Electron BackScatter Diffraction (EBSD) has helped to highlight microstructural changes in UO2 fuel pellets, such as the subdivision of grains into weakly disoriented sub-grains, either after compression tests at high temperature or after irradiation. However, the analyses carried out to date by this method present several limitations.
The main objective of this thesis is to improve their angular and spatial resolution. To this end, high-resolution EBSD (HR-EBSD) and Transmission Kikuchi Diffraction (HR-TKD) will be developed and applied to different restructured fuels. The new data acquired by these methods will improve our knowledge of the defect population (dislocations) and the local mechanical state of the fuel. They will be used in crystalline plasticity models.
This subject will enable the PhD student to acquire skills in advanced microstructural characterisation of materials, exploitation of experimental data and micromechanical modelling, which will be applicable to a wide range of materials.
The thesis work will mainly take place at the Fuel Research Department (IRESNE INstitute, CEA Cadarache) in a laboratory for the characterisation and study of the properties of fresh and irradiated fuels. It will also take place over a shorter period of time at the LEM3 laboratory of the University of Loraine based in Metz, which supervises this thesis in collaboration with the CEA and which has internationally recognized experience in the characterization of materials using the considered techniques in this study.