General information
Organisation
The French Alternative Energies and Atomic Energy Commission (CEA) is a key player in research, development and innovation in four main areas :
• defence and security,
• nuclear energy (fission and fusion),
• technological research for industry,
• fundamental research in the physical sciences and life sciences.
Drawing on its widely acknowledged expertise, and thanks to its 16000 technicians, engineers, researchers and staff, the CEA actively participates in collaborative projects with a large number of academic and industrial partners.
The CEA is established in ten centers spread throughout France
Reference
SL-DES-24-0124
Thesis topic details
Category
Condensed Matter Physics, chemistry, nanosciences
Thesis topics
Calculation of the thermal conductivity of UO2 nuclear fuels and the influence of irradiation defects
Contract
Thèse
Job description
Atomistic simulations of the behaviour of nuclear fuel under irradiation can give access to its thermal properties and their evolution with temperature and irradiation. Knowledge of the thermal conductivity of 100% dense oxide can now be obtained by molecular dynamics and the interatomic force constants[1] at the single crystal scale, but the effect of defects induced by irradiation (irradiation loop, cluster of gaps) or even grain boundaries (ceramic before irradiation) remain difficult to evaluate in a coupled way.
The ambition is now to include defects in the supercells and to calculate their effect on the force constants. Depending on the size of the defects considered, we will use either the DFT (Density Functional Theory) or an empirical or numerical potential to perform the molecular dynamics. AlmaBTE allows the calculation of phonon scattering by point defects and the calculation of phonon scattering by dislocations and their transmission at an interface have also recently been implemented. Thus, the chaining atomistic calculations/AlmaBTE will make it possible to determine the effect of the polycrystalline microstructure and irradiation defects on the thermal conductivity. At the end of this thesis, the properties obtained will be used in the existing simulation tools in order to estimate the conductivity of a volume element (additional effect of the microstructure, in particular of the porous network, Fast Fourier Transform method), data which will finally be integrated into the simulation of the behavior of the fuel element under irradiation.
The work will be carried out at the Nuclear Fuel Department of the CEA, in a scientific environment characterised by a high level of expertise in materials modelling, in close collaboration with other CEA teams in Grenoble and in the Paris region who are experts in atomistic calculations. The results will be promoted through scientific publications and participation in international congresses.
University / doctoral school
Physique et Sciences de la Matière (ED352)
Aix-Marseille Université
Thesis topic location
Site
Cadarache
Requester
Position start date
01/12/2023
Person to be contacted by the applicant
BOUCHET Johann johann.bouchet@cea.fr
CEA
DES/DEC/SESC/LM2C
DES/IRESNE/DEC/SESC/LM2C
Bâtiment 151
13108 Saint-Paul-lez-Durance
0445254407
Tutor / Responsible thesis director
BERTOLUS Marjorie marjorie.bertolus@cea.fr
CEA
DES/IRESNE/DEC/SESC/LM2C
CEA/Cadarache
Batiment 151
13108 Saint-Paul-lez-Durance Cedex
+33 4 42 25 29 33
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