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Ce travail vise à réaliser une intercomparaison de plusieurs spécimens de spectromètres aérodynamiques (Aerodynamic Particle Sizer, TSI modèles 3320 et 3321), qui permettent la mesure de la distribution granulométrique des aérosols entre 0,5 et 20 µm. A cette fin, un protocole reposant sur la génération d'aérosols de sphères de latex calibrées entre 0,7 et 15 µm a été développé, et mis en œuvre sur 6 instruments. Les résultats mettent en évidence des écarts sur les mesures effectuées et soulignent la nécessité de quantifier la variabilité inter-spécimens., This study aims at carrying out an intercomparison of several specimens of aerodynamic spectrometers (Aerodynamic Particle Sizer, TSI models 3320 and 3321), which allow measuring the size distribution of aerosols in the range from 0.5 to 20 µm. For this purpose, a protocol based on the generation of calibrated PSL between 0.7 and 15 µm was developed, and applied to 6 devices. The results show discrepancies between the measurements, highlighting the need for qualifying inter-specimen variability.

This work presents the influence of noise originating from the tube itself on the detectability and sizing accuracy for laboratory-induced outer diameter axial cracks in nuclear steam generator tubes. The variations of signal amplitude and phase angle of the same cracks were analyzed when increasing the signal-to-noise ratio of the tube itself from 9 to 18. It was experimentally verified that the detectability for small cracks was enhanced by increasing the signal-to-noise ratio. The phase angle also rotated to a value representing the actual position and depth of a crack when increasing the signal-to-noise ratio.

The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation is an interesting addition to the current method of periodic inspections. Guided wave tomography had been developed to create a map of the wall thickness using the travel times of guided waves. It can be used for both monitoring and for inspection of pipe-segments that are difficult to access, for instance at the location of pipe-supports. An important outcome of the tomography is the minimum remaining wall thickness, as this is critical in the scheduling of a replacement of the pipe-segment. In order to improve the sizing accuracy we have improved the tomography scheme. A number of major improvements have been realized allowing to extend the application envelope to pipes with a larger wall thickness and to larger distances between the transducer rings. Simulation results indicate that the sizing accuracy has improved and that is now possible to have a spacing of 8 meter between the source-ring and the receiver-ring. Additionally a reduction of the number of sensors required might be possible as well. © 2014 AIP Publishing LLC.

The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation is an interesting addition to the current method of periodic inspections. Guided wave tomography had been developed to create a map of the wall thickness using the travel times of guided waves. It can be used for both monitoring and for inspection of pipe-segments that are difficult to access, for instance at the location of pipe-supports. An important outcome of the tomography is the minimum remaining wall thickness, as this is critical in the scheduling of a replacement of the pipe-segment. In order to improve the sizing accuracy we have improved the tomography scheme. A number of major improvements have been realized allowing to extend the application envelope to pipes with a larger wall thickness and to larger distances between the transducer rings. Simulation results indicate that the sizing accuracy has improved and that is now possible to have a spacing of 8 meter between the source-ring and the receiver-ring. Additionally a reduction of the number of sensors required might be possible as well. © 2014 AIP Publishing LLC.