Towards automated and reconfigurable microfluidic platforms for the study and development of nuclear fuel recycling processes
The main objective of this PhD project is the design and development of the first automatic and reconfigurable microfluidic platform dedicated to research and development on the nuclear fuel cycle. In a context where mastering nuclear processes remains a key challenge, both for energy production and for the sustainable management of nuclear materials, microfluidic devices represent a particularly promising approach. These autonomous laboratories on a chip have already demonstrated their potential in various fields, such as chemistry, materials science, and biology. Their application to nuclear processes would help reduce radiation exposure risks, minimize waste generation, and optimize resources by enabling a larger number of experiments to be performed safely, quickly, and reproducibly. For about a decade, the DMRC has been conducting phenomenological studies on the main stages of the nuclear process (dissolution, solvent extraction, precipitation, etc.) using microfluidic devices. In parallel, it has developed PhLoCs (Photonic-Lab-on-Chips), which allow the miniaturization of several analytical techniques (UV-Vis spectroscopy, LES, holography, etc.) and their integration for online monitoring of the investigated phenomena. Nevertheless, no truly autonomous and fully automated platform currently exists that combines process execution with integrated analytical monitoring.
The aim of this PhD work is therefore to make a decisive step by designing a modular device where several functional chips can be assembled, some dedicated to process operations (e.g., uranium/plutonium separation) and others to online measurements, within a flexible configuration adapted to nuclear environments. In addition, the research will focus on integrating new instrumental techniques directly on chips, such as FTIR and UV-Vis-NIR spectroscopies, which are crucial for studying critical process steps, including solvent degradation. This project thus aims to establish the foundations of next-generation microfluidic platforms that combine safety, modularity, and performance to advance nuclear fuel cycle research. At the end of the PhD, the candidate will have developed unique expertise in microfluidics applied to nuclear processes, combining optical instrumentation and automation. These skills will offer strong career opportunities in research and advanced process engineering.
Design and Optimisation of an innovative process for CO2 capture
A 2023 survey found that two-thirds of the young French adults take into account the climate impact of companies’ emissions when looking for a job. But why stop there when you could actually pick a job whose goal is to reduce such impacts? The Laboratory for Process Simulation and System analysis invites you to pursue a PhD aiming at designing and optimizing a process for CO2 capture from industrial waste gas. One of the key novelties of this project consists in using a set of operating conditions for the process that is different from those commonly used by industries. We believe that under such conditions the process requires less energy to operate. Further, another innovation aspect is the possibility of thermal coupling with an industrial facility.
The research will be carried out in collaboration with CEA Saclay and the Laboratory of Chemical Engineering (LGC) in Toulouse. First, a numerical study via simulations will be conducted, using a process simulation software (ProSIM). Afterwards, the student will explore and propose different options to minimize process energy consumption. Simulation results will be validated experimentally at the LGC, where he will be responsible for devising and running experiments to gather data for the absorption and desorption steps.
If you are passionate about Process Engineering and want to pursue a scientifically stimulating PhD, do apply and join our team!
Understanding the mechanisms of oxidative dissolution of (U,Pu)O2 in the presence of Ag(II) generated by ozonation
The recycling of plutonium contained in MOx fuels, composed of mixed uranium and plutonium oxides (U,Pu)O2, relies on a key step: the complete dissolution of plutonium dioxide (PuO2). However, PuO2 is known to dissolve only with great difficulty in the concentrated nitric acid used in industrial processes. The addition of a strongly oxidizing species such as silver(II) significantly enhances this dissolution step—this is the principle of oxidative dissolution. Ozone (O3) is used to continuously regenerate the Ag(II) oxidant in solution.
Although this process has demonstrated its efficiency, the mechanisms involved remain poorly understood and scarcely documented. A deeper understanding of these mechanisms is essential for any potential industrial implementation.
The aim of this PhD work is to gain insight into the interaction mechanisms within the HNO3/Ag/O3/(U,Pu)O2 system. The research will be based on a parametric experimental study of increasing complexity. First, the mechanisms of generation and consumption of Ag(II) will be investigated in the simpler HNO3/Ag/O3 system. In a second phase, the influence of various parameters on the oxidative dissolution of (U,Pu)O2 will be examined. The results will lead to the development of a kinetic model describing the dissolution process as a function of the studied parameters.
At the end of this PhD, the candidate—preferably with a background in physical chemistry—will have acquired advanced expertise in experimental techniques and kinetic modeling, providing a strong foundation for a career in academic research or industrial R&D, both within and beyond the nuclear sector.
Monitoring and modeling the evolution of microstructural properties during the fabrication of MOX fuel
The nuclear fuel MOX (Mixed OXide), a ceramic obtained from a mixture of uranium and plutonium oxides, represents a strategic alternative for the valorization of plutonium resulting from the reprocessing of spent fuel. MOX pellets are produced industrially using a powder metallurgy process combined with material densification through high-temperature sintering. The rejected products are reintroduced into the process in the form of "chamotte" powder. Yet, the influence of the content and nature of this chamotte on the microstructural stability of the material remains poorly understood, particularly during the pressing and sintering stages. This aspect is critical for both the mechanical integrity and the in-reactor behavior of MOX fuels. A better understanding of these phenomena, combined with refined modeling, would make it possible to optimize industrial processes and ultimately improve the reliability of these fuels.
