Implosion-driven shock tube

Detonation wave striking PETN explosive shell producing implosion or implosion wave in shock tub

Exploring electronic effects on the partitioning of actinides(III) from lanthanides(III) using functionalised bis-triazinyl phenanthroline ligands

The first examples of 4,7-disubstituted 2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzo-triazin-3-yl)-1,10- phenanthroline (CyMe4 -BTPhen) ligands are reported herein. Evaluating the kinetics, selectivity and stoichiometry of actinide(III) and lanthanide(III) radiotracer extractions has provided a mechanistic insight into the extraction process. For the first time, it has been demonstrated that metal ion extraction kinetics can be modulated by backbone functionalisation and a promising new CHON compliant candidate ligand with enhanced metal ion extraction kinetics has been identified. The effects of 4,7- functionalisation on the equilibrium metal ion distribution ratios are far more pronounced than those of 5,6-functionalisation. The complexation of Cm(III) with two of the functionalised ligands was investigated by TRLFS and, at equilibrium, species of 1:2 [M:L] stoichiometry were observed exclusively. A direct correlation between the ELUMO-EHOMO energy gap and metal ion extraction potential is reported, with DFT studies reaffirming experimental findings

Metabolic constituents of grapevine and grape-derived products

The numerous uses of the grapevine fruit, especially for wine and beverages, have made it one of the most important plants worldwide. The phytochemistry of grapevine is rich in a wide range of compounds. Many of them are renowned for their numerous medicinal uses. The production of grapevine metabolites is highly conditioned by many factors like environment or pathogen attack. Some grapevine phytoalexins have gained a great deal of attention due to their antimicrobial activities, being also involved in the induction of resistance in grapevine against those pathogens. Meanwhile grapevine biotechnology is still evolving, thanks to the technological advance of modern science, and biotechnologists are making huge efforts to produce grapevine cultivars of desired characteristics. In this paper, important metabolites from grapevine and grape derived products like wine will be reviewed with their health promoting effects and their role against certain stress factors in grapevine physiology

Novel Disease Susceptibility Factors for Fungal Necrotrophic Pathogens in Arabidopsis

Host cells use an intricate signaling system to respond to invasions by pathogenic microorganisms. Although several signaling components of disease resistance against necrotrophic fungal pathogens have been identified, our understanding for how molecular components and host processes contribute to plant disease susceptibility is rather sparse. Here, we identified four transcription factors (TFs) from Arabidopsis that limit pathogen spread. Arabidopsis mutants defective in any of these TFs displayed increased disease susceptibility to Botrytis cinerea and Plectosphaerella cucumerina, and a general activation of non-immune host processes that contribute to plant disease susceptibility. Transcriptome analyses revealed that the mutants share a common transcriptional signature of 77 up-regulated genes. We characterized several of the up-regulated genes that encode peptides with a secretion signal, which we named PROVIR (for provirulence) factors. Forward and reverse genetic analyses revealed that many of the PROVIRs are important for disease susceptibility of the host to fungal necrotrophs. The TFs and PROVIRs identified in our work thus represent novel genetic determinants for plant disease susceptibility to necrotrophic fungal pathogens.Funding: This work was supported by the Spanish MINECO (BFU2012 to PV), and Generalitat Valenciana (Prometeo2014/020 to PV). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Dobón Alonso, A.; Canet Perez, JV.; García-Andrade Serrano, J.; Angulo, C.; Neumetzler, L.; Persson, S.; Vera Vera, P. (2015). Novel Disease Susceptibility Factors for Fungal Necrotrophic Pathogens in Arabidopsis. PLoS Pathogens. 11(4):1-30. https://doi.org/10.1371/journal.ppat.1004800S13011

Assessment of the anticipated improvement of the environmental footprint of future French nuclear energy systems

International audienceEnvironmental issues are nowadays a growing concern in the public opinion. It is therefore mandatory to propose relevant and qualified assessments of the overall environmental footprint of the different types of energy sources which are envisaged to be possibly implemented in future energy mixes. This question is particularly important for nuclear energy which suffers from a poor image in the public opinion due to the recent Fukushima accident. In this context, we developed a bespoke Life Cycle Assessment (LCA) tool, referred to as NELCAS, based on the current French nuclear energy system. Thanks to the Nuclear Safety and Transparency annual reports, detailed quantitative data are available for each of the fuel cycle facilities. The whole fuel cycle from ore-mining to geological repository was considered as well as data for construction, deconstruction of any plants, including the contribution of transports. All the matter and energy fluxes were considered and normalised versus the electric production. Key environmental indicators, such as land use, water withdrawal and consumption, gaseous releases, waste production as well as potential impact indicators (acidification, eutrophication) were hence assessed and validated with comparison with the few existing LCA results. This model was used to assess the respective figure of merits of the different generation of reactors and fuel cycles. In particular, it demonstrates that actinides recycling has a strong beneficial effect on the overall footprint due to the relative high impact of the front-end activities, specifically the ore mining. In the framework of a joint CEA-EDF-AREVA group, reference deployment scenario for the 4th generation reactors were developed for the French case based on both technical and economic considerations. The NELCAS tool was therefore used to assess the impact on the overall environmental footprint of this reference scenario

