Simulation of radiation-induced segregation mechanisms at grain boundaries using the Phase Field Crystal method: application to Fe-Cr model alloys
The main objective of this postdoctoral research is to develop, calibrate and apply a CPF (crystalline phase field) model capable of simulating irradiation-induced segregation at grain boundaries in model Fe-Cr alloys, which are representative of ferritic-martensitic steels. The work will focus in particular on reproducing the atomic structure of grain boundaries and investigating the influence of their crystallographic orientation on segregation phenomena.
The project will also enable an assessment of the suitability of this approach as an alternative to current mean-field models used to describe irradiation-induced segregation (IIS). Particular attention will be paid to comparing the properties of point defects (formation and migration energies of vacancies and interstitials) obtained using the CPF method with those derived from molecular dynamics (MD) simulations.
New Proton Exchange Membrane Fuel Cell (PEMFC) Architecture for Decarbonized Heavy-Duty Transport
This postdoctoral project aims to develop a novel PEM fuel cell architecture to decarbonize heavy-duty transport (trucks, maritime, rail, and aviation). Current PEMFCs require external humidification to maintain performance, as their polymer membrane needs near 100% humidity. Above 80°C, water management, and especially keeping high hydration level, becomes inefficient, limiting operating temperature and necessitating bulky cooling systems.
The CEA has patented an innovative architecture that doubles fluid inlets/outlets, enabling independent control of cell pairs (bicells). By reversing thermal gradients between the anode and cathode, this design optimizes internal water circulation, maximizing retention and reducing the need for external humidifiers. The goal is to validate this architecture through an instrumented bicell, operational within 1–2 years, combining modeling, experimental testing, and parameter optimization (flow rates, humidity, pressure, thermal gradients).
This project could lead to a new generation of high-temperature PEMFCs (>80°C) without humidifiers, simplifying integration into industrial applications. Results may yield publications and patents.
Coupled X-ray / neutron tomography to reveal fluid evaporation in porous materials made by additive manufacturing for heat pipe applications
Improving efficiency of electronic cooling systems is paramount in many industrial domains. This is why CEA is currently developing a new heat pipe technology, based on the integration of a porous network produced by additive manufacturing. This project is a collaborative work between two laboratories of CEA Grenoble, in which you will develop an experimental bench dedicated to multi-modal tomography using X-ray and neutron beams. The goal is to characterize vapor region formation in porous networks infiltrated by a fluid and in contact with a hot source. Such advanced characterization method will allow you to better understand the physical phenomena at play, and propose new porous designs so as to increase the thermal powder density that can be dissipated by the system. The postdoc will supervise all development regarding the test setup, lead experimental campaign(s) at beamlines such as those offered by the Institute Laue Langevin (or equivalent facilities abroad), and analyze the data.
Exploratory study of actinium-225 production capabilities in research reactors and particle accelerators
This postdoctoral research project will examine various methods of producing the medical radioisotope 225Ac. These methods will involve irradiating 226Ra using either a material testing reactor (such as the Jules Horowitz Reactor) or a particle accelerator (such as a cyclotron or a rhodotron). The study will determine the optimal conditions for producing 225Ac, including the type and energy of the incident particles, the target material used, and the corresponding production yields, as well as the quantity of contaminants generated.
The first part of the work will involve modelling the irradiation characteristics in research reactors and particle accelerators. This modelling will be carried out at the Department of Reactor Studies at the IRESNE Institute, at the CEA Cadarache site. Monte Carlo simulations using TRIPOLI4®, GEANT4 and PHITS – developed by the CEA, CERN and JAEA, respectively – will be employed to model the JHR and the particle accelerators.
The second part of the project will be carried out in close collaboration with several CEA laboratories. These laboratories will host the postdoctoral researcher on an ad hoc basis to support them through the subsequent stages of the project.
The CHICADE facility in Cadarache is responsible for designing the targets. The proposed work involves identifying the main steps for manufacturing the targets by electrodeposition, starting with a stock of 226Ra-containing material. If possible, a feasibility study will also be conducted on non-irradiated targets with the same properties (cerium/barium model material).
In collaboration with the DRMP units responsible for modelling the thermomechanical aspects of the targets, the proposed work will also involve conducting a feasibility study on the ion irradiation of a model target at a facility such as JANNuS-Saclay or GANIL.
Development of advanced nuclear instrumentation for dose and contamination measurement on decommissioning sites.
This postdoctoral project focuses on the development of advanced nuclear instrumentation for dose and contamination measurement on decommissioning sites.
The approach is based in particular on online radiophotoluminescence measurement, in order to obtain sensitive radiological information that can be used in real time and adapted to constrained environments.
A major scientific challenge is to understand the physical mechanisms governing this measurement, from the creation of radiation-induced defects to their optical readout.
Silver-related defects play a central role, particularly their lifetime, temporal stability, and influence on signal reproducibility.
Controlling the excitation and emission processes, especially in the infrared range, is essential to improve sensitivity and the signal-to-noise ratio.
The project will aim to identify the limitations associated with weak signals, noise, drifts, component ageing, and disturbances specific to nuclear environments.
It will combine defect physics, optoelectronic instrumentation, acquisition electronics, ionising radiation metrology, and digital signal processing.
Filtering, drift correction, synchronisation, and anomaly detection methods will be developed to make online measurement more reliable.
System miniaturisation and integration will also be investigated to enable measurements as close as possible to the areas of interest.
The expected results will contribute to the experimental validation of the device and to the scientific dissemination of the project through publications, conferences, and supervision activities.
