Nuclear power fleet replacement: an opportunity for the French energy mix?

International audience– In France, 27% of the electricity is to be produced by renewable resources by 2020. This share is intended to grow continuously up to 2050. The recent European agreement and the French " energy transition law " will promote such a development. The French power system is characterized by high nuclear penetration and nuclear power is meant to remain a significant contributor in the medium and long term, as a low-carbon power source. More than half the French nuclear power fleet was installed in the late seventies / early eighties. Thus, the issue of its replacement is at the core of the French power mix issue. The objective of this paper is to provide some insights about the opportunity it enables for the energy mix. Two plausible replacement scenarios are developed and analyzed as regards the energy cost provided by nuclear power. For a given target level of nuclear installed capacities, the penetration of non-dispatchable renewables with dispatch priority will increase the need for nuclear power modulation at reduced average load factor. The impact of modulation on the nuclear levelized cost of electricity is assessed, according to the considered replacement scenario and for different renewable and nuclear energy penetration scenarios. Results show that, according to the selected assumptions, implementing a progressive shutdown (based on an increased operation lifetime of Nuclear Power Plants) appears a relevant choice since it both provides a lowest power production cost even at reduced average load factor to participate to load following and allows the possibility of " waiting " for choosing most sustainable technologies

Nuclear and non-dispatchable renewables: two compatible supply options? The case of the French power mix

The complementary features of low-carbon power sources are a central issue in designing energy transition policies. The French current electricity mix is characterised by a high share of nuclear power which equalled 73% of the total electric production in 2013. With the increase of non-dispatchable renewable resources, nuclear flexibility is examined as part of the solution to balance electricity supply and demand. Our proposed methodology involves designing scenarios of nuclear and non-dispatchable renewable penetration levels, and developing residual load duration curves in each case. The load modulation impact on the nuclear production cost is estimated. This article shows to which extent the nuclear annual energy production will decrease with high shares of non-dispatchable renewables (down to load factors of 40% for proactive assumptions). However, the production cost increase could be compensated by implementing a progressive replacement of the plants. Besides, incentives proves required for nuclear to compete with combined cycle gas turbines as its alternative backup option. In order to make the social planner and plant operator goals coincide, the solution could be to find new outlets rather than reducing nuclear load factors. To conclude, nuclear flexibility could then be considered through the power use by producing heat or hydrogen

Involvement of the Modifier Gene of a Human Mendelian Disorder in a Negative Selection Process

BACKGROUND:Identification of modifier genes and characterization of their effects represent major challenges in human genetics. SAA1 is one of the few modifiers identified in humans: this gene influences the risk of renal amyloidosis (RA) in patients with familial Mediterranean fever (FMF), a Mendelian autoinflammatory disorder associated with mutations in MEFV. Indeed, the SAA1 alpha homozygous genotype and the p.Met694Val homozygous genotype at the MEFV locus are two main risk factors for RA. METHODOLOGY/PRINCIPAL FINDINGS:HERE, WE INVESTIGATED ARMENIAN FMF PATIENTS AND CONTROLS FROM TWO NEIGHBORING COUNTRIES: Armenia, where RA is frequent (24%), and Karabakh, where RA is rare (2.5%). Sequencing of MEFV revealed similar frequencies of p.Met694Val homozygotes in the two groups of patients. However, a major deficit of SAA1 alpha homozygotes was found among Karabakhian patients (4%) as compared to Armenian patients (24%) (p = 5.10(-5)). Most importantly, we observed deviations from Hardy-Weinberg equilibrium (HWE) in the two groups of patients, and unexpectedly, in opposite directions, whereas, in the two control populations, genotype distributions at this locus were similar and complied with (HWE). CONCLUSIONS/SIGNIFICANCE:The excess of SAA1alpha homozygotes among Armenian patients could be explained by the recruitment of patients with severe phenotypes. In contrast, a population-based study revealed that the deficit of alpha/alpha among Karabakhian patients would result from a negative selection against carriers of this genotype. This study, which provides new insights into the role of SAA1 in the pathophysiology of FMF, represents the first example of deviations from HWE and selection involving the modifier gene of a Mendelian disorder

