scholarly journals An Investigation on a Quantitative Tomographic SHM Technique for a Containment Liner Plate in a Nuclear Power Plant with Guided Wave Mode Selection

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2819 ◽  
Author(s):  
Yonghee Lee ◽  
Younho Cho
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Elastic Wave ◽  
Nuclear Power ◽  
Guided Waves ◽  
Mode Selection ◽  
Wave Mode ◽  
Guided Wave ◽  
Element Analysis ◽  
Wave Tomography

The containment liner plate (CLP) in a nuclear power plant is the most critical part of the structure of a power plant, as it prevents the radioactive contamination of the surrounding area. This paper presents feasibility of structural health monitoring (SHM) and an elastic wave tomography method based on ultrasonic guided waves (GW), for evaluating the integrity of CLP. It aims to check the integrity for a dynamic response to a damaged isotropic structure. The proposed SHM technique relies on sensors and, therefore, it can be placed on the structure permanently and can monitor either passively or actively. For applying this method, a suitable guided wave mode tuning is required to verify wave propagation. A finite element analysis (FEA) is performed to figure out the suitable GW mode for a CLP by considering geometric and material condition. Furthermore, elastic wave tomography technique is modified to evaluate the CLP condition and its visualization. A modified reconstruction algorithm for the probabilistic inspection of damage tomography algorithm is used to quantify corrosion defects in the CLP. The location and shape of the wall-thinning defects are successfully obtained by using elastic GW based SHM. Making full use of verified GW mode to Omni-directional transducer, it can be expected to improve utilization of the SHM based evaluation technique for CLP.

Damage Imaging of Pipes in Nuclear Power Plants Using Torsional Guided Wave Modes

2013 ◽  
Vol 577-578 ◽  
pp. 661-664
Author(s):  
Zhao Xiang Wei ◽  
Hong Xu ◽  
Hong Yuan Li
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Guided Waves ◽  
Axial Position ◽  
Imaging Method ◽  
Long Distance ◽  
Torsional Mode ◽  
Damage Imaging

Ultrasonic guided waves can propagate a long distance in pipeline with little attenuation. This means the damage in nuclear power plant can be detected from a remote single position. In the paper, the propagation of the guided waves are analyzed for the nuclear power plant pipes, and the axisymmetric torsional mode T(0,1) is chosen as the detection mode. An imaging method based on the synthetic focusing algorithm is used to obtain the damage information. The method is then verified by the finite element model. Results illustrate that the damage can be detected and located accurately by the damage imaging method. Not only the axial position, but also the circumferential position can be located simultaneously.

Frequency Analysis of the Motor Control Centers in a Nuclear Power Plant Using Testing and Simulating Methods

2013 ◽  
Vol 479-480 ◽  
pp. 1045-1050
Author(s):  
Wei Ting Lin ◽  
Yuan Chieh Wu ◽  
Chin Cheng Huang
Keyword(s):  
Motor Control ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Shaking Table Test ◽  
Spectral Response ◽  
Shaking Table ◽  
Element Analysis ◽  
Control Center ◽  
Frequency Curves

This study is aim to evaluate the seismic response of the motor control center cabinet in a nuclear power plant using shaking table test and 3D finite element analysis method. Three typical types of motor control center cabinet were used in this study and frequency curves and spectral response acceleration were used as the indices of the dynamic response. The results indicated that the resonance frequency for X and Y direction is about 12 Hz and 15 Hz, respectively, which is verified by the numerical results. The frequencies curves and spectral response acceleration generated by numerical and experimental method were similar and well fitting. Although the numerical method obtained the conservative results, the model accurately represents the dynamic characteristics of the actual motor control center cabinet for seismic verification.

Field Testing to Validate Models Used in Explaining a Piston Problem in a Large Diesel Engine

1993 ◽  
Vol 115 (4) ◽  
pp. 721-727 ◽  
Author(s):  
M. J. Graddage ◽  
F. J. Czysz ◽  
A. Killinger
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Electric Utility ◽  
Analytical Models ◽  
Recording Equipment ◽  
Element Analysis ◽  
Piston Skirt ◽  
Lubrication Conditions ◽  
Engine Start

Two crankcase explosions occurred within one month in diesel engines that drive large emergency generator sets at a nuclear power plant in Eastern Pennsylvania. As a result, the electric utility conducted an extensive investigation to determine the root cause(s) of the problem. Initial inspections confirmed that the crankcase explosions were the result of pistons and liners becoming overheated. The technical challenge was to establish why the pistons and liners were overheating when other engines of the same type did not appear to have the problem in the same duty. Analytical models of piston motion, engine start, and run thermodynamics, and a finite element analysis of piston distortion during engine start and load transients were developed. Preliminary work with these models predicted a feature of the piston design that could adversely affect lubrication conditions during a rapid start and load transient. Final input data to refine the models were needed and these were obtained from tests carried out on a similar diesel generator operated by a municipality in Iowa. This paper describes the successful accomplishment of the field tests using state-of-the-art instrumentation and recording equipment. It also shows how the modeling and test work identified wear at certain locations on the piston skirt as the origin of distress leading to the crankcase explosions. Unfavorable engine starting and loading conditions as well as less than desirable piston skirt-to-liner lubrication conditions in the engines at the nuclear power plant have been identified as the root causes and corrective action has been initiated.

