Institute for Radiation Protection and Nuclear Safety (IRSN)
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Décrypter les mécanismes de reprotoxicité radio-induite chez l'amphipode Gammarus fossarum
No full textNational audienceL’étude des effets chroniques de la contamination radioactive sur la faune sauvage est cruciale pour définir des niveaux de protection pertinents et minimiser les impacts écologiques. Parmi les effets observés, la reprotoxicité est souvent décrite comme l’effet adverse le plus radiosensible chez de nombreux invertébrés (Shuryak et al, 2020). Nos études récentes ont montré que Gammarus fossarum, crustacé amphipode sentinelle de l’environnement, reconnu pour sa sensibilité à la qualité des milieux, ne fait pas figure d’exception. En effet, une exposition au rayonnement ionisant (RI) γ externe de 14 jours des mâles, ou des femelles, impacte fortement la fécondité parentale post-irradiation (i.e. survie de la descendance), de façon plus prononcée chez les mâles, sans affecter la survie, le cycle de mue, ou la capacité à s’alimenter des organismes irradiés (Frelon et al., en révision). Afin de comprendre les mécanismes mis en jeu dans cette reprotoxicité différentielle mâles/femelles chez G. fossarum, une étude intégrée de couples irradiés a été entreprise sur le plan moléculaire, i.e. génotoxicité et abondance des protéines par analyse protéomique shotgun des gonades, et physiologique, i.e. analyse de la fécondité. L’ensemble des données enregistrées a été exploré par des méthodes complémentaires ce qui a conduit à (i) définir les protéines différentiellement exprimées entre le contrôle et le plus faible débit de dose, (ii) sélectionner les protéines répondant de façon significative au gradient d’exposition, et analyser la forme et la sensibilité des réponses (Delignette-Muller et al., 2023), (iii) identifier des groupes de protéines ayant un profil d’expression similaire, plutôt corrélés aux conditions d’exposition et/ou aux effets reprotoxiques chez les mâles et les femelles irradiés (Degli Esposti et al., 2019). L’ensemble de ces résultats participera à déchiffrer les processus biologiques principaux (mode d’action) impactant la capacité reproductive des gammares mâles et femelles exposés aux RI, avec leur significativité, et leur seuil de dose de déclenchement. Cette cartographie des effets sera in fine comparée à celle déjà acquise pour d’autres contaminants chimiques, et aidera à préciser des marqueurs d’effets pertinents pour un suivi des effets des RI. Enfin ces données obtenues pour G. fossarum contribueront également à alimenter un schéma d’action toxique (AOP) conduisant à une baisse de la fécondité après exposition aux RI (Tollefsen et al., 2023).Mots clés - Chronicité – Rayonnement ionisant - Gammare – Protéomique - Analyses statistiques multi-échelles.Remerciements – Les auteurs remercient l’IRSN, l’INRAE, le CEA, le CNRS et EC2CO pour le financement du projet GAMMARRI. RéférencesDegli Esposti, D., Almunia, C., Guery, M.-A., Koenig, N., Armengaud, J., Chaumot, A. and Geffard, O. Co-expression network analysis identifies gonad- and embryo-associated protein modules in the sentinel species Gammarus fossarum Sci Rep. 2019; 9: 7862.Frelon, S., Recoura-Massaquant, R., Dubourg, N., Garnero L., Bonzom, J.-M., Degli Esposti, D. Reproductive capacity but not food consumption is reduced by continuous exposure to the typical genotoxic stressor γ-rays, in the sentinel species Gammarus fossarum. Environmental Toxicology & Chemistry (En révision).Delignette-Muller, M. L., Billoir, E., Siberchicot, A., & Larras, F. (2023). DRomics, a workflow to exploit dose-response omics data in ecotoxicology. Peer Community Journal, Volume 3 (2023), article no. e90. Shuryak, I., Review of resistance to chronic ionizing radiation exposure under environmental conditions in multicellular organisms. J Environ Radioact, 2020. 212.Tollefsen, K.E., et al., Adverse outcome pathways (AOPs) for radiation-induced reproductive effects in environmental species: state of science and identification of a consensus AOP network. Int J Radiat Biol, 2022
Qualité de vie liée à la santé et thérapie par iode radioactif chez les patients atteints d'un cancer de la thyroïde : étude avant-après remerciements
No full textInternational audienceObjectifLa qualité de vie et le bien-être psychologique des patients traités pour un cancer de la thyroïde sont essentiels compte tenu de leur survie très prolongée. Le traitement fait appel à une chirurgie souvent complétée par une thérapie par iode radioactif (RAI). Cette étude vise à examiner les effets potentiels de la thérapie par RAI sur la qualité de vie liée à la santé (Qdv), les symptômes d'anxiété et de dépression, et l'état nutritionnel six mois après traitement.Méthodes Cette étude a inclus 136 patients atteints d’un cancer de la thyroïde. Les doses reçues aux glandes salivaires ont été estimées à partir des dosimètres portés par les patients. La QdV et l'état psychologique des patients ont été évalués avant et 6 mois après le traitement par RAI à l'aide de questionnaires standardisés (notamment le SF-36, qui se traduit en deux scores pour les composantes « physique » et « mentale »). Les analyses statistiques comprenaient des régressions logistiques et linéaires multivariées à effets aléatoires.RésultatsAucune association statistiquement significative n'a été observée entre l'exposition à la RAI et les symptômes d'anxiété ou de dépression. Par contre, une amélioration statistiquement significative du score de la composante physique du SF-36 (diminution des douleurs et du déficit fonctionnel) a été observée en relation avec la dose aux glandes salivaires (β= 0,97, IC95% 0,30;1,65 pour une augmentation de 1-Gy). ConclusionsCette étude montre que la qualité de vie à moyen terme des patients n’est pas altérée par la thérapie par RAI
