Physico-chemical coupling between a bubbles population and the oxido-reduction of glass-forming liquid
The calcination-vitrification process is the solution used in France for more than 30 years for the conditioning of high-level nuclear waste resulting from the reprocessing of spent fuel. During the vitrification process, the waste is incorporated into a borosilicate glass-forming liquid at more than 1000°C. The glass-forming liquid is homogenized in temperature and composition by stirring and gas bubbling. The incorporation of waste into glass-forming liquid can also lead to gas releases, including those of oxygen resulting from redox reactions between species dissolved in the liquid. It is important to properly control the impact of these gases on the glass and the process.
The redox state of glass-forming liquid at equilibrium between the dissolved species has been the subject of various studies at the CEA in the context of the vitrification of nuclear waste. On the other hand, few studies have been devoted to the kinetics of gas reactions in glass-forming liquid. The objective of this thesis aims to study and model the impact of gas bubbles, whatever their nature, on the redox of melting and the kinetics of associated reactions. An approach combining experimentation and digital modeling will be adopted.
The desired candidate will have a taste for experimentation, characterization and interpretation of results addressing different scientific fields (physico-chemistry of materials, electrochemistry). All experiments will be carried out on non-radioactive elements and will involve processing by digital modeling. This PhD thesis will allow acquiring valuable professional experience in the glass and nuclear industry.
Development of machine learning algorithms to improve image acquisition and processing in radiological imaging
The Nuclear Measurements Laboratory at the LNPA (Laboratory for the Study of Digital Technologies and Advanced Processes) in Marcoule consists of a team specializing in nuclear measurements in the field. Its activities are divided between developing measurement systems and providing technical expertise to CEA facilities and external partners (ORANO, EDF, IAEA).
The LNPA has been developing and using radiological imagers (gamma and alpha) for several years. Some of the developments have resulted in industrial products, while other imagers are still being developed and improved. Alpha imaging, in particular, is a process that allows alpha contamination zones to be detected remotely. Locating the alpha source is an important step in glove boxes, whether for a cleanup and dismantling project, for maintenance during operation, or for the radiation protection of workers. The alpha camera is the tool that makes alpha mapping accessible remotely and from outside glove boxes.
The objective of the thesis is to develop and implement mathematical prediction and denoising solutions to improve the acquisition and post-processing of radiological images, and in particular alpha camera images.
Two main areas of research will be explored in depth:
- The development of real-time or post-processing image denoising algorithms
- The development of predictive algorithms to generate high-statistics images based on samples of real images.
To do this, an experimental and simulation database will be established to feed the AI algorithms.
These two areas of research will be brought to fruition through the creation of a prototype imager incorporating machine learning capabilities and an image acquisition and processing interface, which will be used in an experimental implementation.
Through this thesis, students will gain solid knowledge of nuclear measurements, radiation/matter interaction, and scientific image processing, and will develop a clear understanding of radiological requirements in the context of remediation/decommissioning projects.
Physicochemical Properties of Antimony-containing Photovoltaic (PV) Glass
The proposed PhD thesis is part of the ANR GRISBI project (2026–2030), which aims to optimize the recycling of glass from photovoltaic (PV) panels. These glasses, predominantly manufactured in China, are doped with antimony oxide (Sb2O3) to ensure high transparency while keeping production costs low. However, the presence of antimony currently prevents the recycling of these glasses within the European flat glass industry, which would otherwise greatly benefit from this secondary raw material to reduce its environmental footprint — particularly its greenhouse gas emissions, in line with the carbon neutrality targets set by the Paris Agreement (2015). To make the recycling of PV glass into flat glass production feasible, it is therefore essential to gain a deeper understanding of the physicochemical behavior of antimony in glass, and more generally, within the float process, which involves a hot glass / liquid tin interface.
The core scientific objective of the PhD is to determine the redox equilibria between the multivalent species present in PV glasses, in particular the Sb2O3/Sb and Fe2O3/FeO couples. The work will involve preparing glasses with different Sb2O3 contents, then determining the mechanisms of antimony incorporation into the glass structure, as well as the temperature and oxygen partial pressure (pO2) conditions leading to the reduction of Sb³? to metallic Sb°. Experimental results, based on advanced materials characterizations such as SEM, XRD, EXAFS, and XANES, will be used to enrich thermodynamic databases and to develop a methodology enabling the recycling of Sb-doped PV glasses in flat glass production.
The PhD will be conducted at CEA Marcoule, in collaboration with IMPMC (Sorbonne Université) — two laboratories internationally recognized for their expertise in glass science. All glass samples will be synthesized by the PhD student, and their characterization will primarily rely on facilities available at CEA and IMPMC.
A background in Materials Science is required. This research project will provide the PhD candidate with the opportunity to develop strong expertise in applied glass science and industrial recycling technologies.
