A research project in ASME is developing a technical basis for reliability-based load and resistance factor design (LRFD) methods for piping in nuclear power plant. In LRFD, the probabilistic properties of load and resistance of components are taken into considerati on. There are several advantages in LRFD methods comparing to the traditional design methods based on the deterministic theory. In th is document theoretical basis of LRFD is discussed and the present research progress in ASME is reviewed based...
英字タイトル:
Load and Resistance Factor Design For Piping of Nuclear Power Plant

This work investigates the effective method for detecting structural abnormality such as misalignment or unbalance in rotating machines. Experiments are performed which acquire vibration acceleration data of a horizontal pump under various structural abnormality. In order to detect abnormality comparing to the normal state, feature vector is defined as a set of magnitude of rotational frequency and its harmonics of vibration signal, then change of it is evaluated with SBM (Similarity Based Modeling). W...
英字タイトル:
Study of the capability of detection of structural abnormality in rotating machines with multipoint analysis

In order to investigate effective methods to detect the abnormality of pipe supports, vibration data of piping was acquired under various operating pressure and conditions of supports. Single feature value such as RMS of vibration acceleration, vibration velocity, vibration displacement, was not always able to detect the abnormality. To make the feature value more informative, the feature vector was defined as the combination of 3 aforementioned feature value. Then the difference of feature vectors compa...
英字タイトル:
Multivariate analysis method to detect abnormality of pipe supports

In the present study, effect of spurious diagnostics to improvement of safety, and po ssibility of extension in the interval of TBM (Time-Based Maintenance) by introducing CBM (Condition-Based Maintenance) and necessity of TBM were investigated. From these investigations, improvement of safety and reduction of maintenance cost can be seen....
英字タイトル:
Study on Best-Mix of CBM and TBM Considering Effect of Spurious Diagnostics Using State Transition Model

１．背景　米国機械学会は、先駆的に原子力発電設備の維持規格制定に取組み、1971年に供用期間中検査を規定したASME Code Section XIを制定している。その後、ASME Code Section XIの1974年版では、検査で発見された欠陥の成長評価と機器の健全性に基づく欠陥評価基準が新たに導入された。この基準は、供用期間中に発見された欠陥については、製造時の許容基準を超えた場合についても健全性を損なわない範囲で許容し、欠陥が存在したまま継続運転可能とするものであり、1960年代に進展した破壊......

The conventional design of structural components such as piping or vessels is made based on the deterministic method. In the design method, the margin of the design integrity is expressed as empirical safety factor. On t he other hand, the stochastic safety factor is calculated from data such as the standard deviation of the mate rial strength in the LRFD (Load and Resistance Factor Design) method. This method allows a rational design bas ed on the up-to-date knowledge. In this study the optimization met...
英字タイトル:
Development of Maintenance and Design Optimization Method forPiping System Based on Stochastic Theory

This paper discusses maintenance optimization by the automatic planning tool for regular plant outage work in nuclear power plant using the logic programmin g language “Prolog”. As a result of consideration, the following results were obtained. (1) The automatic planning tool for regular plant outage in nuclear power plant was developed. (2) Using this tool, the work plan for BWR primary recirculation system and residual heat removal systemwas automatically made on the condition of flattening man loading o...
英字タイトル:
A Study on Maintenance Optimization by the Automatic Planning Tool for Regular Plant OutageWork in Nuclear Power Plant Using the Logic Programming Language “Prolog”

This study aimed to establish the method for evaluating the amount of bearing flaking in balls. We performed 5 accelerated aging tests of ball bearing s that expedite the occurance of flaking in balls and analyzed the vibraion signal. Some characteristic features for initial stage of flaking in balls are revealed such as sudden decrease of vibarion level or pulse vibration once per several revolutions of a ball. Those knowledge can be used for diag nosing the severity of bearings that indicate the existanc...
英字タイトル:
A Study on Evaluating the Amount of Bearing Flaking in Balls

A new electromagnetic method for the nondestructive evaluation of electric pumps with sliding bearings is proposed. A permanent magnet gen erates a static magnetic field and a coil of several hundred turns wrapped around it is used to pick up eddy currents induced inside rotat ing impellers. This electromagnetic nondestructive evaluation method is applied to the canned pump. By monitoring the movement of the impe ller in a canned pump, the rotation speed, the variance of the impeller position as well as th...
英字タイトル:
Study of Evaluation Method for the Amount of Wear-Out of Plain bearingswith Electromagnetic Sensor

Abstract Maintenance is an activity to keep the functions of systems, structures and components against aging phenomena. Maintenance has so far been carried out based on experience of the experts mainly engaged in the plant. However in order to make a suitable maintenance program, it is necessary to predict the future based on past knowledge and past research data. Then, it is necessary to regard m aintenance as sciences and to systematize maintenance, that is, maintenology needs to be constructed. As the ...
英字タイトル:
The Future Activity for Construction of Maintenology