Institute for Radiation Protection and Nuclear Safety (IRSN)
Not a member yet
7928 research outputs found
Sort by
Rapport sur le 23e Dialogue de Fukushima « Réfléchir ensemble aux enjeux de l’eau traitée de Fukushima Daiichi »
No full textInternational audienceOn 27 November 2021, the non-profit organization (NPO) Fukushima Dialogue held the 23rd Fukushima Dialogue meeting in Naraha Machi, Fukushima Prefecture. The theme was “Sharing the situation surrounding Fukushima Daiichi treated water”. It was the 23rd meeting since the International Commission on Radiological Protection (ICRP) launched the ICRP Dialogue in Fukushima Prefecture in 2011, which the NPO Fukushima Dialogue took over in 2019. Held in a hybrid form, it was open to the public and has gathered up to 120 participants. The first part was devoted to presentations related to the theme of the meeting: technical aspects, testimonies about local (institutional or not) and foreign (Korea) perception, experiences from abroad of stakeholder involvement in the nuclear field. The second part was devoted to a structured dialogue between a panel of local citizens. The audience was participatory. This article summarizes the fruitful exchanges during these two days
Livret des thèses 2023: du 28 au 31 mars - Journée des thèses 2023 : la Grande-Motte
No full textDocument sous Copyright IRSNNational audienceL'IRSN organise chaque année des « Journées des thèses », au cours desquelles tous ses doctorants, qu’ils soient en première, deuxième ou troisième année de thèse, font une présentation orale (15 à 20 minutes) de l'état d'avancement de leurs travaux,. L’auditoire est composé de leurs homologues et d'un certain nombre d'invités : tuteurs de thèse et responsables hiérarchiques d’une part, directeurs de thèses, universitaires et membres du conseil scientifique d'autre part. En préparation à ces journées, il est demandé à chaque doctorant de rédiger un article correspondant au contenu de sa présentation.L'objectif de ces journées, qui s'inscrit dans la politique de formation par la recherche de l'IRSN, est double : donner aux doctorants l'occasion de présenter leurs travaux au moins trois fois durant la durée de leur thèse, devant un public plus large que celui constitué par leurs encadrants, et favoriser les contacts des doctorants entre eux et avec les autres participants IRSN et hors IRSN.Ces journées des thèses sont également une occasion de resserrer de manière tangible les liens tissés avec les universités, notamment en proposant à certains de leurs représentants d’assurer la présidence d’une session.Ouvertes par le directeur général, conclues par le président du Conseil d'administration, ces journées constituent un moment important de la vie scientifique de l'Institut
Time-variable strain and stress rates induced by Holocene glacial isostatic adjustment in continental interiors
No full textInternational audienceIn continental interiors, tectonically-driven deformation rates are low, often to the point where they are undetectable with modern geodesy. However, a range of non-tectonic surface processes, particularly relating to hydrological, cryospheric, and sedimentological mass changes, can produce strain-rates which on geologically-short timescales are substantially greater than those produced by tectonics. Here, we illustrate the problem that such transient strain rates may pose in low-strain environments by considering the impact that the growth and decay of the Fennoscandian and Laurentian ice sheets over the Holocene had on Europe and North America respectively. Induced deformation extended far beyond the periphery of the ice sheets, with the potential to impact on seismicity rates thousands of kilometres south of the maximum ice extent. We consider how the modelled non-tectonic deformation would have interacted with several known active fault systems, including the European Cenozoic Rift System and the New Madrid fault system. In low strain continental interiors, seismic hazard assessment – crucial for the long-term planning of critical infrastructure, including nuclear waste disposal – is often dependent on sparse information from observational and historical seismicity, and from paleoseismological studies of surface fault systems. We recommend that for a more complete seismic hazard assessment, the impact of non-tectonic transients should be considered – both in the context of the role such transients may have played in recent seismicity, and the role they may play in seismicity to come. Whilst such consideration has previously been given to the direct impact on glacial loading in areas directly glaciated, we show that it should also be considered much more broadly
Test Bench Development and Application to a Parametric Experimental Study on the Dynamic Adsorption Capacity of Noble Gases (Kr, Xe) in the Metal–Organic Framework HKUST-1