Multi-criteria Navigation of a Mobile Agent applied to nuclear investigation robotics
Mobile robots are increasingly deployed in hazardous or inaccessible environments to perform inspection, intervention, and data collection tasks. However, navigating such environments is far more complex than simple obstacle avoidance: robots must also deal with communication blackouts, contamination risks, limited onboard energy, and incomplete or evolving maps. A previous PhD project (2023–2026) introduced a multi-criteria navigation framework based on layered environmental mapping and weighted decision aggregation, demonstrating its feasibility in simulated, static scenarios.
The proposed thesis aims to extend this approach to dynamic and partially unknown environments, enabling real-time adaptive decision-making. The work will rely on tools from mobile robotics, data fusion, and autonomous planning, supported by experimental facilities that allow realistic validation. The objective is to bring navigation strategies closer to real operational conditions encountered in nuclear dismantling sites and other industrial environments where human intervention is risky. The doctoral candidate will benefit from an active research environment, multidisciplinary collaborations, and strong career opportunities in autonomous robotics and safety-critical intervention systems.
Origins and consequences of the heterogeneous alteration of nuclear glasses
This PhD project focuses on the long-term behavior of nuclear glasses used to confine long-lived radioactive waste.
In aqueous environments, these glasses generally undergo homogeneous alteration: the transformation into alteration products occurs at a uniform rate across the entire surface.
However, cases of heterogeneous alteration also exist, where the glass/gel interface becomes irregular, forming pits or cavities.
Two key questions arise: what are the mechanisms responsible for that behavior, and what are the consequences for the long-term durability of the glass?
Several hypotheses have been suggested in the literature, such as local fluctuations in solution composition or mechanical stress at the glass surface, but no definitive explanation has yet been established.
The proposed approach combines accelerated experiments with chemical, mechanical, and structural characterizations, as well as modeling (e.g., mesoscopic and Monte Carlo models).
Experiments will be conducted on glasses with various surface states (polished, irradiated, fractured, etc.) using analytical tools such as SEM, TEM, and nanoSIMS.
Once the mechanisms are identified, the long-term impact of these heterogeneous alteration patterns can be assessed.
The project seeks candidates with a background in chemistry or materials science, strong interest in modeling, and solid theoretical knowledge.
Microemulsion model: Towards the prediction of liquid-liquid extraction processes
This multi-scale modeling PhD project aims to develop innovative theoretical approaches and numerical tools to predict the extraction processes of strategic metals, which are essential for the energy transition. Among the existing methods, liquid-liquid extraction is a key process, but its underlying mechanisms remain poorly understood. To address these challenges, the solvent phases will be represented as microemulsions through a synergy of mesoscopic and molecular modeling approaches.
The mesoscopic approach will involve the development of a code based on microemulsion theory using a random wavelet basis. This code will enable the characterization of the structural and thermodynamic properties of the solutions. The molecular approach will rely on classical molecular dynamics simulations to evaluate the curvature properties of the extractants, which are essential for bridging the two scales.
The new high-performance computational code may integrate artificial intelligence techniques to accelerate the minimization of the system’s free energy while accounting for all chemical species present with a minimal number of parameters. This will pave the way for new research directions, such as predicting speciation and calculating thermodynamic instabilities in ternary phase diagrams, thereby identifying unexplored experimental conditions.
This PhD thesis, conducted at the Mesoscopic Modeling and Theoretical Chemistry Laboratory at the Marcoule Institute for Separation Chemistry, will have applications in the recycling domain and extend to the broader field of nanoscience, thereby expanding the impact of this work.
The PhD candidate, with a background in physical chemistry, theoretical chemistry, or physics and a strong interest in programming, will be encouraged to disseminate their scientific results through publications and presentations at national and international conferences. By the end of the thesis, the candidate will have acquired a broad range of skills in theoretical chemistry, modeling, numerical computation, and physical chemistry, providing numerous career opportunities in both academic research and industrial R&D.
Turbulence synthetization methods in porous media from detailed simulations for multi-scale simulations of nuclear cores
The production of electricity through nuclear energy plays a crucial role in the energy transition due to its low carbon impact. To continuously improve safety and performance, it is essential to develop new knowledge and tools.
The core of a nuclear reactor consists of thousands of fuel rods traversed by a turbulent flow. This flow can cause vibrations, leading to wear. Two flow scales are identified: a local scale, where the fluid interacts with the rods, and a global scale, representing the flow distribution within the core. The local scale requires CFD simulations and fluid-structure coupling, while the global scale can be modeled using averaged approaches, such as porous media simulations.
Coupled fluid-structure interaction (FSI) simulations at the CFD scale are limited to small domains. To overcome this limitation, multi-scale approaches are required, combining large-scale porous media simulations and detailed small-scale CFD simulations. The goal of the thesis is to develop methods for synthesizing turbulence from the results of porous media simulations to improve boundary conditions for CFD simulations. The candidate will first study how existing turbulence models can provide details on turbulent flow at the component scale, and then how to synthesize turbulence for local CFD simulations.
This PhD project is the subject of a collaboration between the IRESNE Institute (CEA) and the ASNR (main execution site of the thesis) in Cadarache. Funding is provided by a MSCA Doctoral Network. The PhD student will be integrated into a network of 17 PhD students. To be eligible, the candidate must have resided no more than 12 months in the last 36 months in France.
