Study of embrittlement and thermal fatigue of stainless steels
In order to study the behavior of nuclear materials under dynamic stress, CEA Valduc wishes to develop a new device integrated into a glove box. For this purpose, a collaboration with CEA GRAMAT and an industrial specialist in the field has been set up. During the experiments conducted with thisdevice, some components are subjected to very high temperatures and the presence of gaseous hydrogen for a very short time.
Initially, different grades of austenitic steels were tested under these severe conditions and a prototype was ordered and received at the industrial site.
The study has three objectives. The first is the acquisition of new experimental mechanical and microstructural data at the micrometric scale from the previously exposed steel batches. The second concerns the microstructural analysis of thermal fatigue. Finally, the third and final objective is the integration of these new data into a numerical tool for microstructural evolution simulation aiming at reproducing the global effect of aging, in thermal and pressure cycles by coupling, for example, CALPHAD-type codes and the use of multiphysical COMSOL-type codes.
The work will take place according to the three components carried out in parallel. It will also be requested from the post-doctoral student in charge of this study to:
- participate to the implementation and monitoring of collaborations with recognized experts in the fields of embrittlement, thermal fatigue, and microstructural analysis,
- synthesize and publish, as far as possible, the results obtained in the form of various documents and publications in international journals or conference communications
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.
Hydrodynamic and Magnetohydrodynamic Modelling of HED Plasmas
In the context of fusion, magnetized FCI utilizes external magnetic fields that are compressed during implosion, thereby magnetizing electrons and alpha particles. This reduces transverse heat losses and improves hot spot confinement, enabling ignition at lower surface densities, with slower and more stable implosions. CELIA, a recognized leader in magnetized implosion research [Plasma Phys. Control. Fusion 64, 025007 (2022)], coordinates multiple international and national programs (EUROfusion, NLUF, LBS, NIF Discovery Science, ANR).
Recent large-scale experiments conducted at Omega have demonstrated record-breaking compressed fields (~10 kT) and a temperature increase in hot spots of approximately 50%, thanks to K-layer spectroscopy of argon doping in DD nuclear fuel, enabling the characterization of plasma conditions in the compressed core [Phys. Rev. Research 6, L012018 (2024)].
Upcoming approved experiments include:
• Omega (February and August 2026): control of radiative cooling via argon concentration; multi-dopant spectroscopy; magnetized spherical implosions.
• NIF (May 2026): with 20 times the energy of Omega, study of triton confinement through the analysis of angular-resolved time-of-flight spectra of secondary neutrons, as a probe of magnetic field intensity and topology.
• LMJ (April 2026 and Q1 2027): with laser drive energy equivalent to that of NIF, but with smaller targets, magnetized cylindrical implosions aiming for a compression 3 times greater than that of Omega and NIF; spectroscopy of the double-doped K-layer for spatially resolved core conditions. The interpretation and predictive design of these experiments require advanced 2D/3D MHD simulations, which will be entrusted to the postdoctoral researcher
Numerical simulation of nanosecond laser pulse interaction with porous dielectric material
The context of this work concerns mechanical damage of porous ceramics induced by laser irradiation. The latter excites electrons of the material (energy gain), which in turn modifies its optical properties and the laser propagation itself. The pores in the material bulk also modify laser propagation, giving rise to interference and enhancement in the electric field, which then accelerate the electron dynamics and the laser energy deposition. The latter induces temperature and pressure gradients that form the shock wave responsible for damaging the material. Describing this system therefore requires coupling hydrodynamics with electronic and laser dynamics. The objective of this postdoctoral research is to model and study this complex system. The first part of the work consists in coupling existing codes describing laser energy deposition and hydrodynamics. The obtained code will then be used to carry out physical studies and understand the interaction mechanisms. In particular, the influence of porosity characteristics on shock formation will be studied.
Cell manufacturing and electrochemical testing of solid-state batteries
Holding a PhD in electrochemistry, materials science, chemistry, or process engineering, the postdoctoral researcher will work closely with project partners on the development of manufacturing processes and prototyping of solid-state battery cells of 4?? generation (Li/NMC high-nickel) and 5?? generation (Li/Sulfur).
