Experimental Study of Evaluation Method of Vibrational Stress in Piping System Applying Multiple Laser Displacement Sensors

2007 ◽  
Author(s):  
Masanori Shintani ◽  
Michiyasu Noda ◽  
Akira Maekawa ◽  
Masakazu Sakashita
Keyword(s):  
Measurement Technique ◽  
Nuclear Power ◽  
Evaluation Method ◽  
Stress Measurement ◽  
Vibration Measurement ◽  
Displacement Sensor ◽  
Piping System ◽  
Bending Vibration ◽  
Stress Evaluation ◽  
Displacement Sensors

In the pipe line installed in the nuclear power plant, there are many reports of damage caused by fatigue as a result of machine vibration of a pump etc. Vibrational stress evaluation by the method using the strain-gauge method or the accelerometer as one of the preventive measures of these oscillating troubles etc. is performed. However, since many special skill and working hours are required for these methods, the development of vibration measurement and stress evaluation technology which operates quickly and easily at the spot is desired. The purpose of this research is the development of a technique and equipment which measures vibrational stress immediately using a laser displacement sensor. In the measurement technique proposed, displacement by the bending vibration of piping which vibrates using three sets of laser displacement sensors is measured, and vibrational stress is obtained by calculating the strain produced from those displacement differences for piping. This measuring instrument is a non-contact system, and a miniaturization and short-time measurement of equipment are easy. This paper deals with the concept of the vibrational stress measurement technique, the theory of the measuring method, and the procedure, the authors propose, using three sets of the laser displacement sensors. Furthermore, using a cantilever model, vibration experiments are conducted, displacements and strain are measured. Next, comparison with the stress by using the displacement measured by the experiment based on this technique and the stress from the strain measured by the experiment is performed. The application possibility of the technique is described.

Development of Evaluation Method of Vibrational Stress in Piping System Applying Multiple Laser Displacement Sensors

2007 ◽  
Author(s):  
Michiyasu Noda ◽  
Akira Maekawa ◽  
Michiaki Suzuki ◽  
Masanori Shintani
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Evaluation Method ◽  
Mechanical Vibration ◽  
Measurement Procedure ◽  
Displacement Sensor ◽  
Piping System ◽  
Displacement Sensors ◽  
Vibration Fatigue ◽  
The Difference

Many damages of the piping system in the nuclear power plants have occurred due to the vibration fatigue induced by the mechanical vibration of pumps and so on. One of the preventive measures for the problem of vibration is the evaluation of vibrational stress, which is the methods using the strain gauge and the accelerometer. However, these evaluation methods require highly specialized skills and many man-hours, and nuclear plants are awaiting the development of vibration-measuring techniques and evaluation techniques that are easy to perform and produce accurate results promptly. The purpose of this study is the development of the method and the device measuring the vibrational stress directory using the laser displacement sensor. The proposed method evaluates the vibrational stress as follows: Three laser displacement sensors measure the displacement of the piping induced by vibrating, and the strain of the piping is calculated from the difference among the sensor-measured displacements to determine vibrational stress. The measurement equipment isn’t direct contact with the piping evaluated, can be easily reduced in size, and can realize quick and accurate measurement. This paper describes the concept of the proposed evaluation method of vibrational stress in the piping system using three laser displacement sensors, along with its theory and measurement procedure. And then, refer to the proposal of the evaluation method of torsional vibration using six laser displacement sensors. This paper also compares the stress values calculated based on the cantilever vibration identified by this method and the stress values calculated based on material mechanics, and discusses the applicability of the method in actual plants.

Noncontact Measurement Method of Vibration Stress Using Optical Displacement Sensors for Piping Systems in Nuclear Power Plants

2015 ◽  
Vol 1 (3) ◽  
Author(s):  
Akira Maekawa ◽  
Tsuneo Takahashi ◽  
Takashi Tsuji ◽  
Michiyasu Noda
Keyword(s):  
Nuclear Power ◽  
Measurement Method ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Vibration Measurement ◽  
Piping System ◽  
Noncontact Measurement ◽  
Displacement Sensors ◽  
Optical Displacement ◽  
Vibration Stress

In nuclear power plants, vibration stress of piping is frequently measured to prevent the occurrence of fatigue failure. A simpler and more efficient measurement method is desired for rapid integrity evaluation of piping. In this study, a method to measure vibration stress in a noncontact manner using optical displacement sensors is presented and validated. The proposed method estimates vibration-induced stress of small-bore piping directly using noncontact sensors based on a light-emission diode. First, the noncontact measurement method was proposed, and the measurement instrument based on the proposed method was developed for the validation. Next, vibration measurement experiments using the instrument were conducted for a mock-up piping system and an actual piping system. The measurement results were compared with the values measured by the conventional method of known accuracy using strain gauges. From this comparison, the proposed noncontact measurement method was demonstrated to be able to provide sufficient accuracy for practical use.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 2 — Application of CCFS Method to the Multiply Supported Systems

2014 ◽  
Author(s):  
Koichi Tai ◽  
Keisuke Sasajima ◽  
Shunsuke Fukushima ◽  
Noriyuki Takamura ◽  
Shigenobu Onishi
Keyword(s):  
Power Plant ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Time History ◽  
Piping System ◽  
History Analysis ◽  
Piping Systems ◽  
Isolation Systems ◽  
Seismic Isolation Systems

