The manufacturing process of nuclear fuel is a powder metallurgy process of powders (Uranium UO2 and Plutonium PuO2 oxides), composed of several steps including grinding / mixing. For a better control and understanding of the micro-mechanical mechanisms of these processes, the CEA is investing in the development and application of a numerical approach based on a discrete element method (DEM) used for the predictive simulation of granular materials. The development of efficient algorithms for DEM simulations involves experimental validation strategies. These strategies will be designed to assess the validity of the calculations, guiding the choices and approximations to be implemented in the physical models of the materials and the complex processes simulated.
The objective of this PhD is to propose an experimental validation strategy for DEM algorithms currently developed at CEA for the simulation of manufacturing processes. This strategy will include a spectrum of experiments, using inactive granular materials, ranging from simple ones (for the measurement of certain rheological properties such as internal friction angle) to laboratory experiments with sophisticated instrumentation (LDV, PIV, Laser granulometry analyzer, accelerometer ...). This strategy will also be completed by carrying out targeted experimental tests with UO2/PuO2 powders.
A series of simulation / experiment comparisons should allow identifying sensitive physical parameters underlying physical models and adapting the numerical algorithms.
This CEA thesis will be carried out in very close collaboration between the DEC Department of the IRESNE Institute in CEA Cadarache, the DMRC Department of ISEC Institute in CEA Marcoule and the LMGC laboratory in Montpellier (CNRS). You will be located mainly in Montpelier but will make regular stays at the CEA within the Fuels Simulation Laboratory on which you will depend but also in the experimental teams of the DEC and the DMRC for studies on nuclear fuel materials. You will also collaborate with the INRAE/IATE institute for their experimental expertise on issues related to grinding / mixing powders.
The approaches developed in this thesis guarantee a high scientific level with many potential industrial applications inside and outside the nuclear field.