Miniaturised analytical method dedicated to the screening of candidate molecules for the capture and removal of radionuclides
This project aims at developing a miniaturized multiplex device dedicated to the screening of the chelating ability of potential molecules for the decorporation of certain radionuclides (RN) from the nuclear power industry, for which current treatments are not satisfactory. The objective is to accelerate the identification of the most promising chelating molecules, while benefiting from the advantages of miniaturisation, such as the consumption of very small quantities of molecules and RN. In a previous project, a phosphated monolith of various lengths has been grafted in situ and characterised in capillaries of 100 µm internal diameter. The quantities of UO22+, Zr4+, Sr2+, Co2+, Cs+ and Ag+ immobilised on these monolithic phases have been measured online by coupling to an ICP-MS.Based on this work, the candidate will be responsible for developing and validating the miniaturised screening method with UO22+, for which data and chelating molecules are available, extending the approach primarily to Zr4+, Sr2+, Co2+, and to fabricate the microfluidic device incorporating parallel microchannels, in order to ultimately screen candidate molecules for distinct RNs in a single fluidic microsystem.
Condensation of Humid Air during Loss of Insulation Accident in a LH2 tank (CHALIA Project)
Liquid hydrogen is increasingly becoming the key energy vector for industrial decarbonization in heavy mobility. It is stored at 20K in a double-walled tank with an insulating vacuum. Any compromise to the integrity of the outer wall will allow hot air to enter the insulating vacuum. Nitrogen, oxygen, and water vapor will condense or even desublimate on the cold wall of the inner tank, thereby transferring heat to the cryogen, which will begin to boil. This boiling causes a pressure increase, leading to the opening of safety valves to prevent tank rupture. To better understand these complex phenomena, the CEA, Fenex Collaborative Research Center, and the University of Western Australia have submitted the CHALIA project to the Franco-Australian Center for Energy Transition. This project was approved in October. The post-doctoral position offered by the CEA involves setting up an analytical experiment using an existing glass cryostat to study in detail the various phenomena and measure the heat fluxes transmitted to the cryogen during the different phases of the accident. A gradual approach is proposed, starting with nitrogen entry before progressing to a binary mixture (synthetic air) or a ternary mixture (humid air). The project also aims to identify and quantify the phases involved in the process using various optical methods. The work will be conducted in close collaboration with researchers from the University of Western Australia, who will focus on scaling up the findings.
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.
Thermodynamic study of photoactive materials for solar cells
The development of solar photovoltaic electricity generation requires the development of new materials for converting solar radiation into electron-hole pairs. Organic-inorganic hybrid perovskites (HOIPs) of the CsPbI3 type, with substitutions of Cs by formamidinium (FA) and/or methylammonium (MA) ions, have emerged as very promising materials in terms of performance and manufacturing. Substitutions of Cs with elements such as Rb, Pb with Sn, and I with Br are also being considered to improve stability or performance. The synthesis and optimization of the composition of layers of such materials require a better understanding of their thermodynamic equilibrium properties and stability. The objective is to construct a thermodynamic model of the Cs-Rb-FA-Pb-Sn-I-Br system. The project began with the ternary Cs-Pb-I system, which resulted in a paper [1]. The next step will focus on the ternary Cs-Pb-Br system, followed by the quaternary Cs-Pb-I-Br system. The approach uses the CALPHAD method, which focuses on building a database and an analytical formulation of the phases Gibbs energy, capable of reproducing thermodynamic and phase diagram data. A critical review of the data in the literature will enable this database to be initialized and the missing data will be evaluated by experiments and/or DFT calculations.
Formal Explanations for Artificial Intelligence
The candidate will contribute to the PyRAT formal analyzer, developped in the lab. This state-of-the-art analyzer is both used as a research sandbox and as an industrial-grade tool. As such, the candidate will work at the boundary of academia and industry.
The candidate missions are the following:
- actively build, update and deliver a state of the art on formal verification, in particular formal verification of machine learning and formal explanations
- contribute to scientific and technical discussions on PyRAT's design and implementations, and pursue said implementations
- investigate and apply the uses of PyRAT for formal explanations
- contribute to funded projects, either national or international, both by institutional and industrial actors, in particular by helping writing deliverables on such projects
- contribute to publications and/or technical reports around PyRAT
- help the dissemination of PyRAT, in particular by contributing to tutorials, courses and presentations and presenting them at scientific and industrial venues
High-throughput PVD deposition of semiconducting materials
Lead halide perovskites are a class of emerging semiconductors that have demonstrated considerable potential for utilization in solar cells.Nevertheless, the release of toxic lead into the environment during the lifespan of the cells is still a concern for their further commercialization.
