Modelling of prospective deployment scenarios for hydrogen in France and Europe M/F
One of the major energy transition leverages at the horizon 2050 is decarbonation of uses such as electricity production, transport or industry. If electrification of some uses is part of the solution, a potential is also foreseen in using decarbonized intermediate vectors such as hydrogen, produced by electrolysis, and which can be leveraged both as an energy vector and as a substitute molecule in carbon-emitting industries like chemistry, steel production, etc.
However, the potential high development of hydrogen creates underlying needs for electricity production, leading to questions about the sustainability aspects of such deployments, a possible criteria when choosing between different possible deployment options.
As part of a “PEPR Hydrogène” research project, the study aims at 1/ developing possible quantitative hydrogen deployment scenarios consistent between different geographic scales (from the French regions to the national and European level), in collaboration with project partners, 2/ assessing the consequences of these scenarios on the European electrical production system and consequently on the characteristics of the electricity used for the hydrogen production – in particular from the sustainability point of view (e.g. electricity cost and greenhouse gas emissions).
TREATMENT OF RADIOACTIVE ORGANIC EFFLUENTS
The ECCLOR project (Project labelled 'Investment for the Future') aims to find a management route for challenging radioactive organic effluents. A strategy under investigation is to make the effluents compatible with existing outlets by decontaminating them of radioelements by column filtration. This involves developing ion-selective extractants in a form suitable for use in columns.
Studies are being carried out at CEA to improve the treatment of radioactive aqueous effluents by developing processes capable of achieving "zero discharge" while producing a minimum of waste. The challenge of the ECCLOR project will be to transpose this work to contaminated organic solvents with various radiological compositions and rheological properties. A first post-doctoral contract was dedicated to the development of materials for this application. A number of inorganic supports (silicas, geopolymers, aluminas, etc.) were considered for decontaminating these organic effluents.
The performance of the various materials developed in previous work can be optimised in terms of actinide capacity and selectivity with respect to competitor ions. In particular, the performance of existing materials needs to be studied further on more complex simulated LORs, with the necessary adaptations to the analytical method.
This project is intended for a post-doctoral fellow wishing to develop skills in extraction mechanism comprehension and analytical methods, with an interest in advancing the field of radioactive waste management. It will be will build upon the expertise of two laboratories at CEA Marcoule: the Design and Characterization of Mineral Materials Laboratory for materials elaboration and characterization, and the Supercritical and Decontamination Processes Laboratory for materials grafting and decontamination experiments.
Development of a new generation of reversible polymer adhesives
Polymeric adhesives are generally cross-linked systems used to bond two substrates throughout the lifetime of an assembly, which may be multi-material, for a wide range of applications. At their end of life, the presence of adhesives makes it difficult to separate materials and recycle them. Moreover, it is difficult to destroy the cross-linking of the adhesives without chemical or thermal treatment that is also aggressive for the bonded substrates.
In this context, the CEA is developing adhesives with enhanced recyclability, by integrating recyclability into the chemical structures right from the synthesis of the polymer networks. The first approach involves incorporating dynamic covalent bonds into polymer networks, which can be exchanged under generally thermal stimulus (e.g. vitrimers). A second approach involves synthesising polymers that can be depolymerised under a specific stimulus (self-immolating polymers) and have the ability to cross-link.
The post-doc will develop 2 networks that can be used as adhesives with enhanced recyclability. A first network will be based on a depolymerizable chemistry under stimulus already developed on linear polymer chains, to be transposed to a network. A second vitrimer network will be synthesised on the basis of previous work at the CEA. Activation of the bond exchange in this network will take place via a so-called photolatent catalyst, which can be activated by UV and will make it possible to obtain a UV- and heat-stimulated adhesive. The choice and synthesis of these catalysts and their impact on the adhesive will be the focus of the study. The catalysts obtained could also be used to trigger depolymerisation of the first depolymerisable system under stimulus.
Impact of Microstructure in Uranium Dioxide on Ballistic and Electronic Damage
During reactor irradiation, nuclear fuel pellets undergo microstructural changes. Beyond 40 GWd/tU, a High Burnup Structure (HBS) appears at the pellet periphery, where initial grains (~10 µm) fragment into sub-grains (~0.2 µm). In the pellet center, under high temperatures, weakly misoriented sub-grains also form. These changes result from energy loss by fission products, leading to defects such as dislocations and cavities. To study grain size effects on irradiation damage, nanostructured UO2 samples will be synthesized at JRC-K, using flash sintering for high-density pellets. Ion irradiation experiments will follow at JANNuS-Saclay and GSI, with structural characterizations via Raman spectroscopy, TEM, SEM-EBSD, and XRD. The postdoc project will take place at JRC-K, CEA Saclay, and CEA Cadarache under expert supervision.
Thermochemical and thermodynamic study of chloride molten salts
In today’s climate emergency, access to clean and cheap energy is more important than ever. Several ways have been envisaged for several years now, but a number of technological issues still need to be overcome before they can be put into practice, as they represent breakthroughts. Whether for energy storage than for fourth generation nuclear reactors, molten salt environment used as coolant and/or as fuel is highly corrosive requiring a complexe choice of structural materials.
