Institute for Radiation Protection and Nuclear Safety (IRSN)
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COSMIC ON AIR: A Citizen Science Approach To Hunting Solar Eruptive Phenomena At Flight Altitudes
No full textDOI de ResearchGateInternational audienceCosmic On Air is a citizen science project which aims to increase coverage of measurements of cosmic radiation on board aircraft in the search of solar eruptive phenomena. A number of low-cost, compact, and connected radiation monitors are available to the public for purchase, and the data measured during flights are uploaded to an open data repository for analysis. Dosimetry of aircrew is routinely achieved using numerical approaches validated by measurements made on board aircraft. However, in cases of randomly occurring solar eruptive phenomena, which can produce a burst of sufficiently energetic Solar Particle Events to be classified as a Ground Level Event (GLE), the dose rates at flight altitudes can be significantly increased. Current dosimetry models for GLEs cannot be easily validated due to the very few on-board measurements during such phenomen
An assessment of CFD-scale fluid-structure interaction simulations through comprehensive experimental data in cross-flow
No full textInternational audienceExperimental tests accessing both fluid and structure behaviors are mandatory for a consistent and comprehensive assessment of fluid-structure interaction (FSI) numerical simulations. In this paper, recently published results of an experimental configuration of two in-line cantilever cylinders subjected to water cross-flow were considered: instantaneous fluid velocities measurements are available on several positions inside the test section, together with the cylinder vibrations. FSI simulations were performed by coupling Ansys Fluent (for the fluid domain) with Ansys Mechanical (for the solid domain). URANS simulations and Scale-Adaptive Simulations (SAS) were employed as CFD simulation approach. The structure displacements were taken into account through an Arbitrary LagrangianEulerian approach. The fluid-structure coupling was 2-way explicit. Simulations were performed for two different water mass flow rates. For the highest one, vortex-induced resonance was observed experimentally. The numerical results show consistent agreement in terms of shedding frequency and velocity spectra behind the cylinders. The calculated vibration response is overall consistent, despite some underestimations, for the cylinders not featuring vortex-induced resonance; nevertheless, the experimentally observed vortex-induced resonance could not be reproduced by the numerical simulations
Activity report ciroquo research & industry consortium
No full textThis project emulated the major scientific challenges of the discipline, such as code transposition/calibration/validation, modeling of complex environments and stochastic codes. In each of these scientific fields, particular attention has been paid to large-scale problems. Real-life problems sometimes involve dozens orhundreds of inputs. Methodological advances have been proposed to take account of this additional difficulty. Developments in mathematical research are distinguished from the dominant work in machine learning by the exploration of costly numerical simulations, i.e., by the need to be thrifty in terms of the quantity of data available
Temporal trajectories of artificial radiocaesium 137Cs in French rivers over the nuclear era reconstructed from sediment cores
No full text(IF 3.8;Q1)International audience137Cs is a long-lived man-made radionuclide introduced in the environment worldwide at the earlybeginning of the nuclear Era during atmospheric nuclear testing’s followed by the civil use of nuclearenergy. Atmospheric fallout deposition of this major artificial radionuclide was reconstructed atthe scale of French large river basins since 1945, and trajectories in French nuclearized rivers wereestablished using sediment coring. Our results show that 137Cs contents in sediments of the studiedrivers display a large spatial and temporal variability in response to the various anthropogenicpressures exerted on their catchment. The Loire, Rhone, and Rhine rivers were the most affected byatmospheric fallout from the global deposition from nuclear tests. Rhine and Rhone also receivedsignificant fallout from the Chernobyl accident in 1986 and recorded significant 137Cs concentrations intheir sediments over the 1970–1985 period due to the regulatory releases from the nuclear industries.The Meuse River was notably impacted in the early 1970s by industrial releases. In contrast, theSeine River display the lowest 137Cs concentrations regardless of the period. All the rivers respondedsimilarly over time to atmospheric fallout on their catchment, underlying a rather homogeneousresilience capacity of these river systems to this source of contamination
