Institute for Radiation Protection and Nuclear Safety (IRSN)
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Active faulting in the Alps as seen by GNSS : comparative case-studies from the Belledonne and High-Durance fault systems
No full textInternational audienceIn the W-Alpine context, where active deformation is slow and seismicity is moderate, the question of determining and characterizing active faulting remains a scientific challenge. However, previous studies have shown that reliable geodetic strain rates can be assigned to the High-Durance fault (HDF) system, in accordance with the regional seismicity. In this paper, we propose a comparative analysis of two major faults recognized in the W-Alps: the HDF in the Briançon vicinity and the Belledonne fault (BDF) close to Grenoble. The aim is to investigate the constrains that can be brought by GNSS, in slow deformation ranges of 0.1-1 mm/yr, to decipher active faulting, both in terms of localization at the regional scale and quantitative strain rates. We also aim to compare the seismotectonic framework with the geodetic results. Last but not least, these two major faults bear witness of the main kinematics found within the realm of the W-Alps, that is to say extensional mechanism in the internal zone (along the HDF) and strike-slip in the external zone (along the BDF). They can thus be considered as two major fault systems representative of the overall W-Alpine current deformation. From a quantitative viewpoint, the BDF extends over about 50 km along the western side of the Belledonne External Crystalline Massif. Using up to 20 years of data from 22 permanent GNSS stations, approaches exploiting the redundancy between the individual station velocity estimates provide dextral strike-slip kinematics with a rate of 0.2 ± 0.2 mm/yr. This rate is coherent with a unique strain tensor calculated over the 50 km wide local network, evaluating a NNE-SSW extensional axe of 2.0 ± 0.8 nanostrain/yr, with a WNW-ESE shortening axe of 4.7 ± 1.2 nanostrain/yr. Strain calculations by alternative methods on regular grids evaluate a lower total amplitude of strain rate close to the BDF trace, in particular less compression. Comparatively, the HDF is investigated thanks to a dense network of 30 GPS stations covering the Briançon area, which was surveyed during 5 temporary campaigns in 1996, 2006, 2011, 2016, and 2021. The redundancy of the dense network and the long observation interval after the addition of the fifth campaign in 2021 allow to increase the accuracy of the velocity fields. The average horizontal strain rate over the entire network located in the center of the Briançon Seismic Arc has been evaluated at 20 ± 2 nanostrain/yr of E-W extension across the 50 km network, yielding about 0.5 mm/yr of extension across the NS trending HDF. From a seismotectonic viewpoint, the comparison with seismicity highlight the coherency between seismotectonic and geodetic deformation fields, both for the HDF and BDF systems, in terms of style, direction, and amplitude of deformation
Passive exposure to disinfectants and cleaning products in daycare settings and child wheeze in the French CRESPI cohort
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Aerosol characterization during laser cutting of stainless-steels for underwater, air and nitrogen conditions in the framework of LD-SAFE project
No full textInternational audienceThe knowledge of the size distribution and the morphology of particles releasedduring cutting operations undertaken for nuclear power plant dismantling activitiesis important for safety and radioprotection issues.This paper presents the results of aerosols characterization during laser cuttingtests performed in the DELIA facility (CEA Saclay), undertaken in the framework ofthe LD-SAFE H2020 project. Laser cutting trials were achieved for underwater, air andnitrogen conditions. Two references of stainless steels were used during the trials, 304 L and316, composed of plates of 40 mm of thickness.The full presentation will present the materials and methods for aerosols samplingand characterization, the test protocols, and a comparison of the particlegeneration for various test conditions of laser cutting considering the aerosol size,morphology, mass and number generation and composition
OSL signal of electronic components from portable radios for radiation accident dosimetry
