Orano (France)

The micro-structure, residual stresses, and micro-distortions generated near the surface in the AA6061-B4C metal matrix composite by glass-bead blasting are investigated and compared with those of the bulk. In contrast to the bulk, the sublayer is under compression and contains an extremely low density of B4C and a high density of dislocations. Corrosion behaviour was studied in H3BO3 after immersion at the OCP and after accelerated tests. In the sublayer, initial rapid oxidation (formation of a homogeneous oxide film) is followed by slow oxidation (average corrosion rate: 2 µm/year); the oxidation front moves parallel to the surface. In the bulk, oxidation takes place along preferential paths defined by the distribution of B4C. The driving force is the galvanic coupling between B4C and the matrix. Once corrosion proceeds, corrosion products (oxidation of the sublayer) become weakly adherent, peeling off locally. The bulk is then directly exposed to the solution, promoting corrosion.

We show that a homogeneous single-phase mixed oxide is obtained by blending and sintering commercial UO 2 and nanocrystalline PuO 2 powder; whereas, under the same conditions, conventional PuO 2 powder obtained from oxalate precipitation and composed of platelets, yields two-phase mixed oxide. The use of nanometric PuO 2 results in a larger final grain size.

This case report discusses the management of a male in his early 40s with type 2 diabetes and a history of smoking, evaluated for cardiac risk prior to beginning a half-marathon training program. The patient wore an ŌURA ring before, during, and after a treadmill stress test; however, data review was conducted retrospectively. Although asymptomatic, the patient exhibited frequent premature ventricular contractions and abnormal heart rate recovery during the test, prompting further evaluation. Managed through a hybrid care model that integrated traditional clinical assessment with digital health monitoring, this case highlights the valuable role of wearable technology in identifying and managing cardiac arrhythmias. It also demonstrates how real-time and remote data from the ŌURA ring enhanced clinical decision-making and patient care.

Dans un essai contrôlé randomisé, le vaccin grippal haute dose (HD) a démontré une efficacité vaccinale relative (eVR) supérieure de 24,2% (9,7;36,5%) par rapport aux vaccins à dose standard (SD) pour prévenir la chez les 65+ [1]. Le HD a été introduit en France pour les 65+ à partir de la saison 2021-2022, au cours de laquelle nous avions rapporté une rVE de 23,3% (8.4%-35.8%) contre les hospitalisations pour grippe. Nous présentons ici les résultats de la deuxième saison. MéTHODES: Nous avons mené une étude de cohorte rétrospective à partir du SNDS. Les personnes âgées de 65 ans et plus vivant en communauté et vaccinées contre la grippe au cours de la saison 2022-2023 ont été inclues et suivies depuis la date de vaccination jusqu'au 30 juin 2023/admission en maison de retraite/décès. Les hospitalisations pour grippe et autres causes ont été recueillies à partir de 14 jours après la vaccination. Après un appariement sur score de propension (1:4) avec contrainte exacte sur les groupes d'âge, le sexe, la semaine de vaccination et la région, les ratios de taux d'incidence ont été estimés via modèles de régression. RéSULTATS: 675 412 individus avec HD ont été appariés à 2 701 648 individus avec SD. Au sein de la cohorte appariée, le HD était associé à une diminution de 27,4 % (19,8%-34,3%) des hospitalisations pour grippe par rapport au SD. Certaines hospitalisations non liées à la grippe étaient légèrement plus fréquentes chez les patients ayant bénéficié de l'HD, ce qui suggère un biais résiduel dû à des facteurs de confusion non mesurés. Ce résultat, cohérent avec la littérature et l'analyse 2021-2022 [2], renforce le niveau de preuve quant au bénéfice du vaccin HD sur la réduction des hospitalisations liées à la grippe par rapport au vaccin SD en vie réelle. L'utilisation d'un vaccin HD adapté à la population des 65 ans et plus pourrait contribuer à réduire le fardeau lié aux infections respiratoires.

In recent years, a particular family of molten salt reactors (MSRs) – those designed to burn plutonium and minor actinides – has attracted considerable interest from research institutions and companies, including CNRS and Orano. NRS/LPSC Grenoble has been studying and optimising MSRs since the early 2000s, within which framework the in-house precision-driven material evolution REM code was developed. Depletion simulation of burner MSRs has led to the development of new methods for supply management and the addition of additional constraint parameters to the REM code. These developments make it possible to introduce physico-chemical constraints into the analysis of this kind of reactor, enabling more precise studies. Examples include controlling the alkali or alkaline-earth fraction, or regulating the salt volume either by adjusting the supply or by adding a dynamic expansion tank. This paper presents new perspectives that led to work on the numerical stabilization of the system, which helped smooth out reactor characteristics such as reactivity and fuel supply. This, in turn, opened the way to new supply strategies, e.g., by considering separate supplies for each chemical species or for individual elements. Finally, results are presented showing that, in the case of an extraction scheme with actinide reinjection, element-based supplies better satisfy mass balance requirements than species-based supplies. Conversely, in schemes without reinjection, the opposite trend is observed. Considering these strategies, while taking into account chemical constraints such as element valency and salt electroneutrality, could lead to the development of a new model for material extraction.

This chapter discusses the functional requirements associated with the nuclear fuel reprocessing: mechanical resistance, corrosion resistance and erosion resistance. The processing of spent fuel requires the use of nitric acid in varying concentrations and temperatures that can reach boiling point. The environment is composed of a broad range of chemical elements, most of which come from the spent fuel. The choice of materials varies, depending on the location of the equipment in the reprocessing line. The corrosion kinetics of a material is a result of its oxidation kinetics and the reduction kinetics of the environment. This can be affected by different parameters, such as: corrosion products, oxidizing ions, halides, temperature and/or heat flux, irradiation, and effect of the metallurgical state.

The aim of this work was to study the influence of oxide ions concentration on the stability of 316L stainless steel and its alloying compounds (chromium, iron, nickel and molybdenum) in molten LiCl-KCl-Li2O at 550˚C. An in-situ oxide ions titration method using square wave voltammetry was developed to quantify oxide ions, to accurately control the experimental conditions. The influence of oxide ions concentration was then studied by linear sweep voltammetry and long-term immersions followed by SEM-EDS analysis on pure elements and SS316L. Results showed that chromium was stabilized in presence of O2−, iron was dissolved independently of [O2−], nickel was resistant to corrosion and molybdenum, which was stable in oxide-free media, was found reactive towards O2−. On SS316L, a passivation layer was observed and an enriched chromium-oxygen layer was observed by SEM-EDS. Almost all the iron was dissolved and a small depletion of molybdenum was visible while nickel remained resistant to corrosion. Linear sweep voltammetry studies were consistent with SEM-EDS analysis and each alloying compound exhibited a similar behaviour in the SS316L as its pure form.