Dosimétrie des systèmes IRM-LINAC utilisés en radiothérapie externe : caractérisation des faisceaux et évaluation des distributions de dose
No full textMR-LINAC are radiotherapy devices that combine a linear accelerator (LINAC) and a magnetic resonance imager (MRI), allowing an improved tumor tracking. Dosimetric issues associated with the presence of the static magnetic field have been discussed in the literature. The aim of this thesis is to develop dosimetric tools and robust protocols for use on MRI-LINACs to enhance the knowledge of the doses delivered to patients treated with these devices. The first part of the work focuses on determining output factors (OF) in small fields on this device and studying detectors' responses. No significant variation in response was observed for EBT3 films exposed to different durations in the presence of the magnetic field (0.35 T). This high-resolution 2D detector was then used to perform several series of OF measurements on an MRidian MR-LINAC, which were then compared with measurements using active detectors (ionization chambers, diodes, microdiamond) as well as with data from the treatment planning system (TPS). A good agreement was observed between the measured OF and those calculated by the TPS for field sizes larger than or equal to 2.5x2.5 cm²; an underestimation of the TPS OF was observed for smaller field sizes (0.83x0.83 cm²: 6% for films and f 4% on average for solid active detectors). After applying TRS483 correction factors, measurements with active detectors converge with those obtained with films. These discrepancies with the TPS suggest the need for a more robust adjustment of the TPS algorithm for small fields. Measurements were complemented by Monte Carlo simulations using the Geant4 code to establish correction factors in the presence of a magnetic field for active detectors. The second part focuses on the feasibility of MRI reading of TruView dosimetric gels (ModusQA) manufactured in the laboratory to evaluate dose distributions. These gels, characterized by MRI reading (measuring T2 relaxation time), exhibited a dose-response linearity up to 7 Gy, along with relatively low sensitivity compared to the literature. Significant thermal sensitivity and gel inhomogeneity between the gel surface and deeper layers were observed in non-irradiated gels, and protocols were implemented to address these issues. The feasibility of using dosimetric gels for patient quality control in MR-Linac has been demonstrated, but an enhancement of gel sensitivity is required to achieve reliable dosimetry with this protocol.L'IRM-LINAC est un appareil de radiothérapie guidée par l'imagerie combinant un accélérateur linéaire (LINAC) et un imageur par résonance magnétique (IRM), permettant un meilleur suivi de la tumeur. Des problématiques dosimétriques, associées à la présence du champ magnétique statique, ont été soulevées dans la littérature. L'objectif de la thèse est de développer des outils dosimétriques et des protocoles robustes utilisables sur les IRM-LINAC afin d'améliorer la connaissance des doses délivrées aux patients traités avec ces appareils. La première partie du travail se concentre sur la détermination des facteurs d'ouverture du collimateur (FOC) en petits champs sur cet appareil et sur l'étude de la réponse des détecteurs. Comme aucune variation significative de réponse n'a été observée pour des films EBT3 exposés à différentes durées en présence du champ magnétique (0,35 T), ce détecteur 2D à haute résolution a été utilisé pour réaliser plusieurs séries de mesures de FOC sur un IRM-LINAC MRidian qui ont ensuite été comparées aux mesures par détecteurs actifs (chambres d'ionisation, diodes, microdiamant) ainsi qu'aux données du TPS. Un bon accord est observé entre les FOC mesurés et ceux calculés par le TPS pour les tailles de champ supérieures ou égales à 2,5x2,5 cm², une sous-estimation du FOC TPS est observée pour les tailles de champ inférieures (champ 0,83x0,83 cm² : 6% pour les films, et 4% en moyenne pour les détecteurs actifs solides). Après application des facteurs correctifs du TRS483, les mesures par détecteurs actifs convergent vers celles obtenues avec les films. Ces écarts avec le TPS tendent à suggérer la nécessité d'un ajustement plus robuste de l'algorithme du TPS pour les petits champs. Les mesures sont complétées par des simulations Monte-Carlo réalisées avec le code Geant4 pour établir des facteurs correctifs en présence d'un champ magnétique pour les détecteurs actifs. La seconde partie porte sur la faisabilité de lecture par IRM de gels dosimétriques TruView (ModusQA), fabriqués au laboratoire, pour évaluer des distributions de dose. Ces gels caractérisés par lecture IRM (mesure du temps de relaxation T2), ont montré une linéarité de la réponse en dose jusqu'à 7 Gy ainsi qu'une sensibilité faible comparativement à la littérature. Une sensibilité thermique importante et une inhomogénéité du gel entre la surface du gel et le gel situé plus en profondeur ont été observées pour des gels non-irradiés, et des protocoles ont été mis en place pour s'en affranchir. La faisabilité d'utilisation de gels dosimétriques pour la réalisation de contrôle qualité patient sur l'IRM-Linac a été démontrée, une amélioration de la sensibilité du gel est nécessaire afin d'obtenir une dosimétrie fiable avec ce protocole
