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Thesis
Home   /   Thesis   /   Effect of a density gradient on the sintering of UO2: modeling from the granular scale towards a Representative Elementary Volume

Effect of a density gradient on the sintering of UO2: modeling from the granular scale towards a Representative Elementary Volume

Condensed matter physics, chemistry & nanosciences Engineering sciences Mathematics - Numerical analysis - Simulation Ultra-divided matter, Physical sciences for materials

Abstract

Nuclear energy is one of the means of producing carbon-free electricity, and therefore of fighting global warming. The fuels used in nuclear power plants are ceramics, involving solid phase sintering which is a key manufacturing step allowing the material to be consolidated and densified by obtaining a controlled microstructure (porosity, grain size).
Its modeling was undertaken by the Fuel Study Department of CEA/IRESNE Cadarache with a view to understanding and controlling in particular the sintering of UOx and (U,Pu)O2 fuels. The objective of the CEA and its industrial partners is to ultimately have a scientific calculation tool which will be integrated into the PLEIADES software platform, thus making it possible to simulate nuclear fuel from its manufacture to its behavior in the reactor.
The objective of the thesis is to include in the simulation tool the algorithms developed in the previous thesis (on MOX), and will thus aim to determine the evolution of the microstructure of the UOx fuel during its manufacture, including topological evolutions linked to the growthof grains and the reduction of pore sizes (such as the elimination of closed porosity located in volume or located at grain boundaries). The transition to Representative Elementary Volumes sufficiently large with regard to the phenomena to be studied will initially require parallelization of the code to evolve towards High Performance calculations then, if necessary, towards the implementation of models with a more macroscopic view of the material.
The thesis will take place in a stimulating collaborative environment, including experts in digital modeling and the study of fuel at all scales. Exchanges will also be encouraged with expert sintering experimenters from other CEA units. At the end of the thesis, the candidate will have acquired strong skills in multi-scale modeling of materials, highly valued assets for a career in academic or private research.

Laboratory

Département d’Etudes des Combustibles
Service d’Etudes de Simulation du Comportement du combustibles
Laboratoire de Modélisation Multi-échelles des Combustibles
Université de Lyon
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