The ASME Boiler & Pressure Vessel Code Section XI Committee is currently developing a new Division 2 nuclear code entitled the “Reliability and Integrity Management (RIM) program,” with which one is able to arrive at a risk-informed, NDE-based engineering maintenance decision by estimating and managing all uncertainties for the entire life cycle including design, material selection, degradation processes, operation and non-destructive examination (NDE). This paper focuses on the uncertainty of the NDE methods employed for preservice and inservice inspections due to a large number of factors such as the NDE equipment type and age, the operator’s level and years of experience, the angle of probe, the flaw type, etc. In this paper, we describe three approaches with which uncertainty in NDE-risk-informed decision making can be quantified: (1) A regression model approach in analyzing round-robin experimental data such as the 1981–82 Piping Inspection Round Robin (PIRR), the 1986 Mini-Round Robin (MRR) on intergranular stress corrosion cracking (IGSCC) detection and sizing, and the 1989–90 international Programme for the Inspection of Steel Components III-Austenitic Steel Testing (PISC-AST). (2) A statistical design of experiments approach. (3) An expert knowledge elicitation approach. Based on a 2003 Pacific Northwest National Laboratory (PNNL) report by Heasler and Doctor (NUREG/CR-6795), we observe that the first approach utilized round robin studies that gave NDE uncertainty information on the state of the art of the NDE technology employed from the early 1980s to the early 1990s. This approach is very time-consuming and expensive to implement. The second approach is based on a design-of-experiments (DEX) of eight field inspection exercises for finding the length of a subsurface crack in a pressure vessel head using ultrasonic testing (UT), where five factors (operator’s service experience, UT machine age, cable length, probe angle, and plastic shim thickness), were chosen to quantify the sizing uncertainty of the UT method. The DEX approach is also time-consuming and costly, but has the advantage that it can be tailored to a specific defect-detection and defect-sizing problem. The third approach using an expert panel is the most efficient and least costly approach. Using the crack length results of the second approach, we introduce in this paper how the expert panel approach can be implemented with the application of a software package named the Sheffield Elicitation Framework (SHELF). The crack length estimation with uncertainty results of the three approaches are compared and discussed. Significance and limitations of the three uncertainty quantification approaches to risk assessment of NDE-based engineering decisions are presented and discussed.

The layered high-pressure hydrogen vessels are widely used in hydrogen refueling stations. The head of the high-pressure vessel is made of austenitic stainless steel, and has thick walls, a pipe with a small diameter on the top and a butt-weld structure. It’s difficult to detect effectively, using conventional methods in the inspection of the butt weld on the head. To effectively detect the weld joint, a detecting method was investigated using ultrasonic phased array technique from the inner surface of the small-diameter pipe. By axial focusing and circumferential focusing, the ultrasonic field in austenitic stainless steel could satisfy the specific inspection requirement. Some ultrasonic field analysis and defect detection simulations were carried out with CIVA, for artificial defects such as side-drilled holes. Meanwhile, the test specimen and probe were designed and manufactured, and experiments were conducted. Furthermore, the feasibility and rationality of the detecting method and the simulation method were verified, and the detecting process parameters were determined.

Reliable and accurate NDE (Non-Destructive Evaluation) techniques are required to conduct FFS (Fitness-For-Service) assessments for crack type flaws in equipment. FFS assessments rely on certain flaw detection and flaw sizing assumptions which can only be provided through NDE. The detection and sizing provided by the NDE work is highly dependent on both inspection methodology (e.g., operator, equipment, and procedure) as well as the specific component and application (e.g., part thickness and geometry, flaw type, damage mechanism, etc.). Therefore, the accurate determination of these detection and sizing assumptions requires thorough consideration, modeling, assessments, and determination by NDE specialists. This paper will describe factors that affect flaw detection and sizing results by NDE, the use of synthetic flaws to assess and improve NDE performance, the verified performance of advanced NDE techniques on natural flaws, and the integration of NDE performance results with FFS assessments.

