Institute for Radiation Protection and Nuclear Safety (IRSN)
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Airborne particle characterization during mechanical cutting operations of prototypic fuel debris simulants
No full textInternational audienceThe general context of this article concerns the assessment of radioactive aerosols release risk during fuel debris (FD) retrieval operations at Fukushima Daiichi Nuclear Power Plant (1F). This assessment is crucial for ensuring the safety of workers and the wider public throughout the decommissioning efforts at the 1F facility.The Dust Acquisition (DA) project, led by CRIEPI and carried out as a subsidized project of Decommissioning, Contaminated Water and Treated Water Management, funded by METI, in collaboration with ONET, CEA, and IRSN, aims to evaluate the airborne release fraction (ARF) coefficient, a key metric reflecting the amount of radioactive material suspended in the air, particularly during the mechanical cutting of prototypic FD-simulants containing depleted uranium oxide.The experiments were undertaken by ONET/CEA/IRSN on a dedicated facility named FUJISAN2 located at CEA Cadarache. The generated particles underwent comprehensive sampling and characterization, including size distribution, morphology as well as mass and number concentration, using dedicated aerosol metrology devices.This article will present the experimental facility, including its aerosol instrumentation, the cutting sequences, and the methodology implemented to characterize aerosol physical properties and determine ARF coefficients, using gathered aerosol data measured by the different instruments.Comparative analyses are then presented in terms of particles mass concentration between the cutting trials on the different FD simulants, to understand the influence of the sample properties on particle generation
Microphysical modelling of aerosol scavenging by different types of clouds: description and validation of the approach
No full textInternational audienceWith dry deposition and below-cloud scavenging, in-cloud scavenging is one of the three components of aerosol transfer from the atmosphere to the ground. There is no experimental validation of in-cloud particle scavenging models for all cloud types that is not impacted by uncertainties concerning below-cloud scavenging. In this article, the choice was made to start with a recognised and validated microphysical cloud formation model (the DEtailed SCAvenging Model, DESCAM) to extract a scheme of aerosol scavenging by clouds, valid for different cloud types. The resulting model works for the two most extreme precipitation clouds: from cumulonimbus to stratus. It is based on data accessible a priori from numerical weather prediction (NWP) outputs, i.e. the intensity of the rain and the relative humidity in the cloud. The diagnostic of the altitude of the cloud base proves to be a key parameter, and accuracy in this regard is vital. This new in-cloud scavenging scheme is intended for use in long-distance (> 100 km) atmospheric transport models (ATMs) or global climate models (GCMs)
Clinico-pathological factors associated with radioiodine refractory differentiated thyroid carcinoma status
No full textInternational audiencePurpose Risk factors for developing radioiodine refractory thyroid cancer (RAIR-TC) have rarely been analyzed. The purpose of the present study was to find clinical and pathological features associated with the occurrence of RAIR-disease in differentiated thyroid cancers (DTC) and to establish an effective predictive risk score. Methods All cases of RAIR-DTC treated in our center from 1990 to 2020 were retrospectively reviewed. Each case was matched randomly with at least four RAI-avid DTC control patients based on histological and clinical criteria. Conditional logistic regression was used to examine the association between RAIR-disease and variables with univariate and multivariate analyses. A risk score was then developed from the multivariate conditional logistic regression model to predict the risk of refractory disease occurrence. The optimal cut-off value for predicting the occurrence of RAIR-TC was assessed by receiver operating characteristic (ROC) curves and Youden's statistic. ResultsWe analyzed 159 RAIR-TC cases for a total of 759 controls and found 7 independent risk factors for predicting RAIR-TC occurrence: age at diagnosis ≥ 55, vascular invasion, synchronous cervical, pulmonary and bone metastases at initial work-up, cervical and pulmonary recurrence during follow-up. The predictive score of RAIR-disease showed a high discrimination power with a cut-off value of 8.9 out of 10 providing 86% sensitivity and 92% specificity with an area under the curve (AUC) of 0.95. Conclusion Predicting the occurrence of RAIR-disease in DTC patients may allow clinicians to focus on systemic redifferentiating strategies and/or local treatments for metastatic lesions rather than pursuing with ineffective RAI-therapies.</div
