[en] In the context of LWR pressure vessel surveillance, the significance of the Cv notch impact test instrumented by strain gages has been revised. The load diagram (general yield, maximum, brittle fracture and arrest loads versus temperature ) is the most fundamental feature of the test. It is directly correlated to the appearance (percentage shear) of the fracture surface and also constitutes a straightforward experimental expression of the Davidenkov diagram, by which ductile-brittle transition temperature shifts are linked to irradiation damage mechanisms. In combination with static uniaxial tensile tests, it allows quantification of strain rate effects on the yielding and work hardening capacity of the steel. By contrast, the bulk of the absorbed energy and lateral expansion stems from ductile stable crack growth associated with plastic deformation under conditions, unrepresentative of the constraints and stress-strain field near the tip of a sharp crack in a pressure vessel. It is shown that the temperature at which fixed energy is absorbed in the test (41 or 68 Joules) cannot always trace to acceptable accuracy the effect of steel service exposure on the ductile - brittle transition temperature and on cleavage fracture toughness. It is contented that this can be done more reliably by using characteristic temperatures of the load diagram. An attempt to determine the engineering and regulatory implications of this physically-grounded fracture toughness approach is made

[en] The FAUST (Focusing Adaptative UltraSonic Tomography) system was developed at the French Atomic Energy Commission (CEA) to improve performances of ultrasonic non destructive testing in terms of adaptability to various control configurations and defect characterization. Unlike conventional techniques only allowing fixed focusing, this system can dynamically modify the characteristics of the ultrasonic beam. This system relies on optimized phased array transducers connected to a multi-channel acquisition system supplying amplitude and delay laws allowing to drive the ultrasonic beam. Previous works have demonstrated the skills of this system for ultrasonic beam forming. The reliability of the procedure was proved by comparison with theoretical results, while comparisons with experimental results provided by conventional transducer pointed out the improved capacities of the system. In the first part of paper, we briefly present the model used for the system validation. This field computational model developed at the CEA is used to design optimized phased array transducers dedicated to NDE configurations (immersed transducers used to focus through Fluid/Solid interfaces). Theoretical delay laws and related ultrasonic fields are also calculated from this model. In addition to its ability to dynamically form the ultrasonic beam by taking account of the control configuration, we investigate in the second part of the paper the capabilities of the system to extract informations from he received signals. The ability of the system to store the signals received by all the elements of the array allows one to perform different reconstruction procedures. Useful informations can be extracted from the received signals: experimentally measured delay laws can be determined from reflected signals to obtain an optimal imaging, while the related amplitude distribution over the array points out geometrical characteristics of the reflector. (authors)

[en] Ultrasonic testings of bimetallic welds often show the presence of false calls. In pulse echo mode at oblique incidence, these false calls are detected close to the back wall. They are generally distributed along lines parallel to the buttering. The phenomenon is disturbing because it limits the efficiency of ultrasonic testing in the area of the back wall: false calls can be misinterpreted for echoes from defects or they can mask the presence of real defects. If a defect is detected, they also limit the possibility of characterization. The metallurgical structure and the anisotropic properties of bimetallic welds do not allow an easy interpretation of the phenomenon. Bimetallic welds contain large austenitic column,ar grains with a dendritic structure. The different grain orientations can lead to beam deflection or mode conversion which can generate echoes. The present paper aims at explaining these false calls mechanism of formation. An experimental study has been conducted to characterize the phenomenon. From the resulting data the phenomenon has been interpreted. (authors)

[en] The Array location method, already tested in fundamental experiments, and based on the principle of ultrasound and mode independency, was used here. With real-scale components and structural elements, too, the Array method achieves improved location accuracy as against conventional methods. In addition, the planar location of acoustic emission sources - two possibilities were investigated - was extended to detection and location in depth. The design of the processor was extended by extra elements, and the evaluation algorithm for existing systems modified. Experiments with simulated and natural acoustic emission signals demonstrated, apart from high location accuracy, the possibilities and limits of depth location with enhanced Array techniques. (orig./HP) With 90 figs., 4 tabs

[en] According to the features of nuclear fuel element and composite materials, such as requirements of non-homogeneity, layer and high quality the theoretical analyses for testing bonding quality using broadband ultrasonic technique and the design principles of the developed ultrasonic tester and computer-imaged ultrasonic system are discribed. The experimental results show that the analyses and designs are reasonable and the broadband ultrasonic tester and computerized ultrasonic system have a small dead zone, high resolution, high reliability and satisfactory testing functions. These techniques are used successfully in automatical NDT (non-destructive testing) for varied fuel elemetns, expolosive weldings, electronic elements and manifold layer-composited materials

[en] A setup is described for measuring the velocity, wavelength, and frequency of the waves arising on the surface of draining liquid films. The contactless measurement technique is based on ultrasonic probing of a liquid film through the wall of a pipe, reception of the reflected signals by two acoustical sensors, and statistical computer processing of the data acquired. 3 refs., 4 figs

[en] This volume documents the lectures and reports of the 9th Colloquium on noise emission - status reports on the development and application of noise emission tests. The state of knowledge in some important areas of theory is shown here. Applications of noise emission testing are also introduced. (orig.)

[en] The inspection of pump shafts is not part of the regular in-service inspection programme in Switzerland. However, when, in 1987, cracking was reported in a Recirculation Pump Shaft in a plant in the USA, recommendations for inspections were issued by the pump supplier. Based on this recommendation, the Leibstadt Nuclear Power Plant (KKL) in Switzerland decided to inspect the critical area of both pump shafts during an upcoming outage in 1988. Liquid Penetrant examinations revealed ''turtle back'' cracking in the transition region of shaft to impeller and axial cracking in the heat-exchangers. The cracked shafts and heat exchangers were replaced and thoroughly investigated. Because the crack initiation mechanisms were not known and further cracking could not be excluded in the future, KKL decided to develop and qualify a non-destructive testing (NDT) technique to inspect the shafts ''in-situ''. A feasibility study showed that the best chance for a reliable inspection was from a centre-line borehole. A test block was manufactured from the remaining shaft and circumferentially-oriented EDM-notches of varying depths and locations were introduced. An existing device for manual probe manipulation was modified and linked with an advanced ultasonic examination system. The defect detection capability was studied on the test block and on cracked shafts. (author)

[en] An eddy current flaw detection method and apparatus therefore which can detect non-destructively flaws of a conductive object to be inspected such as very small cracks, defects, and the like, and can distinguish the flaws of the surface layer portion from those of the deep portion. The pulse width of a pulsatile voltage occurring in a secondary coil is measured at a portion which is affected by lift-off but not by the flaws and at another portion which is affected by both lift-off and flaws, and the influences of lift-off in both pulse widths are offset to take out only the signal due to the real flaw and detect the existence of the flaw. (author) figs

[en] A quality control plan was evolved for the NDE of Aluminium-Uranium (U²³³) alloy plate type nuclear fuel elements for the light water cooled and moderated research reactors PURNIMA III and KAMINI. Inspection was carried out at each stage of fabrication using X-ray radiography and micro densitometric scanning for fuel homogeneity evaluation; blister testing and immersion ultrasonic testing for gross and fine non-bond evaluation and metallography for microstructure evaluation. Conventional NDT methods were modified to suit the stringent quality requirements for fuel homogeneity and bond quality. Digital image processing, continuous motion radiography system and immersion ultrasonic testing system with scanner manipulator were developed and successfully employed for the quality control of the fuel plates. (author)