Évaluation de moyens de mitigation innovants du risque hydrogène dans les réacteurs de fusion thermonucléaire

L'un des principaux accidents envisageables dans un réacteur de fusion thermonucléaire de type ITER est la perte de refroidissement du primaire (APRP) entrainant une production d'hydrogène. Dans le cadre des études de sûreté ITER, il faut donc défInir une stratégie de mitigation de ce risque en privilégiant un dispositif pouvant être placé à proximité de la ou des sources d'hydrogène. L'incertitude quant à la présence ou non d'air lors d'un tel scénario interdit l'utilisation des méthodes classiques basées sur la réaction hydrogène/oxygène. De précédentes études ont permis de proposer un procédé basé sur la réduction du mélange dioxyde de manganèse promu par l'oxyde d'argent. La mise en oeuvre de cette réaction gaz-solide en lit fixe a conduit à en déterminer la cinétique par comparaison de résultats expérimentaux avec ceux d'un modèle. Ce travail a également permis de réaliser un pré-dimensionnement d'un dispositif pour le réacteur ITEROne of the main accidents in ITER-type thermonuclear fusion reactors is the loss of coolant leading to hydrogen production. Within the framework of the studies on the ITER fusion reactor, a mitigation strategy for this risk must be devised by focusing on a system, which can be placed near the hydrogen source. The uncertainty as to the air content during such a scenario forbids the use of classic methods based on the hydrogen/oxygen reaction. Former studies have proposed a process based on the reduction of the manganese dioxide enhanced by silver oxide mixture. Realizing this solid/gas reaction in a fixed bel led to the kinetic determination by comparing experimental results with those provided by a model. This work also allowed to achieve a pre-design basis of the device to be implemented on ITER reactorNANCY/VANDOEUVRE-INPL (545472102) / SudocSudocFranceF

Major discrepancy between factual antibiotic resistance and consumption in South of France: analysis of 539,037 bacterial strains

International audienceThe burden of antibiotic resistance is currently estimated by mathematical modeling, without real count of resistance to key antibiotics. Here we report the real rate of resistance to key antibiotics in bacteria isolated from humans during a 5 years period in a large area in southeast in France. We conducted a retrospective study on antibiotic susceptibility of 539,107 clinical strains isolated from hospital and private laboratories in south of France area from January 2014 to January 2019. The resistance rate to key antibiotics as well as the proportion of bacteria classified as Difficult-to-Treat (DTR) were determined and compared with the Mann-Whitney U test, the chi(2) test or the Fisher's exact test. Among 539,037 isolates, we did not observe any significant increase or decrease in resistance to key antibiotics for 5 years, (oxacillin resistance in Staphylococcus aureus, carbapenem resistance in enterobacteria and Pseudomonas aeruginosa and 3rd generation cephalosporin resistance in Escherichia coli and Klebsiella pneumoniae). However, we observed a significant decrease in imipenem resistance for Acinetobacter baumannii from 2014 to 2018 (24.19-12.27%; p = 0.005) and a significant increase of ceftriaxone resistance in Klebsiella pneumoniae (9.9-24.03%; p = 0.001) and Enterobacter cloacae (24.05-42.05%; p = 0.004). Of these 539,037 isolates, 1604 (0.3%) had a DTR phenotype. Over a 5-year period, we did not observe a burden of AR in our region despite a high rate of antibiotic consumption in our country. These results highlight the need for implementation of real-time AR surveillance systems which use factual data