No full textInternational audienceThe objective of this work is to develop a dedicated test bench to study the dynamic noble gases trapping by porous materials, and especially by MOF, in a nuclear context. The well-known coppercontaining HKUST-1 material is used to determine the influence of different parameters such as 2 temperature, concentration, humidity, MOF bed height or diameter, and velocity of the flowrate on noble gases adsorption (Kr, Xe) in breakthrough sorption experiments. Breakthrough time is shown to be directly related to MOF bed height, shaping and gas flow velocity. The adsorption capacities depend on the concentration of noble gases in the gas flow, but also on the flow velocity. Indeed, when the velocity increases from 0.15 to 1 cm.s-1 , the adsorption capacity of Xe increases from 3.46 to 5.15 µmol.g-1 at 25 °C and 1 bar, while the breakthrough time decreases from 7.3 to 2.4 min. On the other hand, temperature and the presence of water vapor have a negative effect on noble gas adsorption in HKUST-1
Rétention du tritium dans les parois en béryllium d'ITER : modélisation ab initio de son insertion dans l'oxyde et aux joints de grains
No full textThe purpose of ITER facility is to demonstrate the feasibility of energy production by thermonuclear fusion from a tritium-deuterium plasma, two hydrogen's isotopes. The fusion reaction is produced in a vacuum chamber around which superconducting magnets allow to confine the plasma. Tritium being radioactive, from safety analysis point of view, it is necessary to study its interactions with the vacuum chamber's materials. In this case, the first wall of the vacuum chamber is made of beryllium, a material chosen for its low tritium absorption and its high affinity towards oxygen, allowing the vacuum chamber to be purified. The study tritium interactions with beryllium will enable to evaluate the effectiveness of the methods put in place by the operator to quantify the tritium inventory in the chamber, the methods of baking the first wall for desorption of the tritium, and to minimize environmental release in the event of vacuum chamber containment loss. Previous work has analysed the interaction of tritium with beryllium and its intrinsic defects, therefore this work aims to extend the study to more complex defects. Beryllium, when combined with oxygen, will form beryllium oxide. In normal operation, a beryllium oxide layer will form on the beryllium wall. The understanding of tritium interaction with the first wall thus also requires an understanding of the behaviour of tritium with beryllium oxide. The first part of this thesis is therefore devoted to the evaluation of tritium solubility and diffusivity in beryllium oxide. The first wall will be formed of polycrystalline beryllium, a second part is therefore devoted to the study of grain boundaries, the interface between two crystals. As the number of possible configurations of grain boundaries is very large, it is first necessary to model the different beryllium grain boundaries to determine which are energetically most favourable. This study is necessary in order to be able to study the segregation of tritium, in this case to determine whether these grain boundaries can have an "escape way" effect, thus increasing diffusion, or a "reservoir" effect, forming pockets that trap the tritium.L’installation ITER a pour finalité de démontrer la maîtrise de la production d’énergie par fusion thermonucléaire à partir d’un plasma de tritium-deutérium, deux isotopes de l’hydrogène. La réaction de fusion est produite dans une chambre à vide autour de laquelle des aimants supraconducteurs permettent de confiner le plasma. Le tritium étant radioactif, du point de vue de l’analyse de sûreté, il est nécessaire d’étudier ses interactions avec les différents matériaux constitutifs de la chambre à vide. En l’occurrence, la première paroi de la chambre à vide est en béryllium, matériaux choisis pour sa faible absorption du tritium et sa grande affinité vis-à-vis de l’oxygène permettant de purifier la chambre vide. L’étude de l’interaction du tritium avec le béryllium va permettre d’évaluer l’efficacité des méthodes mises en place par l’exploitant afin de quantifier l’inventaire en tritium dans la chambre, les méthodes d’étuvage de la première paroi pour la désorption du tritium et minimiser les rejets dans l’environnement en cas de perte de confinement de la chambre à vide. De précédant travaux ont permis d’analyser l’interaction du tritium avec le béryllium et ses défauts intrinsèques, ce travail a donc pour but d’étendre l’étude aux défauts plus complexes. Le béryllium en s’associant à l’oxygène va former de l’oxyde de béryllium. En fonctionnement normal, il va donc se former une couche d’oxyde de béryllium au niveau de la paroi en béryllium. La compréhension de l’interaction du tritium avec la première paroi passe donc également par la compréhension du comportement du tritium avec l’oxyde de béryllium. Une première partie de ce travail de thèse est donc consacrée à l’évaluation de la solubilité et de la diffusivité du tritium dans l’oxyde de béryllium. La première paroi étant formée de béryllium polycristallin, la seconde partie est donc consacrée à l’étude des joints de grain, interface entre deux cristaux. Le nombre de configurations possibles pour les joints de grain étant très important, il est nécessaire dans un premier temps de modéliser les différents joints de grains du béryllium pour déterminer ceux qui sont énergétiquement les plus favorables. Pour ensuite pouvoir y étudier la ségrégation du tritium, en l’occurrence déterminer si ces joints de grain peuvent avoir un effet de type "chemin de fuite" augmentant ainsi la diffusion, ou de type "réservoir" formant des poches qui piègent le tritium