The work will focus on electrode shaping and assembly of solid-state cells, using processes such as coating, extrusion, and alternative approaches including 3D printing. These processes will be optimized to produce prototype cells (button cells and pouch format) with capacities up to 1 Ah, incorporating optimized interfaces. The cells will then be electrochemically tested to evaluate performance in terms of specific capacity, coulombic efficiency, and cycling stability.
Most experimental work will be conducted in controlled environments (gloveboxes), with regular characterization of both electrodes and assembled cells. Main responsibilities will include:
- Contributing to the definition of test plans based on internal data and literature,
- Developing and optimizing manufacturing processes for electrodes and solid-state cells,
- Producing and testing Gen4b and Gen5 prototype cells,
- Evaluating electrochemical performance and analyzing results,
- Presenting results clearly and concisely,
- Proposing improvements, ensuring smooth laboratory operations, and adhering to safety and quality standards,
- Disseminating research through publications, scientific presentations,
Development of isotopic and elemental analysis methods on irradiated fuels for the reduction of sample quantities.
The objective of this postdoctoral research is to develop analytical methods for the overall reduction of sample quantities required for high-precision multi-element isotopic analysis (actinides and PF) of spent nuclear fuel, particularly through the use of novel "low-quantity" introduction methods on multi-collector ICPMS. These developments will notably reduce the amount of radioactive waste (consumables and effluents), the dose rate, and the exposure time of analysts/radioactive samples associated with this type of measurements.
To carry out this project, the candidate will conduct analytical developments in a controlled environment to minimize the quantities of elements required for analysis while maintaining or improving uncertainty levels compared to currently available methods.
Spin-lattice interactions in Machine Learning assisted ab initio simulations
The scientific field addressed by this postdoctoral project lies at the intersection of ab initio molecular dynamics, machine learning, and the thermodynamic characterization of materials under extreme conditions. Traditional AIMD simulations are a powerful tool to study temperature- and pressure-dependent properties from first principles, but their high computational cost limits their widespread use. By developing and applying machine learning-assisted sampling techniques like MLACS, this postdoc aims to drastically reduce the computational burden while retaining ab initio accuracy. This enables the efficient exploration of phase diagrams in high-pressure and high-temperature conditions. This research contributes to both fundamental understanding and practical modeling of materials, offering high-impact tools for the scientific community.
Diamond-based electrochemical sensors for monitoring water pollution in urban environments
This postdoctoral position is offered by CEA List as part of the European UrbaQuantum project ("A novel, Integrated Approach to Urban Water Quality Monitoring, Management and Valorisation"), part of the HORIZON-CL6-2024-ZEROPOLLUTION-02 call for projects. The main objective of this project is to develop, in response to climate change, sensors, models, and protocols for better management of the water cycle in urban environments.
At the Sensors and Instrumentation for Measurement Laboratory (LCIM)of CEA List the postdoctoral fellow will contribute to the development of electrochemical sensors based on synthetic diamond and associated measurement protocols for the detection of pollutants such as pharmaceuticals, heavy metals, PFAS, and pesticides. These sensors will be miniaturized and integrated into a microfluidic cell, in partnership with CEA-Leti, then tested under real-world field conditions.
Study of the Thermodiffusion of Small Polarons in UO2
The position is published on the CEA website at the following address:
https://www.emploi.cea.fr/job/emploi-post-doctorat-etude-en-ab-initio-de-la-thermodiffusion-des-petits-polarons-dans-UO2-h-f_36670.aspx
Impact of Microstructure in Uranium Dioxide on Ballistic and Electronic Damage
During reactor irradiation, nuclear fuel pellets undergo microstructural changes. Beyond 40 GWd/tU, a High Burnup Structure (HBS) appears at the pellet periphery, where initial grains (~10 µm) fragment into sub-grains (~0.2 µm). In the pellet center, under high temperatures, weakly misoriented sub-grains also form. These changes result from energy loss by fission products, leading to defects such as dislocations and cavities. To study grain size effects on irradiation damage, nanostructured UO2 samples will be synthesized at JRC-K, using flash sintering for high-density pellets. Ion irradiation experiments will follow at JANNuS-Saclay and GSI, with structural characterizations via Raman spectroscopy, TEM, SEM-EBSD, and XRD. The postdoc project will take place at JRC-K, CEA Saclay, and CEA Cadarache under expert supervision.