Institute for Radiation Protection and Nuclear Safety (IRSN)
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ASTEC V2.2 code validation: Illustrative results and main outcomes
No full textInternational audienceSignificant efforts are being continuously put for many years into the assessment of the severe accident integral code ASTEC developed by IRSN, through comparison with the results of most of the experiments developed internationally or through benchmarks with other severe accident simulation codes. For this assessment process, the IRSN code developers are supported by international partners, notably in the frame of the recent SNETP-NUGENIA ASCOM collaborative project. This paper relates to the 3rd major version of the ASTEC V2 series, V2.2, that was released in 2021 to the ASTEC community. It aims at providing an overview of the ASTEC V2.2 validation by comparison to experimental data. After a reminder of the ASTEC validation strategy, the ASTEC V2.2 validation matrix is depicted, including more than 300 experimental tests conducted at various scales in more than 50 different facilities worldwide. Then some V2.2 results are discussed for a few representative applications. These calculation examples are selected in a way to cover diverse aspects of severe accident phenomenology in order to provide a good picture of the ASTEC V2.2 modelling status for both in-vessel and ex-vessel processes. Finally, the main lessons drawn from this quite large validation task are summarized, along with an evaluation of the current physical modelling relevance and how it relates to the current state-of-the-art. Based on those outcomes, the ASTEC V2.2 validity domain is specified and some prospects for further improvements are put forward
Summary of Recent Progress and Recommendations for Future Research Regarding the Mediterranean Context and Atmospheric Pollutants Distribution
No full textInternational audienceThis conclusion summarizes the state and variability of Mediterranean air pollution. This volume reflects on the Mediterranean context impacting the atmospheric chemistry (Part I ), the dynamical conditions (II), the distribution, variability, and trends of aerosols (III), and reactive gases (IV). It highlights the region as a “hotspot” in terms of air pollution, sumarizing long-term research efforts made since the 1960s and strengthened in the last decade through the Chemistry-Aerosol Mediterranean Experiment (ChArMEx). ChArMEx has been the largest so far research project in the region on atmospheric pollution and its impacts and facilitated international experiments that combined multiyear monitoring and field measurement campaigns, satellite observations as well as modeling approaches. The spatial and temporal variabilities of atmospheric chemical composition and the understanding of interlinks between air quality, atmospheric dynamic processes, and climate change are addressed. Major results evidence the efficiency of air pollution regulations put in place in the last 20 years. Some topics require further research and include the origin of the secondary pollutants, the trends and future evolution of mineral dust transport, the evolution of the atmospheric circulation, and the impact of very long-distance source areas on the state of the atmospheric composition in the Mediterranean
Les compétences de l’expertise: Le cas de la fabrication d’évaluations de sûreté nucléaire à l’IRSN
No full textCe mémoire original d’habilitation à diriger les recherches porte sur le travail des chargés d’évaluation en sûreté nucléaire de l’IRSN, qui sont décrits comme des « experts-scientifiques » (Roqueplo, 1997), autrement dit des individus qui rendent aux pouvoirs publics des expertises étayées scientifiquement. Les experts constituent une figure familière des industries à risques. Leur activité est toujours investie d’enjeux, d’espoirs, d’attentes et est parfois contestée. Mais, au fond, qu’est-ce que concrètement réaliser une expertise et quelles sont les compétences mises en œuvre dans cette activité ? La fabrication des expertises à l’IRSN s’inscrit dans un cadre institutionnel qui en détermine les grandes étapes, les modalités de réalisation et régule les échanges entre les acteurs concernés. Mais l’expertise est aussi un travail, celui des chargés d’évaluation en sûreté nucléaire, et comme toute activité, sa réalisation ne se laisse pas enfermer dans un cadre normatif. Si les évaluations de sûreté ciblent les risques inhérents à l’utilisation de l’énergie nucléaire, fabriquer une expertise fait aussi courir des risques au regard du retentissement possible d’un texte principalement technique mais aux conséquences sociales et politiques. Et c’est aux experts que revient en grande partie de prendre en charge collectivement et individuellement ces risques. Ce travail montre que l’organisation, les collectifs de travail et les acteurs, pour faire face à ces risques, déploient de nombreuses modalités de production qui font de l’expertise une activité collective et transverse reposant en particulier sur la mobilisation d’une compétence collective qui se construit et se manifeste en situation, dans la confrontation au réel
