Design, Manufacture and Temperature Characterization of Screen-Printed Acoustic Sensors for Monitoring the Release of Fission Gases in Experimental Fuel Rods of the Jules Horowitz Reactor

This article presents the design, manufacture, and testing of a gas composition sensor for measuring the composition of fission gases inside experimental rods coming from an experimental reactor, such as the future Jules Horowitz reactor (JHR). The piezoelectric element is a cerium-modified bismuth niobate titanate (NBT) ceramic screen-printed (SP) onto an alumina substrate. These types of piezoelectric elements have been shown in the past to be capable of operating in environments subject to particular thermal and radiative stresses. Thus, three NBT (Na0.5Bi(4.5−x) Ce(x) Ti4015) ceramics with different dopants of elemental cerium (Ce) were fabricated, characterized, and compared to the state-of-the-art, especially with respect to piezoelectric ( $d_{33}$ ) and dielectric [ $\varepsilon _{r}$ and tan ( $\delta $ )] performance. A study of the electrical impedance at different temperatures concluded that cerium-modified NBT with a Ce dopant of $x =0.04$ and $x =0.06$ was suitable for temperatures up to 340 °C. These two NBT variants were then integrated into an acoustic cavity to form the sensor. The performance of these sensors was tested with two gas mixtures: 1) pure helium and 2) a mixture of 80% helium and 20% xenon. These laboratory sensors have shown the possibility of characterizing the composition of the gas mixtures for limited lower pressures of 40 bar for a helium-xenon mixture. Finally, the sensor is tested in various ternary gas mixtures containing helium, xenon, and krypton, with accuracy of the composition estimation of 5%.