Anoxic corrosion of carbon steel in different cementitious media and high temperature conditions: comparison between laboratory test and in situ experiments result
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Fatigue Behavior in Air of 316L Stainless Steel Obtained by Additive Manufacturing in the Frame of the NUCOBAM European Project
No full textInternational audienceAbstract Additive Manufacturing (AM) opens new opportunities for the nuclear industry by reducing manufacturing costs for complex geometries compared to traditional manufacturing methods. Nevertheless, it should be verified that components obtained by AM meet the performances needed regarding safety-related function and operational requirements as the usual materials used in the nuclear industry. The NUCOBAM (Nuclear Components Based on Additive Manufacturing) European project aims at developing a methodology to qualify components produced via AM. Laser Powder Bed Fusion and the austenitic stainless steel 316L are the AM method and the material under study for this project. One of the major mechanical degradation mechanisms undergone by nuclear materials is fatigue. Therefore, one of the key points of NUCOBAM’s material characterization program is the low cycle fatigue behaviour in air of the AM processed 316L. A complete test matrix has been designed including several strain amplitudes between 0.2% and 1% and test temperatures (room temperature or 300°C). The other parameters under study are the machining direction (resulting in z-oriented or x-oriented specimens), the porosity ratio, the grain structure, the specimen post processing heat treatment, and the thermal ageing heat treatment. This paper aims at giving an overview of the fatigue test program results and discuss them in the light of microstructural characterizations. A comparison of the fatigue mean curve from NUREG/CR-6909 rev1 obtained for wrought stainless steel is discussed. This study was performed on behalf of the NUCOBAM European project that received funding from the Euratom 2014-2018 under grant agreement No 945313
The inducible KPC:APC mouse organoid model for colon carcinogenesis studies
No full textInternational audienceApcmin mouse is a widely used model of colorectal cancer, but inducible models are more suitable for colon carcinogenesis studies. The B6.Cg-Krastm4Tyj Apctm1Tno Tg(CDX2-cre/ERT2)752Erf/MaraJ mouse model (referred to as KPC:APC) recapitulates colon carcinogenesis through the chromosomal instability pathway via inducible Apc and Kras mutations in Cdx2-expressing intestinal cells. However, no corresponding in vitro model existed before. We developed the KPC:APC ex vivo inducible colorectal cancer organoid model to study cellular and molecular pathways involved in Apc-Kras-driven colon carcinogenesis. After generating the KPC:APC organoids in Matrigel, the mutations were induced with 4-OHT. The treatment efficiency was assessed by morphological and molecular analysis. Results showed no dose dependent effect and a better homogeneity when the organoids were treated 2 days after seeding. Morphological and molecular analysis showed that the carcinogenesis was efficiently induced by adding 0,125µL of 4-OHT for 24h in the medium. The validation of the KPC:APC organoid model will allow investigations on the effects of stressors (such as medical diagnostic exposures to low dose radiation) on colon carcinogenesis. The establishment of this ex vivo model combined with the KPC:APC mouse model will also provide the opportunity to conduct parallel histopathologic and mechanistic studies to advance colon cancer research
IRSN Level 2 PSA for the French 1300 Mwe PWRs Series: Some New Features in the Updated Version
No full textInternational audienceIRSN (as TSO of the French Nuclear Safety Authority) has been developing level 2 PSAs for the French NPPs fleet for many years. This paper presents an overview of new features introduced in the level 2 PSA for the French 1300 MWe PWR series. These features are related to interface between level 1 and level 2 PSA, human reliability assessment, reactor containment fragility under severe accident loading (temperature and pressure), ex-vessel accident modelling, and metrics for the accident radiological consequences
Characterization of Aggregate Reactivity by Dissolution
