Effects of the porosity in uranium dioxide on microacoustic and elastic properties

Abstract The laws of variation of the Rayleigh velocity and the longitudinal velocity of the acoustic waves as a function of the porosity in uranium oxide UO 2 has been proven through local acoustic measurements carried out, respectively, by acoustic microscopy and by microechography. The variations of the elastic constants with porosity have been deduced from these laws. Thanks to these results, the role of porosity can be separated and the part of the other factors in the alteration of elastic properties of nuclear fuel materials can be highlighted. These new investigation methods, combined with microindentation techniques are expected to be helpful in improving the nuclear fuel material characterisation at high burn-up.