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.

A Multi-Dimensional Approach to Design and Execution of Modifications, Refurbishments, and Beyond for Existing Nuclear Power Plants

2020 ◽  
Author(s):  
Omid Malekzadeh ◽  
Matthew Monid ◽  
Michael Huang
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Three Dimensional ◽  
Spatial Models ◽  
Technical Information ◽  
Lessons Learned ◽  
Piping System ◽  
Full Potential ◽  
Cad Models

Abstract Three-Dimensional (3D) CAD models are utilized by many designers; however, they are rarely utilized to their full potential. The current mainstream method of design process and communication is through design documentation. They are limited in depth of information, compartmentalized by discipline, fragmented into various segments, communicated through numerous layers, and finally, printed onto an undersized paper by the stakeholders and end-users. Large nuclear projects, such as refurbishments and decommissioning, suffer from spatial, interface, and interreference challenges, unintentional cost and schedule overruns, and quality concerns that can be rooted to the misalignments between designed and in-situ or previously as-built conditions that tend to stem from inaccessibility and lack of adequate data resolution during the transfer of technical information. This paper will identify the technologies and the methodology used during several piping system modifications of existing nuclear power plants, and shares the lessons learned with respect to the benefits and shortcomings of the approach. Overall, it is beneficial to leverage available multi-dimensional technologies to enhance various engineering and execution phases. The utilization and superposition of various spatial models into 3D and 4D formats, enabled the modification projects to significantly reduce in-person plant walkdown efforts, provide highly accurate as-found data, and enable stakeholders of all disciplines and trades to review the as-found, as-designed, and simulated as-installed modification; including the steps in between without requiring significant plant visits. This approach will therefore reduce the field-initiated changes that tend to result in design/field variations; resulting in less reliance on Appendix T of ASME BPVC Section III, reduction in the design registration reconciliations efforts, and it aligns with the overarching goal of EPRI guideline NCIG-05. Beyond the benefits to design and execution, the multidimensional approach will provide highly accurate inputs to some of the nuclear safety’s Beyond Design Basis Assessments (BDBA) and allowed for the incorporation of actual design values as input and hence removing the unnecessary over-conservatisms within some of the inputs.

Software Test of Wireless Vibration Nodes of Nuclear Power Plants

2013 ◽  
Vol 336-338 ◽  
pp. 313-318
Author(s):  
Chang Jian Deng ◽  
Hong Yang Hu ◽  
Jian Zhong Ling
Keyword(s):  
Embedded System ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Failure Modes ◽  
Test Method ◽  
Vibration Sensor ◽  
Vibration Measurement ◽  
Software Test ◽  
Time Cycle

To do Validation and Verification" of wireless vibration sensor nodes in NPPs (nuclear power plants), embedded system software test should be done. The test index is analyzed firstly; then the method of 'Temb' was introduced to analysis ADXL202 vibration nodes; the characteristic of system was used to establish LITO(life cycle, Infrastructure, Techniques, Organization) matrix, they are of emphasizing safety, application in harsh environment, using algorithms of technology and science and so on. The acceleration circulation method using fixed time cycle pretest by instrument and other weak was proved to be infeasible though FMEA (failure modes and effects analysis). Then FTA (fault tree analysis) is used to analyze system, so the software filter and real-time cycle test method were used to improve test precise and reliability of node vibration measurement. Experiments have proved its effective.

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 Elastic-Plastic Constitutive Models for the Evaluation of Nuclear Piping Systems Under Severe Cyclic Loading

2012 ◽  
Author(s):  
Yukio Takahashi ◽  
Yoshihiko Tanaka
Keyword(s):  
Cyclic Loading ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Kinematic Hardening ◽  
Constitutive Models ◽  
Seismic Loading ◽  
Piping System ◽  
Elastic Plastic ◽  
Piping Systems

It is essential to predict the behavior of nuclear piping system under seismic loading to evaluate the structural integrity of nuclear power plants. Relatively large stress cycles may be applied to the piping systems under severe seismic loading and plastic deformation may occur cyclically in some portion of the systems. Accurate description of inelastic deformation under cyclic loading is indispensable for the precise estimation of strain cycles and accumulation potentially leading to the failure due to fatigue-ratcheting interaction. Elastic-plastic constitutive models based on the nonlinear kinematic hardening rule proposed by Ohno and Wang were developed for type 316 austenitic stainless steel and carbon steel JIS STPT410 (similar to ASTM A106 Gr.B), both of which are used in piping systems in nuclear power plants. Different deformation characteristics under cyclic loading in terms of memory of prior hardening were observed on these two materials and they were reflected in the modeling. Results of simulations under various loading conditions were compared with the test data to demonstrate the high capability of the constitutive models.

scholarly journals A Method Using Optical Contactless Displacement Sensors to Measure Vibration Stress of Small-Bore Piping

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Akira Maekawa ◽  
Takashi Tsuji ◽  
Tsuneo Takahashi ◽  
Michiyasu Noda
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Strain Gauges ◽  
Curvature Radius ◽  
Light Emitting ◽  
Displacement Sensors ◽  
Piping Systems ◽  
Vibration Stress ◽  
Vibration Tests ◽  
Prototype Instrument

In nuclear power plants, vibration stress of piping is frequently evaluated to prevent fatigue failure. A simple and fast measurement method is attractive to evaluate many piping systems efficiently. In this study, a method to measure the vibration stress using optical contactless displacement sensors was proposed, the prototype instrument was developed, and the instrument practicality for the method was verified. In the proposed method, light emitting diodes (LEDs) were used as measurement sensors and the vibration stress was estimated by measuring the deformation geometry of the piping caused by oscillation, which was measured as the piping curvature radius. The method provided fast and simple vibration estimates for small-bore piping. Its verification and practicality were confirmed by vibration tests using a test pipe and mock-up piping. The stress measured by both the proposed method and an accurate conventional method using strain gauges were in agreement, and it was concluded that the proposed method could be used for actual plant piping systems.

Assumed Process of Piping Failure in Nuclear Power Plants Under Destructive Earthquake Conditions

1991 ◽  
Vol 113 (2) ◽  
pp. 268-272
Author(s):  
H. Shibata
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Piping System ◽  
Safety Problem ◽  
Type Of Failure

This paper deals with an assumed process of piping failure in nuclear power plants which may cause a catastrophic accident during a destructive earthquake condition. The type of failure discussed is the so-called double-ended guillotine break, DEGB. As a safety problem, we are going to eliminate this type of failure by LBB, and we have assumed that this would then not occur by an earthquake. The author tries to clarify the possibility of failure during earthquakes. He reviews his related papers since 1973, and discusses zipping failure of snubbers and supporting devices. He shows a procedure to simulate the zipping failure of a piping system supported by snubbers.

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