Reactor pressure vessels (RPVs) in nuclear power plants are important components that prevent non-ductile fracture considering neutron irradiation embrittlement as aging degradation and several types of transients. An analysis code called PASCAL for assessing failure frequencies of RPVs based on probabilistic fracture mechanics has been developed by the Japan Atomic Energy Agency. In failure frequency analyses, flaw size distribution in RPVs is one of the most important parameters, and it is determined by considering possible flaws generated during fabrication and the flaw-detection capabilities of nondestructive examinations (NDEs). Flaw-detection capabilities of NDEs are represented as probability of detection (POD) curves related to flaw sizes. In this study, the effects of NDEs on failure frequencies of RPVs are evaluated using PASCAL considering simplified POD curves in terms of minimum detectable flaw size, the smallest probability of non-detection (PND), and flaw size where POD value reaches the smallest PND.

Ultrasonic guided wave technology combined with sparse transducer array provides an efficient and relatively cost-effective means of defect detection and monitoring for rapid interrogation of large in plate-like structures. However, imaging algorithm used baseline subtraction methods may be compromised under mismatched environment and operational conditions. A defect location method based on forward-scattering wave and fuzzy c-means clustering is proposed in this paper. The distance coefficient including location information between sensor pair using exciting and receiving signal and defect is defined to explain feasibility of the method proposed in this paper. A Parallel line array is evaluated using the method to locate defect. Experimental results show that the proposed method can effectively reduce the influence of mismatched environment and operational conditions on the defect location.

The rules on fitness for service for nuclear power plants of JSME are applied for flaw evaluation after detecting defects in the operating nuclear plants in Japan. The rules mainly focus on simple geometry such as straight pipes or vessels and do not provide the evaluation procedure for complex structures. The authors made a draft of flaw acceptance rule for J-groove weld of a bottom mounted instrumentation nozzle at application of the cap repair. The rule contains flaw modeling, fatigue and SCC crack growth calculation and flaw instability assessment. After detecting a defect on a J-groove weld, a flaw will be modeled in the whole of J-groove weld region because of fast SCC crack propagation in the weld region. Due to complex configuration of the evaluation location, FE analysis is needed for obtaining stress intensity factors ( K s) to calculate the crack growth and flaw instability. The proposed rule has a guidance for K calculation by FE analysis with the aim of decreasing dependence of individuals for calculation. The authors performed benchmark analyses to confirm the guidance applicability. The calculation results by three participants agreed within several percent.

The Pacific Northwest National Laboratory (PNNL) has been involved with nondestructive examination of coarse-grained cast austenitic stainless steel (CASS) components for over 30 years. More recent work has focused on mapping the ultrasonic sound fields generated by low-frequency phased-array probes that are typically used for the evaluation of CASS materials for flaw detection and characterization. The casting process results in the formation of large-grained material microstructures that are nonhomogeneous and anisotropic. The propagation of ultrasonic energy for examination of these materials results in scattering, partitioning, and redirection of these sound fields. The work reported here provides an assessment of sound field formation in these materials and provides recommendations on ultrasonic inspection parameters for flaw detection in CASS components. Confirmatory research conducted at PNNL consisted of acquiring sound field data from four CASS components containing columnar, equiaxed, and banded grain structures, and a fine-grained wrought stainless steel specimen used for benchmarking. Phased-array probes with center frequencies of 0.5, 0.8, and 1.0 MHz were used for sound field formation, with a pinducer being raster scanned over the end of the specimen face to capture the sound field energy. Data were collected at multiple refracted and skew angles, and imaging performed for analyses. A 6.4-mm (0.25-in.) thick slice of material was removed from the end of the CASS components and the beam mapping repeated. This slicing and mapping sequence was performed three times to produce multiple beam images through the specimens. Grain sizes were also measured at each mapped specimen face and compared to sound field characteristics. The acquired sound field images were characterized in terms of beam redirection from the theoretical position, beam scatter or coherence, and partitioning. A comparison of the fine-grained beam data to the CASS data is made and conclusions are presented.

Welded structures are examined nondestructively, particularly for critical applications where weld failure can be catastrophic, such as in pressure vessels, load-bearing structural members, and power plants. Ultrasonic Testing (UT) is used in the examination of welds in thinner and thicker gauge materials where the size and location of the flaws are important to detect and interpret. Despite the advantages of the ultrasonic technique, the classification of defects based on ultrasonic signals is still frequently questioned, since the analysis and the identification of defect types depend exclusively on the experience and knowledge of the operator. The problem becomes more acute when high inspection rates, high probability of detection, and low number of false results are required. Thus, the correct classification of the type of flaw present in the material reduces measurement errors, increasing the confidence in the test and consequently the safety of the welded structure during service. In the present study, a new algorithm that allows for the detection and measurement of the length and type of weld defects is proposed. The system is based on a coupled dynamic and static patterns in an A-Scan and uses the defects cited in DIN EN 1713 standard as reference for evaluation. The proposed expert system has been evaluated and validated by examining several specimens containing various types of natural (non-artificial) defects identified in the mentioned standard. The results indicate that, the proposed algorithm has a clear potential in automatic defect detection and presents many advantages to the manual method for defect detection and characterization.

