Institute for Radiation Protection and Nuclear Safety (IRSN)
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High repetition-rate 0.5 Hz broadband neutron source driven by the Advanced Laser Light Source
No full textInternational audienceNeutron beams are an essential tool to investigate material structure and perform nondestructive analysis, as they give unique access to element composition, thus ideally complementing density analysis allowed by standard x-rays investigation. Laser-driven neutron sources, though compact and cost-effective, currently have lower average flux than conventional neutron sources, due to the limited repetition rate of the lasers used so far. However, advancements in laser technology allow nowadays to address this challenge. Here, we report results obtained at the Advanced Laser Light Source characterizing stable production of broadband (0.1–2 MeV) neutrons produced at a high repetition rate (0.5 Hz). The interaction of laser pulses of 22 fs duration and 3.2 J on-target energy with 2-μm-thick tantalum targets produced protons in the Target Normal Sheath Acceleration (TNSA) regime up to 7.3 MeV. These protons were subsequently converted into neutrons by (p,n) reactions in lithium fluoride (LiF). Activation measurements and bubble detectors were used to characterize neutron emissions, with a neutron fluence of up to ∼1.4×105 neutrons/shot/sr and energies mainly between a few hundred of kilo-electron volt and 2 MeV. The total neutron yield was ∼5×105 neutrons/shot. This paves the way for numerous applications, e.g., in homeland security, materials science, or cultural heritage
Modélisation en transport réactif de la dégradation des granulats lors d'une réaction alcali-silice
No full textNational audienceDans le contexte du vieillissement des structures massives en béton, comme les enceintes de confinement des centrales nucléaires ou les barrages hydro-électrique, l'étude de la durabilité des matériaux cimentaires est d'un grand intérêt. En particulier, la Réaction Alcali-Silice (RAS) peut réduire la durabilité des structures. Le mécanisme de réaction se décrit en 4 étapes : transport des ions, dissolution de la silice réactive, précipitation des produits de réaction et gonflement causant la fissuration du système. Un modèle de transport réactif à l'échelle mésoscopique est proposé afin de simuler la dissolution progressive des granulats et la précipitation des gels en fonction des caractéristiques du granulat. Les résultats retrouvent les observations de la littérature où le gel d'alcali-silice se forme à coeur de granulat alors qu'un C-S-H au ratio Ca/Si faible se forme à l'interface entre la pâte et le granulat. Deux études paramétriques montrent la capacité du modèle à simuler les effets de taille du granulat ainsi que l'influence des paramètres diffusifs sur le type de produits formés
Numerical investigation of local aerosol deposition in a real scale T-junction of a ventilation network
No full textInternational audienceLocal particle deposition measurements in a T-junction of a real scale ventilation network are studied and interpreted using RANS CFD simulations. To assess the validity of the simulation, an analysis of the flow at different scales is proposed. The experimental results show a particle deposition tendency to be higher downstream the T-junction and particularly on the outer side of the T-junction. This tendency appears to be linked to a separation downstream the T-junction, with the main flow on the outer side of the junction and secondary flow on the inner side. This separation seems to have an impact on the aerosol repartition in the bulk, which can be linked to aerosol concentrations gradient downstream the T-junction
Présentation du protocole de l'étude CO'WORKER "COntract WORKers monitored for Exposure to ionizing Radiation"
No full textInternational audienceIntroductionLes travailleurs de l’industrie nucléaire constituent une population d’intérêt particulier en épidémiologie des rayonnements ionisants (RI), car ils reçoivent généralement, de manière chronique, de faibles doses de RI. Ils font l’objet d’une surveillance dosimétrique régulière permettant de reconstituer a posteriori leur exposition aux RI. Néanmoins, la santé de travailleurs exerçant des activités de prestation pour le compte des grandes entreprises du secteur nucléaire a été peu étudiée en raison de plusieurs difficultés méthodologiques. L’objectif de CO’WORKER est d’étudier la mortalité et la morbidité des travailleurs sous-traitants de grandes entreprises du secteur nucléaire et leurs associations potentielles avec l’exposition à de faibles doses de RI.Matériel et MéthodesL’étude CO’WORKER propose d’inclure tous les travailleurs sous-traitants des grandes entreprises du nucléaire ayant pu intervenir sur l’un des sites nucléaires