Enjeux économiques de l’énergie nucléaire

Le lecteur assidu des articles sur l’économie du nucléaire constatera sans nul doute combien est différent aujourd’hui un article sur ce sujet de ce qu’il aurait été il y a seulement 3 ou 4 ans. Plusieurs événements d’ampleur considérable sont en effet intervenus depuis : traduction effective dans le système français des directives sur la concurrence entre producteurs d’électricité et en conséquence réflexion en profondeur sur le calcul des prix à payer par les nouveaux entrants pour accéder au nucléaire “historique”, accident de Fukushima, campagne électorale en cours avec une question jusqu’ici peu traitée relative au parc : que faut-il souhaiter en termes d’exploitation des réacteurs actuels ? Ainsi, la conséquence majeure est que la réflexion économique s’est intensifiée en regard des coûts du nucléaire existant, alors qu’il y a peu, l’économie du nucléaire était surtout abordée en termes de compétitivité vis-à-vis des autres moyens de production électriques, dans une perspective donc de construction de nouvelles centrales (une logique dite “en développement”). Cet article reflète très nettement cette nouvelle tendance et une place importante est donnée à l’économie du nucléaire existant. La question de son coût (ou de ses coûts) est présentée en détail. On constate une augmentation certaine des coûts, au regard des évaluations encore récentes : elle est notamment la conséquence de la meilleure prise en compte des coûts de maintien du parc, de démantèlement et de stockage des déchets. Le nucléaire historique produit son énergie pour un coût courant économique de l’ordre de 50 euros/MWh, selon le rapport récent de la Cour des Comptes sur l’économie de la filière nucléaire, hors les options de rénovation possibles. En comptant toutes les rénovations envisageables, y compris induites par la prise en compte de l’accident de Fukushima, ce coût courant économique atteint 54 /MWh, sur la base de la même méthode. Il existe également d’autres méthodes de calcul détaillées dans cet article. un tel niveau est plus compétitif que les autres moyens de production existants ou en développement (hydraulique excepté). C’est ce qui explique l’intérêt économique de prolonger l’exploitation du parc actuel, tant que l’Autorité de sûreté le permet (compte tenu des travaux à réaliser et de leurs coûts). Sous un autre angle, le rapport de la Commission “Energies 2050” évalue le coût total actualisé de l’arrêt du parc actuel, selon l’hypothèse d’une durée d’exploitation limitée à 40 ans, à de l’ordre de la centaine de milliards d’euros. Enfin, nous terminons cet article par un regard sur les coûts actuels des réacteurs en développement, dont l’EPR. Nous concluons à une augmentation significative des coûts, laquelle doit cependant être relativisée. Au total, le nucléaire ne fait pas exception dans l’évolution des coûts de la production et de la distribution d’électricité en France et dans le monde : les évolutions récentes marquent une tendance significative à la hausse. Malgré cela, cette source d’électricité est la plus compétitive quand il s’agit du parc existant, et de loin, et reste l’une de plus compétitives si l’on considère des unités en développement

Development and implementation of a bioremediation plan for an Ile-de-France site

International audienc

Identification and functional consequences of a recurrent NLRP12 missense mutation in periodic fever syndromes

International audienceObjective: To gain insight into the molecular bases of genetically unexplained periodic fever syndromes (PFS) by screening NLRP12, a gene in which only a nonsense and a splice site mutation have so far been identified, and to assess the functional consequences of the identified missense variation.Methods: NLRP12 was screened for mutations by direct sequencing. Functional assays were performed in HEK 293T cells stably expressing the proapoptotic protein ASC and procaspase 1, in order to determine the effects of normal and mutated NLRP12 proteins on speck formation, caspase 1 signaling, and NF-κB activation.Results: A heterozygous NLRP12 missense mutation involving a CpG site (c.1054C>T; p.Arg352Cys) was identified in exon 3, which encodes the nucleotide-binding site (NBS) of the protein, in 2 patients from different countries and carrying different NLRP12 haplotypes. The mutation, which does not alter the inhibitory effect of NLRP12 on NF-κB activation, increases speck formation and activates caspase 1 signaling. To define this new class of PFS, we propose the term NLRP12-associated disorders (NLRP12AD).Conclusion: Given the rarity of known NLRP12-associated disorders, the identification of this NLRP12 molecular defect contributes to the delineation of the clinical spectrum associated with mutations in this gene and highlights the importance of screening NLRP12 in patients presenting with unexplained PFS. This study also demonstrates, by means of functional assays, the deleterious effect of this recurrent missense mutation; the gain of function for speck formation and caspase 1 signaling associated with this NBS mutation is consistent with the inflammatory phenotype of PFS

Role of IL-1b in NLRP12-associated autoinflammatory disorders and resistance to anti-IL-1 therapy

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