1000 resultados para Nondestructive test


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The compressive strength of concrete is an important factor in the design of concrete structures and pavements. To assure the quality of the concrete placed at the project, concrete compressive cylinders are made at the jobsite. These cylinders undergo a destructive test to determine their compressive strength. However, the determination of concrete compressive strength of the concrete actually in the structure or pavement is frequently desirable. For this reason, a nondestructive test of the concrete is required. A nondestructive test of concrete compressive strength should be economical, easily performed by field personnel, and capable of producing accurate, reproducible results. The nondestructive test should be capable of detecting the extent of poor concrete in a pavement or structure due to improper handling, placement, or variations in mixing or materials.

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A round robin program zoos conducted to assess the ability of three different X-radiographic systems for imaging internal fatigue cracks in riveted lap joints of composite glass reinforced fiber/metal laminate. From an engineering perspective, conventional film radiography and direct radiography have produced the best results, identifying and characterizing in detail internal damage on metallic faying surfaces of fastened glass reinforced fiber/metal laminate joints. On the other hand, computed radiographic images presented large projected geometric distortions and feature shifts due to the angular incident radiation beam, disclosing only partial internal cracking patterns.

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The purpose of this research was to summarize existing nondestructive test methods that have the potential to be used to detect materials-related distress (MRD) in concrete pavements. The various nondestructive test methods were then subjected to selection criteria that helped to reduce the size of the list so that specific techniques could be investigated in more detail. The main test methods that were determined to be applicable to this study included two stress-wave propagation techniques (impact-echo and spectral analysis of surface waves techniques), infrared thermography, ground penetrating radar (GPR), and visual inspection. The GPR technique was selected for a preliminary round of “proof of concept” trials. GPR surveys were carried out over a variety of portland cement concrete pavements for this study using two different systems. One of the systems was a state-of-the-art GPR system that allowed data to be collected at highway speeds. The other system was a less sophisticated system that was commercially available. Surveys conducted with both sets of equipment have produced test results capable of identifying subsurface distress in two of the three sites that exhibited internal cracking due to MRD. Both systems failed to detect distress in a single pavement that exhibited extensive cracking. Both systems correctly indicated that the control pavement exhibited negligible evidence of distress. The initial positive results presented here indicate that a more thorough study (incorporating refinements to the system, data collection, and analysis) is needed. Improvements in the results will be dependent upon defining the optimum number and arrangement of GPR antennas to detect the most common problems in Iowa pavements. In addition, refining highfrequency antenna response characteristics will be a crucial step toward providing an optimum GPR system for detecting materialsrelated distress.

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The Road Rater is a dynamic deflection measuring appa-ratus for flexible base pavements. The basic operating principle of the Road Rater is to impart a dynamic loading and measure the resultant movement of the pavement with velocity sensors. This data, when properly adjusted for temperature by use of a nomograph included in this report, can be used to determine pavement life expectancy and estimate overlay thickness required. Road Rater testing will be conducted in the spring, when pave-ments are in their weakest condition, until seasonal correction factors can be developed. The Road Rater does not have sufficient ram weight to effectively evaluate load carrying capacity of rigid pavements. All rigid pavements react similarly to Road Rater testing and generally deflect from 0.65 to 1.30 mils. Research will be continued to evaluate rigid pavements with the Road Rater, however. The Road Rater has proven to be a reliable, trouble free pavement evaluation machine. The deflection apparatus was originally front-mounted, but was rear-mounted during the winter of 1977-78. Since that time, van handling has greatly improved, and front suspension parts are no longer overstressed due to improper weight distribution. The Road Rater provides a fast, economical, nondestructive test method to evaluate flexible pavements. Road Rater test data can be used to predict pavement life, set priorities for asphaltic concrete resurfacing, and design asphaltic concrete overlays. Temperature and seasonal variations significantly affect Road Rater deflection readings and must be considered. A nomograph included in this report adjusts for temperature, but does not correct for seasonal effect. Road Rater testing will be conducted in the spring until seasonal correction factors can be developed. The Road Rater has not successfully evaluated rigid pavements, but research will continue in this area. 1. Recommendations for continuing Road Rater research, evaluation and application are as follows:A computer program should be established to reduce Road Rater raw data (Range and Sensor reading) to HR-178 Road Rater Dynamic Deflections For Determining Structural Rating Of Flexible Pavements mean deflection (mils) and/or structural rating. This computer printout would be similar to present friction testing printouts, and would greatly reduce Road Rater data reduction manpower needs and costs. 2. Seasonal variation study should continue to develop seasonal correction factors. Seasonal test roads will be studied concurrently with routine testing during 1979 to develop this relationship. All Road Rater testing will be conducted in the spring until the seasonal relationship is established. 3. An asphaltic concrete overlay design method should be established based on Road Rater de-flection readings. The AASHTO Interim Guide for Design of Pavement Structures 1972 will be used as a base document for this study. 4. AASHTO Structural numbers should be compared to Road Rater Structural Ratings during 1979 on asphaltic concrete overlay projects. This analysis will enable us to refine Road Rater evaluation of flexible pavements. Roads will be tested before resurfacing and several months

