In situ analytical device based on the LIBS technique for the characterization of hard environment liquid media
The proposed research project aims at developing an in situ analytical device based on the LIBS technique for the characterization of hard environment liquid media such as high temperature melting materials or highly volatile liquid metals used for development of low carbon energy production. The project involves two CEA teams specialized in LIBS instrumentation, analytical developments and high temperature environments.
At high temperature, the molten metals have a high surface reactivity leading to processes of oxidation, slagging … Non-intrusive analysis of this surface by traditional LIBS tools leads to a non-representative results of the molten metal chemical composition. In this project, a new-patented concept based on a mechanical stirring coupled to the LIBS device is developed in order to have a renewable and stable surface of the liquid metal. The aim is to have an on-line representative composition of the metal during the treatment process. The developed demonstrator will be validated for the analysis of impurities (at ppmw ranges) in liquid silicon (T> 1450 °C) during the purification process and the crystallization one for photovoltaic applications. At the end of the project, recommendations for in-situ analysis of liquid sodium (used as cooling fluid in nuclear reactors) will be given.
Hydrothermal carbonization as a pretreatment of wastes before their thermochemical conversion by gasification
Gasification, a thermochemical transformation generally performed at about 850°C, produces a gas that can be valorised in cogeneration, or for the synthesis of chemical products or fuels. Some bottlenecks are still present mainly for the gasification of biogenic or fossil origin wastes: irregular feeding in the reactor due to the heterogeneity in form and composition; formation of inorganic gaseous pollutants (HCl, KCl, NaCl, H2S) or organic ones (tars), which are harmful for the process and/or decrease its efficiency, and must be removed before the final application.
The objective of the post-doctoral work will be to test and optimize a pre-treatment step of the resource based on hydrothermal carbonisation (HTC). This transformation is performed at 180-250°C, in a wet and pressurised environment (2-10 MPa). The principal product is a carbonaceous solid residue (hydrochar), that can be valorised by gasification. HTC aims to limit the release of inorganic and organic pollutants in gasification, and to homogenise and improve the physical properties of the resource.
The proposed approach will consist in: experimentations in batch reactors on pre-selected resources and model materials, together with quantification and analyses of products; analysis of results aiming at elucidating the links between the resource and the properties of the hydrochar, as a function of operating conditions; an evaluation of mass and energy balances for the HTC-gasification process.
Etudes sur la physique des gaz et des interactions matière/laser pour la démonstration à l’échelle laboratoire de l’épuration isotopique du palladium (naturel).
Le palladium est un métal rare dont la demande mondiale est en forte augmentation. Or, il est présent en tant que produit de fission dans les combustibles nucléaires usés qui sont retraités en France. Il serait donc intéressant de recycler ce métal. Pour cela, il est nécessaire de procéder à une épuration isotopique, afin de supprimer un des isotopes du palladium, le 107, qui est un radionucléide artificiel à vie longue émetteur béta. Dans le cadre d'un nouveau projet sur 4 ans construit en réponse à l'appel d'offre du Plan d'Investissement et d'Avenir de l’État, le Service d’Etude des Procédés d’Enrichissement propose un contrat post-doctoral ayant pour objectif la compréhension des interactions gaz/laser dans le procédé de séparation isotopique du palladium par Lasers actuellement en cours de développement. L’objectif principal du projet est la démonstration finale de la faisabilité de séparation de palladium naturel (et non radioactif) pour la phase suivante de développement d’un premier pilote.
Le post-doctorant devra en particulier assurer l’étude du mode de production de la vapeur atomique près du point de fusion du métal pur, des mesures de spectroscopie par laser dans l’UV afin d’affiner les séquences sélectives de photoionisation des isotopes désirés. Pour ce faire, il participera à la définition, au montage et au développement de l'évaporateur, et au couplage des lasers du procédé avec l’enceinte à vide. Des échanges seront mis en place sur ce sujet spécifique avec des spécialistes reconnus au sein de la Direction de la Recherche Fondamentale du CEA. Les mesures de diagnostics des lasers mais aussi les mesures provenant des interactions gaz/laser sont à développer. La programmation (en Python et/ou sous Labview) de ces outils est un point essentiel du poste proposé. Une attention particulière sera portée sur les publications à réaliser essentiellement dans le cadre des interactions gaz/laser (photoionisation sélective des atomes d’intérêt et extraction).
Proton conducting interpenetrating polymer networks as new PEMFC membranes
This subject takes place in the frame of the development of proton exchange membrane fuel cells (PEMFC) and the main objective is to increase their performance and durability for operation above 100°C at low relative humidity.
The current standard membranes for use in PEMFC applications remain perfluorosulfonated ionomers such as Nafion® due their good proton conductivity and chemical stability. Nevertheless, their proton conductivity decreases for relative humidity below 70% especially at high temperature because of a too low density of proton conducting groups. This characteristic is a limitation for their use in the working conditions of the requirements for the automotive application. With these polymers, an increase of the proton conducting group density leads to a decrease of mechanical and dimensional stability. Yet, this stability is already quite low and decreases the PEMFC durability. The goal of this subject is to develop new membrane structures based on interpenetrating polymer networks that do not present this antagonism between good mechanical stability and proton conductivity. This strategy which has recently been patented by CEA (patent application number 08 06890) is based on the association of two entangled polymer networks, one sulfonated for proton conductivity and one fluorinated for mechanical and chemical stability.