This 24-months project aims at optimizing the deposition of lead-free double perovskite thin films for photovoltaic applications using PVD (Physical Vapor Deposition). The optimization of the material will be carried out by implementing high-throughput approaches in both the process and characterisation workflows.
Robust path-following solvers for the finite element simulation of cracking in complex heterogeneous media: application to reinforced concrete structures
Path-following (or continuation) procedures are used to describe the unstable responses of structures exhibiting snap-back or snap-through phenomena. These methods consist in adapting the external load during the deformation process in order to satisfy a control constraint, by introducing an additional unknown, the load multiplier. Several variants exist depending on the controlled quantity: degrees of freedom, strain measures, or variables related to energy dissipation.
In addition to enabling the tracing of unstable responses, a major advantage of these approaches lies in improving the convergence of incremental Newton-type solvers by reducing the number of iterations required. This gain often compensates for the additional computational cost associated with the continuation algorithm. Some formulations have proven both efficient and simple to implement.
However, no objective criterion yet allows one to determine which formulation is best suited for the simulation of reinforced concrete structures, where multiple dissipation mechanisms coexist along with a strong spatial variability of the material properties.
The proposed postdoctoral work aims to develop robust path-following algorithms for such structures, building upon previous research carried out at CEA. It will include a critical analysis of existing formulations, an evaluation of their performance (monolithic or partitioned solvers), followed by their implementation. Finally, representative test cases of industrial structures will be simulated to assess the gain in robustness and computational cost compared to standard solvers.
Novel concentrated alloys (HEA/CCA) for nuclear applications: Corrosion and irradiation resistance in molten salts
This postdoctoral position is part of the national PEPR DIADEM program, within the DIAMS project, which aims to accelerate the discovery of new materials by combining computer design and experimental testing. The research focuses on materials for Molten Salt Reactors (MSRs), which require alloys that are resistant to both molten salt corrosion and irradiation. Certain optimized high-entropy alloys and complex concentrated alloys (HEA-CCA), offer superior performance compared to conventional materials such as austenitic stainless steels (ASS).
The postdoctoral research follows on an IA-based alloy design project carried out at IMN (Nantes), which identified promising compositions produced by conventional metallurgy and characterized after corrosion and irradiation on the JANNuS Saclay platform. The tests were carried out sequentially.
Starting in early 2026, the unique JANNuSel device will enable simultaneous corrosion and irradiation testing on both conventionally processed alloys and new compositions produced by AM (additive manufacturing) on the SAMANTA platform.
The samples will be analysed by SEM, TEM/EDX, EBSD, Raman spectroscopy, Atom Probe Tomography (APT), and synchrotron X-ray diffraction (MARS, SOLEIL) to understand the underlying mechanisms and optimize alloy properties.
The position is based at CEA Saclay, in close collaboration with IMN and Mines Saint-Étienne, and benefits from a rich interdisciplinary research environment.
Experimental and Thermodynamic Modeling of Corium Phases Formed During Severe Nuclear Accidents (24 months)
During severe accidents in pressurized water reactors, uranium dioxide (UO2) fuel reacts with zirconium alloy cladding and the steel vessel, forming a mixture of liquid and solid phases known as "in-vessel corium". If the vessel ruptures, this corium interacts with the concrete raft, forming "ex-vessel corium". This phenomenon occurred in the Chernobyl and Fukushima severe accidents. To simulate these stages, multi-physics codes require accurate thermodynamic and thermophysical data for the various phases of corium. This project aims to fill the data gap through experimental measurements and modeling. The work will involve synthesizing samples, measuring liquidus/solidus temperatures and liquid phase densities, and characterizing samples using advanced techniques. Moreover, the laser heating setup combined with aerodynamic levitation (ATTILHA) used to acquire data will be improved. Experimental results will be compared with thermodynamic models (TAF-ID database), and discrepancies will be resolved using the CALPHAD method. Thermophysical data will also be validated using atomistic simulations and other measurement techniques.