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A new test method based on multipass scratch testing has been developed for evaluating the mechanical and tribological properties of thin, hard coatings. The proposed test method uses a pin-on-disc tribometer and during testing a Rockwell C diamond stylus is used as the “pin” and loaded against the rotating coated sample. The influence of normal load on the number of cycles to coating damage is investigated and the resulting coating damage mechanisms are evaluated by posttest scanning electron microscopy. The present study presents the test method by evaluating the performance of Ti0.86Si0.14N, Ti0.34Al0.66N, and (Al0.7Cr0.3)2O3 coatings deposited by cathodic arc evaporation on cemented carbide inserts. The results show that the test method is quick, simple, and reproducible and can preferably be used to obtain relevant data concerning the fatigue, wear, chipping, and spalling characteristics of different coating-substrate composites. The test method can be used as a virtually nondestructive test and, for example, be used to evaluate the fatigue and wear resistance as well as the cohesive and adhesive interfacial strength of coated cemented carbide inserts prior to cutting tests.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Measuring the polarization of a single photon typically results in its destruction. We propose, demonstrate, and completely characterize a quantum nondemolition (QND) scheme for realizing such a measurement nondestructively. This scheme uses only linear optics and photodetection of ancillary modes to induce a strong nonlinearity at the single-photon level, nondeterministically. We vary this QND measurement continuously into the weak regime and use it to perform a nondestructive test of complementarity in quantum mechanics. Our scheme realizes the most advanced general measurement of a qubit to date: it is nondestructive, can be made in any basis, and with arbitrary strength.

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X-ray computed tomography (CT) refers to the cross-sectional imaging of an object measuring the transmitted radiation at different directions. In this work, we describe the development of a low cost micro-CT X-ray scanner that is being developed for nondestructive testing. This tomograph operates using a microfocus X-ray source and contains a silicon photodiode as detectors. The performance of the system, by its spatial resolution, has been estimated through its Modulation Transfer Function - MTF and the obtained value at 10% of MTF is 661 μm. It was built as a general purpose nondestructive testing device. © 2009 American Institute of Physics.

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National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.

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Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Engenharia Clínica)

