At Oangawa Nuclear Power Station, the maintenance for the plant equipment has been performed by TBM which is based on the operation period of the equipment, and by BDM which is to be repaired the equipment by each break down. However, since FY2007, we have introduced CM to the plant equipment diagnosis for part of equipment, and performed TBM + CM maintenance. From this fiscal year, we evaluated those equipment started CBM performing for those representative TBM + CM to equipment. apply CBM which is ba...
英字タイトル:
Action for the Condition Based Maintenance shift

In-Vessel Visual Inspection (IVVI) is usually conducted as indirect visual inspection with remote TV cameras. We often face the following issues in IVVI. When IVVI is conducted at narrow spa ce in the vessel, it is difficult for inspectors to set the cameras to the best position remotely and manually. When the cameras are quickly moved to reduce hours of IVVI, the visibility be comes poor because of motion blurs. For overcoming these problems, we focused on “Super Resolution (SR)” that is one of image proc...
英字タイトル:
In-Vessel Visual Inspection System using Super Resolution Technique

A newly developed in-vessel visual inspection (IVVI) device designed to improve the quality of visual inspection in Boiling Water R eactors (BWRs) while providing significant critical path savings during refueling outages. And Super Resolution Visual Testing (VT) system enhances the inspection image resolution. The system assists the examiners under the condition of relatively faster scanning speed and longer work distance. The effectiveness of the time saving was qualified by the resolution testing with V...
英字タイトル:
Maintenance and Inspection Technologies for Shorter Outage

Magnetic NDE technique for an estimation of degradation distribution in tensile-tested structural steel has been developed. In order to scan magnetic properties of steel promptly , magnetic yoke-probe having primary and secondary coils wounded around the yoke was adopted. To simplify the detection procedure, the principle same as the transformer was emplo yed. The voltage induced at secondary coil decreases with the increase in the applied tensile stress. As for spatial distribution of output voltage, the ...
英字タイトル:
NDE of degradation distribution in tensile-tested specimen using magnetic sensing

Special attentions have been increasingly paid for the diagnosis of social infrastructures after the collapse of ceiling of Sasago tunnel of Chuo Expressway. It is reported that the main cause was due to the age-related degradation of chemical anchors. Chemical anchors are also frequently used in nuclear power stations. Here we have been trying to apply PFM (Probabilistic Fracture Mechanics) to the diagnosis of social infrastructures using Dr. Mainte, an integrated simulator to optimize maintenance activi...
英字タイトル:
A Study of Application of PFM (Probabilistic Fracture Mechanics) to the Diagnosis of Social Infrastructures ]

Through wall degradation was found on the extraction steam drain piping of Unit 6 of Fukushima Dai-ichi Nuclear Power Plant owned by Tokyo Electric Power Company after replacement of the turbine rotors with those of higher thermal efficiency. The mechanism of this degradation was loss of material due to liquid drop impingement. Since the estimated life time of the piping based on wall thickness measurements before the replacement was at least 9 years, the rapid wall thinning occurred after the replac...
英字タイトル:
Through wall degradation problem of the turbine extraction steam drain piping due to liquid drop impingement and measures taken for this problem at Fukushima Dai-ichi Nuclear Power Plant Unit 6

Mitsubishi Heavy Industries, LTD (MHI) developed accident tolerant in-containment hydrogen monitoring system that can operate under harsh environmental conditions during severe accident. The new hydrogen monitoring system consists of two types of detectors, which have different features and operating principles such as high sensitivity (for monitoring low hydrogen concentration) and wide range (for monitoring high hydrogen concentration of up to 20vol%), and hydrogen indication and transmitting module...
英字タイトル:
Development of In-containment Hydrogen Sensor System against Harsh Environment

1.はじめに 現在、原子力発電所においては経年劣化による設備の 機能喪失を防ぐため保全活動が行われている。プラント 機器の保全において疲労の累積を予測し損傷の防止を図 ることは事故防止につながる重要な活動である。疲労累 積評価は単軸試験で得たデータを基にして作成された設 計疲労曲線を用いて行われている。設計疲労曲線による 評価はもともと機器の設計に用いる目的で作られている ため、運転中の機器の実際の疲労累積状態や余寿命の評 価が難しいという課題がある。 そこで、実機の疲労累積状態を仮想的なき裂の長さに 置......
英字タイトル:
Evaluation of Micro Fatigue Crack Growth under Equi-biaxial Stress by Membranous Pressure Fatigue Test

Rolling bearing is the most part used in rotating machinery of industrial plant. The condition diagnosis technology of rolling bearing is very important and indispensable for the plant safety and operation stability. The purpose o f this study is to improve the accuracy of the life prediction for a rolling bearing. The paper proposes a searchin g method for the optimum mathematic function for the high accurate prediction by using the genetic algorithms (GA)....
英字タイトル:
Life Prediction of Rolling Bearing Using Genetic Algorithm

Abstract Magnetic NDE of ferromagnetic steel using spectrum analysis of induced voltage at pick-up coil and magnetic induction has been studied. Magnetic yoke, having an excitation coil and a pick-up coil, was located on a specimen, and a sinusoidal current was applied to the excitation coil for magnetizing the specimen. A voltage induced at the pick-up coil was measured, and the corresponding magnetic in duction was calculated. Then, their frequency spectrums were obtained thorough Fourier analysis. For ...
英字タイトル:
NDE of ferromagnetic steel using spectrum analysis of changes in inducedvoltage and magnetic flux density