BRO-IA-GE: Multi-sensor instrumentation and hybrid modelling of ball milling processes
The Uranium Fuel Laboratory of the Institute for Research on Nuclear Systems for Low-Carbon Energy (IRESNE) at CEA Cadarache develops innovative tools to improve the understanding and control of nuclear fuel manufacturing processes. In the context of nuclear fuel cycle closure and the renewal of future industrial facilities, mastering powder processing operations has become a strategic challenge.
Ball milling is a key step in the production of UOX and MOX nuclear fuels, as it directly impacts powder homogeneity and particle size characteristics prior to pellet fabrication. Despite its industrial importance, the mechanisms of this process are still poorly understood due to the complexity of the fragmentation mechanisms and the interactions between particles with different properties.
This postdoctoral project aims to develop an in-depth understanding of milling processes through a combination of experimental instrumentation, signal processing, data analysis, and modelling. The successful candidate will rely on an instrumented experimental platform incorporating acoustic emission monitoring and high-speed imaging, as well as on an extensive experimental database currently being established using model materials such as alumina.
Particular attention will be devoted to multi-component powder systems in order to better understand the influence of powder properties on fragmentation, mixing, and homogenization mechanisms. The results will contribute to the development of predictive models and a digital twin of the milling process for real-time monitoring and process optimization.
The candidate will acquire expertise in advanced instrumentation, materials science, granular physics, artificial intelligence, and process modelling. These skills are highly transferable to many industrial sectors involving powders and granular materials, including energy, powder metallurgy, advanced ceramics, pharmaceuticals, and food processing industries.
Experimental and numerical study of irradiation creep deformation mechanisms
This post-doctoral project aims to better understand irradiation creep process. While multiple mechanisms have been proposed, their validity remains debated. Irradiation generates atomic defects (vacancies, interstitials) that diffuse, agglomerate into clusters (e.g., dislocation loops), or interact with microstructural features. Recent TEM observations in stressed pure aluminum at room temperature revealed that interstitial dislocation loops form preferentially in specific crystallographic planes, suggesting a mechanism that may explain primary creep.
The research aims to:
- Study loop growth and orientation under electron irradiation at higher temperatures. Experiments at CEMES (Toulouse) will be paired with object kinetic Monte Carlo (OKMC) simulations.
- Extend findings to ion irradiation (closer to neutron damage), where loops form directly in collision cascades. In-situ TEM at JANNuS-Orsay and molecular dynamics coupled to OKMC will be used for this purpose.
- Explore alternative creep mechanisms, based on dislocation-loop interactions, stress-assisted glide, and helical climb formation, using TEM and electron tomography.
Improvement of High-Temperature Electrolyzer Interconnect Performance
High-Temperature Electrolyzers (HTEs) are currently being developed at the CEA for the production of “green” hydrogen. One of the components, the stainless-steel interconnect, is affected by two phenomena that progressively reduce cell efficiency: surface oxidation and chromium oxide volatilization. For these reasons, protective coatings are being developed at the CEA and with industrial partners. The performance of these samples (oxidation behavior, electrical resistance, etc.) must be evaluated both in contact with air, in contact with an H2/H2O mixture, and under dual-atmosphere conditions with the two environments on either side of the sample.
The proposed postdoctoral position includes several missions presented below:
• Development of an experimental setup to evaluate the oxidation behavior and area-specific resistance of coated and uncoated samples under all environmental conditions.
• Investigation of the observed phenomena using the many characterization techniques available at the CEA (SEM, Raman microscopy, TEM, GD-OES, XPS, XRD, etc.).
• Proposal of the degradation mechanisms involved and identification of the most relevant coating for industrial applications.
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.
Thermal properties of 3D aluminum nitride structures for electronic packaging
The 12-month postdoctoral fellowship is part of the overall 3DNAMIC project, funded by the Occitanie region and involving the Materials platform of the DRTDOCC department and the Laplace laboratory. A thesis began in December 2024 aimed at “the study and characterization of 3D aluminum nitride ceramics for the thermal packaging and management of electronic components.”
The postdoc is scheduled to begin at approximately in September 2026, with the following main objectives:
Objective 1: Perform a comparative analysis of the thermal properties of ceramics produced by AF elements and on model structures using different materials available in the CEA materials platform.
Objective 3: Propose, qualify, and validate, numerically and then experimentally, heat dissipation structures for ceramics obtained by FA as part of the 3DNAMIC project.
In-situ 4D tracking of microstructural evolution in atomistic simulations
The exponential growth of high-performance computing has enabled atomistic simulations involving billions or even trillions of particles, offering unprecedented insight into complex physical phenomena. However, these simulations generate massive amounts of data, making storage and post-processing increasingly restrictive. To overcome this limitation, on-the-fly (in-situ) analysis has emerged as a key approach for reducing stored data by extracting and compressing relevant information during runtime without significantly affecting simulation performance.
In this context, tracking the four-dimensional (space and time) microstructural evolution of materials under extreme conditions is a major scientific challenge. Atomistic simulations provide a unique spatial resolution to analyze crystalline defects such as dislocations, twinning, vacancies and pores, which govern dynamic phase transformations, melting, damage and mechanical behavior. By capturing their spatio-temporal evolution, it becomes possible to study their statistics, correlations and collective effects in out-of-equilibrium regimes, leading to more accurate predictive material models.
This project builds on advances of the exaNBody high-performance computing platform and a recently developed in-situ clustering method in the ExaStamp molecular dynamics code at CEA. This method projects atomic information onto a 3D Eulerian grid to perform real-time clustering. The objective is to extend this approach to full 4D tracking, enabling the time-resolved monitoring of clusters. This will allow dynamic graph-based analysis of their evolution, including changes in size, shape and temporal behavior, providing new insights into microstructural dynamics at the atomic scale.
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.
Preparation and characterization of an oxide/oxide composite
Fiber-reinforced ceramic matrix composites (CMCs) are a class of materials that combine good specific mechanical properties (properties relative to their density) with resistance to high temperatures (> 1000 °C), even in oxidizing atmospheres. They are typically composed of a carbon or ceramic fiber reinforcement and a ceramic matrix (carbide or oxide.
The proposed study focuses on the development of a low-matrix oxide/oxide CMC with suitable dielectric, thermal, and mechanical properties.
This study will be conducted in collaboration with several laboratories at CEA Le Ripault.