Irsn progress on emergency preparedness and response in case of criticality accident
No full textDOI à venir sur https://www.jaea.go.jp/english/publication/International audienceIn France, during nuclear emergency situations, the Institute for Radioprotection and Nuclear Safety (IRSN) provides technical, public health and medical guidance to French public authorities on measures to be taken to protect the population, workers and the environment, while contributing to the restoration of the safety of the facilities. IRSN has an emergency response center where emergency responders are mobilized to assess the emergency situation in several technical units, one of which is dedicated to the assessment of the facility. The main tasks of this "facility assessment" unit are to assess the current state of the damaged "object", predict the development of the emergency situation, evaluate the radioactive materials releases into the environment, and verify the suitability of the operator's measures to minimize the releases and retrieve a stabilized and safe state of the facility. Within this unit, there is a "criticality specialist", whose function is to assess an ongoing or ended criticality accident but also to evaluate the criticality risk in any case of an emergency situation. After a brief overview of IRSN's emergency organization, this article details how the "criticality specialist" function fits into this organization and in which cases it is activated. The article also presents the tools and resources used to fulfil this function, how the "criticality specialists" are recruited and trained, and how they practice to ensure that they are operational during emergency situations. A first experience feedback acquired by this function during its participation in drills and real emergencies is also shared, as well as the resulting perspectives
Statistical and hydrodynamic numerical modeling to quantify storm surge hazard: Comparison of approaches applied to U.S. North Atlantic coast
No full textInternational audienceEstimating the storm surge magnitude and annual exceedance probability is a key element in the siting and design of coastal nuclear power plants in both the U.S. and France. However, differences in storm climatology, specifically the relative importance of tropical cyclones (TCs) versus extratropical storms (XTCs), have driven differences in estimation method development. This work compares purely statistical modeling with combined statistical and numerical simulation modeling approaches for extreme storm surge applied to the U.S. North Atlantic coast which is subject to both tropical and extratropical storms. Two frequency analysis methods are applied to observed water levels and compared to a copula-based joint probability analysis of TCs and automated frequency analysis of XTCs that is enriched with numerically simulated storms. One frequency analysis method is applied using (1) hourly at-site data and (2) hourly at-site data enriched with additional data from a homogeneous region. The other frequency analysis method is applied using (1) hourly at-site data and (2) hourly at-site data enriched with monthly water level maxima. Variables of interest used in the comparison are skew storm surge, maximum instantaneous storm surge, non-tidal residual and maximum seal level. The performance of the methods (mean surge and water level estimates and confidence intervals) depend on the variable of interest and, to some extent, on return period. Inclusion of additional information (e.g., regional water levels, and monthly maxima) in the frequency analysis methods does not have a large impact on estimated mean surge and water levels, but significantly reduces resulting confidence intervals (over 40% reduction in some cases). However, the confidence intervals still grow with increasing return period. Inclusion of simulated storms in the joint probability analysis results in significantly different mean surge and water level estimates (up to 25% higher than the frequency analysis in some cases). The joint probability analysis confidence intervals are wider than those for the frequency analysis methods lower return periods (e.g., 60%-80% wider at 100 years), but they grow much more slowly and are significantly narrower for higher return periods (e.g., 40%-60% narrower at 1 000 years). Although there are appreciable differences between the results documented in this paper, these are reasonable due to differences in the data and methods used in this comparison
