Study of potential attacks on data and model and their countermeasures in the context of distributed AI for intelligent energy systems
This post-doctoral fellowship is part of the AI-NRGY research project, which aims to propose an AI-based distributed architecture for intelligent energy systems made up of a large number of dynamic components (e.g. smart grids, electric vehicles, renewable energy sources). More specifically, the aim of this post-doc is to protect AI-based services against malicious disruptions that could affect the essential functionality of energy systems. Given the ubiquity of AI systems in modern digitised systems, their potential corruption poses a major threat to critical infrastructures. Two types of threats can be investigated: privacy threats (such as pattern reversal or data mining) and security threats (such as evasion attacks or data poisoning).
Privacy threats have been widely addressed by the scientific community and the CEA has conducted extensive work on integrating and optimising robust cybersecurity primitives. However, emerging security such as model poisoning (which arises from data poisoning) and adversarial attacks now require additional processing. Data poisoning is a cyber attack that can be used to simply compromise the convergence of the learning phase and result in underperforming models, but it can also be used to embed a ‘backdoor’ into the learned model that allows the expected result to be manipulated.
This post-doctoral position will enable the candidate to carry out theoretical and applied research in the field of privacy and security in distributed machine learning, particularly in the context of intelligent energy systems. More specifically, the candidate will study the potential threats of distributed/federated learning, and propose solutions to defend against the attacks identified as the most relevant.
Ageing battery analysis with internal multi-sensors analysis: development of sensors and operando measurements
CEA and CNRS collège de France lead the PEPR Batterie , a French National project with the objective to achieve the European Roadmap from Battery2030+ for the development of “smart battery”. The Sensiga project is a part of PEPR Battery. This project aims to develop new sensors technologies for monitoring the critical parameters of the Lithium ion cells during cycling to improve performances, safety and ageing. This new sensors technology will increase the knowledge of the internal physical, chemical and electrochemical process occurs in the cell. The large amount of data measuring operando will be used to developing new algorithm and strategies to improve the battery management systems. In the context of the Sensiga project, doctoral and postdoctoral position was open at CEA for working on this topic with a multidisciplinary and laboratory team. The aims of the work is to developing new sensing technology for in-situ and operando monitoring of the cell. The candidate will integrate a team specialized in the development of specific sensors for Lithium ion battery in the Laboratory of Postmortem Analysis and Security at CEA Grenoble.
The scope of the position will focus on the development of optical fibre sensors, the integration of theses sensors inside pouch cell and performing electrochemistry test for ageing study. This kind of sensors will be used to monitor the internal temperature, strain, and pressure and lithium concentration. The second type of sensors using in the project is the reference electrode using for electrode potential measurement. These data’s are crucial to access to the degradation mechanisms of each materials in operando. The candidate will be participate to the ageing test campaign and to the post-mortem analysis. This analysis compare to the ageing test will be used to identify the degradation mechanisms and correlate it to the sensors signal. The candidate will integrate a multidisciplinary team.
Aerosol generation and transformation mechanisms during the fuel debris cutting at Fukushima Daiichi future dismantling
During Fukushima Daiichi nuclear reactor accident, several hundred tons of fuel debris (the mixture generated by the reactor core melting and its interaction with structural materials) have been formed. Japanese government plans to dismantle with 30 to 40 years Fukushima Daiichi nuclear power station, which implies recovering these fuel debris that are there. CEA is part to several projects aiming at mastering the risks due to aerosols generated during fuel debris cutting.
The post-doctoral work objective is to exploit the large experimental database created thanks to these projects in order to study the generation and transformation mechanisms of these cutting aerosols for both thermal and mechanical cutting. An important source of aerosol seems to be partial evaporation/condensation, close to fractional distillation. A thermodynamic modelling shall be proposed, coupled with some kinetic effects. For mechanical cutting, aerosol analyses shall be compared to fuel debris block microstructure to quantify a preferential release of some phases.
After a bibliographic study, a synthesis of the experimental results will be carried out and completed, where necessary, by chemical or crystallographic analyses. The aim will be to propose a modelling of these aerosol generation and transformation mechanisms.
The postdoctoral researcher will work within an experimental laboratory of about 20 staff within CEA IRESNE institute (Cadarache site, Southern France).
Development of an innovative way of end-of-life plastics recycling by hydrothermal depolymerization
End of life plastics are scarcely recycled due to technical, health or structural constraints. To address this issue, a solvolysis route may be considered in order to recover monomers or other valuable molecules. Although good results are obtained after polymers sorting, this method remains sensitive to the composition of incoming flows, as well as the presence of contaminants. The Supercritical and Decontamination Processes Laboratory has developed an original depolymerization method in hydrothermal conditions (150 to 300°C and autogenous pressure) allowing to consider treatment of a mixture of end of life polymers (PET, PU, PC, PE, PVC). A parametric study will be carried out on a mixture of polymers of known composition by studying the influence of process parameters on the composition of the aqueous and organic phases, to define performance criteria such as conversion and depolymerization yields. Several end-of-life plastic wastes, alone or in a mixture, will be considered, to highlight a possible synergistic effect on the recovery of all or part of the recoverable monomers or products. Finally, an energy and mass balance will be implemented to study the complete life cycle of the process and to evaluate the relevance of the depolymerization process in hydrothermal conditions.
Recycling of metals of interest from end of life solar panels
Global solar energy production exceeds 1 TW in 2023 , representing 3/4 of global renewable energy production. According to projections, this production will double within 10 years, and multiply by 20 by 2050. This massive development of photovoltaic solar technology is leading to an increase in the volume of waste associated with the end-of-life of solar panels.