Study of precipitation in microfluidic-scale droplets of MoZr and actinide oxalate compounds.
Understanding the precipitation reactions that occur during the various stages of the spent nuclear fuel reprocessing process is a major scientific challenge for ensuring optimal control of this process.
In this context, the postdoctoral research project aims to study, at the microfluidic scale, the nucleation of species under different chemical conditions for two key systems:
-On the one hand, the formation of MoZr compounds, for which the aim of the study is to define the precipitation conditions and nucleation mechanism in order to limit their formation in the industrial system,
-On the other hand, the precipitation of plutonium oxalate, for which the objective is to evaluate the impact of hydrodynamics on the particles formed.
Since the microfluidic approach allows for better control of the conditions under which solutions are implemented, it will be essential to develop microfluidic tools suited to studying the precipitation of these species and then to plan their adaptation to a nuclear environment while coupling them with various characterization equipment for conducting parametric tests (SWAXS, DLS, etc.). This work on adaptation to a nuclear environment and system integration will be carried out with the assistance of specialists in this field.
Robust path-following solvers for the finite element simulation of cracking in complex heterogeneous media: application to reinforced concrete structures
Path-following (or continuation) procedures are used to describe the unstable responses of structures exhibiting snap-back or snap-through phenomena. These methods consist in adapting the external load during the deformation process in order to satisfy a control constraint, by introducing an additional unknown, the load multiplier. Several variants exist depending on the controlled quantity: degrees of freedom, strain measures, or variables related to energy dissipation.
In addition to enabling the tracing of unstable responses, a major advantage of these approaches lies in improving the convergence of incremental Newton-type solvers by reducing the number of iterations required. This gain often compensates for the additional computational cost associated with the continuation algorithm. Some formulations have proven both efficient and simple to implement.
However, no objective criterion yet allows one to determine which formulation is best suited for the simulation of reinforced concrete structures, where multiple dissipation mechanisms coexist along with a strong spatial variability of the material properties.
The proposed postdoctoral work aims to develop robust path-following algorithms for such structures, building upon previous research carried out at CEA. It will include a critical analysis of existing formulations, an evaluation of their performance (monolithic or partitioned solvers), followed by their implementation. Finally, representative test cases of industrial structures will be simulated to assess the gain in robustness and computational cost compared to standard solvers.
Development of an innovative instrumentation architecture using an array of magneto-resistive sensors to create a fast tomography system for fuel cells
Developing an innovative instrumentation architecture using an array of magneto-resistive sensors to create a rapid tomography system for fuel cells.
The goal is to develop a TRL 4 demonstrator in the laboratory to demonstrate a proof of
concept on a low-temperature fuel cell stack. This will include four measurement boards
with several dozen of synchronized magnetic sensors for simultaneous acquisitions. Experimental results and a description of the instrumentation system will be published. Historical data will be used to validate current density resolution algorithms and compare their performance to solutions based on Physics Informed Neural Network. Estimated current density results will be used for an additional publication.
The instrumentation system will be integrated into a CEA test bench dedicated to optimal control, transient observation, fault detection and exploration of defect propagation phenomena. This approach will offer dynamic and non-invasive observation of current distribution in the fuel cell, thereby improving the understanding of its operation and facilitating the optimization of its performance and lifespan.
Modelling and analysis of prospective scenarios for the deployment of hydrogen infrastructure in France and Germany
The use of hydrogen produced by electrolysis or of molecules derived from electrolytic hydrogen (synthetic methanol, synthetic kerosene, etc.) is one of the solutions envisioned to decarbonise certain sectors such as the steel industry and long-distance sea and air transport.
The development of a Europe-wide hydrogen transport infrastructure is considered to facilitate the development of electrolytic hydrogen production on the continent. This infrastructure could provide access to massive underground hydrogen storages unevenly distributed across Europe, facilitate exchanges between regions with high solar or wind energy potential and major industrial hubs and, in certain areas, limit the cost of reinforcing the electricity transmission network.
The goal of the CrossHy project is to analyse the possible deployment pathways for hydrogen transport infrastructure in France and Germany. Two complementary modelling tools (REMix, ANTARES) are going to be used and to develop a European-scale model and a regional-scale model of a cross-border-region.
Regular physical meetings between the French and German research teams are planned during the project; the post-doc will include a 3-month visit to Stuttgart to work and exchange with the DLR team involved in the project.
Decomposition of Fission Fragment Energy from Microscopic Approaches to Provide Input Data for the FIFRELIN Code
The FIFRELIN code (FIssion FRagment Evaporation modeLINg), developed since 2009 at the CEA, simulates the formation and decay of nuclear fission fragments. It contributes to the enrichment of the European nuclear data library JEFF, which is used for reactor simulations. The calculation proceeds in two steps: the generation of fission fragments (with their physical properties), followed by their decay using a Monte Carlo Hauser-Feshbach approach. At the moment of scission into two fragments, the total energy is split between kinetic energy (TKE) and excitation energy (TXE). The TXE is further divided into deformation energy and intrinsic excitation energy, which govern the emission of neutrons and photons. Accurate knowledge of both TXE and TKE is essential to improve FIFRELIN’s performance. Microscopic theoretical approaches (such as Hartree-Fock-Bogoliubov and the Generator Coordinate Method) are used and developed within DES to provide theoretical input supporting evaluated nuclear data. This postdoctoral position aims to use and enhance these models to gain a more detailed understanding of nuclear properties at scission. The desired candidate has several years of experience (3 years or more) in nuclear mean-field theory (such as Hartree-Fock-Bogoliubov, relativistic mean-field, etc.) or in the generator coordinate method.