en France métropolitaine, et ayant au moins un enregistrement dosimétrique dans le Système d'Information de la Surveillance de l'Exposition aux Rayonnements Ionisants (SISERI) entre 2005 et 2019. L’exposition aux RI Hp(10), enregistrée par des badges individuels, est extraite de SISERI. Un recueil des historiques de carrière de ces travailleurs est envisagé pour prendre en compte l’exposome professionnel présent et passé via l’utilisation de matrices emploi-exposition.Les données de santé des travailleurs de la cohorte seront obtenues via le Système National des Données de Santé (SNDS) : causes médicales de décès (CépiDC), informations issues des hospitalisations (PMSI) et autres consommations de soins de ville (DCIR). La santé au sein de la cohorte sera comparée à celle de la population générale par le calcul de rapports standardisés de mortalité et d’incidence approchée.RésultatsPlus de 54 000 travailleurs répondant aux critères d’inclusion ont été identifiés à la date de point (01/11/2022), dont 87% sont des hommes (moyenne d’âge à l’inclusion 30,4 ans ±9,4). Avec un suivi moyen de 6,5 ans, la moyenne individuelle d’exposition totale entre 2005 et 2022 était de 5,4 mSv (± 12,3) [min 0 ; max 166,9 mSv]. Les démarches administratives sont en cours afin de solliciter l’accès aux données du SNDS et d’obtenir des informations sur les historiques de carrière des personnes. ConclusionsLes sous-traitants des grandes entreprises du nucléaire intervenant sur des sites nucléaires en France représentent un effectif relativement élevé, avec des expositions pouvant être non négligeables selon les postes de travail. L’accès aux données du SNDS permettra une évaluation de l’état de santé de cette population par rapport à celui de la population générale, et de renforcer les connaissances sur les effets des RI à faibles doses. Néanmoins, certaines difficultés administratives pour l’accès aux données restent à surmonter
Utilisation des datations au radiocarbone et 3He cosmogénique pour estimer les taux d'incision et de soulèvement à la marge du Massif Central, le long de la terminaison nord-est du Système de failles cévenol
No full textInternational audienceStable continental zones such as metropolitan France are characterized by slow deformation. As a result, fault slip rates are low and return periods long. However, these zones are not devoid of seismicity and can produce major earthquakes (e.g. Lambesc 1909 – Mw 6.0). The seismic hazard is therefore not negligible and needs to be better assessed. One way of improving estimates of long-term deformation (> 10 ka) is to measure large-scale displacements using certain morphological objects. In this study, we combine the use of 14C and cosmogenic 3He to date ancient alluvial terraces of the Escoutay River. This river has the particularity of crossing the Cevennes fault system (CFS) where the Le Teil earthquake (11.11.2019) of Mw 4.9 recently occurred on a fault considered to be inactive. This event has called into question our knowledge of regional geodynamics, the seismogenic potential of the CFS and the seismic hazard in the middle Rhône Valley where many sensitive infrastructures are located. By dating MIS 2, 3 and 4 river terraces we constrain an incision rate of [0.43 - 0.70] mm.y-1 along the Escoutay valley. This incision rate is consistent with previous studies carried out along the southern CFS on a 100 ka timescale. When compared to studies on the Ma timescale, this proposed incision rate is one order of magnitude faster. After discussing internal and external factors, we consider local tectonics as the primary driving mechanism of incision implying an acceleration in uplift rate since the Late-Pleistocene along the CFS. These preliminary results are a first milestone of a more extensive work that aims to compare across-fault incision rates along the CFS between its northeastern and southwestern extremities, near Montélimar and Montpellier, respectively.Les zones continentales stables telles que la France métropolitaine sont caractérisées par une déformation lente. De ce fait, les taux de glissement des failles sont faibles et les périodes de retours longues. Cependant, ces zones ne sont pas dépourvues de sismicité et peuvent produire des séismes importants (e.g. Lambesc 1909 – Mw 6.0). L'aléa sismique n'y est donc pas négligeable et nécessite d'être mieux contraint. Un moyen de mieux estimer cette déformation long-terme (> 10 ka) est de mesurer les déplacements à grande échelle en utilisant certains objets morphologiques. Dans cette étude nous combinons l'utilisation du 14C et du 3He cosmogénique pour dater d'anciennes terrasses alluviales de la rivière Escoutay. Cette rivière a la particularité de traverser le faisceau de faille des Cévennes (CFS) où s'est récemment produit le séisme du Teil (11.11.2019) de Mw 