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
2024-33247
Description de l'unité
The Service d'Etudes et de Simulation du Comportement des Combustibles (SESC) carries out the following tasks
- the design of fuel elements and assemblies forming the core of nuclear reactors
- the design, supervision and performance of irradiation experiments to test the behaviour of fuels under irradiation conditions
- the development, validation and maintenance of computational tools within the PLEIADES nuclear fuel behaviour simulation platform (architecture, computational codes, applications and components, numerical methods),
- the development, maintenance and loading of all fuel behaviour databases,
- the construction of physical models to describe the fabrication processes and the behaviour of the fuel under irradiation, in order to feed the fuel performance codes used in the behaviour simulations,
- Theoretical simulation of the effects of irradiation by means of separate effects studies in order to improve the knowledge (basic data and models) of the behaviour of the fuel under irradiation, using data from major instruments (synchrotron, accelerators) or high performance computers (GENCI, CCRT).
Position description
Category
Materials, solid state physics
Contract
Internship
Job title
A digital twin to predict the microstructural evolution of the grain boundary in nuclear fuel
Subject
Like other industrial sectors, the nuclear industry is developing 'digital twins', applications that simulate the behaviour of an industrial component, such as a car, plant, reactor or, in our case, a fuel rod. The proposed work is part of this approach and contributes to the development of a digital twin of a grain / grain boundary that can be used to simulate its microstructural evolution under irradiation.
Contract duration (months)
6
Job description
The microstructure of nuclear fuel (uranium oxide) is severely damaged during irradiation in a reactor: the atoms produced by the fission of uranium nuclei displace the atoms in the material in a cascade, creating irradiation defects (vacancies and interstitials) whose aggregation leads to the gradual appearance of cavities and dislocation loops. These extended defects influence the volume of the material, its creep and its retention of fission gases. The physical model of the phenomenon is cluster dynamics: a set of kinetic equations representing the chemical reactions of defect aggregation by diffusion in the material.
Rare gases can migrate towards grain boundaries and give rise to the same type of bubble nucleation-growth phenomenon. The aim of the internship is therefore to extend the use of DA to predict the microstructural evolution of the grain boundary.
The main steps planned to achieve this are
- Theory: adapting the model to the case of a planar medium (while the grain is three-dimensional), in particular studying how to write the kinetic parameters of the chemical reactions that lead to the aggregation of defects.
- Computation: Coupling the DA model of the grain to that of the joint. This will be a specific development in the CEA-EDF Crescendo code.
- Simulation-interpretation: The model will then be applied to new situations, such as irradiation in fuel cells, with the aim of predicting the microstructure (density of bubbles or loops and dislocation lines, both in volume and at grain boundaries).
This internship offers the candidate the opportunity to contribute, from a central position and from a synthetic point of view, to the development of numerical physics applied to multiscale modelling and to discover diverse and complementary activities in this field (theory, numerics, simulation-interpretation). It will allow students to experience for themselves how simulation tools, based on the most fundamental microscopic data, can be used to treat and explain practical situations.
Further readings:
R. Skorek, Étude Par Dynamique d’Amas de l’influence Des Défauts d’irradiation Sur La Migration Des Gaz de Fission Dans Le Dioxyde d’uranium, PhD Thesis, Univ. Aix-Marseille, 2013.
E. Gilabert, D. Horlait, M.-F. Barthe, P. Desgardin, M.-L. Amany, G. Carlot, M. Gérardin, S. Maillard, and T. Wiss, D2.2 - Behaviour of Fission Gases and Helium in Uranium Dioxide, EC report, 2020.
Methods / Means
Using/improving simulation codes, simple coding of physical mechanisms
Position location
Site
Cadarache
Job location
France, Provence-Côte d'Azur, Bouches du Rhône (13)
Location
Saint Paul lez Durance
Candidate criteria
Prepared diploma
Bac+5 - Master 2
Recommended training
Master's degree or equivalent in materials physics, modelling or numerical physics
PhD opportunity
Oui
Requester
Position start date
01/01/2025
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