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[en] In the present study, the partial loss and distortion of turbine blades were acoustically detected while the turbine was rotating. An ultrasonic signal of a specific frequency (300 kHz) was transmitted in the form of continuous sine waves to the rotating turbine model. The signal was reflected on the turbine blade and received by a receiver. The amplitude of the given frequency component in the received signal was analyzed by signal processing. Because ultrasounds are attenuated easily when propagated into air and have a straight characteristic like light, the characteristics of the signals were examined by a quantitative test. The signal attenuation with respect to distance and the signal reduction by eccentricity were observed and compared with the experimental results. Partial loss decreased the sound reflection area; thus, the signal amplitude was reduced. The signal amplitude was inversely proportional to the size of the defect. Distortion caused larger eccentricity between the transmitter and the receiver. Weaker signals were detected with the more distorted blade. When the blade was distorted by more than 20 dg, the amplitude of the signal decreased significantly. In short, defects of turbine blades cause a reduction in the acoustic signal. It was verified that acoustic diagnosis can be applied to detect the partial loss and distortion of turbine blades.
[en] In this paper we present a study on the mechanical properties of nanodiamond enhanced tungsten strengthened aluminium alloy 7075, stored for 28 months under different conditions. One of the samples was stored in terrestrial conditions and the other sample was mounted on the outside of the International Space Station for the same period. The purpose of the experiment is to determine tensile strength, Young’s modulus and Poisson's ratio using different testing procedures and to compare the results with those obtained using the ultrasonic volumetric method Key words: aluminium and alloys, nanodiamond, ultrasonic volumetric method, tensile strength, outer space structures
[en] This document shall be applied for in-service inspections with mechanized ultrasonic testing equipment performed on the components of the primary circuit of light water reactors. This document is also applicable for basic tests on components of the primary circuit and on other components of nuclear facilities. Ultrasonic testing techniques for the detection of inhomogeneities (surface and volume), requirements for the ultrasonic testing equipment, preparation of the testing and instrumentation, performance of the test and recording are specified. This document was prepared by the working committee NA 062-07-47 AA "Non-destructive testing in nuclear technology" in the DIN Standards Committee for Materials Testing (NMP).
[de]Dieses Dokument ist anzuwenden für wiederkehrende Prüfungen mit mechanisierten Ultraschallprüfeinrichtungen, die an den Komponenten des Primärkreises von Leichtwasserreaktoren durchgeführt werden. Dieses Dokument ist auch für Basisprüfungen an Komponenten des Primärkreises und an anderen Komponenten kerntechnischer Anlagen anwendbar. Es werden Ultraschallprüftechniken zum Nachweis von Inhomogenitäten (Oberfläche und Volumen), Anforderungen an die Ultraschallprüfeinrichtungen, an die Vorbereitung der Prüf- und Gerätetechnik, an die Durchführung der Prüfung und an die Protokollierung festgelegt. Dieses Dokument wurde vom Arbeitsausschuss NA 062-07-47 AA "Zerstörungsfreie Prüfung in der Kerntechnik" im DIN-Normenausschuss Materialprüfung (NMP) erarbeitet.
[en] The present work explores the diameter- and temperature-dependent ultrasonic characterization of wurtzite indium phosphide nanowires (WZ-InP-NWs) using a theoretical model based on the ultrasonic non-destructive evaluation (NDE) technique. Initially, the second- and third-order elastic constants (SOECs and TOECs) were computed using the Lennard-Jones potential model, considering the interactions up to the second nearest neighbours. Simultaneously, the mechanical parameters (Young’s modulus, shear modulus, elastic anisotropy factor, bulk modulus, Pugh’s ratio and Poisson’s ratio) were also estimated. Finally, the thermophysical properties and ultrasonic parameters (velocity and attenuation) of the InP-NWs were determined using the computed quantities. The obtained elastic/mechnical properties of the InP-NWs were also analyzed to explore the mechanical behaviors. The correlations between temperature-/size-dependent ultrasonic attenuation and the thermophysical properties were established. The ultrasonic attenuation was observed to be the third-order polynomial function of the diameter/temperature for the InP nanowire.