Characterisation of reaction pathways leading to thermal runaway for new battery technologies
The development of all-solid-state cells is no longer a mere hypothesis today. As part of the Safelimove project, we assessed the safety of hybrid polymer cells of 1 Ah and 3 Ah, which led to a publication. Additionally, within the Sublime project, we evaluated the safety of 1 Ah sulfide-based cells (argyrodite), and a publication is currently being submitted.
With the arrival of these new cells, it becomes even more crucial to support their development with a detailed safety assessment and the identification of the complex mechanisms involved. Large-scale instruments such as synchrotrons and neutron reactors offer a powerful opportunity to achieve this goal, as they provide the best spatial and temporal resolutions. For example, thanks to fast X-ray radiography at ESRF, it is possible to visualize the inside of a cell during thermal runaway, thereby identifying the local impact of (electro)chemical reactions on the microstructure of components and validating our thermal runaway models. Moreover, with wide-angle X-ray scattering (WAXS), it is possible to monitor in situ the evolution of the crystalline structure of active materials during a very rapid thermal runaway reaction. Indeed, synchrotron radiation allows the acquisition of one diffractogram every 3 milliseconds. The neutron beam at ILL also enables us to track the evolution of lithium metal structure before, during, and after runaway. It is important to emphasize that these three techniques are currently mastered by the LAPS teams and have already led, or will lead, to publications.
Furthermore, new complementary techniques may be explored, such as studying the impact of thermal/mechanical stress on active materials using the BM32 beamline, or evaluating the oxidation states of metals via X-ray absorption spectroscopy (XAS) on ID26.
More conventional laboratory characterizations will also be carried out, such as DSC, TGA-MS, and XRD.
As part of our various collaborations, the cathode active materials will likely include NMC, LMFP, and NVPF. The electrolytes used will be based on sulfide, halide, or polymer, while the anode will consist of lithium metal, lithium-silicon alloy, or hard carbon. The thesis will aim, among other things, to identify, depending on the materials used, whether reactions occur before cathode destabilization, whether the solid electrolyte reacts with the oxygen from the cathode or with the anode material, and whether these parallel reactions contribute to better or worse cell safety.
The three years of the PhD will be structured as follows: the first year will be dedicated to a literature review and the characterization of sulfide technology. Following the first milestones (1st CSI) and the evaluation of ongoing work on sulfides, the second year will focus either on sodium-ion technology or on further development of sulfide technology. Finally, the third year, in addition to the thesis writing, will concentrate more specifically on the impact of the identified materials on safety.
Direct lithium extraction from brine through adsorption
The development of electric vehicles due to climate and the decision to turn towards a greener energy has increased sharply the demand of lithium over the past decade and will continue to escalate. Thus, lithium extraction projects are proliferating worldwide. Since mining presents a quite highly energy-consuming and polluting solution, alternative lithium sources like brine deposits or seawater are being currently investigated. In this study, we will focus on the approach of a direct lithium extraction from brine sources with different concentrations by adsorption. The first step will be to synthesize and characterize a wide range of materials as adsorbents, from classic oxides (LMO, LTO, etc) to functionalized hybrid porous materials (ZIFs, MOFs, etc). It is also intended to shape these materials with the help of an extruder, in order to enhance performances. Then, these materials will be evaluated both in static and dynamic conditions. Various parameters like the concentration of lithium, the presence of other cations and their concentration will be also evaluated and optimized so that we obtain a facile, efficient and selective process. The results of this study will be valorized through the deposit of patents and the submission of scientific articles along the whole duration of the thesis.
Fast charging of lithium-ion batteries : Study of the lithium plating phenomenon using operando NMR
The focus of the thesis is the fast-charging process of lithium-ion batteries and, more specifically, the phenomenon of lithium plating, which will be studied using operando NMR. The target application is electric mobility. The objective of the thesis is to study the dynamics of lithium insertion and lithium metal deposition at the graphite or graphite/silicon-based negative electrode in order to understand the mechanisms leading to plating formation.
Operando NMR is an ideal technique for this study because it offers the unique possibility of simultaneously tracking the signals of the lithiated graphite phases and of deposited lithium during the electrochemical processes. The coupling of electrochemistry and operando NMR will allow us to determine the onset of plating, i.e. the potential of the negative electrode at which deposition begins, and the kinetics of lithium metal deposition and reinsertion at different temperatures and different charging current regimes. We will study Li-ion batteries with a pure graphite negative electrode, but also with graphite-silicon electrodes, in order to investigate the impact of silicon on this phenomenon. The data obtained on the onset mechanisms and the kinetics of lithium metal deposition and reinsertion will be used in a multiphysics model that has already been developed in the laboratory to improve the prediction of plating onset. We will then be able to evaluate the chargeability gains on an NMC 811 // Gr+Si system incorporating optimized electrodes and propose innovative charging protocols.