In situ and real-time characterization of nanomaterials by plasma spectroscopy
The objective of this Phd is to develop an experimental device to perform in situ and real time elemental analysis of nanoparticles during their synthesis (by laser pyrolysis or flame spray pyrolysis). Laser-Induced Breakdown Spectroscopy (LIBS) will be used to identify the different elements present and their stoichiometry.
Preliminary experiments conducted at LEDNA have shown the feasibility of such a project and in particular the acquisition of a LIBS spectrum of a single nanoparticle. Nevertheless, the experimental device must be developed and improved in order to obtain a better signal to noise ratio, to increase the detection limit, to take into account the different effects on the spectrum (effect of nanoparticle size, complex composition or structure), to automatically identify and quantify the elements present.
In parallel, other information can be sought (via other optical techniques) such as the density of nanoparticles, the size or shape distribution.
Study of the behaviour of mixed oxide fuels with degrade isotopy at the beginning of life.
France has decided to adopt a 'closed' nuclear fuel cycle. This involves processing spent fuel to recover valuable materials such as uranium and plutonium, while other compounds such as fission products and minor actinides constitute final waste. UO2 fuel irradiated in pressurised water reactors (PWRs) is currently reprocessed to produce plutonium (PuO2), which is then reused in the form of mixed oxide (MOX) fuel. This fuel is then irradiated in PWRs, a process known as plutonium monorecycling. The CEA is currently studying the multi-recycling of materials using fuels containing Pu from the processing of spent MOX assemblies. However, this multi-recycled plutonium contains a higher proportion of highly alpha-active isotopes (Pu238, Pu240 and Pu241/Am241), resulting in more severe alpha self-irradiation than current MOX fuels experience [1]. This exacerbates certain physical phenomena [2-5], such as fuel swelling due to helium precipitation and the creation of crystal defects and decreased thermal conductivity [6-8], which can alter its behaviour in the reactor.
The proposed thesis will study the impact of these phenomena on the behaviour of MOX fuels at the beginning of the irradiation, using a combination of experimentation and modelling. Heat treatments will be employed to analyse the mechanisms of crystal defect healing and helium behaviour. Various experimental techniques will be employed to characterise the structure and microstructure (X-ray diffraction, scanning electron microscopy (SEM), Raman spectroscopy and microprobe analysis), defect densities (transmission electron microscopy (TEM)), helium release (KEMS), thermal gradient reproduction (CLASH laser) and thermal conductivity (LAF laser). The results will inform simulations modelling the microstructure and thermal properties.
This cross-disciplinary study will improve our understanding of the phenomena involved in the initial power-up of fuels damaged by alpha self-irradiation, particularly the impact of helium produced by decay.
You will be based at the Multi-Fuel Design and Irradiation Laboratory (LECIM) within the Research Institute for Nuclear Systems for Low-Carbon Energy Production at CEA/Cadarache. For the experimental part of the project, you will collaborate with the Chemical Analysis and Materials Characterisation Laboratory (LMAT) at CEA/Marcoule and the European Research Centre (JRC) in Karlsruhe. You will have the opportunity to publish your results through scientific publications and conference presentations. This role offers the chance to develop your expertise in a variety of techniques that can be applied across multiple fields of materials science and engineering.
[1]O. Kahraman, thésis, 2023.[2]M. Kato et al., J Nucl Mater, 393 (2009) 134–140.[3]L. Cognini et al., Nuclear Engineering and Design 340 (2018) 240–244.[4] T. Wiss et al., Journal of Materials Research 30 (2015) 1544–1554.[5]D. Staicu et al., J Nucl Mater 397 (2010) 8–18.[6] T. Wiss et al.,Front. Nucl. Eng. 4 (2025) 1495360.[7]E.P. Wigner, J. Appl. Phys. 17 (1946) 857–863.[8]D. Staicu et al., Nuclear Materials and Energy 3–4 (2015) 6–11.