Chapter 3. Molecular Radiation Biology
No full textInternational audienceVarious exogeneous and endogenous factors constantly cause damages in the biomolecules within a cell. For example, per day, 10,000–100,000 molecular lesions occur in DNA per cell. The molecule modifications that are formed disturb the structure and function of the affected molecules. The purpose of this chapter is to introduce the damages to biomolecules caused by radiation, the associated repair pathways, and the effect on the cellular function. Special interest lies on the damages induced to DNA, the carrier of the human genome, and the consequence to genomic integrity, cell death, and cell survival. Additionally, related effects regarding inflammation and immunity, epigenetic factors, and omics are discussed. The chapter concludes with an explanation of the molecular factors of cellular hyper-radiosensitivity and induced radiation resistance
Godiva-IV dosimetry exercise 2022 preliminary results
No full textInternational audienceIntegral Experiment Request (IER) 538 is part of a series of dose characterization and nuclear accident dosimetry (NAD) exercises performed under the Department of Energy (DOE) Nuclear Criticality Safety Program (NCSP). This is the second NAD exercise using the Godiva-IV critical assembly and the third NAD exercise overall. The participating laboratories provided their own dosimeters that were mounted on the Lawrence Livermore National Laboratory (LLNL) BOttle Manikin ABsorption (BOMAB) phantoms and aluminum plates. The BOMABs and plates were placed at two, three, and four meters away from the center of Godiva. Alongside the NADs, there was a LLNL Passive Neutron Spectrometer (PNS), Atomic Weapons Establishment (AWE) PNS, and Y-12 Sphere present to measure the neutron dose from Godiva-IV. Two irradiations were conducted to test the NAD performance from each laboratory and assesses their performance to the DOE-STD-1098-2017 part 515 criteria. Neutron and gamma doses were measured prior to this exercise. This work presents a model for the neutron and gamma dose
Main Outputs from the OECD/NEA ARC-F Project
No full textInternational audienceThe Analysis of Information from Reactor Buildings and Containment Vessels of Fukushima Daiichi Nuclear Power Station (FDNPS) (ARC-F) project was initiated in January 2019 for three years with 22 signatories from 12 countries. Three main tasks were implemented in the ARC-F project, which were relevant to 1) refinement of analysis for accident scenarios and associated fission product (FP) transport and dispersion, 2) compilation and management of data and information, and 3) discussion for the nextphase project. Various activities were performed in Task 1, covering improvement of analysis for accident scenarios, and in-depth analyses for specific phenomena such as in-vessel melt progression, molten core/concrete interaction, FP transport and source term, hydrogen combustion and atmospheric dispersion of FPs. Through these studies, analyses for accident scenarios with severe accident codes were refined and important phenomena with large uncertainties were clarified. In order to share well selected and organized information from the FDNPS with the project partners, two databases, information source database and sample database, were built under Task 2. The analysis techniques including the separation of iodine species were developed also in Task 2 and applied to the analysis of FPs in several samples taken from the FDNPS. The next-phase project was discussed in Task 3, resulting in launching the Fukushima Daiichi Nuclear Power Station Information Collection and Evaluation (FACE) project. The FACE project officially started in July 2022 with the participation of 23 organizations from 12 countries and the European Commission
Contribution à la modélisation des courants de gravité enrégime stationnaire pour des fluides miscibles