Time Reversal Technique for Ultrasonic Guided Wave Inspection

2006 ◽  
Vol 321-323 ◽  
pp. 776-779
Author(s):  
Hak Joon Kim ◽  
Sung Jin Song ◽  
Jung Ho Seo ◽  
Jae Hee Kim ◽  
Heung Seop Eom
Keyword(s):  
Time Delay ◽  
Power Plant ◽  
Time Reversal ◽  
Nuclear Power ◽  
Guided Waves ◽  
Performance Enhancement ◽  
Guided Wave ◽  
Ultrasonic Waves ◽  
Ultrasonic Guided Waves ◽  
Ultrasonic Guided Wave

For the long range inspection of structures in nuclear power plant using array transducers, it is necessary to focus waves on defects under interrogation. To take care of such a need, in this study we adopt a time reversal technique that is claimed to be very robust to focus ultrasonic waves on defects. Specifically, we calculate the appropriate time delay using the time reversal technique and re-generate ultrasonic guided waves that are focusing to an interrogated defect with the calculated time delay. In this paper, we describe the principle of the time reversal technique briefly and present the performance enhancement obtained by the time reversal techniques.

scholarly journals High-resolution thickness maps of corrosion using SH1 guided wave tomography

2021 ◽  
Vol 477 (2245) ◽  
pp. 20200380
Author(s):  
Andreas A. E. Zimmermann ◽  
Peter Huthwaite ◽  
Brian Pavlakovic
Keyword(s):  
Petrochemical Industry ◽  
Guided Waves ◽  
Corrosion Damage ◽  
Wave Mode ◽  
Guided Wave ◽  
Resolution Limit ◽  
First Order ◽  
Wave Tomography ◽  
Plane Direction ◽  
Shear Horizontal

Quantifying corrosion damage is vital for the petrochemical industry, and guided wave tomography can provide thickness maps of such regions by transmitting guided waves through these areas and capturing the scattering information using arrays. The dispersive nature of the guided waves enables a reconstruction of wave velocity to be converted into thickness. However, existing approaches have been shown to be limited in in-plane resolution, significantly short of that required to accurately image a defect target of three times the wall thickness (i.e. 3 T) in each in-plane direction. This is largely due to the long wavelengths of the fundamental modes commonly used, being around 4 T for both A0 and S0 at the typical operation points. In this work, the suitability of the first-order shear-horizontal guided wave mode, SH1, has been investigated to improve the resolution limit. The wavelength at the desired operating point is significantly shorter, enabling an improvement in resolution of around 2.4 times. This is first verified by realistic finite-element simulations and then validated by experimental results, confirming the improved resolution limit can now allow defects of maximum extent 3T-by-3T to be reliably detected and sized, i.e. a long-pursued goal of guided wave tomography has been achieved.

scholarly journals Mode Selection Model for Rail Crack Detection Based on Ultrasonic Guided Waves

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Bo Xing ◽  
Zujun Yu ◽  
Xining Xu ◽  
Liqiang Zhu ◽  
Hongmei Shi
Keyword(s):  
Crack Detection ◽  
Guided Waves ◽  
Mode Selection ◽  
Wave Mode ◽  
Guided Wave ◽  
Selection Model ◽  
Cross Sectional ◽  
Detection Mode ◽  
Modal Vibration ◽  
Wave Modes

The cross-sectional geometry of a rail is complex, and numerous guided wave modes can be propagated in rails. In order to select a mode which is the most suitable for detecting a specific crack on a rail, a mathematical model of guided wave mode selection is constructed. The model is composed of a modal vibration factor and a modal orthogonal factor. By setting a reasonable vibration coefficient and orthogonal coefficient, the mode with the highest sensitivity to cracks is selected for crack detection. Taking a vertical crack on the rail bottom as an example, mode 1 at a frequency of 60 kHz is selected as the most suitable detection mode. At the same time, mode 7 and mode 11 are selected as comparative modes, and these three modes are simulated to detect rail cracks. Among them, mode 1 is the best, which verifies the correctness of the mode selection model. In addition, vertical cracks are manufactured artificially on the side of the rail bottom. The cracks are successfully detected by mode 1, and the positioning error is 0.07 m. After correction, the error is reduced to 0.02 m. The model can effectively select guided wave modes suitable for detecting arbitrary cracks on rails, which provides a theoretical solution for rail crack detection.

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