Nuclear Fuel Elastic Properties: Application of Local Non-Destructive Acoustic Methods on UO2, UMO, HTR Fuels

Abstract

In 2001 we have presented a paper in which our approach and first results concerning the effect of porosity or simulated burnup on UO₂ mechanical properties were given. In this new communication, these data have been extended. On irradiated fuel, we show that from 0 to 100 GWj/tU a decrease (25 %) of the elastic moduli, mainly due to porosity and fission products occurs. Furthermore, the intrinsic elastic properties of the fuel (this means corrected from porosity) decrease between 30 GWj/tU and 75 GWj/tU. From 75 to 100 GWj/tU, an increase is then observed and the fuel recovers elastic moduli similar to these measured on non irradiated UO₂. This increase, which is not observed on SimFuel seems to be an intrinsic characteristic of high burn-up restructured fuels. More recently, measurements on new nuclear fuels such as UMo and HTR particles have been performed and show that acoustic microscopy could also give interesting information.