No full textInternational audienceThe portable radio (hand-held device) is the preferred means of communication for the first responders from the homeland security forces and is systematically carried during intervention. This electronic device could therefore be a good candidate as a possible fortuitous dosimeter to estimate the dose received by the members of these security forces in the event of a radiological accident. For this purpose, the dosimetric properties of electronic components extracted from the circuit board of portable radios used by a French specialised intervention unit were investigated using the OSL technique. The dosimetric properties of such electronic components were compared to those of resistors extracted from mobile phones to determine whether an OSL protocol developed for mobile phone resistors could be applied also to these electronic components. The OSL dosimetric properties were generally similar and the results of a dose recovery test using these components removed from a portable radio were in good agreement with the nominal dose. Further experiments showed the importance of knowing the storage temperature conditions of these devices to accurately estimate the dose in case of a radiological accident
Respective contributions of ³H discharges from 7 nuclear facilities and resulting frequency of coastal marking on the English Channel coastlines: modelling inputs from MARS2D
No full textInternational audienceThe English Channel is a highly nuclearized sea, all the more so with the impending commissioning of the Flamanville EPR and construction of two EPR2s at the Penly nuclear power plant (Seine-Maritime, France). Current radionuclide releases into the Channel mainly include those of the ORANO La Hague spent fuel reprocessing plant (Manche, France), as well as those from the four nuclear power plants (NPPs) along the French coastline (Flamanville, Paluel, Penly, and Gravelines) and from the Seine River (Nogent-sur-Seine NPP). Samples are regularly taken along the French coastlines to monitor the impact of those installations; and the marking of those samples often is the result of the cumulated impact of those various sources and of the local radiological background. As such, field sampling rarely allows for the discrimination of those various sources. Modelling studies on the other hand offer the potential to deconvolute those sources. We present results on the dispersion of 3H discharges modelized using MARS2D, a hydrodynamic model which calculates the movements of water masses and the resulting dispersion of dissolved elements. We focused our study on the Seine-Maritime coastline, and took into account the 3H discharges from La Hague reprocessing plant and from Paluel and Penly NPPs. We calculated the frequency of coastal marking and the respective contribution of the three facilities to that marking.Dispersion processes were similar around the two power plants, and calculated 3H levels were always above classical liquid scintillation detection limits on French coasts: on average, between 5 and 20x103 Bq.m-3 ; activities were maximal around La Hague (103 to 5x104 Bq.m-3). Around Paluel and Penly NPPs, activities were lower, comprised between 1x103 and 3x103 Bq.m-3. La Hague plumes were the only ones to impact British shorelines east of the Isle of Wight (contribution of 100%, frequency of 65%), as well as French coasts west of the Cotentin peninsula (contribution of 100%, frequency of 100%). From the Cap de Barfleur to the Strait of Dover, the plumes from the nuclear power plants were the main sources of radionuclides (resp. contributions of each NPP to the marking of it’s nearby shoreline: 85% and 70%, frequency of 75-100%). Paluel was the main contributor (contribution of 60%) to the Seine Bay coastal marking. This study highlights a potential coastal return current in this area. This feature has not been previously documented in the literature to the best of our knowledge, and will need confirmed by future studies of the currents in this area. It also highlights a need for a complementary validation of the Mars2D model in that near-field coastal area
Climate change impacts on the river-sea interface of a large French catchment delta undergoing multiple anthropogenic pressures
No full textInternational audienceThe rise of sea level rise is a major effect of climate change. It may induce modifications in deltas and estuaries dynamics, with a probable increase in salt water inflows, leading to water use problems in coastal areas. We tried to simulate future salt water inflows in the delta of a large French catchment (the Rhône River, France). We used an estuarine transfer function, DRACAR (Désorption des RAdionuCléides à l’interfAce littoRale). Upstream water inputs for this function under RCPs 4.5 and 8.5 come from the Soil and Water Assessment Tool (SWAT). SWAT was able to represent water inputs to the delta at monthly time scale. We found that future discharges of the Rhône river might be reduced by 80% in August under RCP 8.5. These riverine fluxes lead to an extent of the salt wedge from 17 km from river mouth nowadays to more than 30 km. These results may impact current agricultural activities in the delta that depends on pumps withdrawing water from the Rhône River