Absorption du technétium-99 par les cultures en conditions de plein champs
No full textInternational audienceLong-term field experiments have been carried out in the Chornobyl Exclusion zone to determine parameters describing technetium (99Tc) transfer into five food plants (Lettuce, Radish, Wheat, Bean, and Potato) from four types of soil, namely Podzoluvisol, Greyzem, Phaeozem, and Chernozem. Technetium was added to the soils under field conditions in a pertechnetate form. In the first two years, soil type had little effect on Tc uptake by plants. In the first and second years after contamination, the concentration ratios (CR), defined as 99Tc activity concentration in the crop (dry weight) divided by that in the soil (dry weight), for radish roots and lettuce leaves ranged from 60 to 210. For potato tubers, the CR was d 0.4–2.3, i.e., two orders of magnitude lower than for radish and lettuce, and for summer wheat grain it was lower at 0.6 ± 0.1. After 8–9 years, root uptake of 99Tc by wheat decreased by 3–7 fold (CR from 0.016 ± 0.005 to 0.12 ± 0.034) and only 13–22 % of the total 99Tc added remained in the upper 20 cm soil layers. The time taken for half of the added 99Tc to be removed from the 20-cm arable soil layer due to vertical migration and transfer to plants was short at c. 2–3 years
L'Anthropocène scruté par la géochimie isotopique : révélations sur l'empreinte de l'ère nucléaire sur l'environnement
No full textInternational audienceOver the past centuries, humans have caused changes that may surpass Nature's 'restorative' abilities. In this new geological era, the Anthropocene, the impact of humans on the environment is not always apparent. Isotope geochemistry provides tools and reasoning that reveal the human impact on the environment long before the effects become manifest, thereby anticipating environmental and societal consequences.The discovery of Esperium by Enrico Fermi in 1930 paved the way for the nuclear era, with its two main branches: military and civilian nuclear power. Like any human activity, manipulating the atom is not without consequences for the environment. From ore extraction to nuclear tests, and from nuclear incidents/accidents to the nuclear waste disposal, each of these stages can leave its own mark on the environment.What role does isotope geochemistry play in understanding the impact of nuclear activities on the environment? How can isotope “fingerprints” highlight potential sources of pollution, and provide information on their evolution in space and time?During the presentation, examples of sites and soils impacted by nuclear activities will be presented, highlighting the use of isotope tracers to answer these questions. The presentation will also emphasize the importance of a thorough understanding of the geochemical behavior of these tracers, the advantage of using multiple tracers, and the connection of isotope geochemistry with cutting-edge analytical developments. This approach aims to tackle complex issues, thus stimulating the development of strategies for managing contaminated sites and associated wasteAu cours des derniers siècles, l'Homme a provoqué des changements qui pourraient surpasser les facultés « réparatrices » de la Nature. Dans cette nouvelle ère géologique, l'Anthropocène, l'impact de l’Homme sur l'environnement n'est pas toujours évident. La géochimie isotopique fournit des outils et des raisonnements permettant de révéler l'empreinte de l'Homme sur l'environnement bien avant que les effets ne se manifestent, anticipant ainsi les conséquences environnementales et sociétales.La découverte de l'Esperium par Enrico Fermi en 1930 a ouvert la voie à l'ère nucléaire, avec ses deux principales filières : le nucléaire militaire et civil. Comme toute activité humaine, la manipulation de l'atome n'est pas sans conséquences pour l'environnement. De l'extraction du minerai aux essais nucléaires, en passant par les incidents/accidents nucléaires et l'entreposage/stockage des déchets, chacune de ces étapes peut laisser sa propre empreinte sur l’environnement.Quel est le rôle de la géochimie isotopique dans la compréhension de l’empreinte nucléaire sur l'environnement ? Comment ces outils et raisonnements peuvent-ils mettre en évidence une