[en] Elastic properties of EuRh2Si2 have been investigated by means of ultrasonic measurements. The measurements of longitudinal and shear elastic constants (CL and CT) in polycrystalline EuRh2Si2 have performed. A clear dip for the both elastic constants was observed at the magnetic ordering temperature of TN = 25 K in a zero field. The elastic anomaly shifts hardly and disappears rapidly when external magnetic field is applied. In addition, it is found that both elastic constants exhibit a clear shallow-minima around 10 K, where its magnetic susceptibility show a very tiny cusp, even far below TN = 25 K. This elastic anomaly is also suppressed rapidly and dependent significantly on the external magnetic field strength. From the results of various temperature and magnetic field scans, we summarized them in the magnetic phase diagram. We discuss the elastic property and the nature of the order parameter and some types of possible phases in EuRh2Si2 at low temperature, in connection with the non-trivial topological property likely derived from its Dirac-cone-shaped band structure. (author)
[en] Corrosion and erosion lead to partial wear inside pipes. This wear induces some roughness of the inner pipe wall and decreases its thickness. This could cause a fatal accident in nuclear and thermal power plants. In general, nondestructive inspection by ultrasonic devices measures only the thickness, not the roughness. When reflected on a rough surface ultrasonic waves scatter and attenuate. Then this study aims to estimate the surface roughness of the pipe wall from ultrasonic attenuation estimation, based on the analysis of the acquired waveforms on several specimens that have been machined in order to simulated a corroded rough surface. The experimental data exhibit a clear relationship between the roughness and the ultrasonic attenuation, in good agreement with theoretical models available in the literature, for both bulk longitudinal and shear waves. (author)
[en] Previous studies on the effect of temperature on various types of concrete have been mainly focused on the case of fire in which the exposure duration is short. Limited data has been obtained regarding the effect of high temperature on concrete properties under severe accident condition in which the concrete structure may be exposed to heat radiation from melting nuclear fuels for a long time. The present study aimed to examine the applicability of the ultrasonic wave-based method for concrete damaged extremely by heat simulating a severe accident. The conventional ultrasonic test was conducted in concrete cylindrical with the size of φ100 × 200 mm after exposure to high temperatures 105, 200, 400, 600, 700, 800℃. The results revealed that this method is sensitive to indicate thermal damage as results from water content loss and decomposition of portlandite. A strong correlation between dynamic and static elastic modulus was obtained for concrete exposed to temperature range of 25 to 400℃, corresponding to dynamic elastic modulus range from 20 - 40 GPa. The degradation within this range is due to water loss. At higher temperatures, the concrete integrity is not maintained due to the formation of cracks and the decomposition of cement paste phases, which cause a significant decay of the ultrasonic waves. (author)
[en] A mercury target vessel for the spallation neutron source at the J-PARC, which has the triple-walled structure, was improved to promote its robustness and reliability with conducting structural integrity simulations and mockup tests to confirm the suitable fabrication and inspection procedures. A monolithic structure fabricated by the wire electric discharge machining was adopted to reduce a number of welding lines. The total length of welding lines at the fore part of the mercury target vessel decreased drastically to approximately 53%. After the weld, an immersion ultrasonic testing which could detect small defects of more than 0.2 mm was adopted as a nondestructive inspection method. Stable beam operation at the beam power of 500 kW has been achieved and experienced the maximum beam power of 1 MW for an hour during a beam experiment. (author)
[en] This comprehensive document published by the Swiss Nuclear Safety Inspectorate ENSI presents the opinions of the Oeko-Institute on the proof of safety for the reactor pressure vessel in the Beznau 1 nuclear power station in northern Switzerland. The opinions presented by the institute are listed. These concern the ultrasonic measurements made, the part-replica of the pressure vessel and its radiation-induced embrittlement as well as the quantification of uncertainties. The opinions of the Oeko-Institute are commented on by ENSI. The conclusions presented by the institute are heavily contradicted in detail by ENSI.
[en] The ultrasonic testing (UT) is a major nondestructive technique for inservice inspection (ISI) of light water nuclear power plants in Japan and conventional UT techniques (A-scan display type UT instrument) have mainly been used. In recent years, although ultrasonic testing using phased array technology has been applied to other non-nuclear fields, it is not actively applied to detect cracks in ISI. Despite scope to use phased array technology according to codes and regulations, the technology is only applicable to special cases such as crack depth sizing or vessel internal inspections and the lack of demonstration data for field applications hinders application of the technology. In this basic study, crack detectability is compared between the phased array UT technique and the conventional UT method and a method for fabricating a crack induced specimen usable to detect defects was developed. When replacing the conventional method with phased array technology under the same conditions, the detectability is approximately equivalent to or improved compared to the focused area. When the sensitivity is confirmed by calibration, although detection of the crack sought is possible, it is preferable to consider calibration not only via a side drilled hole but also a notch to compare with the conventional UT method. (author)