Nondestructive Evaluation Reliability Research Articles

Non-Destructive Evaluation of the Quality of Adhesive Joints Using Ultrasound, X-ray, and Feature-Based Data Fusion

The aim of this work is to achieve reliable nondestructive evaluation (NDE) of adhesively bonded aerospace components by developing novel multidimensional data fusion techniques, which would combine the information obtained by ultrasonic and X-ray NDE methods. Separately, both NDE techniques have their advantages and limitations. The integration of data obtained from pulse echo immersion ultrasound testing and radiography holds immense potential to help improve the reliability of non-destructive evaluation. In this study, distinctive features obtained from single techniques, traditional ultrasonic pulse echo testing, and radiography, as well as fused images, were investigated and the suitability of these distinctive features and fusion techniques for improving the probability of defect detection was evaluated. For this purpose, aluminum single lap joints with brass inclusions were analyzed using ultrasound pulse echo and radiography techniques. The distinctive features were extracted from the data obtained, and images of features obtained by both techniques were fused together. Different combinations of features and fusion algorithms were investigated, considering the desire to automate data evaluation in the future.

Magnetic Flux Leakage Sensing and Artificial Neural Network Pattern Recognition-Based Automated Damage Detection and Quantification for Wire Rope Non-Destructive Evaluation.

In this study, a magnetic flux leakage (MFL) method, known to be a suitable non-destructive evaluation (NDE) method for continuum ferromagnetic structures, was used to detect local damage when inspecting steel wire ropes. To demonstrate the proposed damage detection method through experiments, a multi-channel MFL sensor head was fabricated using a Hall sensor array and magnetic yokes to adapt to the wire rope. To prepare the damaged wire-rope specimens, several different amounts of artificial damages were inflicted on wire ropes. The MFL sensor head was used to scan the damaged specimens to measure the magnetic flux signals. After obtaining the signals, a series of signal processing steps, including the enveloping process based on the Hilbert transform (HT), was performed to better recognize the MFL signals by reducing the unexpected noise. The enveloped signals were then analyzed for objective damage detection by comparing them with a threshold that was established based on the generalized extreme value (GEV) distribution. The detected MFL signals that exceed the threshold were analyzed quantitatively by extracting the magnetic features from the MFL signals. To improve the quantitative analysis, damage indexes based on the relationship between the enveloped MFL signal and the threshold value were also utilized, along with a general damage index for the MFL method. The detected MFL signals for each damage type were quantified by using the proposed damage indexes and the general damage indexes for the MFL method. Finally, an artificial neural network (ANN) based multi-stage pattern recognition method using extracted multi-scale damage indexes was implemented to automatically estimate the severity of the damage. To analyze the reliability of the MFL-based automated wire rope NDE method, the accuracy and reliability were evaluated by comparing the repeatedly estimated damage size and the actual damage size.

Scatter of a plane elastic wave by a rough crack edge

The aim of this paper is to investigate the effect of roughness of the crack edge on the reliability of ultrasonic NDE (nondestructive evaluation). The rough crack face has been modeled by earlier authors as a mosaic of large triangular facets and the effect of this roughness has been simulated using the Kirchhoff approximation. We now augment this model by the rough crack edge that is a polygonal line. We then model the scattered field using the Isakovich approach, originally developed for modeling scatter from rough surfaces, also with the help of the Kirchhoff approximation.

State-of-the-Practice & Challenges in Non-Destructive Evaluation of Utility Poles in Service

In this paper, the state of the practice and challenges in Non-Destructive Evaluation (NDE) of utility poles in service in Australia are discussed. NDE techniques, R&D programs and reliability based maintenance of timber utility poles are reviewed in the context of a systematic asset management system that allows decision-making based on balance of risk and cost. The question is not only which NDE technique should be used, but also when and how the technique should be implemented to provide a cost-effective maintenance strategy. More efforts are needed to develop new or improve existing NDE techniques for more accurate, cost-effective and reliable assessment of utility poles and for better management of these assets.

FHWA’s Nondestructive Evaluation Validation Center: A National Resource

Since the inception of the National Bridge Inspection Program, much time and money have been invested in the development of nondestructive evaluation (NDE) techniques. These techniques provide bridge inspectors with tools to more accurately assess the condition of highway structures. These nondestructive evaluation methods, however, are sometimes used without a clear understanding of the factors that affect their reliability, performance, and implementation. Before NDE systems can be used with confidence, the technology and methods must be validated and all factors affecting their reliability identified. In response to this need, FHWA established the NDE Validation Center to identify and evaluate the factors affecting NDE reliability and performance. The NDE Validation Center uses a series of unique resources to evaluate and assess the factors affecting the reliability and performance of NDE systems. The Validation Center is based out of a combination of specialized laboratory and office space located at the Turner Fairbank Highway Research Center in McLean, Virginia. To supplement the capabilities of the laboratory facilities, a series of bridges located in northern Virginia and eastern Pennsylvania is used to conduct field investigations. Additionally, a collection of component test specimens is used in various test programs. The NDE Validation Center is a national resource for the evaluation of existing and emerging NDE techniques. The resources of the NDE Validation Center are available to federal and state agencies, the academic community, and industry. The Validation Center was developed to perform critical evaluations of NDE technologies and to provide a source of information and guidance to users and developers of NDE systems.