empreinte, identifier les sources potentielles de pollution et apporter des informations sur leur évolution dans l'espace et dans le temps ?Lors de la présentation, des exemples de sites et de sols marqués par des activités nucléaires seront présentés, mettant en lumière l'usage des traceurs isotopiques pour répondre à ces questions. La présentation mettra également en évidence l’importance d’une compréhension fine du comportement géochimique de ces traceurs, de l’avantage de l’utilisation de plusieurs traceurs et de la connexion de la géochimie isotopique avec les avancées technologiques de pointe. Cette démarche vise à aborder des questions complexes, stimulant ainsi l'élaboration de stratégies de gestion des sites contaminés et des déchets associés
Novel approach for emergency dosimetry: Investigations of screen protectors for smartphones by EPR spectroscopy
No full textInternational audienceScreen protectors for smartphone are investigated in attempts for emergency dosimetry as for example in case of malicious attacks with radioactive sources or accidental overexposure. Electron Paramagnetic Resonance (EPR) measurements were carried out on six different types of screen protectors (SPs). The inter and intra batch variability of the EPR signals characteristics (sensitivity, stability, signal shape) were studied. Contrary to touch screen (De Angelis et al., 2015; Juniewicz et al., 2020), UVB exposure for SP is not a limiting confounding factor. All samples under irradiation exhibit same EPR signals. The nature of the radio-induced point defects was identified (HC1 and HC2) as well as their evolution according to dose. The linear dose response was studied in the 0–5 Gy dose range with a detection limit estimated of 750 mGy with a field deployable benchtop EPR spectrometer. Large variability of the dose response prevents presently from using universal calibration curve. Therefore, further work is needed to consider possible application for triage in the case of large-scale accidents scenarios
Health-related quality of life and radioiodine therapy in thyroid cancer patients: a before-and-after study
No full textInternational audienceThyroid cancers are on the rise, but the associated vital prognosis and long-term survival rates are very good. Therefore, treated patients’ quality of life and psychological well-being are important considerations. The treatment usually involves surgery and radioactive iodine (radioiodine) ablation. This study aims to investigate potential effects of radioiodine ablation therapy on health-related quality of life, anxiety and depression symptoms, and nutritional status at 6 months post-therapy.This study included 136 patients diagnosed with thyroid cancer. Absorbed doses to the salivary glands were estimated from dosimeters worn by patients. Patient health-related quality of life, psychological status and nutritional status were assessed before and 6 months after therapy using standardized questionnaires (including SF-36, Hospital Anxiety and Depression (HAD) scale). Statistical analyses included random-effects logistic and linear regressions adjusted for potential confounders.While no significant association was found between radioiodine exposure and anxiety or depression symptoms, or nutritional status, a significant increase in the SF-36 role physical sub- score was observed in relation with the salivary gland dose (β= 6.54, 95%CI 2.71;10.36 for a 1-Gy increase).The findings suggest an improved physical health-related quality of life, namely reduced pain and functional impairment, 6 months after radioiodine therapy in thyroid cancer patients. No significant association was found between radioiodine exposure and mental health-related quality of life, anxiety or depression scores nor nutritional status. This study does not provide any evidence that radioiodine therapy has a potentially adverse effect on patient health-related quality of lif
Exposure to tungsten particles via inhalation triggers early toxicity marker expression in the rat brain