Long-term behaviour of Cs-137, Cs-133 and K in beech trees of French forests
No full textInternational audienceIn the long-term after atmospheric deposit onto a forest ecosystem, Cs-137 becomes incorporated into the biogeochemical cycle of stable elements and progressively reaches a quasi-equilibrium state. This study aimed at determining to what extent Cs-137 activity distribution in tree vegetation could be predicted from that of stablecaesium (Cs-133) and potassium (K), which are known to be stable chemical analogues and competitors for Cs-137 intake in tree organs. Field campaigns that focused on beech trees (Fagus sylvatica L.) were conducted in 2021 in three French forest stands with contrasted characteristics regarding either the contribution of global vs. Chornobyl fallouts, soil or climatic conditions. Decades after Cs-137 fallouts, it was found that more than 80% of the total radioactive inventory in the system remained confined in the top 20 cm mineral layers, while organic layers and beech vegetation (including roots) contributed each to less than 1.5%. The enhanced downward migration of Cs-137 in cambisol than podzol forest sites was presumably due to migration of clay particles andbioturbation. The distribution of Cs-137 and Cs-133 inventories in beech trees was very similar among sites but differed from that of K due a higher accumulation of Cs isotopes in roots (40–50% vs. <25% for K). The aggregated transfer factor (Tag) of Cs-137 calculated for aerial beech organs were all lower than those reported in literature more than 20 years ago, this suggesting a decrease of bioavailability in soil due to ageing processes. Regarding their variability, Tags were generally lower by a factor 5 at the cambisol site, which was fairly well explained by a much higher value of RIP (radiocesium immobilisation potential). Cs-137 concentrations in trees organs normalized by the soil exchangeable fractions were linearly correlated to those of Cs-133 and the best fit was found for the linear regression model without intercept indicating that no more contribution of the foliar uptake could be observed on long term. Provided that the vertical distribution of caesium concentrations and fineroot density are properly measured or estimated, Cs-133 was shown to be a much better proxy than K to estimate the root transfer of Cs-137
The ICRP, MELODI, and ALLIANCE workshop on effects of ionizing radiation exposure in offspring and next generations: a summary of discussions
No full textInternational audiencePurpose: Task Group 121 – Effects of ionizing radiation exposure in offspring and next generations– is a task group under the Committee 1 of the International Commission on RadiologicalProtection (ICRP), approved by the Main Commission on 18th November 2021. The main goals ofTask Group 121 are to (1) review and update the scientific literature of relevance to radiationrelatedeffects in the offspring of parent(s) exposed to ionizing radiation in both human and nonhumanbiota; (2) to assess preconceptional and intrauterine effects of radiation exposure andrelated morbidity and mortality; and, (3) to provide advice about the level of evidence and howto consider these preconceptional and postconceptional effects in the system of radiological protectionfor humans and non-human biota.Methods: The Task Group is reviewing relevant literature since Publication 90 ‘Biological effectsafter prenatal irradiation (embryo and fetus)’ (2003) and will include radiation-related effects onfuture generations in humans, animals, and plants. This review will be conducted to account forthe health effects on offspring and subsequent generations in the current system of radiologicalprotection. Radiation detriment calculation will also be reviewed. Finally, preliminary recommendationswill be made to update the integration of health effects in offspring and next generations inthe system of radiological protection.Results: A Workshop, jointly organized by ICRP Task Group 121 and European RadiationProtection Research Platforms MELODI and ALLIANCE was held in Budapest, Hungary, from 31stMay to 2nd June 2022. Participants discussed four important topics: (1) hereditary and epigeneticeffects due to exposure of the germ cell line (preconceptional exposure), (2) effects arising fromexposure of the embryo and fetus (intrauterine exposure), (3) transgenerational effects on biota,and (4) its potential impact on the system of radiological protection.Conclusions: Based on the discussions and presentations during the breakout sessions, newerpublications, and gaps on the current scientific literature were identified. For instance, there aresome ongoing systematic reviews and radiation epidemiology reviews of intrauterine effects.There are newer methods of Monte Carlo simulation for fetal dosimetry, and advances in radiationgenetics, epigenetics, and radiobiology studies. While the current impact of hereditary effects onthe global detriment was reported as small, the questions surrounding the effects of radiationexposure on offspring and the next generation are crucial, recurring, and with a major focus onexposed populations. This article summarizes the workshop discussions, presentations, and conclusionsof each topic and introduces the special issue of the International Journal of RadiationBiology resulting from the discussions of the meeting
Progress in the Modeling of High Burn up Structure: Application of the TRANSURANUS//MFPR-F Coupling to the NRC-192 Studsvik LOCA TEST
No full textInternational audienceThe MFPR-F (Module for Fission Product Release – France) code coupled with the TRANSURANUS fuel performance code was applied to the Studsvik NRC-192 Loss of Coolant Accident experiment on a high burnup UO2 fuel rod. The presented study, conducted in the framework of the R2CA project, focuses on the formation of the High-Burnup Structure during irradiation and on the fission gas release during the LOCA transient. MFPR-F code supplements TRANSURANUS code with a more in-depth description of the local microstructure in the UO2 matrix, allowing to predict the onset of fuel restructuring [1]. This modelling is used in the present study to calculate the width of the HBS zone in the fuel rod at the end of irradiation, which is found to be 400 µm. Regarding the LOCA transient, the MFPR-F model for fission gas release from the HBS pores, based on an empirical parameter related to the pore over-pressurization, predicts that a large part the gas is released for over-pressure ranging from 150 to 300 MPa
A novel methodology to estimate the importance of isotopic exchange in the CH3I adsorption by impregnated activated carbons
No full textInternational audienceActivated Carbons (AC) are widely used in the ventilation lines of nuclear facilities for the removal of volatileiodine species. In this paper, new experimental methodologies have been developed in order to measure theBreakThrough Curves (BTC) of both radioactive and stable CH3I for KI- or TEDA- impregnated AC {T = 20 –30 ◦C, dry conditions}. Non-impregnated and KI-impregnated AC were shown to display similar performances forthe trapping of stable CH3127I. In that case, only physical interactions within the micropores were involved in theadsorption process. A significant improvement of the retention occurred after TEDA impregnation. Regarding thetrapping of the γ-labelled CH3I, a significant enhancement of AC performances during both retention andbreakthrough phases is observed after KI impregnation due to the promotion of isotopic exchange phenomenon.Therefore, the contribution of KI, still rarely studied in the literature, was isolated for the first time from the othermechanisms (physisorption and chemisorption). The in-depth analysis of BTC data obtained under active andinactive conditions allowed quantifying the contribution due to isotopic exchange
Unveiling the origins and transport processes of radioactive pollutants downstream from a former U-mine site using isotopic tracers and U-238 series disequilibrium
No full textInternational audienceHigh U concentrations (reaching up to 14,850 mg ⋅ kg−1), were determined in soils and sediments of a wetland downstream of a former U mine in France. This study aims to identify the origin of radioactive contaminants in the wetland by employing Pb isotope fingerprinting, (234U/238U) disequilibrium, SEM, and SIMS observations. Additionally, information about U and 226Ra transport processes was studied using U-238 series disequilibrium. The results of Pb fingerprinting highlighted inherited material inputs of different U-mines with mainly two types of U-ores: i) pitchblende (UO2), and ii) parsonsite (Pb2(UO2)(PO4)2). Moreover, significant disequilibrium of (230Th/238U) and (226Ra/230Th) activity ratios highlighted the mobility of 238U and 226Ra in the wetland, primarily driven by the water table fluctuations. Finally, this work uncovered a limitation of Pb isotope fingerprinting in the case of parsonsite materials, as the high natural Pb content of this mineral may hide the uranogenic Pb signature in the samples