We are developing remote filed eddy current testing (RFECT) method using pancake coils for evaluating local wall thinn ing of large diameter pipes. This paper shows a study to improve the detectability and sizing capability of this RFECT method. The study was performed by numerical calculations and laboratory experiments. The results show that introduci ng differential pick-up coils makes detection signals more stable and improves the detectability of our RFECT method....
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Improvement of remote field eddy current testing using pancake coils

This study proposes a novel nondestructive evaluation method of chill contents in gray cast irons by means of AC magnetization method. For the purpose, magnetic properties of cast irons w ith different chill contents were evaluated by B-H loop analyzer. Results were discussed in view of matrices and graphite, and it was found that some magnetic parameters, especially B-H l oop area, correlate well with ratio of cementite area to graphite one. Focusing on the fact, AC magnetic method was applied to evaluati...
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Evaluation of Chill Contents in Flaky Cast Irons Based on AC Magnetization Method

It is difficult to predict an initiation and growth of ageing/degradation like SCC in plant comp onents, subsequent component failures, function losses or a behavior of gigantic, complex plant system like a nuclear power plant. But if it is possible to predict them, it could drastically improve the safety and economic efficiency of such plant systems. This study considered a struc ture and system of maintenance since that could improve a predictive performance of maintenance related science and engineerin...
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Study of How to Confirm the Completeness of Maintenance Activity Planby Using Maintenance Scientific Imagination

This paper shows phase characteristics of crack indications obtained with a multi-coil ECT probe, and proposes a method to reduce noise and extract crack indications from the detection signals of this multi-coil ECT p robe based on these phase characteristics. Because this multi-coil ECT probe performs two kinds of scanning patterns: U-scan and T-scan, and obtains two sets of signal distributions for one scanning area simultaneousl y, the proposed method uses a two-stage process that includes so-called a m...
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Extraction of crack indications from ECT signals by using signal phase characteristics

The authors have proposed a novel eddy current testing(ECT) probe for thick-walled plates. A basic concept of the probe is that a couple of differential pick-up coils is arranged between two exciting coils carrying currents opposite to each other. This arrangement allows strong eddy currents opposite to scan surfaces and the weak decay of eddy currents in the thickness direction. In this study, the present probe was applied to ECT of welding area. For the purpose, experiments were carried out u...
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Weld Inspection Using Eddy Current Testing Probe for Thick-walled Plates

In this study, a relationship between nuclear safety and inspection/monitoring was discussed. As a result of consideration, the followings were made clear. (1) Nuclear safety is secured by the combination of safety funct ns of nuclear plant system and plant managements by the human system including plant operator’s organization. (2) Nuclear plant systems should be managed for each safety system because safety functions are fulfilled for each safety system. (3) The integrity of concerned system in the futur...
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Study of the relationship between nuclear safety and inspection

In this study, a relationship between nuclear safety and inspection/monitoring was discussed. As a result of consideration, the followings were made clear. (1) Nuclear safety is secured by the combination of safety functions of nuclear plant system and plant managements by the human system including plant operator’s organization. (2) Nuclear plant systems should be managed for each safety system because safety functions are fulfilled for each safety system. (3) The integrity of concerned system in th...
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Study of the relationship between nuclear safety and inspection (The second report)

For creating a corrective measure plan for industrial plants like nuclear power plants, it is necessary to have a well-grounded basis. Therefore, this paper proposes a method for determining the fol lowing three elements of such a plan: the equipment to be repaired, the corrective measure method to be adopted, and the timing of its implementation using a scientific approach. The key idea is to analyze the components of the plan and also to take an approach of creating a plan based on the performance of the...
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Discussion of Corrective Action Planning for Nuclear Power Plants

For creating an inspection plan for industrial plants like nuclear power plants, it is necessary to have a well-grounded basis. Therefore, this paper proposes a method for determining the following three elements of such a plan: the equipment to be inspected, the inspection method to be adopted, and the timing of its implementation using a scientific approach. The key idea is to analyze the components of the plan by employing the understanding of cancer detection and diagnosis in medical science and a...
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Discussion of In-service Inspection Planning for Nuclear Power Plants

One of the most important things which should be explored in Maintenance Science is to make clear a structure and system of maintenance or maintenance activitie s. This study considered similarities between maintenance and emergency response in nuclear power plants from the viewpoint of Maintenance Science. As a result of consideration, this study showed the followings. (1) There are similarities b etween maintenance and emergency response in nuclear power plants -2Considering based on the similarities bet...
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Consideration on Similarities between Maintenance and Emergency Response in Nuclear Power Plants from the Viewpoint of Maintenance Science