Expérimentations et modélisation opérationnelle des dépôts secs et humides du chlore 36 sous forme gazeuse et particulaire sur une prairie
No full textChlorine 36 (36Cl, T1/2 = 301,000 years) is a radionuclide of both natural and artificial origin that can be released in gaseous or particulate form during the decommissioning of nuclear facilities or the recycling of nuclear waste. Once released into the atmosphere, 36Cl can be transferred to terrestrial ecosystems through dry and wet deposition. However, due to analytical constraints, knowledge about these deposits remains limited. Given its relatively high mobility in the geosphere and high bioavailability, understanding the behavior of 36Cl in the environment is crucial for human impact studies and the assessment of the safety of radioactive waste storage. Therefore, the objectives of this thesis are to quantify dry and wet deposits on 36Cl on grass, followed by modeling these deposits based on parameters related to ground cover and atmospheric turbulence. To achieve this, a sampling system (gas, particles, rainwater, and grass) and micro-meteorological measurement equipment were installed at the IRSN La Hague Technical Platform (PTILH), located 2 km from the Orano La Hague facility, which chronically emits small quantities of 36Cl. To determine the concentrations in the various samples, an original radiochemistry method was developed and validated. Following the collection of samples, chlorine extraction via alkaline fusion and specific chemical preparation for 36Cl measurement by Accelerator Mass Spectrometry (AMS-ASTER) at CEREGE were carried out. The alkaline fusion extraction of NIST leaf standards allowed for the determination of an average extraction yield of 83 ± 5% and method validation. 36Cl levels in the atmosphere and rainwater at the study site were on average one to two orders of magnitude above natural background levels. Gaseous 36Cl represented an average of 72.9% of atmospheric 36Cl, while 27.1% was in particulate form. Enrichment of 36Cl was observed in grass samples, indicating the transfer of 36Cl from the atmosphere to the grass during experimental campaigns at the study site. Dry deposition velocities of 36Cl on grass were determined for the first time in this study, with values ranging from 1.0 x10-3 to 1.1 x10-2 m.s-1. Measurements of 36Cl deposition flux showed that dry deposition contributed on average to 51.8% of the total 36Cl deposition at our study site, compared to 48.1% for wet deposition. The study of wet deposition flux also highlighted the existence of a "rainout" phenomenon in the environment. Parametrization of dry and wet 36Cl deposition, both gaseous and particulate, was carried out based on meteorological data and adaptation of existing models. The values calculated by the modeling were in good agreement with experimental data, with less than a threefold difference for dry deposition velocities and less than a fourfold difference for wet deposition flux. Combining the dry deposition model with the wet deposition model revealed that 36Cl deposits on PTILH are dominated by the gaseous fraction, contributing 91.9% to the total deposition (dry and wet deposition by "washout"), with 8.9% attributed to the particulate fraction. Regarding deposition mechanisms, it was calculated that dry deposition accounts for an average of 41.6% of 36Cl deposits, compared to 14.9% for wet deposition by "washout" and 44.4% for wet deposition by "rainout." The results obtained and the knowledge acquired during this study will contribute to improving the characterization of the transfer of radionuclides in the environment, including their impact on humans.Le chlore 36 (36Cl, T1/2 = 301000 ans) est un radionucléide d’origine naturelle et artificielle susceptible d’être rejeté sous forme gazeuse ou particulaire lors des opérations de démantèlement de centrales nucléaires ou lors du recyclage des déchets nucléaires. Une fois émis dans l’atmosphère, le 36Cl peut être transféré vers les écosystèmes terrestres par des dépôts secs et humides. Cependant, du fait des contraintes analytiques, les connaissances sur ces dépôts sont encore très parcellaires. Or, du fait de sa mobilité élevée dans la géosphère et de sa biodisponibilité, le 36Cl est un radionucléide dont l’étude du devenir dans l’environnement est importante pour les études d’impacts à l’humain ainsi que pour l’évaluation de la sûreté des stockages de déchets radioactifs. Ainsi, cette thèse a pour objectifs la quantification des dépôts secs et humides du 36Cl sur une prairie suivie d’une modélisation de ces dépôts en fonction de paramètres liés au couvert et à la turbulence atmosphérique. Pour cela, un dispositif de prélèvements (gaz, particules, eau de pluie et herbes) et de mesure des paramètres micrométéorologiques a été installé sur le site de la plateforme technique IRSN La Hague (PTILH) située à 2 km de l’usine Orano La Hague, rejetant de façon chronique du 36Cl en faibles quantités. Afin