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RESUME Dès le printemps 2004, la construction d'une 2ème ligne de métro est entreprise dans la ville de Lausanne en Suisse. En reliant Ouchy, au bord du lac Léman (alt. 373 m) à Epalinges (alt. 711 m), le nouveau métro "M2" traversera dès 2008 l'agglomération lausannoise du Sud au Nord sur une distance de 6 km. Depuis l'avant-projet, en 1999, une grande quantité de données géologiques a été récolté et de nombreux forages exécutés sur le site. Ceci nous a donné une occasion unique d'entreprendre une étude de microgravimétrique urbaine de détail. Le mode de creusement du tunnel dépend fortement des matériaux à excaver et il est classiquement du domaine du géologue, avec ses connaissances de la géologie régionale et de la stratigraphie des forages, de fournir à l'ingénieur un modèle géologique. Ce modèle indiquera dans ce cas l'épaisseur des terrains meubles qui recouvrent le soubassement rocheux. La représentativité spatiale d'une information très localisée, comme celle d'un forage, est d'autant plus compliquée que le détail recherché est petit. C'est à ce moment là que la prospection géophysique, plus spécialement gravimétrique, peut apporter des informations complémentaires déterminantes pour régionaliser les données ponctuelles des forages. La microgravimétrie en milieu urbain implique de corriger avec soin les perturbations gravifiques sur la mesure de la pesanteur dues aux effets de la topographie, des bâtiments et des caves afin d'isoler l'effet gravifique dû exclusivement à l'épaisseur du remplissage des terrains meubles. Tenant compte de l'intensité des corrections topographiques en milieu urbain, nous avons donné une grande importance aux sous-sols, leurs effets gravifiques pouvant atteindre l'ordre du dixième de mGal. Nous avons donc intégré ces corrections celle de topographie et traité les effets des bâtiments de manière indépendante. Nous avons inclus dans le modèle numérique de terrain (MNT) la chaussée et les sous-sols afin de construire un modèle numérique de terrain urbain. Nous utiliserons un nouvel acronyme « MNTU »pour décrire ce modèle. Nous proposons d'établir des cartes de corrections topographiques préalables, basées sur les données à disposition fournies par le cadastre en faisant des hypothèses sur la profondeur des sous-sols et la hauteur des bâtiments. Les deux zones de test choisies sont caractéristiques des différents types d'urbanisation présente à Lausanne et se révèlent par conséquent très intéressantes pour élaborer une méthodologie globale de la microgravimétrie urbaine. Le but était d'évaluer l'épaisseur du remplissage morainique sur un fond rocheux molassique se situant à une profondeur variable de quelques mètres à une trentaine de mètres et d'en établir une coupe dans l'axe du futur tracé du métro. Les résultats des modélisations se sont révélés très convaincants en détectant des zones qui diffèrent sensiblement du modèle géologique d'avant projet. Nous avons également démontré que l'application de cette méthode géophysique, non destructive, est à même de limiter le nombre de sondages mécaniques lors de l'avant-projet et du projet définitif, ce qui peut limiter à la fois les coûts et le dérangement engendré par ces travaux de surface. L'adaptabilité de la technique gravimétrique permet d'intervenir dans toutes les différentes phases d'un projet de génie civil comme celui de la construction d'un métro en souterrain. KURZFASSUNG Seit dem Frühling 2004 ist in der Stadt Lausanne (Schweiz) die neue U-Bahn "M2" in Konstruktion. Diese soll auf 6 km Länge die Lausanner Agglomeration von Süd nach Nord durchqueren. Die dem Projekt zu Grunde liegende technische Planung sieht vor, daß die Bahnlinie hauptsächlich in der Molasse angesiedelt sein wird. Seit dem Vorentwurf (1999) ist eine große Anzahl geologischer Angaben gesammelt worden. Daraus ergab sich die einmalige Gelegenheit, die Informationen aus den damit verbundenen zahlreichen Bohrungen zu einer detaillierten mikrogravimetrischen Studie der Stadt Lausanne zu erweitern und zu vervollständigen. Das Ziel bestand darin, die Mächtigkeit der die Molasseüberdeckenden Moräneablagerung abzuschätzen, um eine entsprechendes geologisches Profile entlang der künftigen Bahnlinie zu erstellen. Weiterhin sollte gezeigt werden, daß die Anwendung dieser nicht-invasiven geophysikalischen Methode es ermöglicht, die Anzahl der benötigten Bohrungen sowohl in der Pilotphase wie auch im endgültigen Projekt zu reduzieren, was zu wesentlichen finanziellen Einsparungen in der Ausführung des Werkes beitragen würde. Die beiden in dieser Studie bearbeiteten Testzonen befinden sich im Nordteil und im Stadtzentrum von Lausanne und sind durch eine unterschiedliche Urbanisierung charakterisiert. Das anstehende Gestein liegt in verschiedenen Tiefen: von einigen Metern bis zu etwa dreißig Metern. Diese Zonen weisen alle Schwierigkeiten einer urbanen Bebauung mit hoher Verkehrsdichte auf und waren daher massgebend bei der Ausarbeitung einer globalen mikrogravimetrischen Methodologie für die Stadt Lausanne. Die so entwickelte Technik ermöglicht, die störenden Auswirkungen der Topographie, der Gebäude, der Keller und der Öffentlichen Infrastrukturen sorgfältig zu korrigieren, um so die ausschließlich auf die Mächtigkeit des Lockergesteins zurückzuführenden Effekte zu isolieren. In Bezug auf die Intensität der Auswirkungen der topographischen Korrekturen im Stadtgebiet wurde den Untergeschossen eine besonders grosse Bedeutung zugemessen da die entsprechenden Schwerkrafteffekte eine Grösse von rund einem Zehntel mGal erreichen können. Wir schlagen deshalb vor, vorläufige Karten der topographischen Korrekturen zu erstellen. Diese Korrekturen basieren auf den uns vom Katasterplan gelieferten Daten und einigen Hypothesen bezüglich der Tiefe der Untergeschosse und der Höhe der Gebäude. Die Verfügbarkeit einer derartigen Karte vor der eigentlichen gravimetrischen Messkampagne würde uns erlauben, die Position der Meßstationen besser zu wählen. Wir sahen zudem, daß ein entsprechenden a priori Filter benutzt werden kann, wenn die Form und die Intensität der Anomalie offensichtlich dem entsprechenden Gebäude zugeordnet werden können. Diese Strategie muß jedoch mit Vorsicht angewandt