No full textInternational audienceObjective: Our work is focused on tungsten, considered as an emerging contaminant. Its environmental dispersion is partly due to mining and military activities. Exposure scenarii can also be occupational, in areas such as the hard metal industry and specific nuclear facilities. Our study investigated the cerebral effects induced by the inhalation of tungsten particles.Methods: Inhalation exposure campaigns were carried out at two different concentrations (5 and 80 mg/m3) in single and repeated modes (4 consecutive days) in adult rats within a nose-only inhalation chamber. Processes involved in brain toxicity were investigated 24 hours after exposure. Results and discussion: Site-specific effects in terms of neuroanatomy and concentration-dependent changes in specific cellular actors were observed. Results obtained in the olfactory bulb suggest a potential early effect on the survival of microglial cells. Depending on the mode of exposure, these cells showed a decrease in density accompanied by an increase in an apoptotic marker. An abnormal phenotype of the nuclei of mature neurons, suggesting neuronal suffering, was also observed in the frontal cortex, and can be linked to the involvement of oxidative stress. The differential effects observed according to exposure patterns could involve two components: local (brain-specific) and/or systemic. Indeed, tungsten, in addition to being found in the lungs and kidneys, was present in the brain of animals exposed to the high concentration. Conclusion: Our data question the perceived innocuity of tungsten relative to other metals and raise hypotheses regarding possible adaptive or neurotoxic mechanisms that could ultimately alter neuronal integrity
First production of X-rays at the ThomX high-intensity Compton source
No full textInternational audienceWith the increase in laser power and finesse of optical cavities over the last decade, laboratory-size Compton sources are very promising. These sources produce X-rays through interactions between relativistic electrons and laser photons and, in term of brightness, fall between large synchrotron facilities and classical laboratory X-ray sources. The ThomX source is the French project in this field. This article first presents a state of the art of high-intensity Compton sources, then the ThomX source is briefly described, and the first results are detailed, in particular the production of the first X-rays, the acquisition of the first spectrum and the first image of the beam. Finally, the next objectives are discussed.Les sources X Compton offrent des perspectives très encourageantes, grâce aux progrès depuis dix ans des cavités de stockage optique, en termes de puissance laser et de finesse. Ces sources produisent des rayons X par interaction entre photons laser et électrons relativistes, et présentent des brillances intermédiaires entre sources X classiques de laboratoire, et synchrotrons. ThomX est le projet français de ce domaine. Cet article présente tout d'abord l'état de l'art des sources Compton intenses, puis décrit brièvement la source ThomX, et détaille ses premiers résultats, en particulier la production des premiers X, l'acquisition du premier spectre et la première image du faisceau. Nous discutons enfin des objectifs à suivre
Early Impairment of Paracrine and Phenotypic Features in Resident Cardiac Mesenchymal Stromal Cells after Thoracic Radiotherapy
No full textInternational audienceRadiotherapy-induced cardiac toxicity and consequent diseases still represent potential severe late complications for many cancer survivors who undergo therapeutic thoracic irradiation. We aimed to assess the phenotypic and paracrine features of resident cardiac mesenchymal stromal cells (CMSCs) at early follow-up after the end of thoracic irradiation of the heart as an early sign and/or mechanism of cardiac toxicity anticipating late organ dysfunction. Resident CMSCs were isolated from a rat model of fractionated thoracic irradiation with accurate and clinically relevant heart dosimetry that developed delayed dose-dependent cardiac dysfunction after 1 year. Cells were isolated 6 and 12 weeks after the end of radiotherapy and fully characterized at the transcriptional, paracrine, and functional levels. CMSCs displayed several altered features in a dose- and time-dependent trend, with the most impaired characteristics observed in those exposed in situ to the highest radiation dose with time. In particular, altered features included impaired cell migration and 3D growth and a and significant association of transcriptomic data with GO terms related to altered cytokine and growth factor signaling. Indeed, the altered paracrine profile of CMSCs derived from the group at the highest dose at the 12-week follow-up gave significantly reduced angiogenic support to endothelial cells and polarized macrophages toward a pro-inflammatory profile. Data collected in a clinically relevant rat model of heart irradiation simulating thoracic radiotherapy suggest that early paracrine and transcriptional alterations of the cardiac stroma may represent a dose- and time-dependent biological substrate for the delayed cardiac dysfunction phenotype observed in vivo