No full textInternational audienceIn the context of concrete structures ageing, the study of cementitious material durability is of critical importance, particularly the degradations caused by the Alkali-Silica Reaction (ASR). This reaction is driven by the reactive silica dissolution of the concrete aggregate and can unfold in different manner according to the aggregate. The goal of the study is to improve the evaluation of the aggregate reactivity, in terms of quantity of reactive silica and dissolution rate, linked to the form and state (crystalline, amorphous, micro-crystalline) of the aggregate structure. Four aggregates were selected for this study: Potsdam sandstone, Springhill greywacke, Spratt limestone, and a non-reactive Quartzite (used as a reference). For dissolution properties assessment, the aggregates were immersed in a basic solution to promote the degradation of their reactive structure. To reproduce an idealized highly alkaline solution close to a concrete pore solution, dissolution tests were performed on a 1M NaOH solution. Two particle size fractions for each aggregate: 0.5 mm–1 mm and 1–2 mm (with a solid to solution mass ratio of 1:4) and three temperatures: 25, 38, and 60 ℃ were considered. Silica concentration in the solution was measured by complexometric titration. The study displays the dissolution rate constants and analyses the cause of the differences in dissolution
VIKTORIA experiments in the frame of R&D project on sump filtration during a Loss Of Coolant Accident
No full textInternational audienceDuring a Loss Of Coolant Accident (LOCA), in PWR’s, water is injected by the Emergency Core Cooling System (ECCS) to ensure the long-term core coolability and by the Containment Spray System (CSS) to remove residual heat and to maintain containment integrity. After the drainage of the Refueling Water Storage Tank (RWST), water is taken from sumps in the lower part of the reactor building. A filtering system is implemented to collect debris produced by the pipe break as well as other latent materials, such as fiberglass, paint and concrete particles, and to minimize the amount of debris entering in the ECCS and CSS systems. IRSN has launched an experimental R&D project investigating the clogging of sump filters by integral tests performed in the VIKTORIA loop. The main objectives are to investigate the head loss of the filter (physical and chemical clogging) for prototypic upstream debris source term in relevant thermal hydraulic conditions (water temperature and flow velocity on the filter surface) in co
A multiscale steel–concrete interface model for structural applications
No full textInternational audienceIn this paper, a new multiscale macro-element formulation for the steel–concrete interface modeling is proposed. This element allows for the representation of the behavior of steel and the interface zone surrounding it. It can also model the interfacial bond stresses in between. Compared to conventional interface models of the literature, which employ separate mesh elements for the steel and the interface, utilizing a macro-element to model both components simplifies the creation of a reinforced concrete structure mesh. Moreover, the macro-element equilibrium is solved using a sub-structuring method that aims to reduce the computational cost. At the global level, it is considered as a four-node element linked to two-dimensional and three-dimensional concrete elements. At the local level, an assembly of multiple three-node bar elements with bond stresses is performed. An inner mesh discretization is therefore possible at the local level independently of the global level. The coupling between the two modeling scales is done using a static condensation technique. The formulation of the macro-element is presented in this paper. A selection of numerical examples is provided. The presented applications demonstrate the robustness of the proposed interface model and its capacity to reproduce the experimental behavior of reinforced concrete structural elements
Changes in the structure of alkali activated slag mortars subjected to accelerated leaching
No full textInternational audienceThe chemically induced degradation of alkali-activated materials exposed to the surrounding environment is a critical concern for durability. In this study, the leaching of alkali activated slag mortars (AASs) subjected to a 6M NH4NO3 solution was investigated by integrating techniques including ICP-OES, XRD/QXRD, TGA/DSC, ATR-FTIR, and 29Si MAS-NMR. The results revealed that the main leachable elements from the AASs and their leaching rates decreased in the following order: Na, K, Ca, and Mg. In contrast, Si and Al, the key elements in the C-A-S-H gel, displayed a remarkable resistance to leaching. Upon NH4NO3 attack, the primary phase (C-A-S-H) becomes more siliceous and has a greater mean chain length through decalcification and dealumination. The second phase, Mg, Al-layered double hydroxide (Mg, Al-LDH, or hydrotalcite), incorporated nitrate from the surrounding solution, sulfate from precursor dissolution, and Ca from gel decalcification to form nitrate/sulfate-bearing Ca, Al-LDH phases. Remarkably, the water-to-binder ratio exerted a nuanced influence, dictating the pace of element leaching, while exhibiting a relatively modest impact on the stability of the solid phases after 28 days of exposure. This work proposes a leaching mechanism for understanding the leaching process occurring in AASs based on an in-depth experimental exploration of mineralogical alterations