No full textThis thesis is part of the fire risk and smoke behaviour analysis within the framework of the CIGEO project, a deep geological storage facility for nuclear waste. This work aims to provide a simplified model to calculate the evolution of a smoke layer resulting from a fully developed fire in an inclined tunnel. This kind of smoke flow can be assimilated to a gravity current, which appears in a wide range of environmental (pyroclastic flows, underwater flows) and industrial (release of pollutants into the atmosphere, oil spills) processes.The theoretical modelling developed in this manuscript proposes to characterise the longitudinal flow using three primary variables: its velocity U (x), its density ρ(x) and its thickness H (x).The combination of the conservation equations for mass, momentum and energy gives a system of coupled ordinary differential equations to calculate the evolution of these three variables. This system also reveals the Richardson number. This number corresponds to the ratio between the buoyancy and the inertial forces and characterises the stability of the layer.The system of differential equations exhibits a mathematical singularity that prevents the equations from being fully resolved when the Richardson number is unitary. To circumvent this problem, a hydraulic jump is applied. The location and amplitude of this jump depend on a hydraulic condition at the exit of the domain.Comparisons between the theoretical model and LES simulations are proposed and indicate that the model provides satisfying results, especially considering the calculation time between the LES simulations (several days) and the model (a few seconds). The hydraulic jump reproduces a non-monotonic behaviour observed in the simulations. This theoretical model is then extended to the configuration with a slope. In this configuration, the mathematical singularity no longer appears but the slope must be included in the estimation of the entrainment between the fluid and its environment.Dans le cadre du stockage des déchets radioactifs en couche géologique profonde,l’étude du risque incendie, et plus particulièrement de l’aéraulique des fumées, revêtune importance fondamentale. Cette importance est encore accrue dans des configurationsfortement inclinées comme celles du projet CIGEO. En effet, ces fumées sonttoxiques et dangereuses, et il est nécessaire de comprendre leur propagation de cesdernières afin de dimensionner et proposer des solutions de sécurité viables.Cette thèse s’inscrit dans ce contexte de compréhension de la physique de propagationdes fumées. Son objectif principal est de proposer une modélisation simple del’évolution d’une nappe de fumée issue d’un incendie pleinement développé dansune galerie inclinée. Une telle nappe de fumée est assimilable à un courant de gravité,écoulement présent dans une large gamme de phénomènes environnementaux (couléespyroclastiques, écoulements sous-marins) et industriels (relargages de polluantsdans l’atmosphère,marées noires).La modélisation théorique présentée au cours de ce manuscrit propose de caractériserlongitudinalement la nappe à l’aide de 3 variables primaires : sa vitesseU(x), samasse volumique ρ(x) et son épaisseur H(x).En combinant les équations de conservation de la masse, de la quantité de mouvementet de l’énergie, un système d’équations différentielles ordinaires coupléespermettant de calculer l’évolution longitudinale de ces 3 variables est obtenu. Cesystème fait aussi apparaître le nombre de nombre de Richardson correspondant aurapport entre les forces de flottabilité et d’inertie. Ce nombre caractérise la stabilité dela nappe dont dépend l’entraînement, phénomène de mélange entre le courant et sonenvironnement.Le système d’équations différentielles présente une singularité mathématique empêchanttoute résolution des équations lorsque le nombre de Richardson est unitaire.Afin de passer outre ce problème et de maintenir la conservation des flux, un sauthydraulique est modélisé. La localisation ainsi que l’amplitude de ce dernier sontfixées à l’aide d’une condition hydraulique présente à la sortie du domaine.Des comparaisons entre le modèle théorique et des simulations LES indiquentque le modèle fournit des résultats satisfaisants, surtout en tenant compte de ladifférence de temps de calcul entre les simulations LES (plusieurs jours) et le modèle(quelques secondes). Le ressaut hydraulique permet de reproduire un comportementnon-monotone observé dans les simulations.Ce modèle théorique est par la suite étendu à la configuration avec pente. Danscette configuration, la singularité disparaît à partir d’inclinaisons très faibles. Dansce cas, il est également nécessaire d’introduire la pente pour estimer l’entraînemententre le fluide et son environnement
The French Coccinelle study: Risk of lympho-hematopoietic malignancies after medical ionizing radiation exposure from cardiac catheterization during childhood