4.9 sur une faille considérée comme inactive. Cet événement a remis en cause la connaissance de la géodynamique régionale, du potentiel sismogénique du CFS et de l'aléa sismique dans la moyenne vallée du Rhône où les infrastructures sensibles sont nombreuses. En datant les terrasses alluviales du MIS 2, 3 et 4 nous contraignons un taux d’incision de 0.43 - 0.70 mm.y-1 le long de l’Escoutay. Ce taux d’incision est en accord avec les précédentes études à l’échelle des centaines de milliers d’années sur la bordure méridionale du CFS. En comparaison avec des études à l’échelle du million d’années, le taux d’incision proposé s’avère être un ordre de grandeur plus rapide. Après avoir discuté les facteurs internes et externes, nous considérons la tectonique locale comme étant le moteur principal de l’incision. De ce fait, nous suggérons une accélération du taux de soulèvement le long du CFS depuis le Pléistocène supérieur. Ces résultats préliminaires sont une première étape d’un travail plus large qui vise à comparer les taux d’incision de part et d’autre des failles le long du CFS entre ses terminaisons Nord-Est et Sud-Ouest, près de Montélimar et Montpellier, respectivement
A Historical Survey of Key Epidemiological Studies of Ionizing Radiation Exposure
No full textInternational audienceIn this article we review the history of key epidemiological studies of populations exposed to ionizing radiation. We highlight historical and recent findings regarding radiationassociated risks for incidence and mortality of cancer and non-cancer outcomes with emphasis on study design and methods of exposure assessment and dose estimation along with brief consideration of sources of bias for a few of the more important studies. We examine the findings from the epidemiological studies of the Japanese atomic bomb survivors, persons exposed to radiation for diagnostic or therapeutic purposes, those exposed to environmental sources including Chornobyl and other reactor accidents, and occupationally exposed cohorts. We also summarize results of pooled studies. These summaries are necessarily brief, but we provide references to more detailed information. We discuss possible future directions of study, to include assessment of susceptible populations, and possible new populations, data sources, study designs and methods of analysis
Radiation Adverse Outcome pathways (AOPs): examining priority questions from an international horizon-style exercise
No full textInternational audienceThe Organisation for Economic Co-operation and Development (OECD) Adverse Outcome Pathway (AOP) Development Programme is being explored in the radiation field, as an overarching framework to identify and prioritize research needs that best support strengthening of radiation risk assessment and risk management strategies. To advance the use of AOPs, an international horizon-style exercise (HSE) was initiated through the Radiation/Chemical AOP Joint Topical Group (JTG) formed by the OECD Nuclear Energy Agency (NEA) High-Level Group on Low Dose Research (HLG-LDR) under the auspices of the Committee on Radiological Protection and Public Health (CRPPH). The intent of the HSE was to identify key research questions for consideration in AOP development that would help to reduce uncertainties in estimating the health risks following exposures to low dose and low dose-rate ionizing radiation. The HSE was conducted in several phases involving the solicitation of relevant questions, a collaborative review of open-ended candidate questions and an elimination exercise that led to the selection of 25 highest priority questions for the stated purpose. These questions were further ranked by over 100 respondents through an international survey. This final set of questions was judged to provide insights into how the OECD's AOP approach can be put into practice to meet the needs of hazard and risk assessors, regulators, and researchers. This paper examines the 25 priority questions in the context of hazard/ risk assessment framework for ionizing radiation. Conclusion: By addressing the 25 priority questions, it is anticipated that constructed AOPs will have a high level of specificity, making them valuable tools for simplifying and prioritizing complex biological processes for use in developing revised radiation hazard and risk assessment strategies
Dynamic Characterization of Five Historical Bell Towers in the Mugello Basin (Italy)
