High-Temperature Ultrasonic Sensor for Fission Gas Characterization in MTR Harsh Environment

In this paper, we present the first steps in the development of a new generation of ultrasonic sensors devoted to fission gas characterization in a material testing reactor harsh environment. The piezoelectric active material is a sodium bismuth titanate thick film fabricated using a screen-printing method. Characterization of piezoelectric and dielectric properties and material parameter studies based on temperature were carried out. The key results of this paper are demonstrated and discussed in terms of feasibility for application to a new sensor device operating at high temperature (350 °C). An acoustic test in a cylindrical cavity shows high sensitivity to measurements of liquid substances at room temperature. To verify its applicability to gas detection, a theoretical model based on electromechanical properties and impedance matching equations was introduced. This model was used in the studies on gas measurement under room temperature and at 350 °C. It was theoretically shown that the sensor was able to operate for gas in situ under harsh temperature conditions.