Recycling the Actinides, a Key Choice for Improving the Nuclear Energy Environmental Footprint

International audienceActinides recycling still remains a controversial issue for many countries which do not yet have make a definite and clear choice about the back-end of their nuclear fuel cycles. In particular, recycling is often questioned about its effective impact on the overall nuclear energy sustainability. In order to address this key issue, we developed a Life Cycle Assessment (LCA) tool, referred to as NELCAS, based on the current French nuclear energy system. Thanks to the Nuclear Safety and Transparency annual reports, detailed quantitative data were available for each of the fuel cycle plants. The whole fuel cycle from ore-mining to geological repository was considered as well as data for construction, deconstruction of any plants as well as the contribution of the transport. All the matter and energy fluxes were considered and normalised versus the electric production. Key environmental indicators as well as potential impact indicators were hence assessed and validated with comparison with the few existing LCA results.NELCAS was also used to derive other fuel cycles by correcting when necessary the relevant flux of matter and energy all along the fuel cycle. A particular focus was put on the once-through cycle with no recycling at all and the effect of the introduction of fast neutron reactors which allow actinides multi-recycling. For the very first time, it hence allows a direct and robust assessment of the effect of recycling operations on the most widely used environmental indicators. Among others, it clearly demonstrates the beneficial effect of Pu and U recycling on most of the indicators. This improvement increases with any recycling increase and is directly related to the very high contribution of the front-end operations in the overall environmental footprint. Most of the indicators are very significantly decreased with the implementation of long-term recycling strategies. This presentation will therefore detail how actinides recycling help to improve the environmental footprint and sustainability of the overall nuclear energy

From the Bataille's Law to the Am-recycling integral experiments, overview of 25 years of RandD in CEA on Minor Actinides Partitioning Processes

International audienceIn Dec.1991, French Parliament voted the first French waste management Act which among others, requests the launching of a large RetD program to study the potential partitioning and transmutation of long-lived radionuclides (LLRN) in order to decrease the waste long-term toxicity and volume. Indeed, LLRN transmutation was thought to be able to reduce the half-life of most of the waste to be buried to a couple of hundred years, overcoming the concerns of the public related to the long-life of the waste. This research has been supported since that date by the successive French governments. First it allows France to demonstrate that recycling the long lived fission products is not worth to be done, and in the new Waste Management Act voted in 2006, it was decided to focus the work on the sole minor actinides. This research effort was very significant and was for a significant part conducted within the well-known Atalante nuclear facility in Marcoule. Over the 25 years of development, different types of strategies were studied, from the early multi-stage and complex DIAMEX-SANEX-SESAME processes to the most recent innovative SANEX, covering both the grouped extraction of MA within the GANEX process and the most recent sole-Americium recycling within the EXAm process. These developments were supported by a robust and long-standing approach allowing successively the screening of the potential extractants, the quantification of their extractive properties, the development of relevant chemical models to model the actinides-extracting molecules interactions the development of specific separation equipments. At the end, all these processes were successively qualified on a few kg of spent nuclear fuel within the Atalante CBP facility. This wide research program allows France to get in hands a flexible portfolio of MA recycling processes for different types of strategies that could in the future be industrially deployed after an industrial upscaling phase. In order to complete this large program, CEA initiated in 2010 a demonstration experiment, the so-called integral experiment, which aims to re-irradiate in a Material Testing Reactor some fuel pellet manufactured from recycled Americium. A few grams of americium have already been recovered from commercial spent nuclear fuel thanks to the EXAm process and is now going to be converted in powder and pellets.This large research program also associated the European scientific community thanks to successive European Research Projects which were selected and funded by the European Commission under the coordination of CEA. With this long-standing research program, France demonstrated the feasibility of recycling minor actinides for transmutation within 4th generation fast neutrons reactors. A general overview of these 25 years of successful and innovative research history will be synthesised in this presentation

NELCAS, an efficient and relevant tool to assess key environmental indicators for nuclear energy

International audienceNuclear energy is anticipated to be one of the possible energy sources which can allow the production of energy at high load with a high level of reliability without significant impact on the environment, specifically in terms of green-house gases It could therefore promote the mitigation of the anticipated global climate change. However, nuclear energy is regularly questioned about its overall environmental impact and footprint, in particular after the Fukushima accident. However, very little information is available on the actual footprint of current and future nuclear systems. In order to bring insights on this issue, we developed a Life Cycle Assessment (LCA) simulation tool NELCAS based on the French nuclear system which allows the calculation of representative key environmental indicators and potential impact indicators for the whole nuclear systems. Indicators were chosen based on their occurrence in literature. Calculations were performed while considering the whole fuel cycle from ore-mining to geological repository and for each of the plant, the contribution from their construction, their operation and their future cleaning and dismantling. Transports were also considered all along the fuel cycle. All the matter and energy fluxes were considered and normalized versus the electric production. Whenever it is possible, actual and recent data were chosen. In particular we widely used the Transparency and Safety Annual reports issued for each fuel cycle plant in France. Finally, statistical influence of the severe accidents was also considered based on the recent Fukushima accident.This presentation will detail the methodology and the overall results obtained for the different indicators. A specific emphasis will be given on the relative benefice of the nuclear energy by comparison to other energy sources