Institute for Radiation Protection and Nuclear Safety (IRSN)
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Radioprotection dans une cohorte de professionnels de santé : connaissances, attitudes, pratiques, auto-perception et exposition aux ri dans les hôpitaux français -étude experts
No full textInternational audienceObjectifs Le nombre de travailleurs du secteur de la santé exposés professionnellement aux rayonnements ionisants (RI) augmente chaque année. Étant donné que des effets sur la santé dus à l'exposition à de faibles doses de RI ont été observés, la radioprotection (RP) dans le contexte des activités professionnelles est une préoccupation majeure. Sur le plan légal, une surveillance dosimétrique impliquant le port d’un/plusieurs dosimètre(s) doit être mise en place pour tous les travailleurs potentiellement exposés aux RI, lesquels doivent suivre des formations en RP. L’étude EXPERTS (EXposition des Professionnels de santE aux RayonnemenTs ioniSants) a plusieurs objectifs, notamment d’évaluer l’adhésion des travailleurs à ces pratiques de RP et ses associations avec la dose cumulée enregistrée, la profession, ainsi que l’auto-perception de l’exposition aux RI et des risques potentiels.Méthodes Tout salarié d’un service médical (diagnostic ou soins) de l'un des neuf hôpitaux français participants avec au moins un enregistrement dosimétrique en 2009, 2014 et 2019 dans le registre SISERI (Surveillance de l'Exposition aux Rayonnements Ionisants) a été inclus et invité à remplir un questionnaire en ligne comprenant des informations sur son exposition professionnelle, sa perception du risque d'exposition aux RI et ses connaissances générales en matière de RP. Les doses de Hp(10) ont également été fournies par le système SISERI. Des régressions logistiques multivariées ont été utilisées.Résultats428 travailleurs ont répondu au questionnaire, soit un taux de réponse de 29%. Les répondants et les non-répondants étaient similaires en termes de niveau d’exposition aux RI. Parmi les répondants, 80% ont déclaré porter toujours ou souvent leur dosimètre individuel, 82% utilisent des moyens de RP, et 62% participent régulièrement à des sessions de formations en RP. Les principales raisons pour le non-port ou la non-adhésion aux pratiques de RP étaient le manque de temps et le caractère parfois inadapté des outils de RP aux activités des professionnels de santé. Le port du dosimètre et l’adhésion aux pratiques de RP étaient fortement associés au "sentiment d'être exposé aux RI" (OR=3,69, CI95% 2,04-6,66 ; OR=4,60, CI95% 2,28-9,30, respectivement). Toutefois, aucun de ces facteurs n'était associé à la participation aux sessions de formation sur les RI. Enfin, pour les travailleurs qui déclaraient porter toujours ou souvent leur dosimètre, la dose moyenne annuelle Hp(10) sur la période 2009-2019 a diminué progressivement. Cependant, l’analyse par service a montré une augmentation de cette dose moyenne en médecine nucléaire uniquement (β=0.017, IC95% 0.006-0.027 mSv/an).Conclusions Sensibiliser les travailleurs exposés à leur propre exposition aux RI semble être un élément clé à aborder dans les cours de formation en RP. Ce type de questionnaire pourrait être introduit dans des études épidémiologiques de plus grande taille pour mieux évaluer les freins et motivations à l’adhésion aux pratiques de RP
The hoard from Prakhon Chai. A new insight for provenience and dating of the Buddhists bronzeimages from the study of their historical iron armatures
No full textInternational audienceIn 1964, a cache of Buddhist bronze images, the most important ever discovered in Southeast Asia, was found in a burial pit on the grounds of a tenth-century Buddhist brick temple in Lahan Sai district, Buriram province (present-day northeastern Thailand). The hoard, whose original term that referred to was Prakhon Chai, includes preaching Buddhas, four-armed Bodhisattva Maitreya and Avalokiteśvara. After discovery, the pieces of the hoard were dispersed to collections both within Thailand and abroad, resulting in a great loss of information. The images are lost-wax cast in a copper alloy and for the larger ones, iron armatures were used to build and/or secure the clay core, and provide stability during the casting process. Interest in these religious objects has largely focused on their aesthetic/religious traits and stylistic chronological associations facilitated by analogy with stone images. A very few dating data were supported by thermoluminescence analyses of core material, and compositional analyses of bronze samples were done to determine the compositional range of the alloy usually identified on the Prakhon Chai bronzes. While the ensemble is relatively coherent in technical and stylistic terms, distinctive features have nevertheless been identified that may testify to several traditions. Our research aims to document these statues in a new way, particularly in terms of their origin and dating, by providing data from the investigation of a previously undocumented component: the iron armatures. The milestones of our method are multiple. They depend both on the type of sample it has been