Design artificial intelligence tools for tracking Fission Product release out of nuclear fuel
The Laboratory for the Analysis of Radionuclide Migration (LAMIR), part of the Institute for Research on Nuclear Systems (IRESNE) at CEA Cadarache, has developed a set of advanced measurement methods to characterize the release of fission products from nuclear fuel during thermal transients. Among these innovative tools is an operando in situ imaging system that enables real-time observation of these phenomena. The large amount of data generated by these experiments requires dedicated digital processing techniques that account for both the specificities of nuclear instrumentation and the underlying physical mechanisms.
The goal of this PhD project is to develop an optimized data processing approach based on state-of-the-art Artificial Intelligence (AI) methods.
In the first phase, the focus will be on processing thermal sequence images to detect and analyze material movements, aiming to identify an optimal image-processing strategy defined by rigorous quantitative criteria.
In the second phase, the methodology will be extended to all experimental data collected during a thermal sequence. The long-term objective is to create a real-time diagnostic tool capable of supporting experiment monitoring and interpretation.
This PhD will be carried out within a collaborative framework between LAMIR, which has recognized expertise in nuclear fuel behavior analysis and imaging, and the Institut Fresnel in Marseille, known for its strong background in image analysis and artificial intelligence.
The candidate will benefit from a multidisciplinary and stimulating research environment, with opportunities to present and publish their work at national and international conferences and in peer-reviewed journals.
Development of manganese-doped uranium oxide fuel: sintering mechanisms and microstructural changes
This PhD project focuses on developing nuclear fuels with improved properties through the addition of a dopant, for use in pressurized water reactors.
In nuclear reactors, the fuel consists of uranium dioxide (UO2) pellets stacked inside zirconium alloy cladding. These pellets, in contact with the cladding, must withstand extreme conditions of temperature and pressure. One of the challenges is to limit chemical interactions that may occur during the migration of fission products from the center to the periphery of the pellet and with the cladding. A notable example of such a phenomenon is the stress corrosion assisted by iodine, which can occur during accidental transients.
One strategy is to dope the UO2 ceramic with a metal oxide in order to control the material’s microstructure and also to modify its thermochemical behavior, thereby limiting both the mobility and corrosive nature of fission gases. Among the possible dopants, manganese oxide (MnO) represents a promising option and a potential alternative to chromium oxide (Cr2O3), which is currently a mature solution for the industry.
This PhD will explore the role of manganese in the sintering of UO2, particularly the microstructure and final properties of the fuel. The work will take place at the CEA Cadarache center, within the Institute for research on nuclear systems for low-carbon energy production (IRESNE).
During these three years, you will be hosted in the Laboratory for the study of uranium-based fuels (LCU) within the fuel study department (DEC), in close connection with the Laboratory for fuel behavior modeling (LM2C).
This research, combining experimentation and modeling, will be structured around three main topics:
• Study of the influence of manufacturing conditions on the microstructure of Mn-doped UO2,
• Investigation of the impact of doping on defect formation in UO2 and the associated properties,
• the contribution to the thermodynamic modelling of the system, based on experimental tests.
During this PhD, you will gain solid experience in the fabrication and advanced characterization of innovative materials, particularly in the field of ceramics for the nuclear industry. Your work could lead to publications, patents, and participation in national and international conferences.
You will also acquire numerous technical skills applicable across various research and industrial fields, including energy, microelectronics, chemical and pharmaceutical industries.
Characterization of radiolytic mechanisms in tritiated water–zeolite systems under storage conditions
The operation of the tritium facilities at Valduc generates low-activity tritiated liquid effluents, which are stored in an adsorbed form on 4A zeolite for operational reasons. Understanding the mechanisms of self-radiolysis of this confined water is essential for optimizing storage conditions.
