Study by acoustic microscopy of irradiated and non-irradiated uranium dioxide

Abstract

The investigation of nuclear fuel properties at high burnup often yields difficulties in accounting for the fuel pellet fragmentation, the sharp properties gradient accross the pellet radius and the troubles met in the surface preparation of such a multiphase material. Nevertheless there is a strong need for modelling to assess to the local mechanical properties of the materials. This is the reason for EDF to participate in the developement of new investigation techniques, such as microindentation with the ITU, and microacoustic devices with the Montpellier University. Concerning the second technique, a feasibility phase has been achieved in the years 1996–1997 on irradiated fuels, showing many applications for this non-destructive techniques. The target of this first study was to demonstrate the feasibility of the Rayleigh wave measurement by acoustic microscopy on non-irradiated and irradiated uranium dioxides. This work has confirmed the normal functioning of the whole experimental device and particularly of the acoustic probes in a heavy irradiated environment. The works are still going on, combining microechography and microacoustics. It will be the matter for the next publication to come in 1999, more dedicated to the correlation between the Rayleigh wave velocity and the local porosity volume.