possible to extract from the statues, on recent methodological developments, and on the content of the database of the IRANGKOR research project, which focuses on iron metallurgical activities in the Angkorian kingdom. We propose to discuss the contribution of this ad-hoc approach which combines several analyses (metallographic, chemical, ICP-MS, SEM-FEG, LA-ICP-MS, 14C dating, Os isotopic), to document the provenance and dating of the heterogeneous set of samples. A network of multiple collaborations has enabled the study of a selection of statues from the Asia Society, the Metropolitan Museum of Art, the Asian Art Museum and the Rijksmuseum. The cross-fertilization of data makes it possible to provide unprecedented evidences on the history of these religious icons of the Angkorian world, while a more global comparison of the assemblage sheds light some distinctive features
Amhyco Project overview and first outcomes
No full textInternational audienceA severe accident in a nuclear power plant represents a potential risk to both, humans, and the environment. To prevent and/or mitigate the consequences of such an event, it is paramount to have adequate accident management measures in place to ensure the containment integrity. During a severe accident, one of the potential threats to the containment is the release of combustible gases — especially hydrogen and carbon monoxide — leading to combustion risk in the air and steam-filled nuclear containment building. In modern plants, Severe Accident Management Guidelines (SAMG) as well as dedicated mitigation hardware are in place to minimize/mitigate this combustion risk and, thus, protect the containment integrity to avoid an unacceptable release of radioactive material into the environment. Advancements in SAMGs are in the focus of AMHYCO, an EU-funded Horizon 2020 project (Euratom 2019/2020, GA No 945057) officially launched on October 1st, 2020. The project consortium consists of 12 organizations (from six European countries and one from Canada) and is coordinated by the Universidad Politécnica de Madrid (UPM). AMHYCO benefits from worldwide experts in combustion science, accident management and nuclear safety in its Advisory Board. Thereby AMHYCO covers the most used PWR reactor designs in continental Europe: Westinghouse-type, Siemens-KWU-type and VVER-type.In the proposed paper, the progress of the first three years of the AMHYCO project is presented. A comprehensive bibliographic review has been conducted, providing a common foundation to build the knowledge gained in the course of the project. An extensive set of accident transients was simulated, covering in-vessel as well as ex-vessel phenomena. Based on these simulations, a set of challenging sequences from the combustion risk perspective for the different power plant types was under consideration. At the same time, three generic containment models for the three considered reactor designs have been created to enable full containment analysis simulations with lumped parameter models, 3-dimensional containment codes and CFD codes. In order to further consolidate the modelling base, combustion experiments and performance tests on passive auto-catalytic recombiners under explosion prone H2/CO atmospheres were performed respectively at CNRS (France) and FZJ (Germany)
A simplified approach for predicting fire performance of reinforced concrete fire compartment structures
No full textInternational audienceThe load-bearing fire compartment structures in the nuclear facilities have to be designed for minimum two-hours of fire resistance according to the regulations of the French Nuclear Safety Authority. The analysis for evaluating the fire resistance rating of reinforced concrete (RC) structures may be carried out according to recognized design solutions of Section 5 of EN 1992-1-2 (tabulated data method) which are valid only for the standard temperature-time curve. This method proposes the minimum dimensions of the structural elements as well as the axis distance of the main reinforcement from the exposed surface(s). The standard fire resistance rating consists of the time at which failure of the structural elements in fire situation is expected to occur. Whoever, the functional requirement for providing fire safety in nuclear power plants is stated in terms of post-fire safe shutdown. As a result, the fire response of RC compartment structures needs also to be carefully assessed for long enough to allow dissipation of the temperatures in the structure. In this regard, advanced numerical analysis is often used to assess fire performance of a structure in natural fire considering a growth-fire stage and a decay-fire stage until extinction.This paper presents a simplified approach to verify the fire resistance of the RC slabs and walls exposed to natural fire when designed following tabulated data. This approach is based on a new metrics to quantify the fire resistance under natural fires considering fire ignition until extinction. This fire resistance rating is evaluated for RC fire compartment structures. Temperature time curves are produced using the EN 1991-1-2 parametric