techniques to Detect Fatigue Crack

Electromagnetic acoustic transducer (EMAT) is suited to monitoring because of its non-contacting nature. However, a standard EMAT tends to give overestimating results because the estimated thickness is associated with the average of varying thickness over an area under the coil of EMAT. To solve this problem, Point-Focusing EMAT (PF EMAT), which concentrates ultrasonic waves at a certain point, was applied to thickness gauging. This study evaluates the focusing property of PF EMAT and its applicability to l...
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Evaluation of Point Focusing EMAT using ultrasonic wave visualization system and finite element analysis

The electromagnetic acoustic resonance (EMAR) method with an electromagnetic acoustic transducer (EMAT) is proposed for pipe wall thinning measurement in the previous study. In this study, the Cepstrum method is proposed to process the data obtained by an EMAR method, and it is compared with the previous autocorrelation function (ACF), superposition of nth compression (SNC), multiplication of nth compression (MNC) methods. The Cepstrum method can evaluate the thickness range of the specimen under EMAT. Also...
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Piping System, Risk Management based on Wall Thinning Monitoring and Prediction Data Processing Methods of Pipe Wall Thinning Measurement by Electromagnetic Acoustic Resonance (EMAR)

Electromagnetic acoustic transducer (EMAT) generates ultrasonic wave without direct contact with the specimen. This feature allows EMAT to be used under higher temperature environment compared with piezoelectric transducer, which means EMAT has a potential to be applied to monitoring of the piping system of operating power plants. However, the conventional EMAT may read thicker than the actual thickness of the pipe wall in the case of degraded pipes with rough surface. This is because the reflected signal i...
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Development of point focusing electromagnetic acoustic transducer for accurate pipe wall thinning measurement

In the decommissioning measures of Fukushima Daiichi Nuclear Power plant (1F), it is important to ensure the thermal stability of the reactor and the whole system by the cooling system in order to prevent criticality of fuel and fuel debris. However, wall thinning is concerned due to the corrosion in the piping of the cooling system. In order to maintain the safety of the system, it is necessary to manage the piping thinning. In this study, the EMAT thickness monitoring system, which can measure thickne...
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Application of monitoring system using electromagnetic acoustic transducers for wall thickness measurement to Fukushima Daiichi nuclear power plant Unit 4 spent fuel pool cooling piping

The electromagnetic acoustic resonance (EMAR) method provides accurate and stable evaluation in high temperature environment, and it is an effective tool for online monitoring. In this study, the EMAR method and the superposition of the nth compression (SNC) for data processing are applied to online monitoring of pipe wall thinning, and the accuracy and reliability of the measurements are demonstrated through field tests using a large-scale corrosion test loop at high temperature. To measure the thic...
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Online Monitoring of Pipe Wall Thinning with Electromagnetic Acoustic Resonance Method