Abstract: This study proposes a reliability assessment method for two pipe wall thickness inspection techniques, the electromagnetic acoustic resonance (EMAR) and pulse-EMAR methods, using statistical analysis. The statistical analysis uses an EMAR technique with a signal processing method called the superposition of nth compression (SNC) method, which is used to calculate the normalized SNC peak value, and is concerned with the difference between the thicknesses obtained by the EMAR method and the rea...
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Reliability Assessment for Electromagnetic Acoustic Resonance (EMAR) and Pulse-EMAR Methods by Statistical

Abstract..This paper investigates the influence of machining process on eddy current signals of fatigue cracks in low carbon austenite stainless steels. Several fatigue cracks are created using four point bending method. The grinding process on crack mouth after the formation of fatigue crack seals the crack and gives certain amount of conductivity. This phenomenon on fatigue cracks is confirmed through comparison with the numerical simulation of ECT signals. ...
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Reliability evaluation of Fatigue crack signal in austenite stainless steels 佐藤 打美亥 Dummy SATOU

In the previous study, it has been found that amplitude of ECT signal of fatigue cracks which are introduced in type 316 and 316L austenite stainless steels decrease after heat treatment. As the result, evaluation of the ECT signals with error leads to the underestimation of fatigue cracks sizing. In this study, the relation between loading conditions of fatigue test and ECT signal change is investigated, in order to figure out the phenomenon. The results show the amplitude change of eddy current is rel...
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Evaluation of the Influence of Fatigue Crack Closure on Eddy Current Testing Signals

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

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

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...
英字タイトル:
Online Monitoring of Pipe Wall Thinning with Electromagnetic Acoustic Resonance Method

Abstract The electromagnetic acoustic resonance (EMAR) method provides accurate and stable evaluation and its capability has been demonstrated through online monitoring using a large-scale corrosion test loop in oper ation at high temperature. This study applies EMAR with the signal processing method of the superposition of n'“ compression to the thickness evaluation of piping in a nuclear power plant during shutdown. Sections of piping evaluated by EMAR include those having long-term service, where thinni...
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Implementation applicability of piping inspection using electromagneticacoustic resonance

Electromagnetic acoustic transducer (EMAT) provides non-contacting measurements and is often applied to monitoring in high temperature environment. Electromagnetic acoustic resonance method (EMAR) is transmits an ultrasonic burst wave, and the driving frequency of bust wave is swept. Then signal amplitude of each frequency is computed by the superheterodyne processing at the interval. Pulse-EMAR method is transmits an ultrasonic pulse wave propagating, but the pulse wave is not swept. Then echo waves recei...
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Influence of bottom shape in the pipe wall thinning inspection using an electromagnetic acoustic resonance method