Several PhD projects have already investigated these mechanisms by combining experiments and modelling. Early work showed that below 13% hydration, the radiolytic gases H2 and O2 can recombine within the zeolite. Subsequent studies, based on DFT calculations and molecular dynamics, identified the adsorption sites and the mobility of the gases. They revealed a hydration threshold (13–15%) above which gas diffusion becomes very low, consistent with the experimentally observed cessation of recombination. However, these simulations rely on idealized models.
The new proposed PhD aims to shift the project back toward experimental work in order to better reflect real storage conditions. It will begin with a detailed characterization of the zeolite used industrially. Water–zeolite reservoirs will then be irradiated to simulate the effect of tritium, and analyzed by NMR and possibly by Electron Spin Resonance (ESR) to detect reactive species. The experimental results may feed into a macroscopic model (Kinetic Monte Carlo, KMC), also developed previously, to predict the evolution of the system and identify possible optimizations for storage. The work will be carried out mainly at the NIMBE laboratory (CEA-CNRS), with simulation collaboration in Besançon and regular exchanges with CEA Valduc.
Study of homogeneous SIMMOX synthesis and dissolution based on hydroxide pathway
The dissolution of spent nuclear fuel is an essential first step in its reprocessing. The kinetics of irradiated (U,Pu)O2 (MOX) dissolution currently hinders industrial-scale reprocessing and therefore requires a better understanding of the mechanisms involved in order to overcome this industrial obstacle. However, studying the dissolution of irradiated MOX fuel in order to identify and model the various stages and mechanisms involved is hampered by the high radiotoxicity of such material and the representativeness of the available samples. In order to simplify these studies and establish representative models, numerous tests have been carried out on model compounds (e.g., non-irradiated UO2 and MOX). Among these, SIMfuel (U,Pu)O2 compounds doped with up to 11 fission products aim to represent the chemical complexity of irradiated fuels. The conventional approach to manufacturing SIMfuel by mixing solid-phase reagents requires sintering of fuel pellets at high temperatures (>1600°C). In order to reproduce the behavior of fission products (reduction-oxidation, distribution, etc.) for irradiated fuels at lower temperatures, an alternative approach has been developed based on the synthesis of oxides via the hydroxide route. This method allows for the simultaneous and homogeneous precipitation of numerous metal cations and significantly lowers the sintering temperature. This approach has already enabled the study of SIMfuel incorporating rare earths, platinoids, and molybdenum under representative conditions. However, this approach has never been implemented for the synthesis of SIMfuel containing both plutonium and all fission products relevant to the study of dissolution.
The objective of this thesis is to implement such syntheses, based on recent results obtained concerning the synthesis of MOx by the hydroxide route. To this end, SIMfuels will be synthesized to represent spent MOx-type fuels (SIMMOx). To represent the different zones present in spent fuel, SIMMOx with different Pu/(U+Pu) ratios will be considered. These SIMMOx will undergo dissolution tests to characterize their behavior during this stage.
III-V semiconductor nanoplatelets
Colloidal semiconductor nanoplatelets (NPLs) are a class of two-dimensional nanostructures that have electronic and optical properties distinct from those of spherical quantum dots (QDs). They exhibit strong quantum confinement in a single dimension, their thickness, which can be controlled on the monolayer level using solution chemistry. As a result, NPLs emit light with an extremely narrow spectral width and at the same time, they have a very high absorption coefficients. These properties make them ideal candidates for various applications (e.g., light-emitting diodes for low-power-consumption displays, photocatalysis, single-photon emitters).
At present, only the synthesis of metal chalcogenide NPLs has been mastered. These materials either contain toxic elements (CdSe, HgTe, etc.) or have a large bandgap (ZnS, ZnSe). For these reasons, the development of synthesis methods for III-V semiconductor NPLs, such as InP, InAs and InSb is currently a major challenge. In this thesis, we will develop new synthetic approaches for the growth of InP NPLs, exploring different avenues and using in situ characterizations as well as machine learning assisted design of experiments. Numerical simulations will be used to determine the reactivity of precursors and to model the mechanisms inducing anisotropic growth.
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.
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.