It is essential to start developing new méthodologies for recycling metals contained in solar panels, that will need to be processed in the near future. Among these metals, silver and copper are strategic, and their commercial value makes them particularly attractive for recycling.
The aim of the project is to develop a chemical route for recycling silver and copper as bimetallic nanoparticles of the type Cu@Ag. The nanoparticles must match the average composition of photovoltaic waste. The aim of obtaining nanoparticles remains in their ability to be processed as electrically conductive ink. After obtaining the nanoparticles, a conductive ink will be prepared.
In collaboration with the LPH laboratory of CEA INES, the above mentioned ink will be used in the metallization of silicon cells. Then, the performance of the metallization will be measured and compared with the performance of commercially available inks.
Recycable and biosourced resins for lightweight battery composites
Fibre reinforced polymers are high performance materials obtained from thermoset resins and a continuous fibre reinforcement that can be found in battery casing at different sublevels (modules, pack), and that are, as of today, petrosourced and hardly recycled.
Possible recycling paths for these materials consist in breaking covalent bonds from the reticulated resin though chemical (acids or strong oxydants) or thermal (cracking) treatments, leading to important energy and environmental costs. Despite of these disadvantages, such approaches are currently used to recover carbon fibers that represent most of composite cost, the resin matrix being lost in the process.
The post-doc position will consist in developing alternative resins to those currently used in composites and will be biosourced and recyclable. Biosourced monomers will be selected and/or modified and the recyclability will be obtained by incorporating dynamic bonds into the system. The formulation will be then optimized according to chemical and mechanical characterizations. Then, a foamed version of the resin will be developed and characterized.
The developed resins will then be used in the fabrication of fibre reinforced composites (carbon and/or natural fibers) that will also be characterized and optimized. At the end of the project, a composite prototype for the application in batteries will be fabricated using the developed knowledge.
Numerical performance and sensitivity of the thermo-hygro-corrosive model of the French underground radioactive waste storage tunnels
In recent years, a multiphysics model that represents the complex physical phenomena that influence the accumulation of rust in the storage tunnels (alveoli) has been numerically implemented in the finite element method (FEM) software Cast3M. Seeking to estimate the thermo-hygro-corrosive properties of the alveoli at long time scales, recent (and ongoing) works on improving the execution time of the resolution algorithm were undertaken. However, for a FEM numerical model to be considered as a rigorous engineering/scientific tool, error bars must be associated to all computational results; therefore, the careful quantification of the plethora of modeling uncertainties is primordial. To undertake such an endeavor, multiple issues must first be tackled, begininning with an improvement of the physical representativity of the multiphysics model, following with an improvement of the computational performance of the numerical model, and ending with rigorous sensitivity studies of the implemented model. Work on computational performance is necessary, so as to render program execution fast enough to ensure that the large sets of numerical experiments required run in reasonable times.
Design and fabrication of miniaturized extraction devices for sample purification hyphenated to elemental and isotopic analysis
The LANIE laboratory is focused on downscaling the sample purification steps performed by solid-phase extraction chromatography. The strategy is based on the implantation of functionalized polymeric monoliths within the channels of microsystems made of cyclic olefin copolymer (COC), material known to be easy to process but chemically inert. Once this key step is validated, this project aims to set up a comprehensive analytical pipeline in the laboratory, starting from the design, prototyping, and manufacturing of integrated miniaturized extraction devices, up to their de facto implementation for the reduced-scale analysis of U- and Pu- based samples.
Development of a 2D kinetic model for the high-temperature oxidation of chromia-forming alloys.
For many industrial applications, the high temperature oxidation phenomena of components need to be assessed in order to optimise the design of the component. This is the case, for example, for aircraft engine turbines in the aerospace industry (ambient temperatures of 1000°C), heat exchanger tubes in power plants (temperatures of 300 to 600°C), vitrification pots for long-lived radioactive waste (temperatures in excess of 1000°C), etc. All these applications use Fe-Ni-Cr alloys, the oxidation of which leads to the formation of a layer of chromium oxide, Cr2O3. The development of reliable models and simulation tools for the oxidation of Fe-Ni-Cr alloys at high temperatures (from 350°C) is therefore a major challenge for limiting the costs associated with high-temperature applications.
The post-doc will be divided into two parts: the first will involve using a simulation tool created at the CEA (EKINOX-FeNiCr) and the second will be based on the transition from the 1D model to the 2D model in order to take into account the finite size of components or geometric singularities.
The generality of this subject, which can be applied to many industrial cases, and the detailed understanding of oxidation phenomena will enable the student to move into both academic and industrial research at the end of the post-doctorate.
Post-doctoral position in Solid State Electrochemistry / Ceramic and metallic materials / High temperature corrosion
High-temperature electrochemical solid oxide (SOC) devices (650-850 °C) are considered as one of the most promising technologies thanks to various advantages such as a high efficiency, a relative low cost and a good reversibility in fuel cell (SOFC) and electrolysis (SOEC) operating modes. To better understand and limit metallic interconnect oxidation and chromium evaporation through the use of coatings remains a key challenge for the optimization of the system durability in SOFC and SOEC operation (degradation rate 3000 h). The post-doctoral work represents the main part of this project and is exclusively funded by it. The evaluation of protective coatings and a contact layer will be mainly performed thanks to electrochemical characterizations of performances and durability of the adjacent cell, and post-test microstructural characterizations as well compared to the bare steel. This work should lead to at least 1 publication and 1 presentation at EFCF conference in 2026.