werden, denn falls weitere Anomalien dazukommen, können bedeutende Verschiebungen durch Übèrlagerungen der Schwerewirkung verschiedener Strukturen entstehen. Die Ergebnisse der Modellierung haben sich als sehr überzeugend erwiesen, da sie im Voraus unbekannte sensible Zonen korrekt identifiziert haben. Die Anwendbarkeit der in dieser Arbeit entwickelten gravimetrischen Technik ermöglicht es, während allen Phasen eines Grossbauprojekts, wie zum Beispiel bei der Konstruktion einer unterirdischen U-Bahn, einzugreifen. ABSTRACT Since Spring of 2004 a new metro line has been under construction in the city of Lausanne in Switzerland. The new line, the M2, will be 6 km long and will traverse the city from south to north. The civil engineering project determined that the line would be located primarily in the Molasse. Since the preparatory project in 1999, a great quantity of geological data has been collected, and the many drillings made on the site have proved to be a unique opportunity to undertake a study of urban microgravimetry. The goal was to evaluate the thickness of the morainic filling over the molassic bedrock, and to establish a section along the axis of the future line. It then had to be shown that the application of this nondestructive geophysical method could reduce the number of mechanical surveys required both for a preparatory and a definitive project, which would lead to real savings in the realization of a civil engineering project. The two test zones chosen, one in the northern part of the city and one in the city centre, are characterised by various types of urbanisation. Bedrock is at a depth varying from a few metres to about thirty metres. These zones well exemplify the various difficulties encountered in an urban environment and are therefore very interesting for the development of an overall methodology of urban microgravimetry. Microgravimetry in an urban environment requires careful corrections for gravific disturbances due to the effects of topography, buildings, cellars, and the infrastructure of distribution networks, in order to isolate the gravific effect due exclusively to the thickness of loose soil filling. Bearing in mind the intensity of the topographic corrections in an urban environment, we gave particular importance to basements. Their gravific effects can reach the order of one tenth of one meal, and can influence above all the precision of the Bouguer anomaly. We propose to establish preliminary topographic correction charts based on data provided to us by the land register, by making assumptions on the depths of basements and the heights of buildings. Availability of this chart previous to a gravimetry campaign would enable us to choose optimum measuring sites. We have also seen that an a priori filter can be used when the form and the intensity of the anomaly correspond visually to the corresponding building. This strategy must be used with caution because if other anomalies are to be associated, important shifts can be generated by the superposition of the effects of different structures. The results of the model have proved to be very convincing in detecting previously unknown sensitive zones. The adaptability of the gravimetry technique allows for application in all phases of a civil engineering project such as the construction of an underground metro line. RIASSUNTO Dalla primavera 2004 una nuova linea metropolitana é in costruzione nella città di Losanna in Svizzera. La nuova metropolitana "M2" traverserà per la lunghezza di 6 km il centro urbano di Losanna da sud a nord. II progetto d'ingegneria civile prevedeva un tracciato situato essenzialmente nel fondo roccioso arenaceo terziario (molassa). Dalla redazione del progetto preliminare, avvenuta nel 1999, una grande quantità di dati geologici sono stati raccolti e sono stati eseguiti numerosi sondaggi. Questo sì é presentato come un'occasione unica per mettere a punto uno studio microgravimetrico in ambiente urbano con lo scopo di valutare lo spessore dei terreni sciolti di origine glaciale che ricoprono il fondo roccioso di molassa e di mettere in evidenza come l'applicazione di questo metodo geofisico non distruttivo possa limitare il numero di sondaggi meccanici nella fase di progetto preliminare ed esecutivo con conseguente reale risparmio economico nella realizzazione di una tale opera. Le due zone di test sono situate una nella zona nord e la seconda nel centro storico di Losanna e sono caratterizzate da stili architettonici differenti. II fondo roccioso é situato ad una profondità variabile da qualche metro ad una trentina. Queste due zone sembrano ben rappresentare tutte le difficoltà di un ambiente urbano e ben si prestano per elaborare una metodologia globale per la microgravimetria in ambiente urbano. L'applicazione di questa tecnica nell'ambiente suddetto implica la correzione attenta delle perturbazioni sulla misura dell'accelerazione gravitazionale, causate dalla topografia, gli edifici, le cantine e le infrastrutture dei sottoservizi, per ben isolare il segnale esclusivamente causato dallo spessore dei terreni sciolti. Tenuto conto, dell'intensità delle correzioni topografiche, abbiamo dato grande importanza alle cantine, poiché il loro effetto sulle misure può raggiungere il decimo di mGal. Proponiamo quindi di redigere una carta delle correzioni topografiche preliminare all'acquisizione, facendo delle ipotesi sulla profondità delle cantine e sull'altezza degli edifici, sulla base delle planimetrie catastali. L'analisi di questa carta permetterà di scegliere le posizioni più adatte per le stazioni gravimetriche. Abbiamo anche osservato che un filtro a priori, qualora la forma e l'intensità dell'anomalia fosse facilmente riconducibile in maniera visuale ad un edificio, possa essere efficace. Tuttavia questa strategia deve essere utilizzata con precauzione, poiché può introdurre uno scarto, qualora più anomalie, dovute a differenti strutture, si sovrappongano. I risultati delle modellizzazioni si sono rivelati convincenti, evidenziando zone sensibili non conosciute preventivamente. L'adattabilità della tecnica gravimetrica ha mostrato di poter intervenire in differenti fasi di un progetto di ingegneria civile, quale è quella di un'opera in sotterraneo.