This paper provides a part of series of “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”. Paper is focused on the seismic evaluation method of the multiply supported systems, as the one of the design methodology adopted in the equipment and piping system of the seismic isolated nuclear power plant in Japan. Many of the piping systems are multiply supported over different floor levels in the reactor building, and some of the piping systems are carried over to the adjacent building. Although Independent Support Motion (ISM) method has been widely applied in such a multiply supported seismic design of nuclear power plant, it is noted that the shortcoming of ignoring correlations between each excitations is frequently misleaded to the over-estimated design. Application of Cross-oscillator, Cross-Floor response Spectrum (CCFS) method, proposed by A. Asfura and A. D. Kiureghian[1] shall be considered to be the excellent solution to the problems as mentioned above. So, we have introduced the algorithm of CCFS method to the FEM program. The seismic responses of the benchmark model of multiply supported piping system are evaluated under various combination methods of ISM and CCFS, comparing to the exact solutions of Time History analysis method. As the result, it is demonstrated that the CCFS method shows excellent agreement to the responses of Time History analysis, and the CCFS method shall be one of the effective and practical design method of multiply supported systems.

Self-Calibrating Optical Displacement Sensor

2013 ◽  
Vol 543 ◽  
pp. 59-62
Author(s):  
Kalman Babković ◽  
László F. Nagy ◽  
Damir Krklješ
Keyword(s):  
Optical Sensors ◽  
Force Measurement ◽  
Calibration Procedure ◽  
Vibration Monitoring ◽  
Vibration Measurement ◽  
Displacement Sensor ◽  
Sensor Output ◽  
Reflective Surface ◽  
Displacement Sensors ◽  
Adjustment System

Commercially available reflective optical sensors can be used as displacement sensors which in turn can be used in vibration monitoring, positioning, force-measurement and other applications. The sensor output depends in all cases on the distance between the component and a suitable reflective surface. In this paper a sensor system applicable to vibration measurement (e.g. monitoring a vibration-generating machine mounted on elastic isolation mountings) is presented where a special mechanism enables the controlled adjustment of the reflective surfaces position. This feature allows continuous operating point adjustment while the sensor measures vibration. On the other hand, during the intervals when the vibration measurement is not active (e.g. the machine is not in use), the system can be used to automatically calibrate the sensor, i.e. to measure the dependence of the optical sensor output from the distance to the reflective surface. This allows accurate measurements under various circumstances: temperature change, optical component replacement, staining of the reflective surface, ingress of dirt etc. The reflective surface adjustment system is controlled by an embedded digital system which also controls the calibration procedure. Range depends largely on the type of reflective sensor. In case of the component TCRT1000 used in the experiments, range is up to 4 mm.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 1 — The Work Schedule of Project and a Seismic Design of Crossover Piping System

2014 ◽  
Author(s):  
Yutaka Suzuki ◽  
Kunihiko Sato ◽  
Hirohide Iiizumi ◽  
Masakazu Hisatsune ◽  
Shigenobu Onishi
Keyword(s):  
Seismic Design ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Response Spectrum ◽  
Piping System ◽  
Piping Systems ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Main Steam

This paper provides a part of series of “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities” [1]–[4]. This part describes the work schedule of this project and the summary of a seismic design for crossover piping system. Since the Southern Hyogo Prefecture Earthquake in 1995, a seismic isolated design has been widely adopted for Japanese typical buildings. The Japanese government accepted utilizing seismic isolation technology for nuclear power facilities with the 2006 revision of the “Regulatory Guide for Reviewing Seismic Design of Nuclear Power Reactor Facilities”. Under these backgrounds, the Japan national project with the participation of all electric power companies and reactor vendors has been started from 2008 to develop seismic isolation systems of nuclear power facilities under the support of the Ministry of Economy, Trade and Industry. In the design of seismic isolated plant, the crossover piping systems, such as Main Steam line and other lines related to the safety system have the important roles for overall plant safety. Therefore, the design of multiply supported piping systems between isolated and non-isolated buildings is one of the major key issues. This paper focuses on the seismic response analysis of Main Steam crossover piping between seismic isolated Reactor Building and non-isolated Turbine Building. Multiple input response spectra and time history analyses of the crossover piping have been performed and the structural integrity of piping and the validity of the multiple input analysis method have been verified based on comparisons with the results obtained by conventional response spectrum analysis using enveloped floor response spectrum.

Non-Linear Design Verification of Nuclear Power Piping According to ASME III NB/NC

2008 ◽  
Author(s):  
Lingfu Zeng ◽  
Lennart G. Jansson
Keyword(s):  
Nuclear Power ◽  
Design Evaluation ◽  
Piping System ◽  
Design Verification ◽  
Intensive Study ◽  
Non Linear ◽  
Piping Systems ◽  
Design Requirements

A nuclear piping system which is found to be disqualified, i.e. overstressed, in design evaluation in accordance with ASME III, can still be qualified if further non-linear design requirements can be satisfied in refined non-linear analyses in which material plasticity and other non-linear conditions are taken into account. This paper attempts first to categorize the design verification according to ASME III into the linear design and non-linear design verifications. Thereafter, the corresponding design requirements, in particular, those non-linear design requirements, are reviewed and examined in detail. The emphasis is placed on our view on several formulations and design requirements in ASME III when applied to nuclear power piping systems that are currently under intensive study in Sweden.

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