NuFuel & MMSNF 2015

First Workshop on Research into Nuclear Fuel in Europe
and Materials Modeling and Simulation for Nuclear Fuels Workshop
Karlsruhe, Germany, November 16th to 18th, 2015

Updated: Tue 08 Dec 2015, 14:27

Talk 5.7: First-principles modelling of the structural and electronic modifications induced by point defects in actinide mixed oxides

Y. Li, L. Shi, E. Vathonne, M. Bertolus, Michel Freyss
  • CEA, DEN, DEC, Centre de Cadarache, F–13108 Saint Paul Lez Durance Cedex, France

Abstract

The first-principles DFT+U method is used to study structural, electronic and thermodynamic properties of actinide mixed oxides and their point defects. The objective is to determine the effect of the chemical composition and of the deviation from stoichiometry on the properties of these materials. First-principles electronic structure calculations enable one to get insight into some aspects of these phenomena at the atomic scale, in particular to identify the point defects that accommodate deviations from stoichiometry and to determine the structural and electronic modifications induced by the presence of the defects.

This approach is applied to the study of the actinide mixed oxides (U,Ce)O2 and (U,Pu)O2, the former being of interest as a weakly radioactive mixed oxide model material for separate effect experiments. We focus on oxygen defects with various chemical environments in mixed oxides of various compositions.

The results are confronted to experimental data from the literature, obtained by X-ray absorption spectroscopy and X-ray diffraction, and to the results obtained in pure UO2.