Ultrasonic guided wave technology is presented as a new non-destructive pipeline inspection method for its rapid, long distance inspection and applied to special pipelines which are inaccessible by other conventional NDT methods. It can be widely used in the field of long range pipeline inspection. Dispersion and attenuation characteristics of torsional modes of ultrasonic guided wave in pipeline are presented. Propagation characteristics of T (0, 1) mode at different frequencies are studied. T (0, 1) mode excited by utilizing the magnetostrictive ultrasonic guided wave detection system is applied to detect the defects of pipeline. It can be concluded that the surface condition of the pipeline, the T (0, 1) mode excitation of different patterns and frequency have great effects on defect detection and the distance of guided wave propagation. Multiple factors should be considered to select the optimal frequency and excitation patterns as pipeline inspection in field.

In recent years, substantial research has been devoted to monitoring and predicting performance degradations in real-world complex systems within large entities such as nuclear power plants, electrical grids, and distributed computing systems. Special challenges are posed by the fact that such systems operate in uncertain environments, are highly dynamic, and exhibit emergent behaviors that can lead to catastrophic failure. Discrete Time Markov chains (DTMCs) provide important tools for analysis of such systems, because they represent dynamic behavior succinctly, provide a means to measure uncertainty, and can be used to make quantitative measurements of the potential for change to system performance. Moreover, DTMCs can be extended to be time-inhomogeneous, i.e. to represent behavior that varies over long durations. To date, DTMCs have been proposed for tasks such as fault detection and long-term condition equipment monitoring in real-world complex systems. However, the scope of these models has generally been restricted to describing states and state transitions that directly concern fault conditions or states of degradation. Less work has been done on using DTMCs to represent a more complete range of states a system may enter into during normal operation. Of special interest are sequences of states that involve failure scenarios, in which a system evolves from a normal operating state into undesirable state that leads to widespread performance degradation. Unfortunately, use of large DTMCs often involves large search spaces, a problem which in part motivates our work. This paper describes progress made on developing an approach for using larger, more detailed DTMC models of operational complex systems to uncover potential failure scenarios. The approach uses a combination of methods to perturb a DTMC, simulate alternative system evolutions, and identify scenarios in which a system proceeds from normal operation to failure. Key to the approach is the use of graph theory techniques to reduce the size of the search space involved in exploring alternative behaviors. We show how graph theory techniques can be used to identify critical state transitions which can be perturbed to simulate performance degradation. Using critical transitions, it is also possible to estimate the rate of performance degradation and to understand how this rate is likely to change in response to increased failure incidence. Examples are provided of the use of this approach on a DTMC of significant size to identify failure scenarios in a distributed resource allocation system.

A major thrust in the past 20 years has been to upgrade nondestructive examinations (NDE) for use in inservice inspection (ISI) programs to more effectively manage degradation at operating nuclear power plants. Risk-informed ISI (RI-ISI) is one of the outcomes of this work, and this approach relies heavily on the reliability of NDE, when properly applied, to detect sources of expected degradation. There have been a number of improvements in the reliability of NDE, specifically in ultrasonic testing (UT), through training of examiners, and improved equipment and procedure development. However, the most significant improvements in UT were derived by moving from prescriptive requirements to performance based requirements. Even with these substantial improvements, NDE contains significant uncertainties and RI-ISI programs need to address and accommodate this factor. As part of the work that PNNL is conducting for the U. S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, we are examining the impact of these uncertainties on the effectiveness of RI-ISI programs. One of the primary objectives of in-service inspection, including a RI-ISI program, is to manage potential degradation that may occur, but that had not been foreseen through previous operating experience. However, RI-ISI programs in the U.S are primarily based on history, looking back at past failures in the operating fleet. Therefore, RI-ISI may not adequately manage degradation events that are yet to occur, such as those that may have a long incubation (initiation) time, but a potentially fast growth rate. For this reason, RI-ISI will always be reactive to such failure events. Successful ISI needs to determine what NDE is required, when and how frequently it needs to be applied, how effective the NDE must be and where the NDE needs to be applied. Both flaw detection and accurate characterization need to be addressed. This paper will examine the reliability and uncertainties of NDE, and how these may impact RI-ISI.