Development of In-Service Inspection Priorities for Pressurized Water Reactor High-Pressure Injection System Components

The multiyear program entitled Nondestructive Evaluation Reliability for In-Service Inspection of Light Water Reactors, sponsored by the US Nuclear Regulatory Commission, is being conducted at the Pacific Northwest Laboratory. The goals of the program are to determine the reliability of current in-service inspection of pressure boundary systems and components and to develop recommendations that can ensure a suitably high inspection reliability. The long-term objective is to develop recommendations for improved in-service inspections. In meeting program objectives, a risk-based method has been developed to guide the development of inspection plans. The method uses results of probabilistic risk assessment and failure modes and effects analysis techniques to identify and prioritize the most risk-important systems and components for inspection at nuclear power plants. The Surry Nuclear Power Station Unit 1 was selected for demonstrating the methodology. The specific system addressed in this study was the high-pressure injection/recirculation (HPI/R) system. The results provide a risk-based ranking of components within the HPI/R system, which can be used to guide the development of improved inspection plans for nuclear power plants. This work will subsequently be used in supporting the revisions of the American Society of Mechanical Engineer's codes and standards.

Risk assessment in setting inservice inspection priorities at light water reactors

As part of the Nondestructive Evaluation Reliability Program, sponsored by the U.S. Nuclear Regulatory Commission, Pacific Northwest Laboratory is developing a method that uses risk-based approaches to establish inservice inspection plans for nuclear power plant components. The method first uses probabilistic risk assessment (PRA) results and Failure Modes and Effects Analysis (FEMA) techniques to identify and prioritize the most risk-important systems and components for inspection. The acceptable level of risk from structural failure for important systems and components is then apportioned as a small fraction of the total PRA estimated risk for core damage. This process determines the target (acceptable) risk and failure probability values for individual components. The Surry Unit 1 Nuclear Power Station was selected for pilot applications of the method. The specific systems addressed are the reactor pressure vessel, the reactor coolant, the low-pressure injection, and the auxiliary feedwater. The results provide a risk-based ranking of components within these systems and relate the target risk to target failure probability values for individual components. These results will be used to guide the development of improved inspection plans for nuclear power plants.

Development of In-Service Inspection Plans for Nuclear Components at the Surry Unit 1 Nuclear Power Station

As part of the nondestructive evaluation reliability program sponsored by the US Nuclear Regulatory Commission at Pacific Northwest Laboratory, a methodology has been developed for establishing in-service inspection priorities of nuclear power plant components. The method uses results of probabilistic risk assessment in conjunction with the techniques of failure modes and effects analysis to identify and prioritize the most risk-important systems and components for inspection at nuclear power plants. Surry nuclear power station unit 1 was selected for demonstrating the methodology. The specific systems selected for analysis were the reactor pressure vessel, the reactor coolant, the low pressure injection including the accumulators, and the auxiliary feedwater. The results provide a risk-based ranking of components that can be used to establish a prioritization of the components and a basis for developing improved in-service inspection plans at nuclear power plants.

Estimates of Rupture Probabilities for Nuclear Power Plant Components: Expert Judgment Elicitation

This paper reports that as part of the nondestructive evaluation reliability program sponsored by the U.S. Nuclear Regulatory Commission (NRC), Pacific Northwest Laboratory (PNL) developed a risk-based method for establishing inspection priorities for systems and components at nuclear power plants. In this method, the results of probabilistic risk assessment (PRA) are used to estimate the safety consequences of component failures. The method also requires estimates of the probabilities of structural failures. Since sufficient operating experience data and detailed fracture mechanics analyses are not available, an expert judgment elicitation is conducted to estimate component rupture probabilities. (An expert judgment process is generally adapted from the NRC severe accident risk program).

Probabilistic Risk Assessment Based Guidance for Piping In-Service Inspection

Some of the goals of the Nondestructive Evaluation Reliability Program sponsored by the U.S. Nuclear Regulatory Commission at Pacific Northwest Laboratory are to assess current inspection requirements for all pressure boundary systems and components, to determine whether improvements to the requirements are needed, and, if necessary, to develop recommendations for revising the American Society of Mechanical Engineers Boiler and Pressure Vessel Code and regulatory requirements. Part of the work performed in addressing this goal was the development and demonstration of a method to establish in-service inspection priorities through the use of probabilistic risk assessment (PRA) results. The Oconee-3 PRA and the observed weld failure data of the nuclear plants operating in the United States are used to identify and prioritize the most risk-important systems for inspection. Failure modes and effects analysis methodology is then used to identify and prioritize the most riskimportant piping sections of the Oconee-3 emergency feedwater system. Based on the results of this study, this method is demonstrated to be a useful tool for identifying systems and piping sections or welds that need to be inspected.