No full textInternational audienceStructural and dynamic identifications of historical buildings provide key input parameters in present archeo-seismological research. The ambition of the research project ACROSS (ArChaeology, inventory of RecOnstruction, Seismology and Structural engineering), involving different institutions in France and Italy, is to study past earthquakes through their impact on historical masonry buildings. Within this context, and among the first tasks, an ambient vibrations recording campaign was carried out to characterize five ancient bell towers in the Mugello basin in Tuscany (Italy) that suffered damage from at least one strong earthquake during medieval times. Operational Modal Analysis (OMA) allows us to identify the five slender masonry towers' main vibration modes (frequencies, modal shapes, and damping coefficients). Mode shapes exhibit the singularities of the bell towers related to their geometrical complexity, the use of numerous building techniques, and the relationships with other structures, particularly the adjacent naves. Of particular interest is the study of the response of one of the bell towers (pieve di St Cresci in Valcava) to bell-swinging excitation that has given insight into its non-linear dynamic response. Apart from helpful information about the relation between slenderness, irregularities in height, and main resonance frequencies, the results of the OMA study serve as the basis for building numerical models of slender structures that will help understand past (and future) dynamic behavior under different earthquake scenarios
Tracing the impact of former uranium mine sites using stable Pb isotopes: A review
No full textInternational audienceTracing pollution originating from uranium (U) mining activities is a key challenge due to the diversity of U sources (geochemical background versus U-ore) and its daughter radionuclides. Among the available tracers that can be used to highlight the impact of these activities on the environment, the application of Pb stable isotopes is relevant. This paper is an overview of the use of Pb isotopes for tracing U-mining impacts due to mining and milling activities. For this purpose, this work outlines the different Pb isotope sources in the environment with a focus on the primary U-rich ores until the mineralized area. This information is an important prerequisite for the understanding of Pb fate during the physical and chemical processing of U-ores. Moreover, an important review regarding the Pb isotope composition of the different types of U mining waste is carried out. Finally, an additional part of analytical procedures including sample preparation and Pb isotopic analysis are also be presented
Radon exposure and potential health effects other than lung cancer: a systematic review and meta-analysis
No full textInternational audienceContext and objective: To date, lung cancer is the only well-established health effect associated with radon exposure in humans. To summarize available evidence on other potential health effects of radon exposure, we performed a comprehensive qualitative and quantitative synthesis of the available literature on radon exposure and health effects other than lung cancer, in both occupational and general populations. Method: Eligible studies published from January 1990 to March 2023, in English and French languages, were identified in PubMed, ScienceDirect, Scopus, ScieLo and HAL. In the meta-analysis, we estimated average weighted standardized incidence ratios (metaSIR), standardized mortality ratios (metaSMR), and risk ratio (metaRR) per 100 unit (Bq/m 3 or Working level Month) increase in radon exposure concentration by combining estimates from the eligible studies using the random-effect inverse variance method. DerSimonian & Laird estimator was used to estimate the between-study variance. For each health outcome, analyses were performed separately for mine workers, children, and adults in the general population. Results: A total of 129 studies were included in the systematic review and 40 distinct studies in the meta-analysis. For most of these health outcomes, the results of the meta-analyses showed no statistically significant association, and heterogeneity was only present among occupational studies, especially between those included in the metaSIR or metaSMR analyses. However, the estimated exposure-risk associations were positive and close to the statistical significance threshold for: lymphohematological cancer incidence in children (metaRR = 1.01; 95%CI: 1.00–1.03; p = 0.08); malignant melanoma mortality among adults in the general population (metaRR = 1.10; 95%CI: 0.99–1.21; p = 0.07); liver cancer mortality among mine workers (metaRR = 1.04; 95%CI: 1.00–1.10; p = 0.06); intestine and rectal cancer mortality combined among mine workers (metaRR = 1.02; 95%CI: 1.00–1.04; p = 0.06). Conclusion: Although none of the exposure-risk associations estimated in the meta-analyses reached statistical significance, the hypothesis that radon may have other health effects apart from lung cancer could not be ruled-out and call for additional research. Larger and well-designed studies are needed to further investigate this question