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

This paper proposes a novel concept of the measurement-integrated virtual system aiming at next-gene ration uclear power plants with intelligent system. The present system is composed of wireless sensor s, a measurement-integrated simulator and a lifecycle simulator. Some element research activities to realize the measurement-integrated virtual system are introduced, and future efforts are overviewed....
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Ceasurement-integrated virtual system aiming at next-generation nuclear power plants with intelligent system

For creating a corrective measure plan for industrial plant components, it is very important to have a well-grounded basis. Therefore, this paper proposes a method for determining the following three elements of such a plan: an equipment to be repaired, a corrective measure method to be adopted, and a timing of its implementation using a rational approach. And the importance of corrective measure in plant maintenance is also discussed. ...
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Codes and Standards in Repair and Replacement Process .Importance of Corrective Action in Maintenance Activities

In this study, superconducting electromagnetic acoustic transducer (EMAT) is developed to transmit strong ultrasound, which is expected as an experimental tool for mechanism study of nonlinear ultrasound. For the purpose, EMAT experiment is carried out using uniform and strong filed generated by a superconducting magnet, and surface displacement of specimen is measured by a laser Doppler vibrometer. As the result, the linear relationship between the surface displacement and magnetic flux density was co...
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Development of superconducting electromagnetic acoustic transducer system and quantitative evaluation of ultrasound transmission by numerical analysis

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

This paper discusses the feasibility of characterization of graphite morphology in gray cast irons based on electromagnetic method. For the pur pose, gray cast iron with different graphite morphology was systematically evaluated. In order to discuss electromagnetic property of gray cast iron with different graphite morphology, conductivity and permeability were measured. It was found that both conductivity and permeability mai nly depend on graphite morphology. It was shown that the graphite morphology of ...
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Characterization of graphite morphology of gray cast irons using electromagnetic method

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