In the field of nondestructive inspection by eddy current testing, various approaches to the depth-sizing of SCCs by numerical inversion analysis have been taken so far. However, its accuracy is not so high and limited to a certain extent because of no information about the real value of inner conductivity of SCCs. Therefore, we first investigated experimentally the inner conductivity distribution of several artificial SCCs by a precise mechanical processing and 4 terminal resistance measurement. From ...
英字タイトル:
Improvement of a SCC depth-sizing technique using ECT analysis with detailed investigation of SCC conductivity distribution

Our Company, aims at tracking huge plant parameters (Big Data), managed by Nuclear Power Plants. By application of this Big Data, along with NEC Corporation we developed a system to detect any equipment abnormalities accurately and as much as possible at an early stage. After the implementation of the system, checks of the actual working of the system can be conducted and performance gains enhanced drastically. ...
英字タイトル:
Development of the Plant Monitor System utilized Invariant Analysis Technology and Big Data

The experiments that imitate wear in pump impellers were performed, in which various physical values such as outlet pressure, suction pressure, flow rate and motor current were acquired simul taneously. Three impellers with various wear amount and a normal one were tested. Similarity Based Modeling (SBM) was applied to the data for detection of the abnormality. SBM is a non-parame tric modeling method that makes a model of a certain state by sampling vectors that consists of various physical values at the ...
英字タイトル:
Investigation of multivariate analysis for detection of wear in pump impellers

A method that applies the neural network to acoustic data to detect abnormalities of horizontal pumps is proposed. In the experiments, running sound of a pump with bearing damage or misalignment was acquired from various distance while another pump in the same room was running or not running as a possible noise source. By applying the neural network to the appropriately processed frequency spectrum of acquired data, abnormality can be accurately detected regardless of the distance between the sensor and ...
英字タイトル:
Detection of abnormality of pumps by acoustic diagnosis using neural network

Rationalization of the plant maintenance is one of the main topics being investigated in Japanese nuclear power industries. Optimization of the inspection and replacement period of equipments is effective for the maintenance cost reduction. The more realistic model of the replacement policy is proposed in this study. It is based on the classical replacement policy model and its cost is estimated. Then, to consider the inspection for the maintenance, the formulation that includes the risk concept is d...
英字タイトル:
Optimization on Replacement and Inspection Period of Plant Equipment

A new electromagnetic method for the nondestructive evaluation of electric pumps with ball bearings is proposed. A permanent magnet generates a static magnetic field and a coil of several hundred turns wrapped around it is used to pick up eddy currents induced inside rotating ball bearings and impellers. First, a method that makes use of the autocorrelation is applied to the signals of the ball bearings. A relation between the processed signals and the size of the defects in the bearings is obtained....
英字タイトル:
Electromagnetic Nondestructive Detection for Wounded Bearings and Correlation of Size of Defect and Signal

We have developed the prediction monitoring and diagnostic system for the purpose of the early detection of the abnormal behavior of the complicated system like a nuclear power plant. Furthermore, the techniques for the modeling of the relationships between sensors are applied to evaluate the system performance. The developed method is applied to the primary loop recirculation (PLR) pumps and the system performance indicator is calculated. The results are compared with the maintenance record of the PLR p...
英字タイトル:
Application of Prediction Monitoring and Diagnostic System to Plant Performance Evaluation

1．はじめに：普遍性と階層構造原子力発電設備でとられている保全の基本原理の中に「階層性」と「階層原理」を導入できないかという命題は検討に値する。階層原理とは、例えば原子力プラントが電力を生産するまでにたどるプロセスは、設計と建設と運転管理、の三つの部分からなり、それらが階層的な役割を果たしながら全体として電力の安定供給という機能を果たしている仕組みを言う。階層性が存在し階層原理が正常に機能すれば、設計、建設、運転管理の三つの行為が適切に機能し、その結果電力は正常に国民に供給される、という目標が達成される。......

1．はじめに原子力発電に関わらず、プラントの保全は設計・運転・管理に携わるエキスパートによってその内容が立案され実施されている。計画立案の際に最も有効な情報は実はエキスパートの業務経験に基づく知識であり、過去のトラブル等の運転実績である。特に原子力の場合、他の産業に比べて日が浅いことから、現場の人たちの試行錯誤によって保全計画の改善がなされてきた側面が強い。しかしながら、運転経験の蓄積にともない従来の経験に基づく保全から理論に基づいた保全へと移行する機運が高まってきた。保全の体系化とはこの一連の流れにおい......

1．はじめにプラントシステムの保全計画は、体系化された学問に基づき立案・実施されるというよりも、現場で実務に携わる専門家の経験に基づき、多くの試行錯誤を経て段階的にその精度を高めていくという手法が、これまで一般的にとられてきている。これは、原子力発電プラントの保全計画についても同様であり、プラントの安全性・信頼性確保を目標に、運転経験と技術知見の蓄積を可能な限り保全計画に反映してきた結果として現在の完成度の高い保全計画が構築されているものの、まだまだ定量的な要素も少なく、そのため論理的な要素の導入にも限界......