Evidence of subsurface liquefied zone geometries along the Kupa River following the 2020 Petrinja earthquake (Croatia)
No full textInternational audienceDuring the Petrinja earthquake sequence in December 2020, numerous liquefied sand ejections came to the surface along the Kupa, Sava and Glina rivers in Quaternary alluvial sediments. In October 2022, we performed field investigation in the epicentral area, involving geotechnical and geophysical techniques, at different sites with sand ejecta or lateral spreading along the Kupa river to specify the geometries of the various subsurface sedimentary layers and in particular the liquefied zones in depth. For all sites, the sandy ejecta most likely originates from sandy point bars buried under silty layers and located preferentially in the convex parts of meanders. This paper presents and discusses models to highlight the different geometries obtained by geophysics or built from geotechnical soundings for one site located on the eastern edge of an abandoned former meander of the Kupa River
Comparaison des effets radio-induits par les rayonnements beta reçus à l’ADN et à l’organisme entier chez le poisson zèbre, Danio rerio
No full textTritium is a radioactive isotope of hydogen and is present in all environmentalcompartments. It can exist under the form of tritiated thymidine, and this form wasselected in this work in order to better characterize its toxic effects. Its internalizationand toxicity have been studied on the zebrafish, Danio rerio. This biological model hasbeen chosen as it allows the comparison between the results obtained in this work andin previous ones, but also because of its various experimental advantages, as its rapiddevelopment and the transparency of its embryos. Exposure of zebrafish embryosand larvae to an absorbed dose rate as low as 22 µGy/h led to its internalization inboth the organism and the DNA. The development was temporarily slowed down afterexposure to 22 and 170 µGy/h, while the hatching was delayed after exposure to 170and 470 µGy/h. Exposure of the embryos and larvae to 470 µGy/h for 24 and 72 hoursled to, respectively, an increase in the embryonic activity and to a decrease in thelarval cardiac rhythm. The ROS (reactive oxygen species) production increased afterexposure to 170 µGy/h for 96 hours, and DNA damage were induced after exposures toall selected absorbed dose rates for 24 and 96 hours. A surexpression of various geneswas also observed after exposure to 22 µGy/h for 24 hours. Micro- and nanodosimetrysimulations confirmed the effect of the cell volume on the energy depositing processes, while also highlighting the formation of a majority of SSB (single strand breaks)and of indirect damage. These experiments showed that various differences existbetween the toxicity of aqueous tritium, organically bound tritium and cesium (137Cs),while leading to a better understanding of the toxicity mechanisms arising from theexposure to tritiated thymidine.Le tritium est un isotope radioactif de l’hydrogène qui est présent dans tous lescompartiments environnementaux. Ce dernier existe, entre autres, sous forme dethymidine tritiée, forme sélectionnée dans le cadre de ce travail de doctorat afin decaractériser la toxicité du tritium. L’internalisation et la toxicité de la thymidine tritiéeont été étudiées sur le poisson zèbre, Danio rerio. Ce modèle biologique a été choisiafin de permettre une comparaison des résultats obtenus avec ceux obtenus par lepassé, mais également pour ses nombreux avantages expérimentaux, tels que sonrapide développement et la transparence de ses œufs. L’exposition des embryons etlarves de poisson zèbre entraîne une internalisation du tritium dans l’organisme etl’ADN dès 22 µGy/h. Un ralentissement du développement est également observéà 22 et 170 µGy/h, ainsi qu’un retard d’éclosion à 170 et 470 µGy/h. L’expositiondes embryons à 470 µGy/h pendant 24 et 72 heures entraîne, respectivement, uneaugmentation de l’activité des embryons dans leur chorion et une diminution durythme cardiaque des larves. La production des ROS (espèces réactives de l’oxygène)augmente après 96 heures d’exposition à 170 µGy/h, et l’induction de dommages àl’ADN est significative dès 24 heures d’exposition à 22 µGy/h. Une surexpression denombreux gènes est également observée après 24 heures d’exposition à 22 µGy/h.Les simulations de micro- et nanodosimétrie, quant à elles, confirment l’effet duvolume des cellules sur la déposition d’énergie, ainsi que la formation majoritaire deSSB (cassures simple brin) et de dommages indirects. Ces expériences permettent demettre en évidence des différences de toxicité entre le tritium organique, le tritiumlibre et le césium (137Cs), mais également d’avoir une meilleure compréhension desmécanismes de toxicité de la thymidine tritiée