fire curves. A thermal analysis is carried out to determine the minimum values of RC slab thickness and the axis distance of longitudinal reinforcement for parametric fire resistance rating in light of natural fires. This method can be applied to RC concrete walls but provides less accurate estimate of the fire resistance because of the risk of instability failures. An approach for evaluating residual strength of RC walls, associated reduction in strength of steel and concrete under natural fires, is proposed in this paper. This approach aims at capturing the effects of growth-fire stage and a decay-fire stage until extinction on the walls. A comparison of residual strength predictions with EN 1992-1-2 tabulated data indicates that the proposed approach is able to evaluate the resistance of fire-exposed RC walls under natural fire
ASTEC core degradation calculations in support of Level-2 ProbabilisticSafety Assessment for 1300MWe French reactors: methodology and preliminary results
No full textInternational audienceThe Institute for Radiation Protection and Nuclear Safety (IRSN) in France has updated its Level-2Probabilistic Safety Assessment (L2 PSA) for the French 1300MWe Pressurized Water Reactors (PWRs) aspart of the decennial safety reevaluation for these specific reactor units. This study was particularlyunderpinned by computations performed using the IRSN ASTEC V2.2 code. ASTEC, which stands forAccident Source Term Evaluation Code, is the reference integral code employed by IRSN for modeling andpredicting the progression of severe accidental sequences. Within this framework, IRSN has conducted atotal of 554 simulations of accidental sequences, for both conditions of 100% Nominal Power and of reactorshutdown. These accidental sequences have been defined based on the IRSN results of Level-1 PSA. Theyencompass the entire spectrum of events starting from initiating event to the point of vessel rupture.Furthermore, these simulations implement state-oriented Emergency Operating Procedures (EOPs) andSevere Accident Management Guidelines (SAMGs). This paper presents the different calculations carriedout, outlines the methodology used to define them and the primary outcomes derived
Caractérisation du mélange des écoulements à densité variable dans les confluences de rivières
No full textInternational audienceTwo concurrent phenomena govern the mixing pattern and efficiency at river confluences: the turbulent diffusion and the dispersion due to secondary currents. This dispersion may be caused, for example, by a strong momentum or density ratio among both inflows or a step at one inflow. The dominant type of mixing affects the length necessary for the good mixing hence, the ecological conditions and the water uses downstream of the confluence. The main goal of this publication is to present a way of visualizing the mixing pattern downstream a confluence, to identify the mixing interface and evaluate both phenomena. This methodology is applied to field measurements taken in various natural and man-made confluence configurations.Deux phénomènes concurrents régissent le modèle de mélange et l'efficacité aux confluences des rivières : la diffusion turbulente et la dispersion due aux courants secondaires. Cette dispersion peut être provoquée, par exemple, par un fort rapport de quantité de mouvement ou de densité entre les deux flux entrants ou par une différence de hauteur de lit au niveau d'un flux entrant. Le type de mélange dominant affecte la longueur nécessaire au bon mélange donc les conditions écologiques et les usages de l'eau en aval des confluences. L'objectif principal de cette publication est de présenter une manière de visualiser le type de mélange dominant en aval d'une confluence, d'identifier l'interface de mélange et d'évaluer les deux phénomènes. Cette méthodologie est appliquée aux mesures de terrain prises dans diverses configurations de confluences naturelles et artificielles
Saturation of the compression of two interacting magnetized plasma toroids evidenced in the laboratory
No full textInternational audienceInteractions between magnetic fields advected by matter play a fundamental role in the Universe at a diverse range of scales. A crucial role these interactions play is in making turbulent fields highly anisotropic, leading to observed ordered fields. These in turn, are important evolutionary factors for all the systems within and around. Despite scant evidence, due to the difficulty in measuring even near-Earth events, the magnetic field compression factor in these interactions, measured at very varied scales, is limited to a few. However, compressing matter in which a magnetic field is embedded, results in compression up to several thousands. Here we show, using laboratory experiments and matching three-dimensional hybrid simulations, that there is indeed a very effective saturation of the compression when two independent parallel-oriented magnetic fields regions encounter one another due to plasma advection. We found that the observed saturation is linked to a build-up of the magnetic pressure, which decelerates and redirects the inflows at their encounter point, thereby stopping further compression. Moreover, the growth of an electric field, induced by the incoming flows and the magnetic field, acts in redirecting the inflows transversely, further hampering field compression
