Proposal for ultrasonic technique for evaluation elastic constants in UO2 pellets

Abstract

 This work aims to develop and propose an ultrasonic technique to evaluate the elastic constants of UO₂ pellets. However, because of the difficulties in handling nuclear material, we proposed an initial study using alumina (Al₂O₃). Alumina pellets are also ceramic material and their porosity and dimensions are in the similar range of UO₂ pellets. They also are used as thermal insulation in the fuel rods, operating under the same conditions. They were fabricated and used in two different sets of 10 Al₂O₃ pellets with densities of 92% and 96%. The developed ultrasonic technique evaluates the traveling time of ultrasonic waves, longitudinal and transverse, and correlates the observed time and the elastic constants of the materials. Equations relating the speed of the ultrasonic wave to the elastic modulus, shear modulus and Poisson's ratio have led to these elastic constants, with graphics of correlation that showed excellent agreement with the available literature for Al₂O₃. According to the results and considering the ease of implementation of this technique, we believe that it should be applied for UO₂ pellets, justifying further studies for that application.

This Work was presented in INAC - 2015