Low-frequency dispersion of fundamental waves in anisotropic piezoelectric plates

International audienc

Acoustic wave degeneracies in two-dimensional phononic crystals

International audienc

The role of electromagnetic waves in the reflection of acoustic waves in piezoelectric crystals

International audienc

The state-vector formalism and the Peano-series solution for modelling guided waves in functionally graded anisotropic piezoelectric plates

International audienc

Adaptation of a High Frequency Ultrasonic Transducer to the Measurement of Water Temperature in a Nuclear Reactor

AbstractMost high flux reactors possess for research purposes fuel elements composed of plates. Their relative distance is a crucial parameter, particularly concerning the irradiation history. For the High Flux Reactor (RHF) of the Institute Laue-Langevin (ILL), the measurement of this distance with a microscopic resolution becomes extremely challenging. To address this issue, a specific ultrasonic transducer, presented in a first paper, has been designed and manufactured to be inserted into the 1.8mm width channel existing between curved fuel plates. It was set on a blade yielding a total device thickness of 1mm. To achieve the expected resolution, the system is excited with frequencies up to 70MHz and integrated into a set of high frequency acquisition instruments. Thanks to a specific signal processing, this device allows the distance measurement through the evaluation of the ultrasonic wave time of fight. One of the crucial points is then the evaluation of the local water temperature inside the water channel. To obtain a precise estimation of this parameter, the ultrasonic sensor is used as a thermometer thanks to the analysis of the spectral components of the acoustic signal propagating inside the sensor multilayered structure. The feasibility of distance measurement was proved during the December 2013 experiment in the RHF fuel element of the ILL. Some of the results will be presented as well as some experimental constraints identified to improve the accuracy of the measurement in future works

Moisture content characterization in composite materials based on ultrasonic transmission measurements

International audienc

About the limits of optical microscopy for research reactor fuel cladding depth measurement

International audienc

High Frequency Transducer Dedicated to the High-resolution in Situ Measurement of the Distance between Two Nuclear Fuel Plates

International audienceMost high flux reactors for research purposes have fuel elements composed of plates and not pencils. The measure of inter-plate distance of a fuel element is tricky since a resolution of a micron is searched to measure plate swellings of about ten microns while the dimension between the plates is close to the millimeter. This measure should provide information about the fuel and particularly its history of irradiation. That is the reason why a solution has been considered: a robust device based upon high frequency ultrasonic probes adapted to the high radiation environment and thinned to 1 mm to be inserted into a 1.8 mm width water channel between two fuel plates. To achieve the expected resolution, the system is excited with frequencies up to 150 MHz. Thanks to a specific signal processing, this device allows the distance measurement through an ultrasonic wave's time of flight. The feasibility of such challenging distance measurement has already been proved with success on a full size irradiated fuel element of the RHF