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Internship - Experimental study of turbulent flow in fuel assembly bundles H/F

Vacancy details

General information


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



Description de l'unité

The Research Institute for Nuclear Systems for a Low Carbon Energy Production (IRESNE) is one of three institutes forming the Energies Division of the CEA (French Alternative Energies and Atomic Energy Commission). IRESNE leads studies on low carbon energy production systems using or adding value to energy from nuclear technology sources. It also provides support for experimental reactors and nuclear propulsion systems design.

Within IRESNE and its Section of Industrial Components and Processes (STCP, part of the Department of Nuclear Technology), the Laboratory of Hydro-mechanical Experiments and studies (LETH) carries out research and development activities to improve knowledge of hydro-mechanical and thermal-hydraulic behaviour of components from reactor cores and their cooling circuits, under nominal and accidental conditions.

To that purpose, the LETH operates several thermal-hydraulics loops within POSEIDON experimental platform, allowing among other things the study of turbulent flow behaviour through fuel rod bundles. Combined to analytical and numerical work, these experimental activities allow LETH researchers to refine the understanding of fluid-structure interactions in reactor cores.

Position description


Thermohydraulics and fluid mechanics



Job title

Internship - Experimental study of turbulent flow in fuel assembly bundles H/F


Post–processing and analysis of flow measurements data (velocity fields and pressure) from a mock up representative of a sub-assembly

Contract duration (months)


Job description

Fuel assemblies constitute the core of nuclear reactor core. Those small tubes attached together by grids are submitted to a strong turbulent flow. Amplified by grids, turbulent structures induce vibrations that can lead to fretting wear damages.  


The topic of this internship is the study of the effect of different geometrical features of fuel assemblies on turbulent flow quantities, to understand their role in rod vibrations and grid-to-rod fretting. It could include the following activities (non-exhaustive list):

- brief literature review on turbulent flows in core fuel sub-assemblies;

- brief literature review on Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV) post-processing and analysis;

- analysis of measurements data from previous experimental campaigns by relevant post-processing (Python or commercial tool);

- comparison with existing numerical results when possible.


The internship will include mostly analysis of experimental campaigns measurements, but the student could also be involved in the simulation work (CFD) done in the laboratory.

Methods / Means

literature review, measurements analysis and post processing (Python)

Applicant Profile

This internship requires understanding of fundamentals of fluid mechanics (turbulent flows) and numerical methods (finite differences, Fourier transform…) and fluency in English (most of relevant literature on the topic is in English).

Prior knowledge of turbulent flow in reactor core is not required.

Position location



Job location

France, Provence-Côte d'Azur, Bouches du Rhône (13)



Candidate criteria


  • English (Fluent)
  • French (Fluent)

Prepared diploma

Bac+5 - Diplôme École d'ingénieurs

Recommended training

MSc / Engineering school with major in fluid dynamics (final year student)

PhD opportunity



Position start date