The aim of this subject proposed in the Corrosion and Materials Behavior Section is to study in depth the chemical properties of different chloride molten salts : the basic ternary salt (NaCl-MgCl2-CeCl3) but also the corrosion/fission/activation products that can be produced (MxCly with M=Cr, Fe, Te, Nd, Ni, Mo,…). The activity coefficients and solubility limits of these metallic elements will be determined using various techniques such as electrochemistry and Knudsen cell mass spectrometry. If required, this study can be completed by the phase transition temperature and heat capacity measurements using differential scanning calorimetry.
Optimizing phytotechnologies for the remediation of contaminated nuclear sites
CEA is recruiting a postdoctoral researcher for a research project aimed at optimizing phytotechnologies for the remediation of contaminated nuclear sites. This research is part of the risk management and remediation of contaminated soils, in particular those resulting from the decommissioning of nuclear facilities. The aim of the project is to develop an advanced mechanistic model of soil-plant transfers, in order to gain a better understanding of contaminant mobility in lightly contaminated soils, and to optimize the use of suitable plants to stabilize these contaminants.
Development of new Potassium-ion cells with high performances and low environmental impact
Lithium ion batteries are considered as the reference system in terms of energy density and cycle life and will play a key role in the energetic transition, especially concerning electric vehicles. However, such a technology involves the use of a large amount of critical elements and active materials are synthesised using energy intensive processes.
In this way, our team is developing a new Potassium-ion batteries technology with high performances but with a low environmental impact.
For this innovative and ambitious project, CEA-LITEN (one of the most important research institute in Europe) is looking for a talented post-doctoral researcher in material chemistry. The post-doctoral position is opened for a young researcher with a high scientific level, interested by valorising her/his results through different patents and/or scientific publications.
MULTI-CRITERIA ANALYZES OF HYDROGEN PRODUCTION TECHNOLOGIES BY ELECTROLYSIS
LITEN, strongly involved in electrolysis technologies, wishes to compare via a multi-criteria analysis all electrolysis technologies currently available commercially (AEL, PEMEL), in the pre-industrialization phase (SOEL), or in R&D (AEMEL and PCCEL).
Our previous studies were based on specific use cases (fixed hypotheses on the size of the factory, the source of electricity, the technology, etc.).
The objective of this new work is to be able to position the different electrolysis technologies according to parameters which will be defined at the start of the project, these parameters being of a contextual type (e.g. number of operating hours, expected flexibility), technical ( ex yield, lifespan) or technical-economic (ex CAPEX OPEX) and environmental (ex GHG impacts, materials). The aim here will be to develop an original methodology which makes it possible to define the areas of relevance of each of the electrolysis technologies according to these parameters, depending for example on the cost of the hydrogen produced and its environmental impact
Modeling the corrosion behavior of stainless steels in a nitric acid media with temperature
Controlling the aging of equipment materials (mainly stainless steel) of the spent nuclear fuel reprocessing plant is the subject of constant attention. This control requires a better understanding of the corrosion phenomena of steels by nitric acid (oxidizing agent used during the recycling stages), and ultimately through their modeling.
The materials of interest are Cr-Ni austenitic stainless steels, with very low carbon content. A recent study on Si-rich stainless steel, which was developed with the aim of improving the corrosion resistance of these steels with respect to highly oxidizing environments [1 , 2 ]; showed that the corrosion of this steel was thermally activated between 40 °C and 142 °C with different behavior below and above the boiling temperature (107 °C) of the solution [3]. Indeed, between 40°C and 107°C, the activation energy is 77 kJ/mol and above boiling point, it is much lower and is worth 20 kJ/mol. This difference may be due to a lower energy barrier or a different kinetically limited step.
The challenge of this post-doctoral subject is to have a predictive corrosion model depending on the temperature (below and beyond boiling). With this objective, it will be important to analyze and identify the species involved in the corrosion process (liquid and gas phase) as a function of temperature but also to characterize the boiling regimes. This model will be able to explain the difference in activation energies of this Si-rich steel below and above the boiling temperature of a concentrated nitric acid solution but will also make it possible to optimize the processes of the factory where temperature and/or heat transfer play an important role.
Study of the seismic behavior of piping systems using mechanical models of different degrees of fidelity
Piping systems are part of the equipment to which particular attention is paid as part of the safety review or design of nuclear installations. They are designed in accordance with codes, standards and regulations to withstand loads that occur or may occur over the life of a facility. These systems must therefore be designed to withstand accidental loads such as earthquakes. Feedback shows that piping systems generally behave well in the event of an earthquake. When failures are observed, they are more likely to be due to significant anchor movement, brittle materials, unwelded joints, corrosion, piping support failures, or seismic interactions. In practice, to be able to estimate the beyond design seismic behavior and the associated failure risks, the engineer can implement numerical models involving varying degrees of refinement depending on needs. This study consists of taking stock of the numerical modeling capabilities of piping systems under earthquake. For reasons of computational burden, global modeling based on beam elements is often favored, considering simplified material laws such as bilinear material laws with kinematic hardening. We know the “theoretical” limits of these models but it is difficult to have clear ideas about their real limits of applicability depending on the level of loading and the damage targeted. To make this assessment, we propose to interpret, using different numerical models involving different degrees of fidelity, the results of the experimental campaign carried out by the BARC and which was used for the MECOS benchmark (METallic COmponent margins under high Seismic loads).