Résumé
For several years, the IES laboratory has been collaborating with the CEA to develop acoustic instrumentation for nuclear applications. As part of this collaboration, the IES acoustic team is designing a miniaturized sensor capable of measuring gas composition in situ within a fuel rod. Initial evidence of this approach dates back to 2010 with the REMORA 3 experiment, conducted in the OSIRIS reactor at CEA Saclay, which enabled acoustic measurements of fission gas release at 150°C. The new sensors, however, are designed to operate up to 300°C, thanks to a modified Bismuth Titanate (NBT) piezoelectric material, integrated by screen printing on an alumina substrate. This paper focuses on an experiment conducted in January 2024 in a high-pressure vessel at CEA Saclay, where the sensors were tested at 350°C and 120 bar in various gas mixtures. Impedance and acoustic signal measurements were performed to evaluate sensor ageing and performance. After 79 hours, slight degradation was observed, but the sensor continued to emit acoustic signals and demonstrated its potential for reliable in situ gas composition monitoring. These results are a key step toward validating the device before irradiation tests planned for 2025.