This paper addresses uncertainties in probabilistic fracture mechanics (PFM) calculations for pressure boundary components at commercial nuclear power plants. Such calculations can predict the probability that a component will have failed after a specified period of operation, but with large uncertainties that are difficult to quantify. PFM models only approximate details of as-built components as well as actual operating conditions over the lifetime of the component. Statistical distributions used as inputs to the calculations are subject to uncertainties, which also results in large uncertainties in calculated failure probabilities. This paper describes from the author’s perspective various uncertainties that are associated with PFM calculations. Efforts to quantify PFM uncertainties are described along with their impacts on calculated failure probabilities. Many uncertainties are explicitly addressed by statistical distributions for input parameters to the PFM models (e.g. crack growth rates, material strengths, probabilities of flaw detection, etc.). Other calculations have gone further by estimating uncertainties in the parameters of these statistical distributions along with uncertainties in parameters treated as deterministic inputs to the PFM models. Examples from the author’s experience with uncertainty analyses for pressure vessels and piping components are described.

Plant in the power generation, petrochemical and metals processing industries is subject to increasingly onerous operational and regulatory requirements. Where plant that operates at high temperature is involved, the costs associated with shutdown for planned or unplanned inspection to meet these requirements can be particularly high. The ability to perform condition monitoring or flaw detection at on-line plant temperatures would enable plant to remain in operation for longer periods, reduce the risk of damage from thermal cycling associated with periodic shutdowns and allow shutdowns to be completed more quickly. The associated minimizing of the loss of revenue caused by frequent and lengthy shutdowns is a highly attractive proposition to the plant operators. This paper reports on progress in the Ultrasmart Project, which is being undertaken by a consortium of UK companies and aims to address the problems associated with performing ultrasonic inspection on pressure vessels and piping at temperatures exceeding ∼350°C. A brief review of the state of current industry capabilities is given and then details of the developments investigated within Ultrasmart are reported and discussed. These include: • Liquid cooled transducers and automated scanning mechanisms suitable for deployment on components with surface temperatures up to ∼500°C. • Permanently mounted piezoelectric transducers suitable for long term flaw growth or component thickness monitoring at temperatures up to ∼750°C. • Techniques, procedures and protocols necessary to achieve reliable and quantifiable inspection capability at high temperatures. • Use of a novel non-resonant thin film Aluminum Nitride (AlN) transducer for in-situ component monitoring.

Welds have been inspected by radiography for years, but this technology has major drawbacks: low detection rates for critical planar defects (i.e. cracks and lack of fusion), subjective interpretation, no vertical sizing capability, significant safety hazards, licensing issues, plant closures, and is generally slow. For decades, the main alternative was manual ultrasonics, which is also slow, subjective and normally has little hardcopy record. New technology and techniques are now available for improved weld inspections, specifically phased array technology and diffraction techniques. Phased arrays are essentially the industrial version of medical ultrasound, but require a very different approach. In contrast to medical activities, industrial applications typically require a correctly angled beam, with large quantities of data, on variable component geometry, and the ability to save and image defects. All this capability is now packaged in a portable unit, which can be used for rapid and reliable weld inspections. Specifically, the OmniScan MX can now perform a single linear scan of the weld, while the instrumentation performs multiple scans at different angles simultaneously. In addition, phased arrays can perform unique scans, like S-scans (sectorial scans), record and display all data in “top, side, end” views or similar, and perform multi-mode scans. Phased arrays permit electronic rastering in many different modes, which saves considerable inspection time; for example, some estimates show that phased arrays are five or more times quicker than manual scanning. Besides being portable and requiring just a single operator, portable phased arrays are now economically competitive with other weld inspection techniques — and generally provide a much better inspection. The “new” techniques consist of forward and backward diffraction for sizing defects. In reality, both these techniques have been around for years, but new technology has made them more practical. Forward diffraction (TOFD or Time-Of-Flight Diffraction) is now well established, and has been demonstrated for many applications. For most weld inspections, TOFD just requires a single linear pass, with two transducers (or arrays) on either side of the weld. TOFD provides good sizing and defect detection in the midwall, though it has dead zones at the two surfaces. Generally, sizing with TOFD is significantly better than with amplitude techniques, but is limited to defects ∼3 mm and up. TOFD also has the great advantage that it is highly independent of defect orientation, unlike pulse echo techniques. Even better, phased arrays can perform both pulse echo and TOFD simultaneously during a single linear scan, so giving essentially a “complete” weld inspection. Another diffraction sizing technique which has received relatively little attention until recently is “tip back diffraction”. This approach uses the low amplitude signals reflected back from crack tips to size defects. Back diffraction has the great advantages that it is intuitive, and can size defects as small as ∼1 mm, which is generally better than TOFD. However, tip back diffraction has the major disadvantage that it is sometimes difficult to correctly distinguish the crack tips from other signals, and signal-to-noise ratio is usually poor. These two limitations are largely overcome by phased arrays; first, the imaging allows correct determination of the crack tip, and second, new piezo-composite arrays with focusing and filtering give significantly improved signal amplitudes. S-scan imaging can be performed with off-the-shelf phased array equipment. Some of the more advanced phased array techniques include: 2D and 1.5D arrays for improved beam shaping and focusing; curved arrays, also for better sizing; special TRL-PA (Transmit-Receive Longitudinal Wave-Phased Array) probes for austenitic steels; additional beams for special inspections. Examples of these inspections on welds will be given. Overall, a combination of phased arrays with TOFD or back diffraction allows the operator to perform cost-effective inspections with high reliability, repeatability, good defect sizing and full data storage.

