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Thermomechanical behaviour at high temperature of an irradiated nuclear ceramic


Thesis topic details

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-25-0269  

Thesis topic details

Category

Engineering science

Thesis topics

Thermomechanical behaviour at high temperature of an irradiated nuclear ceramic

Contract

Thèse

Job description

This thesis is part of the studies on pellet-cladding interactions in nuclear fuel rods used in NPP. The operator must ensure and demonstrate the integrity of rods in any situations. The mechanical stresses on the clad, the first safety barrier, are linked to the viscoplastic properties of the fuel. It is therefore necessary to know these behaviors and their evolution in operation.
The topic proposed will focuse on the characterization, in hot lab, of an irradiated fuel. One of the main difficulties is that the irradiated fuels in a reactor are multi-cracked, which makes their mechanical characterization particularly complex. However, an ongoing thesis (2022-25) has reached different steps: (i) the design of a specific thermomechanical testing machine, (ii) the partial qualification of this device, (iii) the implementation of tools and cracked sample extraction method, (iv) and a whole system model (digital twin).
The thesis will be the continuation of this work and will be built in four stages on three experimental platforms available at the CEA:
1. Getting the knowledge and improving existing digital and experimental tools,
2. Implementation of the device in hot-cell on an existing furnace,
3. Thermomechanical testing on irradiated fuel, a world first time in these conditions.
The tests will require dedicated post-processing based on simulation-experiments comparisons. Once the experimental base is sufficiently developed and interpreted, it will then be possible to confirm or revise the irradiated fuel behaviour laws. A link with the microstructure of materials could be addressed.
Throughout these stages, the PhD student will draw on skills and expertise of laboratories of the Fuel Research Department (IRESNE Institute, CEA Cadarache) and on a academic collaboration. This thesis also fits into the framework of the European project OPERA HPC and is a major issue.
The PhD student should have a strong taste for the experimental approach and some facilities for the use of digital tools. Knowledge of materials science is the minimum required. During the three years, the PhD student will improve his multiphysical skills in experimental device design and high-temperature material behavior, as well as in numerical simulation, which will facilitate his professional integration.

University / doctoral school

Sciences pour l’Ingénieur : Mécanique, Physique, Micro et Nanoélectronique (SIMPMN)
Aix-Marseille Université

Thesis topic location

Site

Cadarache

Requester

Position start date

01/10/2025

Person to be contacted by the applicant

COLIN Christian christian.colin@cea.fr
CEA
DES/DEC//LAMIR
CEA
Centre de Cadarache
DEN/DEC/SA3E
Bat. 315, P7
13115 Saint Paul lez Durance
04 42 25 43 72

Tutor / Responsible thesis director

LEBON Frédéric lebon@lma.cnrs-mrs.fr
Aix-Marseille Université
LMA
Laboratoire de Mécanique et d’Acoustique
4 impasse Nikola Tesla
CS 40006
13453 Marseille Cedex 13


04.84.52.42.22

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