X-ray diffraction analysis and data interpretation of stabilized zirconia inert matrix fuel doped with plutonium

Abstract

Yttria stabilized zirconia doped with erbia and plutonia has been selected as an inert matrix fuel (IMF) at PSI in order to destroy fissile plutonium in the form of a uranium-free fuel in an effective way. The crystallographic structure (lattice parameters) of cubic zirconia strongly depends on the choice of the stabilizer and other dopants i.e. burnable poisons or fissile material. An extensive study of X-ray diffraction measurements was performed on zirconia samples containing different amounts of additives with the aim to observe lattice parameter and crystallite size changes in the IMF. A semi-quantitative model already available in literature was used and adapted to predict the “theoretical” lattice parameters of IMF with plutonia. The results show a good agreement of theory and experiment. Furthermore, for the first time the structure of active IMF based on zirconia has been investigated and been compared to the X-ray diffraction patterns of undoped zirconia. As a consequence, it is now possible to predict lattice parameters and final densities of IMF with varying compositions, and a good control of the sample dimensions during the fabrication can be guaranteed.