Today's NPPs follow prescriptive requirements for maintenance and inspection of components, structures, and systems. While many of these requirements are derived from several decades of operational experience, they nonetheless do not take into consider ation the actual equipment conditions in determining the need for maintenance and operational adjustments. Continuous condition monitoring in current nuclear power plants is limited to sensor technologies that must be applied externally to already exi sting ...
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Recent Accomplishment in Ultrasonic Health Monitoring for Nuclear Power Plants

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

This study demonstrates the mechanism of y ? a transformation in creep test on the basis of the energy o f the system. The experimental result shows that the strain energy around M23Co carbide becomes very high due to dislocations stored during creep. As a result, the system free energy in the local region near the carbide increases with increasing creep time but it decreases by the formation of ferromagnetic a phase....
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Formation of ferromagnetic phase in SUS304 steel by strain energy stored during creep test

The necessity of a stable driving of equipment and effective maintenance achievement rises, and the effectiveness of CBM (Condition Based Maintenance) has bee n recognized again in recent years. It is a vibration diagnosis technology of the rotating equipment that especially a lot of the results exist. We have aimed at the introduction of the vibration diagnosis technology in Japan since fast time (middle of the 1970's), and are working on the commercialization of the dia gnostic system positively. Here, i...
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Condition Monitoring System by vibration method

Nuclear reaction with enormous energy, as a rich source of energy that has been brought to the human race, have developed as a nuclear power. However, the nuclear power generation is intended to provide a basic inherent “radioactivity risk“, the accident in Fukushima Dai-ichi Nuclear Power Plant was allowed to elicit it. Design, operation, and must be addressed to ensure safety measures in accordance with the role in the disaster areas. Prevention of abnormal event occurs, the enforcement of the mitiga...
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Nuclear safety to think with the society

In recent years, the inspection of pipes is being carried out by using inspection techniques which employ ultrasonic and eddy current testing, endoscope (CCD cameras or optical fiber). Currently, the inspection devices can be performed only a visual check of the pipes. In case of a damage, they cannot be repaired. In such case, the damaged portion has to be excluded or the pipe has to be replaced. The authors develop a laser processing head comprising an optical fiberscope. It is capable of inspection...
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Development of a laser processing head for the inspection and repair of damages inside of a half-inch pipe

Abstract: The conventional narrowband power-line communication (NB-PLC) is a two-wire system, that have transmitted its signal between wires with a capacitive coupler. When performing communication between floors at a large-sized building, the signal has to travel over long-distances across a switchboard which supplies electricity to distribution boards. Moreover, the signal is attenuated also at the switchboard and distribution boards. Then signal amplifiers have had to be installed at the boards. In...
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Proposal of Signal Repeater by One Wire PLC system

An area detector technique has to be applied to the strain scanning method for materials with coarse grains. A new rotating slit system was designed for a 2-dimensional (2D) detector strain scanning method. The rotating slit system can focus the 2D detector on the center of the goniometer, and the gauge volume is made by the rotating slit system. The stress measurements were examined with the rotating slit and 2D detector. The measured diffraction spots shifted for the 2D strain scanning. The magnitu...
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Evaluation of Internal Stresses using Area Detectors

Additional monitoring is occasionally done on suspicious equipment such as pumps, motors, valves and so on, when monitoring parameters are different from normal operation in Nuclear Power Plant If the suspicio us equipment is located in high radiation area, it is hard to arrange for the additional monitoring So, wireless data transmission system is desired And maintenance persons desire to watch the additional moni toring data in their office on P C We can enable to transfer the desired live data from ...
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DATA transmission by 2.4GHz radio frequency and LANfrom Nuclear Power Plant to office