Condition monitoring of rolling elements bearings is investigated in this paper. Recently [12, 13], we have developed a diagnosis procedure that combines a signal processing tool, i.e. Time Synchronous Averaging (TSA), and a pattern recognition method, i.e. Support Vector Machines (SVM), for bearing fault detection and prediction. As the generalization performance of the SVM-boundaries was strongly affected by the signal transmission path, this paper is then concerned with the integration of Spectral Kurtosis (SK) analysis in the diagnosis procedure to improve efficiency in such cases. We validate the use of both Time Synchronous Averaging and Spectral Kurtosis analysis, as signal processing tools that will automatically highlight bearing defect frequencies in the envelope spectrum. Twenty-one features (rms, peak, crest factor, band spectral energy, etc...) are extracted from the envelope of signals obtained from these two analyses and are used in the learning scheme. Results show that the generalization performance is less affected by the signal transmission path and the faulty bearing location, thus demonstrating that the modified diagnosis procedure can actually find some underlying patterns that are common to each type of bearing failure. The case-dependency of the support decision tool can therefore be reduced.

Recent advances in computer technology, internet communication networks, and finite element modeling and analysis capability have made it feasible for engineers to accelerate the feedback loop between the field inspectors of a structure or component for critical flaws by nondestructive evaluation (NDE) and the office engineers who do the damage assessment and recommendations for field action to prevent failure. For example, field inspection data of critical flaws can be transmitted to the office instantly via the internet, and the office engineer with a computer database of equipment geometry, material properties, past loading/deformation histories, and potential future loadings, can process the NDE data as input to a damage assessment model to simulate the equipment performance under a variety of loading conditions until its failure. Results of such simulations can be combined with engineering judgment to produce a specific recommendation for field action, which can also be transmitted to the field by the internet. In this paper, we describe a web-based NDE data analysis methodology to estimate the reliability of weld flaw detection, location, and sizing by using a public-domain statistical data analysis software named DATAPLOT and a ten-step sensitivity analysis of NDE data from a two-level fractional factorial orthogonal experimental design. A numerical example using the 1968 ultrasonic examination data of weld seam in PVRC test block 251J, and the 1984 sectioning data of 251J containing 15 implanted flaws, is presented and discussed.

