Abstract The present paper tries to evaluate the applicability of conventional sound analysis techniques and modern machine learning algorithms to rotating machine health monitorin g. These techniques include support vector machine, deep leaning neural network, etc. The inner ring defect and misalignment anomaly sound data measured by a rotating machine mock up test facility are used to verify the above various kinds of algorithms. Although we cannot find remarkable difference of anomaly discrimination per...
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Proposal of Rotating Machine Health Monitoring Based on Modern Machine Leaning Methods

Sabotage by malicious insider is one of significant and serious threats for nuclear security of nuclear power plants. It is difficult, however, to distinguish abnormal behaviors from normal works such as their daily maintenance activities. In this study, a technique was proposed to subdivide the abnormal behavior due to sabotage by image analysis and then to detect and identify the abnormal behavior in real time. ...
英字タイトル:
Proposal of Insider Detection Method for Nuclear Security

This study proposes new signal processing methods to restore surface shapes of flaws from eddy current testing（ECT）signals. A linear discriminant analysis method is applied to ECT signals embedded in multi-dimensional state space to identify flaw signals form background noises in prior. A new concept of equivalent point spread function is introduced, and the real flaw shape is restored by utilizing a deconvolution filter based on Richardson-Lucy algorithm. An EDM notch covered by large welding noises...
英字タイトル:
New Signal Processing Methods for Surface Shape Restoration in Eddy Current

Abstract In operation of nuclear power plants (NPPs), it is required not only to preserve and improve the reliability and safety, but also to introduce more efficient and lower cost maintenance strategy simultaneously, due to the power trading deregulation in recent years. For this purpose, Condition Based maintenance (CBM), which has been extensively applied i n the nuclear power plant of U.S., is introduced as a maintenance method for rotating machines in Japanese nuclear power plant. TOSHIBA develops t...
英字タイトル:
Development and application of Monitoring and Diagnosis Techniques for Condition Based Maintenance in Nuclear Power Plant

The present paper discusses a concept of safety design and accident models in complex systems. Modern artifacts or engineering products in our daily life are usually controlled by embedded computers and inevitably connected to Internet. Due to big progress of computer hardware and software performance, control algorithms become more and more sophisticated, intelligent and complex. This makes difficult to assure the safety of the system. Since the current safety assessment tools such as FTA/ETA, FMEA o...
英字タイトル:
Safety Design and Reliability Management of Complex Systems

Depth sizing of multiple closely located parallel cracks are studied as a simplification of stress corrosion crack (SCC). Because of the interference from other cra cks, eddy current testing (ECT) signals of the multiple cracks are different from that of a single one, and the method used for the depth sizing of a single crack i s not practical for that of multiple cracks. In order to find a depth sizing index which is sensitive to just the maximum depth of multiple cracks, an optimum model finding method b...
英字タイトル:
A New Depth Sizing Method for Complex Shape Stress Corrosion Cracks from ECT Signals

Abstract In operating of nuclear power plants, it is required not only to preserve and improve the reliability and safety, but also to introduce more efficient and lower cost maintenance strategy simultaneously, due to t he power trading deregulation in recent years. In addition, as the number of experienced operators / maintenance personnel decreases, comprehensive implementation of objective and transparent information provision syste m on plant operation and maintenance (O&M) being compliant with the la...
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Development of Remote Operation & Maintenance Support service system

A partial-contact stress corrosion crack (SCC) is electrically modeled as a crack region with non-zero conductivity in eddy current testing (ECT). This partial-contact effect is excluded by an optimally designed crack-conductivity-insensitive depth sizing index, and consequently the master curves obtained from electric-discharge machining (EDM) notches can be utilized directly in the depth sizing of SCCs. This approach is numerically validated and applied to the characterization of SCCs in SUS304 from...
英字タイトル:
A New Depth Sizing Method for Partial-Contact Stress Corrosion Cracks from ECT Signals

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

Electromagnetic acoustic transducer (EMAT) provides non-contacting measurements and is often applied to monitoring in gh temperature environment. One of drawbacks of EMAT is its low sensitivity and S/N ratio. One way to overcome the uwback is to introduce an Electromagnetic acoustic resonance meth od (EMAR); it has a high capability of evaluating ckness or ultrasonic velocity, and it is applied to the measurement of thickness, elastic constants, damping propertiesso on. Since the principle of the method is...
英字タイトル:
Measurement and Evaluation of Pipe Wall Thinning by Electromagnetic Acoustic Resonance