de déterminer les concentrations dans les différents échantillons prélevés, une méthode de radiochimie originale a été développée et validée. A la suite des prélèvements, les échantillons ont subi une extraction du Cl par fusion alcaline suivie d’une préparation chimique spécifique pour la mesure du 36Cl par spectrométrie de masse par accélérateur (AMS-ASTER) au CEREGE. L’extraction du chlore par fusion alcaline des standards NIST de feuilles a permis de déterminer un rendement d’extraction moyen de 83 ± 5% et de valider la méthode. Les teneurs en 36Cl dans l’atmosphère et l’eau de pluie sur le site d’étude étaient en moyenne 1 à 2 ordres de grandeur au-dessus du bruit de fond naturel. Le 36Cl gazeux représentait en moyenne 72,9% du 36Cl atmosphérique contre 27,1% pour le 36Cl particulaire. Un enrichissement en 36Cl a été observé dans les échantillons d’herbe traduisant un transfert du 36Cl de l’atmosphère vers l’herbe durant les campagnes expérimentales sur le site d’étude. Les vitesses de dépôt sec du 36Cl sur l’herbe ont été déterminées pour la première fois dans cette étude avec des valeurs comprises entre 1,0.10-3 et 1,1.10-2 m.s-1. La mesure des flux de dépôts du 36Cl a montré que le dépôt sec contribuait en moyenne à 51,8% du dépôt total de 36Cl sur notre site d’étude contre 48,1% pour les dépôts humides. L’étude du flux de dépôt humide a également mis en lumière l’existence d’un phénomène de "rainout" dans le milieu. La modélisation des vitesses de dépôt sec et des flux de dépôt humide du 36Cl a été réalisée à partir des données météorologiques et par adaptation des modèles existants. Les valeurs calculées par la modélisation étaient en accord avec les données expérimentales, avec moins d'un facteur 3 de différence pour les vitesses de dépôt sec du 36Cl et moins d'un facteur 4 pour les flux de dépôts humides. En unissant le modèle de dépôt sec et le modèle de dépôt humide, il ressort que les dépôts de 36Cl sur la PTILH sont dominés par la fraction gazeuse avec une contribution de 91,9% au dépôt total (dépôt sec et dépôt humide par "washout") contre 8,9% pour la fraction particulaire. Concernant les mécanismes de dépôts, il a été calculé que le dépôt sec représente en moyenne 41,6% des dépôts de 36Cl contre 14,9% pour le dépôt humide par "washout" et 44,4% pour le dépôt humide par "rainout". Les résultats obtenus et les connaissances acquises au cours de cette étude serviront à l’amélioration de la caractérisation des transferts des radionucléides dans l’environnement et vers l’humain
EURADOS intercomparison for whole-body neutron dosemeters from 2012 to 2022
No full textInternational audienceWithin the EURADOS (European Radiation Dosimetry Group) self-sustained programme of regular intercomparisons (ICs) for individual monitoring, three campaigns had been performed in 2012, 2017 and 2022 to assess the performance of neutron personal dosemeters routinely used to measure personal dose equivalent, Hp(10). The irradiation schemes were established to provide participants with useful information regarding linearity, reproducibility and response of their dosimetry systems at different energies and angles of incidence. Small alterations were made in irradiation plans for subsequent exercises. Combinations of standard calibration fields and simulated workplace fields were employed, using bare and moderated neutron sources as well as monoenergetic and thermal neutron fields. Neutron energies used to evaluate dosemeter performance ranged from thermal to several MeV. Dose values varied between 0.3 mSv and 15 mSv. The number of participating laboratories in the three campaigns was stable: 31 in IC2012n, 32 in IC2017n and 29 in IC2022n. The dosimetry systems could have been categorized according to their detection principle into albedo and track dosemeters, or a combination of both. In 2012, a category ‘other’ had to be introduced to consider active personal dosemeters and fission track detectors. In 2012, participants were asked to provided results in a two-step procedure: (i) with no information on the radiation fields, and (ii) after receiving additional simplified a priori information on the energy distribution of the neutron fields to enable correction for dosemeter response. In 2017 and 2022, based on a one-step procedure, however, participants might have requested a priori information upon registration, which was reported in the certificate of participation. Intercomparison results were analysed against the acceptance criteria of the ISO 14146:2018 standard, although there were no standardized performance requirements for neutron personal dosemeters at the time of IC2012n. The paper compares the results of the three exercises, identifies major problems for individual monitoring services and shows trends in dosimetric performance. In all three intercomparisons, a few systems had shown problems related to calibration. Data do not allow to draw a universally applicable conclusion with regard to potentially superior performance of one particular dosimetry system