Phased arrays offer significant technical advantages for weld inspections over conventional ultrasonics. The phased array beams can be steered, scanned, swept and focused electronically. Beam steering permits the selected beam angles to be optimized ultrasonically by orienting them perpendicular to the predicted defects, especially Lack of Fusion. Electronic (linear) scanning permits very rapid coverage of the welds. Beam steering (usually called sectorial or azimuthal scanning) can be used for mapping welds at appropriate angles to optimize Probability of Detection of defects. Electronic focusing permits optimizing the beam shape and size at the expected defect location, also to optimize Probability of Detection. Overall, the use of phased arrays permits optimizing defect detection while minimizing inspection time. The paper describes the application of phased arrays for inspecting pressure vessel welds. Phased arrays offer significant practical advantages over conventional automated inspections. Thick section weld inspections typically use the established “top, side, end” or “top, side, TOFD” views of the weld. Other displays can be used, e.g. strip charts for zone discrimination scanning of narrow gap welds. Special inspections can be easily performed with phased arrays, e.g. additional beams for extra coverage, multiple angles or inspection set-ups simultaneously, or special scans such as tandem probes. Different delivery systems and instrumentation can be assembled for any required scan. Fitness-For-Service inspections requiring high PoD and accurate sizing can be performed using upscale systems. These phased array inspections can be tailored to any known code requirements.

There is a need to analyze locomotive wheels for flank cracks in a non-destructive manner in order to prevent catastrophic failures. Flaw, shape, and size are desired parameters in establishing the quality of commercial tires. A variety of defects such as voids, inclusions, surface and internal cracks, or the like, must be discerned in order to prevent failure. This paper exhibits and compares the benefits of a number of different techniques used for flaw detection. Non-destructive evaluation (NDE) techniques used are magnetic particle inspection, dye penetrant, eddy current, electro-magnetic acoustic transducer (EMAT). The techniques vary in their ability to ascertain the flaw characteristics. Using a non-contact sensor such as the EMAT, to scan the wheels in an automated manner offers greater inspection speed at lower manpower. This paper reviews the basic concept of EMATs, introduces a recently developed technique for simulating EMAT performance by Finite Element calculation and features bench top results of waveform acquisition and signal-to-noise ratio dependence on lift-off. Next presented are calibration results for spark-eroded flaws in wheel sections for a variety of locations and sizes. Finally data are on flaw detection in a railroad service facility on several locomotives with wheels spinning at speeds up to 40 meters/minute. Results for both artificial and actual flaws are shown.

Cracks by SCC (stress corrosion cracking) and high cycle fatigue were detected at the welded joints of nickel based alloy of reactor vessel, pressurizer and core internal of nuclear power plants in recent years. To ensure the integrity of plants, it is necessary to improve NDT (non-destructive testing) techniques for reliable detection and evaluation of defects in the nickel-base alloy. Basic studies on the flaw detection and characterization by eddy current examination of inconel, a typical nickel-base alloy, are carried out. Specimens made of inconel and inconel weld metal are prepared, fabricated with EDM (Electro-Discharge Machining) notches and fatigue cracks. The detecting and sizing capability of eddy current method is investigated through analytical and experimental approaches. Numerical analysis helps in choosing an appropriate probe and examination condition, and evaluating a crack from the measured signals. All or part of a planar crack is reconstructed using an inversion approach. The result from ECT (eddy current testing) is compared with that of UT (ultrasonic testing). The research presented in this paper shows that by choosing a proper testing situation, eddy current examination is feasible for the detection and sizing of surface-breaking cracks in inconel welds.

Liquid Penetrant Test (PT) and Magnetic Particle Test (MT) are widely used in industry to detect surface defects. It is extremely important to maintain the repeatability and reproducibility of PT and MT so that they are able to detect any defect that might affect the quality of a product, especially the weld joints of welded structures. In the present paper, calibration methods for visual conditions for PT and MT are proposed with the use of a visual resolution gauge. In addition, a “PT/MT support System” applying digital image processing techniques, which enables us to perform “Remote Inspection” is proposed. A visual resolution gauge is a transparent plate on which line pairs are printed with equivalent hue to the indications of PT and MT, which ensures proper resolution for visual testing. In Japan, the standard for calibration methods for visual conditions using these resolution gauges for PT and MT were published in the Japanese Industrial Standards (JIS) Z 2340 in 2002. By applying these visual resolution gauges, we developed a “PT/MT support system.” In this system, the PT or MT digital images, which are captured by digital camera with resolution gauges, are converted into hue and saturation data by image processing. These images are then divided into two categories of defects and false indications. This is useful in detecting defects and establishing standard evaluation criteria. Furthermore, this will also enable “Remote Inspection,” which is a method in which PT and MT digital images are observed from remote place (as opposed to direct observations). This enables the possibility of inspections being performed from remote places and manufacturers, inspectors, customers, and government inspectors in remote areas can share the inspection results as electronic data.