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Premature failure of concrete pavement contraction joint seals is an ongoing and costly problem for the Iowa Department of Transportation. Several joint seal test sections consisting of variations in sawing methods, joint cleaning techniques, sealant installation, and sealant types have been established over the past few years. Laboratory analysis and field inspections were done as a part of the tests, and core samples were taken for laboratory adhesion pull tests. Such methods often cover specifically small areas and may not expose hidden failures. Some tests are also labor-intensive and destructive, especially that of coring. An innovative, nondestructive, broad coverage joint seal tester that yields quick results has been designed and developed for evaluation of pavement joint seal performance. The Iowa vacuum joint seal tester (IA-VAC) applies a low vacuum above a joint seal that has been spray-covered with a foaming water solution. Any unsealed area or leak that exists along the joint will become quickly and clearly visible by the development of bubbles at the leak point. By analyzing the results from the IA-VAC tests, information on the number and types of leaks can be obtained; such information will help identify the source of the problem and direct efforts toward a solution.

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Wiss, Janney, Elstner Associates, Inc. (WJE) evaluated potential nondestructive evaluation (NDE) methodologies that may be effective in 1) identifying internal defects within slip formed concrete barriers and 2) assessing the corrosion condition of barrier dowel bars. The evaluation was requested by the Bridge Maintenance and Inspection Unit of the Iowa Department of Transportation (IaDOT) and the Bureau of Bridges and Structures of the Illinois Department of Transportation (IDOT). The need arose due to instances in each Department’s existing inventory of bridge barriers where internal voids and other defects associated with slip forming construction methods were attributed to poor barrier performance after completion of construction and where, in other barrier walls, unintentional exposure of the dowel bars revealed extensive corrosion-related section loss at previously uninspectable locations, reducing the capacity of the barriers to resist traffic impact loads. WJE trial tested potential NDE techniques on laboratory mock-up samples built with known defects, trial sections of cast-in-place barriers at in-service bridges in Iowa, and slip formed and cast-in-place barrier walls at in-service bridges in Illinois. The work included review of available studies performed by others, field trial testing to assess candidate test methods, verification of the test methods in identifying internal anomalies and dowel bar corrosion, and preparation of this report and nondestructive evaluation guidelines.

