Taking Advantage of Signal Processing Techniques for the Life Management of NPP Components

2006 ◽  
Author(s):  
L. Chatellier ◽  
S. Dubost ◽  
F. Peisey ◽  
B. Richard ◽  
L. Fournier ◽  
...  
Keyword(s):  
Signal Processing ◽  
Eddy Current ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Industry ◽  
Destructive Testing ◽  
Small Surface ◽  
Plant Operator ◽  
Processing Techniques ◽  
Signal Processing Techniques

The long term management of nuclear power plants raises several major issues among which the aging management of key components ranks high, from both technical and economic points of view. In order to detect and characterize potential defects on cast components, a program of in-service inspections is carried out by non-destructive testing (NDT) methods. In general, defect detection is the first step of an inspection procedure. Should a defect be detected, the plant operator must evaluate whether the component should be replaced or repaired (now or later) and will be required to prove that the component still meets regulatory requirements. That is why the characterization of the defect in terms of locating and sizing is essential, especially when the proof relies on mechanical calculations. In this paper we provide an overview of advanced signal processing techniques based on regularization of inverse problems. Those techniques have a strong potential for improving defect positioning and sizing. This has already been demonstrated in several R&D studies in the field of radiography and ultrasonics, leading in some cases to expertise-oriented applications. After a presentation of the general principles, we detail how regularization can be applied to process eddy current probe signals and provide good estimates of the depth of small surface breaking defects. Encouraging laboratory results have been obtained so far, which may lead to re-consider the scope of the eddy current technique as presently used in the nuclear industry. For example, its eligibility as an alternative NDE method could be explored in cases dealing with this kind of defect, if ultrasonics failed to meet the required characterization performance.

scholarly journals Latest Advances in Common Signal Processing of Pulsed Thermography for Enhanced Detectability: A Review

2021 ◽  
Vol 11 (24) ◽  
pp. 12168
Author(s):  
Yoonjae Chung ◽  
Seungju Lee ◽  
Wontae Kim
Keyword(s):  
Signal Processing ◽  
Infrared Thermography ◽  
Heat Diffusion ◽  
Thermal Excitation ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Pulsed Thermography ◽  
Processing Techniques ◽  
Non Destructive ◽  
Signal Processing Techniques

Non-destructive testing (NDT) is a broad group of testing and analysis techniques used in science and industry to evaluate the properties of a material, structure, or system for characteristic defects and discontinuities without causing damage. Recently, infrared thermography is one of the most promising technologies as it can inspect a large area quickly using a non-contact and non-destructive method. Moreover, thermography testing has proved to be a valuable approach for non-destructive testing and evaluation of structural stability of materials. Pulsed thermography is one of the active thermography technologies that utilizes external energy heating. However, due to the non-uniform heating, lateral heat diffusion, environmental noise, and limited parameters of the thermal imaging system, there are some difficulties in detecting and characterizing defects. In order to improve this limitation, various signal processing techniques have been developed through many previous studies. This review presents the latest advances and exhaustive summary of representative signal processing techniques used in pulsed thermography according to physical principles and thermal excitation sources. First, the basic concept of infrared thermography non-destructive testing is introduced. Next, the principle of conventional pulsed thermography and signal processing technologies for non-destructive testing are reviewed. Then, we review advances and recent advances in each signal processing. Finally, the latest research trends are reviewed.

scholarly journals Thermographic Inspection of Internal Defects in Steel Structures: Analysis of Signal Processing Techniques in Pulsed Thermography

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6015
Author(s):  
Yoonjae Chung ◽  
Ranjit Shrestha ◽  
Seungju Lee ◽  
Wontae Kim
Keyword(s):  
Signal Processing ◽  
Power Plants ◽  
Principal Component ◽  
Steel Structures ◽  
High Energy ◽  
Internal Defects ◽  
Pulsed Thermography ◽  
Processing Techniques ◽  
Signal Processing Techniques ◽  
Defect Detectability

This study performed an experimental investigation on pulsed thermography to detect internal defects, the major degradation phenomena in several structures of the secondary systems in nuclear power plants as well as industrial pipelines. The material losses due to wall thinning were simulated by drilling flat-bottomed holes (FBH) on the steel plate. FBH of different sizes in varying depths were considered to evaluate the detection capability of the proposed technique. A short and high energy light pulse was deposited on a sample surface, and an infrared camera was used to analyze the effect of the applied heat flux. The three most established signal processing techniques of thermography, namely thermal signal reconstruction (TSR), pulsed phase thermography (PPT), and principal component thermography (PCT), have been applied to raw thermal images. Then, the performance of each technique was evaluated concerning enhanced defect detectability and signal to noise ratio (SNR). The results revealed that TSR enhanced the defect detectability, detecting the maximum number of defects, PPT provided the highest SNR, especially for the deeper defects, and PCT provided the highest SNR for the shallower defects.