Insights on the UO2+x/U4O9 phase characterization in oxidized UO2 pellets as a function of the hyper-stoichiometry
No full textInternational audienceWe present new insights on the study of the UO2+x/U4O9 equilibrium in UO2 as a function of the hyperstoichiometry x, by coupling HERFD-XANES at the uranium M4-edge and micro-Raman spectroscopy mapping. XANES allowed to measure the uranium speciation in the samples while Raman spectroscopy was used to characterize individually the composition and localization of the different oxide phases. UO2 pellets were oxidized under dry conditions at temperatures above the UO2+x/U4O9 phase transition to reach hyper-stoichiometries in the range 0.01 x 0.1. Combining both technics, we could determine the proportion between U4O9 and UO2+x. We show that at low O/U ratio, U4O9 is present as small clusters inside UO2 grains. As the O/U increases, we evidence the formation of a network of U4O9 crystallized inside UO2+x grains. The variation of the UO2+x phase hyperstoichiometry (x) was evaluated as a function of the sample oxidation
Biocide and other semi-volatile organic compounds in settled indoor dust of CRESPI daycare centers and implication for public health
No full textInternational audienceThis study investigates the presence of biocides and other semi-volatile organic compounds (SVOCs) used in cleaning products in the settled dust of daycare centers and discuss their health impact through ingestion by young children. In Paris metropolitan area, 106 daycares area were investigated between 2019‐2022. Fifteen substances were analyzed in settled indoor dust by gas chromatography-tandem mass spectrometry. Detection rates ranged from 5 to 100%. Galaxolide and benzophenone showed highest median concentration: respectively 884 ng/g and 819 ng/g. The daily intakes (DI) of each chemical through settled dust ingestion were estimated and compared to those from food, inhalation, and dermal contact reported in the literature. Daily intakes from settled dust for musks, triclosan, geraniol, benzophenone, 2-phenylphenol, bifenthrin, and 4-n-nonylphenol were lower than those reported in the literature for other countries. The proportion of dust ingestion to total DI was negligible, except for benzophenone (DI=34%) for children aged 3 to 11 months. The DIs were well below the respective toxicological reference values for isothiazolinones, 4-tert-butylphenol, chlorocresol, and diclosan.Our results suggest that exposure to these biocides and the other SVOCs, taken individually, by dust ingestion in daycares, is not a major public health concern. However, benzophenone, presumed carcinogen for humans, may require further investigation because of its presence in several daycares
New creep device for experimentation on the effect of biaxial prestressing on concrete creepNew creep device for experimentation on the effect of biaxial prestressing on concrete creep
No full textInternational audienceThe containment structures of nuclear power plants undergo biaxial prestressing. These biaxial compressive stresses induce concrete creep which lead to a loss of prestress. If compressive creep strains are too high in case of specific Thermo-Hydric conditions, tensile stresses can develop during the periodic containment test and can generate a risk of concrete cracking affecting its structural permeability. The primary objective is to gain a deeper understanding of the underlying phenomena and provide data to enhance numerical models. To achieve this goal, an original creep frame was specifically designed for the experimental application of biaxial compressive stresses in the laboratory. An optical fiber sensor system was chosen to monitor strains in the three directions inside concrete specimens under controlled environmental conditions. Various loading configurations were systematically applied, including scenarios of both uniaxial and biaxial compression, in symmetric and asymmetric conditions, with stress levels set at 8.5 MPa and 12 MPa, representing the actual stresses experienced within containment building structures. The paper first focus on the description of the device used to obtain axial and biaxial concrete creep. Then, the experimental results are presented. In case of biaxial loading, the asymmetric stress distribution reveals the notable Poisson's effect between the two directions. Remarkably, the less-loaded direction (8.5 MPa) exhibits a significant reduction in creep , while the more heavily loaded direction (12 MPa) displays much more pronounced creep strain compared to the symmetric biaxial creep. Consequently, asymmetric loading plays a crucial role in the development of creep strain in the different directions. By comparing biaxial and uniaxial results, it can be concluded that creep strains strongly depend on loading conditions, whether they involve a 1D or 2D loading state and whether they are symmetric or asymmetric