Use of RBS to validate europium surface implantation as a marker for the corrosion study of zirconia

Abstract

This study is related to the nuclear waste management and to the long-term behaviour of radionuclides in deep storage. The aim of this paper is to study the corrosion of zirconium in deep storage. In order to simulate the inner side of zircaloy cladding tubes, the zirconium samples were oxidised in air at 500°C during 3 h. Two hundred keV-implanted europium ions were used as marker to follow the evolution of the ZrO 2–liquid interface. In a first step, air annealings were performed in the temperature range 850–950°C. Diffusion profiles were measured using 3 MeV alpha-particles Rutherford backscattering spectrometry (RBS) at each step of annealing. By extrapolation it is shown that at 300°C the europium diffusion in ZrO 2 is negligible. In a second step, the specimens were exposed to a basic solution (pH 13.5) at 300°C in autoclave under a 10 7 Pa pressure. By means of RBS, it was possible to deduce the fraction of dissolved ZrO 2. It was shown that this dissolution is inhomogeneous. These results are confirmed by scanning electron microscopy (SEM).