No full textInternational audienceCardiac catheterization (CC) has largely improved the diagnosis and treatment of congenital heart disease in children over the last decades, but it leads to exposure to low doses of Xrays. Children have a greater radiation sensitivity, however, little is known about the long-term radiation associated cancer risks.Objective: This study aims to assess the risk of lymphohematopoietic malignancies among children diagnosed and/or treated with CC.Methods: The COCCINELLE cohort includes children from 15 French paediatric cardiology departments who underwent a first CC between 2000—2013, before 16 years old. The cohort was linked with national registries to identify cancer cases and collect information on predisposing factors to cancer (PF). Individual cumulative doses to active bone marrow (ABM) were calculated with the PCXMC software, based on detailed dosimetric information retrieved from reports of 1,139 CC procedures. Standardised incidence ratios (SIRs) and relative risks (RR) of haematological malignancies associated with the 2-year lagged ABM dose were calculated.Results/Expected results: The cohort included 17,104 children, followed 6.5 years on average. 22,227 CC procedures were collected, with a mean individual ABM cumulative dose of 3.0 mGy. 38 lympho-hematopoietic malignancies were counted (23 lymphoma and 15 leukemia). A significant excess of cancer incidence was observed (SIR = 3.8 [95% confidence interval 2.9; 4.9]), which wasn’t anymore observed after excluding patients with PF (SIR = 1.3 [0.6;2.7]). The ABM dose wasn’t significantly associated with the risk of lympho-hematopoietic malignancies (RR/mGy = 1.00 [0.88; 1.10]) or lymphoma (RR/mGy = 1.03 [0.90; 1.14]) after adjustment for attained age, gender and PF.Conclusion/Perspectives: No significant increase of cancer incidence was observed after excluding patients with PF and no dose-response relationship was observed between the risk oflympho-hematopoietic malignancies or lymphoma and cumulative ABM dose arising from CC procedure. The extension of the COCCINELLE study and the European Harmonic project will help to better assess health effects of CC exposure during childhood
Identification of a cohesive zone model for cement paste-aggregate interface in a shear test
No full textInternational audienceThe development of tools, using a micromechanical approach, predicting the macroscopic behaviour of heterogeneous materials such as concrete, requires the knowledge of their microstructures (geometrical properties of phases), the behaviour of phases and the interaction laws between phases. This study is focused on a numerical modelling of a local shear test on a cement paste-aggregate composite using a cohesive zone model with the objective to identify the behaviour of the cement paste-aggregate interface. The computations use a 3D finite element modelling of the composite, using a cohesive law at the interface between the two phases. The cohesive model mimics the behaviour of the well-known interfacial transition zone. This work presents a methodology for the identification of cohesive law parameters at different stages of hydration and for different confining stresses using experimental results
Resilience after a nuclear accident: readiness in using mobile phone applications to measure radiation and health indicators in various groups (SHAMISEN SINGS project)
No full textInternational audienceAn anonymous web-based survey was developed to check different aspects (SHAMISEN SINGS project): stakeholder awareness and perceptions of available mobile applications (apps) for measuring ionising radiation doses and health/well-being indicators; whether they would be ready to use them in the post-accidental recovery; and what are their preferred methodologies to acquire information etc. The results show that participation of the citizens would be most beneficial during post-accident recovery, providing individual measurements of external ionizing dose and health/well-being parameters, with possible follow-up. Also, participants indicated different preferences for sources to gain knowledge on ionising radiation and for the functions that an ideal app should have. The level of awareness and readiness to use apps to measure ionising radiation dose depended on two main aspects: individual differences (age & gender) and whether people were from countries affected by the previous major accidents. We concluded that stakeholders could have benefits from the data management plan: (1) it potentiates resilience at individual and community level; (2) citizens' measurements contribute to environmental monitoring and public health screening; (3) linkages between different types of data (environmental exposure, individual behavioural diaries, and measurements of health indicators) allow to perform more rigorous epidemiological studies