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
2024-33915
Description de l'unité
The DM2S (‘Département de Modélisation des Systèmes et des Structures' - Systems and Structures Modelling Department) develops simulation tools for the design and assessment of systems in the basic disciplines of energy, i.e. thermomechanics, thermohydraulics and neutronics, across all sectors. To do this, it relies on tests and software platforms, developed in-house or in partnership.
The SEMT (‘Service d'Études Mécaniques et Thermiques' - Mechanical and Thermal Studies Service), with 2 experimental platforms and simulation tools that it develops (MANTA, EUROPLEXUS, CAST3M), is the DES's unit of competence in mechanics, thermics and fluid-structure interaction. It is involved in CEA projects, many of them in cooperation with EDF, FRAMATOME and IRSN, as well as national and European research programmes.
Within SEMT, the ‘Laboratoire d'Études de Dynamique' (DYN) is in charge of studies and research in the fields of structural dynamics, possibly interacting with fluids: vibrations, vibrations under flow, and fast dynamics. One of the laboratory's strengths is its skills and resources in physical modelling, numerical simulation and testing (analytical or validation) at its own facilities (RESEDA platform), in conjunction with the industrial activities of its long-standing partners (EDF and FRAMATOME).
Position description
Category
Engineering science
Contract
Internship
Job title
Finite volume method for simulating fast transient flows through obstacles
Subject
Evaluation of the finite volume method for the simulation of fluid-structure interaction in fast transient flows through obstacles using simplified 1D models
Contract duration (months)
6
Job description
Loss of coolant accident (LOCA) in pressurized water reactors (PWR) leads to fast transient phenomena, such as the propagation of rarefaction waves through the reactor’s internal structures. These waves cause transient pressure loads in different zones, such as the reactor core and the bypass region, which generate stress on the baffle. The deformation of this structure may compromise the reactor’s structural integrity and hinder the handling of fuel assemblies and/or control rods after the accident.
This 6-month internship focuses on evaluating the use of the finite volume method for simulating fluid-structure interaction phenomena in fast transient flows, using simplified 1D models.
All calculations will be performed with the fast dynamics code EUROPLEXUS (http://www-epx.cea.fr/), co-owned by the Commissariat à l’Énergie Atomique et aux Énergies Alternatives (CEA) and the Joint Research Centre of the European Commission (EC/JRC), and developed within a consortium that includes CEA (DES/ISAS/DM2S in Saclay), the European Commission (JRC - IPSC in Ispra), as well as EDF, ONERA, and Framatome.
The main goal of this internship is to compare the results of the finite volume method with those previously obtained with EUROPLEXUS using the finite element method. This comparison will assess whether the finite volume method is more suitable for this type of simulation.
The performance of both methods will be evaluated through simulations of rarefaction wave propagation in simple geometries, replicating experiments conducted on the MADMAX platform over the last three years.
Numerical results will be validated by comparison with the aforementioned experimental results obtained on MADMAX, as well as with results from more complex reference numerical models (2D axisymmetric, 3D), also obtained with EUROPLEXUS.
The internship may also involve the development and implementation of a new impedance model in EUROPLEXUS, depending on the specific needs of the simulations.
This internship can continue into a PhD, with the aim of improving the modeling of physical phenomena related to the propagation of a depressurization wave in the primary circuit of a PWR following a pipe rupture, as well as its propagation through the core and into the bypass outside the baffle. To achieve this, further configurations and improvements to the current experimental system will be necessary to provide experimental data that will both serve to validate the models implemented in EUROPLEXUS and to improve the understanding of the physical phenomena involved.
Methods / Means
Simulations with EUROPLEXUS, programming in Fortran, validation with experimental results
Applicant Profile
You are preparing a Bac+5 (Engineering School Diploma or equivalent) in Mechanical, Energy or Nuclear Engineering.
Position location
Site
Saclay
Job location
France, Ile-de-France, Essonne (91)
Location
Saclay
Candidate criteria
Prepared diploma
Bac+5 - Diplôme École d'ingénieurs
Recommended training
Master student (Bac+5 – Master 2 / Diplôme École d'ingénieurs)
PhD opportunity
Oui
Requester
Position start date
03/02/2025
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