The applicant will make the membranes and then will characterize their mechanical properties, proton conductivity as well as gas permeability. He will also quantify their performance and durability in a running fuel cell.
Couplings between the distributions of water and current density in operating Proton Exchange Membrane Fuel Cell (PEMFC)
The post-doc work will be focused on the measurement of the current density and of the water distributions in an operating fuel cell with a real design, in order to give a better understanding of PEMFC operation as a function of the operating parameters (Temperature, Gas hydration, Pressure, Gas composition). The measurement of the distribution of the current density will be performed using a reliable commercial setup on a full size cell. CEA developed a technique based on Small Angle Neutron Scattering (SANS) as a non-intrusive tool in order to quantify the water distribution during fuel cell operation within and without the membrane. CEA benefits for international recognition on this topic. These measurements will be conducted in high flux neutron reactors, such Institut Laue Langevin (ILL). Some specific high and low resolution neutron imaging experiments could be also be conducting additionally in order to have a complete 3D view of water repartition.
Development of processing by Artificial Intelligence of a measuring and forecasting station
This post-doctoral proposal is part of the French atomic commission (CEA) project "MultiMod'Air", which involves developing an « intelligent » prototype of air quality measurement and forecasting station within two years. The work proposal is to develop the bricks of Artificial Intelligence (AI) of the project: correction by ANN (Artificial Neuronal network) of the measurements obtained through low cost sensors, correction ANN of weather forecasts at the station level, which are simple treatments to implement. The actual research work will concern the development of a AI based pollution forecast at the station by learning from past events.
DEM’N’MELT Process : Optimisation of operating conditions by modelling
Within the framework of the PROVIDENCE project (Plan Relance, France), the DEM'N'MELT process was developed with the aim of marketing a solution for the treatment and conditioning of high and medium level waste to sites operators undergoing dismantling or remediation, in France and abroad. In this context, studies have been undertaken to optimise the operating conditions of the process.
The candidate will have to take in charge the software used in our Laboratory (Fluent, Workbench, SpaceClaim, Meshing), to appropriate the existing models. These models will have to evolve to :
o take into account additional measurements to calibrate the model
o study the sensitivity of the system to the physical properties of the glass
o optimise furnace operation and manage the feed capacity according to the filling level
o add agitation to the glass bath.
The candidate will be able to rely on the skills of the LDPV Laboratory, both experimentally and in modelling.
Researcher in Artificial Intelligence applied to self-driven microfluidic
This postdoctoral position is part of the 2FAST project (Federation of Fluidic Autonomous labs to Speed-up material Tailoring), which is a part of the PEPR DIADEM initiative. The project aims to fully automate the synthesis and online characterization of materials using microfluidic chips. These chips provide precise control and leverage digital advancements to enhance materials chemistry outcomes. However, characterising nano/micro-materials at this scale remains challenging due to its cost and complexity. The 2FAST project aims to utilise recent advances in the automation and instrumentation of microfluidic platforms to develop interoperable and automatically controlled microfluidic chips that enable the controlled synthesis of nanomaterials. The aim of this project is to create a proof of concept for a microfluidic/millifluidic reactor platform that can produce noble metal nanoparticles continuously and at high throughput. To achieve this, feedback loops will be managed by artificial intelligence tools, which will monitor the reaction progress using online-acquired information from spectrometric techniques such as UV-Vis, SAXS, and Raman. The postdoctoral position proposed focuses on AI-related work associated with the development of feedback loop design, creation of a signal database tailored for machine learning, and implementation of machine learning methods to connect various data and/or control autonomous microfluidic devices.
Modelling and evaluation of the future e-CO2 refinery
In the context of achieving carbon neutrality by 2050, the CEA has initiated a project in 2021 to assess the relevance of coupling a nuclear power system with a direct atmospheric carbon capture device (DAC) thanks to the use of the system's waste heat.
As a member of a team of about twenty experts(energy system evaluation, techno-economic engineering, energy system modeling, optimization and computer programming), you will participate in a research project on the modeling and evaluation of a CO2 refinery dedicated to the production of Jet Fuel fed by a nuclear reactor and coupled with an atmospheric CO2 capture process.
Large-scale depletion calculations with Monte Carlo neutron transport code
One of the main goals of modern reactor physics is to perform accurate multi-physics simulations of the behaviour of a nuclear reactor core, with a detailed description of the geometry at the fuel pin level. Multi-physics calculations in nominal conditions imply a coupling between a transport equation solver for the neutron and precursor populations, thermal and thermal-hydraulics solvers for heat transfer, and a Bateman solver for computing the isotopic depletion of the nuclear fuel during a reactor cycle. The purpose of this post-doc is to carry out such a fully-coupled calculation using the PATMOS Monte Carlo neutron-transport mini-app and the C3PO coupling platform, both developed at CEA. The target system is core of the size of a commercial reactor.