Eddy Current Examination of Fatigue Cracks in Inconel Welds

2006 ◽  
Vol 129 (1) ◽  
pp. 169-174 ◽  
Author(s):  
Weiying Cheng ◽  
Ichiro Komura ◽  
Mitsuharu Shiwa ◽  
Shigeru Kanemoto
Keyword(s):  
Eddy Current ◽  
Nuclear Power ◽  
Power Plants ◽  
Base Alloy ◽  
Fatigue Cracks ◽  
Current Method ◽  
Destructive Testing ◽  
Eddy Current Method ◽  
Nickel Base ◽  
Basic Studies

Basic studies on the eddy current examination of defects in Inconel, a typical nickel-base alloy used in the reactor vessel, pressurizer, and core internal of nuclear power plants, are carried out. The detecting and sizing capability of the eddy current method is investigated through analytical and experimental approaches. Probe’s detectability is numerically evaluated, and appropriate probe and examination conditions are correspondingly selected. The numerical signal calculation and crack reconstruction approach is confirmed in terms of the study of the eddy current examination of electrodischarge machining notches in Inconel base metal, and further applied to eddy current examination of fatigue cracks in Inconel welds. The profiles of fatigue cracks are reconstructed using eddy current testing signals. Crack depths estimated by eddy current reconstruction agree well with that of ultrasonic testing and are consistent with the crack depths revealed from destructive testing. The research presented in this paper shows that by choosing a proper testing situation, eddy current examination is feasible for detecting and sizing of surface-breaking cracks in Inconel welds.

Improving Nuclear Plant Reliability by Developing an Eddy Current Test Strategy to Identify Uncommon Condenser Tube Defects

2014 ◽  
Author(s):  
James A. Kocher ◽  
Robert Frazee ◽  
Matthew Wolf
Keyword(s):  
Eddy Current ◽  
Nuclear Power ◽  
Power Plants ◽  
Test Procedure ◽  
The United States ◽  
Nuclear Plant ◽  
Nuclear Industry ◽  
Condenser Tube ◽  
Remedial Action ◽  
Exploratory Testing

Eddy Current Testing (ECT) of condenser tubes is essential to maintaining good plant reliability and availability. Early identification of defects can allow for adequate remedial action and prevent forced outages caused by condenser tube leaks. The well-known catastrophic failure in the nuclear industry in Japan has not only raised concern in Japan over aging nuclear power plants, but has also raised concern over safe operations in the United States and around the world. Ongoing reliability and instability issues due to reported leaks in condensers have also been the topic for nuclear watchdogs. This focus on the nuclear plant condenser has brought to light the various levels of sophistication and capability in ECT. In ECT, the type of defect present in a condenser tube is determined by the characteristics it presents under test. The tubes must be adequately cleaned prior to testing and some awareness or evidence of the type of defect to be uncovered should be available to the testing team. In cases where defects are discovered that are inconsistent with prior awareness further exploratory testing is common. Exploratory testing can proceed to test areas of suspected defects in the tubing, and it may result in a complete redefinition of the test procedure, inclusive of instruments, probe types and other key ECT criteria. A comprehensive knowledge of testing options and their practical application is necessary to redefine a test that will yield meaningful results and achieve the intended objective; to identify the type and extent of defect and take remedial action therefore preventing failure. This paper addresses such a case at the South Texas Project (STP) Nuclear Power Plant where peculiar defects were undeterminable under standard ECT procedures. The defects continued to negatively impact reliability and stability at the plant until a new ECT process and test procedure were developed, demonstrated and deployed. The result achieved was accurate defect detectability and improved nuclear plant reliability.

Advanced Signal Processing Techniques in Non-Destructive Testing

2011 ◽  
pp. 127-146
Author(s):  
A. Al-Ataby ◽  
W. Al-Nuaimy
Keyword(s):  
Pattern Recognition ◽  
Signal Processing ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Recent Advances ◽  
Processing Techniques ◽  
Non Destructive ◽  
Signal Processing Techniques

This chapter describes some recent advances in signal processing as applied to NDT problems. This is an area that has made progress for over twenty years and its importance is gaining attention gradually, especially since the new advanced techniques in signal processing and pattern recognition.

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