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One of the primary goals for food packages is to protect food against harmful environment, especially oxygen and moisture. The gas transmission rate is the total gas transport through the package, both by permeation through the package material and by leakage through pinholes and cracks. The shelf life of a product can be extended, if the food is stored in a gas tight package. Thus there is a need to test gas tightness of packages. There are several tightness testing methods, and they can be broadly divided into destructive and nondestructive methods. One of the most sensitive methods to detect leaks is by using a non destructive tracer gas technique. Carbon dioxide, helium and hydrogen are the most commonly used tracer gases. Hydrogen is the lightest and the smallest of all gases, which allows it to escape rapidly from the leak areas. The low background concentration of H2 in air (0.5 ppm) enables sensitive leak detection. With a hydrogen leak detector it is also possible to locate leaks. That is not possible with many other tightness testing methods. The experimental work has been focused on investigating the factors which affect the measurement results with the H2leak detector. Also reasons for false results were searched to avoid them in upcoming measurements. From the results of these experiments, the appropriate measurement practice was created in order to have correct and repeatable results. The most important thing for good measurement results is to keep the probe of the detector tightly against the leak. Because of its high diffusion rate, the HZ concentration decreases quickly if holding the probe further away from the leak area and thus the measured H2 leaks would be incorrect and small leaks could be undetected. In the experimental part hydrogen, oxygen and water vapour transmissions through laser beam reference holes (diameters 1 100 μm) were also measured and compared. With the H2 leak detector it was possible to detect even a leakage through 1 μm (diameter) within a few seconds. Water vapour did not penetrate even the largest reference hole (100 μm), even at tropical conditions (38 °C, 90 % RH), whereas some O2 transmission occurred through the reference holes larger than 5 μm. Thus water vapour transmission does not have a significant effect on food deterioration, if the diameter of the leak is less than 100 μm, but small leaks (5 100 μm) are more harmful for the food products, which are sensitive to oxidation.

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This work present the application of a computer package for generating of projection data for neutron computerized tomography, and in second part, discusses an application of neutron tomography, using the projection data obtained by Monte Carlo technique, for the detection and localization of light materials such as those containing hydrogen, concealed by heavy materials such as iron and lead. For tomographic reconstructions of the samples simulated use was made of only six equal projection angles distributed between 0º and 180º, with reconstruction making use of an algorithm (ARIEM), based on the principle of maximum entropy. With the neutron tomography it was possible to detect and locate polyethylene and water hidden by lead and iron (with 1cm-thick). Thus, it is demonstrated that thermal neutrons tomography is a viable test method which can provide important interior information about test components, so, extremely useful in routine industrial applications.