The objective of this PhD project is to study and model the evolution of the microstructural properties of MOX fuel as a function of the proportion and nature of the chamotte added during fabrication. The thesis strategy will rely on an integrated approach combining experimental studies with numerical simulations. It will be based on multi-scale characterization of the microstructure, coupling imaging and spectroscopy techniques, as well as on the three-dimensional reconstruction of the microstructure from experimental 2D images. The ultimate goal is to establish a link between the elastic properties of the material and its microstructure. This work will build on a combined experimental and modeling approach, bringing together the expertise of the supervisory team for experiments on plutonium-bearing materials, and for numerical modeling (micromechanical modeling, FFT-based calculations).
At the end of this PhD, the graduate student, with initial training in the physical chemistry of materials, will master a wide range of experimental techniques as well as advanced numerical modeling methods applied to ceramic materials. These skills will open up many job opportunities in academic research or industrial R&D, both within and outside the nuclear sector.
Development of functionalized supports for the decontamination of complex surfaces contaminated by chemical agents
In the case of contamination by a toxic chemical agent, treatment begins with rapid emergency decontamination. Those working in the field must take into account the risk of contamination transfer, in particular by wearing suitable protective clothing. These clothing, as well as the small equipment used, must then be decontaminated before considering undressing to avoid self-contamination. The procedure includes a “dry” decontamination phase generally by applying powders (often clays) which are then wiped off using a glove or sponge. However, this device does not neutralize chemical contaminants and the powder re-aerosolizes easily, so its use is limited to unconfined and ventilated environments. The objective of this thesis is to develop an alternative technology for the decontamination of complex surfaces (clothing, small equipment). We propose to study the functionalization of different supports (such as gloves, wipes, microfibers, sponges, hydrogels, etc.) by adsorbent particles (zeolites, ceramic oxides, MOFs, etc.). A preliminary bibliographic study will allow us to select the most suitable adsorbents and supports for the capture of model chemical agents. The work will focus on the preparation of the supports, and different ways of incorporation of the particles in/on these supports will be compared. The materials will be characterized (incorporation rate, homogeneity, mechanical strength, non-reaerosolization, etc.), then their transfer, sorption and inactivation properties will be evaluated with model molecules.
This subject is aimed at dynamic chemists, motivated by the multidisciplinarity (chemistry of mineral and/or polymer materials, solid characterization and analytical chemistry), and having a particular interest in the development of experimental devices. The candidate will work within the Supercritical Processes and Decontamination Laboratory at the Marcoule site, and will benefit from the laboratory's expertise in decontamination and the development of adsorbent materials, as well as the support and expertise of the ICGM institut in Montpellier on functional polymers and hydrogels. The student will interact with the laboratory's technicians, engineers, doctoral students and post-doctoral fellows. The doctoral student will be involved in the different stages of the project, the reporting and publication of its results, and the presentation of its work in conferences. He/She will develop solid knowledge in the fields of nuclear and environmental science, as well as in project management.
Elaboration and durability evaluation of water-permselective multilayer membranes for the CO2 conversion into e-fuels
The catalytic hydrogenation of CO2 into e-fuels is considered to decarbonize certain modes of transport that are difficult to electrify. However, some of the considered reactions are thermodynamically balanced (limited CO2 conversion efficiencies) and catalyst degradation by the produced water is observed. The use of membrane reactors, allowing water separation, is envisaged. For this, the development of water-permselective membranes, without defects and resistant to synthesis conditions, is necessary. Previous studies have targeted LTA and SOD zeolite membranes for this application. However, the presence of defects reduces their selectivity, and their performance deteriorates during operation. The objective of this thesis is therefore to study the sealing of membrane defects and the deposition of protective layers on their surface to improve their performance and durability. To achieve this, the deposition of permselective zeolite layers will first be carried out hydrothermally on suitable porous supports. The sealing of defects by impregnation/conversion of silica precursors in a supercritical CO2 environment will then be studied. Finally, different protective layers (zeolite, ceramic oxide, etc.) will be deposited on the membranes (sol-gel, supercritical CO2, hydrothermal methods). The coatings will be characterized (XRD, SEM, porosimetry, elipsometry, etc.) to ensure their chemical nature, thickness/homogeneity, and porosity. Gas permeation performance will be evaluated at the various stages of preparation, and the durability of the membranes will be studied in the presence of water vapor at different temperatures.
The candidate will work within the Supercritical Processes and Decontamination Laboratory (Marcoule), and will benefit from the laboratory's expertise in ceramic membranes. The student will interact with the laboratory's technicians, engineers, doctoral students and post-doctoral fellows and will exchange with the collaborators of the Reactors and Processes Laboratory (Grenoble). The doctoral student will be involved in the different stages of the project, the publication of results and the presentation of their work at conferences. They will develop solid scientific knowledge in the fields of environment and energy, as well as in project management.