Institute for Radiation Protection and Nuclear Safety (IRSN)
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Changes induced in the human respiratory tract by chronic cigarette smoking can reduce the dose to the lungs from exposure to radon progeny
No full textInternational audienceChronic cigarette smoking leads to changes in the respiratory tract that might affect the dose received from exposure to radon progeny. In this study, changes induced by cigarette smoking in the respiratory tract were collected from the literature and used for calculation of the dose received by the lungs and organs outside the respiratory tract. Morphological and physiological parameters affected by chronic smoking were implemented in the human respiratory tract model (HRTM) used by the International Commission of Radiological Protection (ICRP). Smokers were found to receive lung doses 3% smaller than the ICRP reference worker (non-smoking reference adult male) in mines and 14% smaller in indoor workplaces and tourist caves. A similar dose reduction was found for the extrathoracic region of the HRTM. Conversely, kidneys, brain, and bone marrow of smokers were found to receive from 2.3- up to 3-fold of the dose received by the respective organ in the ICRP reference worker, although they remained at least two orders of magnitude smaller than the lung dose. These results indicate that the differences in the lung dose from radon progeny exposure in cigarette smokers and non-smokers are smaller than 15%
From the instrumental to the organizational genesis of a new imaging system in radiotherapy: a meeting point between French-speaking ergonomics and macroergonomics
No full textInternational audienceThis communication forms part of the articulation of two research programs carried out within the Social Human Sciences Research Laboratory of the Institute for Radiation Protection and Nuclear Safety (IRSN). The first is concerned with transversal organizations (processes, supply chains, etc.) and the complex nature of performance (safety, security, quality, etc.) in these organizations which are characterized by a fragmentation of the activity. The second analyzes the way in which technologies are integrated into the activity of actors and to what extent they allow this activity to develop. These two research programs come together in particular around the concept of “organizational genesis” (Folcher & Bationo Tillon, 2018, 2019; Bationo-Tillon, Poret & Folcher, 2020; Folcher, Bationo-Tillon, Poret & Couillaud, 2021). This concept is presented here from a research carried out in the field of radiotherapy. In this area, advances related to the development of computing and imaging have played and continue to play an essential role in the evolution of treatments. At the same time, these advances, which are experiencing a sustained rate of development, raise the question of their appropriation by radiotherapy professionals, directly linked to that of patient safety. Indeed, if these advances contribute to the quality of treatments, they can also bring out new risks for patients.Understanding the process of appropriation of a technical novelty is at the heart of the research presented here. Starting from this focus on the relationship between the actors and the technique, our results show that the introduction of the technical novelty has effects not only on the individual level, but also on the radiotherapy treatment process as a whole. In other words, from an analysis of the appropriation which could be similar to an analysis of the Human-Machine interaction, our research has highlighted the way in which a modification of the technical system leads to modifications at the level of the cross-functional collective activities (Poret, Folcher, Motté, Haradji, 2016) founding the organization. With the concept of organizational genesis, which allows this passage between different levels of understanding, our research conceptually anchored in French-speaking ergonomics meets the objectives of macroergonomics (Carayon, Karsh, Gurses, Holden, Hoonakker, Hundt, Montague, Rodriguez, Wetterneck, 2013; Kleiner, 2008).We hope that this communication, and the concept of organizational genesis presented therein, will open up discussions between two ergonomic traditions - French speaking ergonomics and macroergonomics, which present numerous complementarities for the analysis and design of organizations
Application of SAPIUM guidelines to Input Uncertainty Quantification: the ATRIUM project
No full textInternational audienceIn the past few decades, there has been an increasing interest in the use of Best Estimate Plus Uncertainty (BEPU) methodologies for the safety analyses of nuclear reactors. One of the crucial issues is to quantify the input uncertainties associated to the physical models in the thermal-hydraulic codes. Such a quantification can be performed by comparison with experimental data, and it is usually referred to as Inverse Uncertainty Quantification (IUQ). Focusing on discussing IUQ methodologies, the OECD/NEA SAPIUM (Development of a Systematic APproach for Input Uncertainty quantification of the physical Models in thermal-hydraulic codes) good practice guidance led to the definition of a new systematic approach for transparent and rigorous IUQ. It highlighted that IUQ should be performed as a global process involving a clear identification of the transient to be simulated and the uncertainties of key phenomena to be quantified, an efficient strategy to construct adequate experimental database and an assessment of the simulation models. The uncertainty ranges and distributions can then be quantified with adequate IUQ methods and finally validated. However, no full application of the guidelines was performed within the SAPIUM project.In this paper, the new OECD/NEA project ATRIUM (Application Tests for Realization of Inverse Uncertainty quantification and validation Methodologies in thermal-hydraulics) is presented. The goal is to perform practical IUQ exercises to bring new insights on the applicability of the SAPIUM best-practices and on the possible improvements necessary when quantifying model input uncertainties. Two IUQ exercises with increasing complexity are planned to quantify the uncertainties associated to the critical/chocked flow and post-Critical Heat Flux (CHF) heat transfer phenomena, which are important during a Loss Of Coolant Accident (LOCA). A particular attention will be dedicated to the evaluation of the adequacy of the experimental databases. The final step of the project consists in the propagation of the quantified uncertainties on the Hot Leg Intermediate Break LOCA IB-HL-01 Integral Effect Test performed in the framework of the OECD/NEA ROSA-2 (Rig-of-Safety Assessment) joint experimental project in the LSTF (Large Scale Test Facility), to validate their application in LOCA type experiments at larger scale
Nuclear Data Uncertainties and Adjustments Using Deterministic and Monte-Carlo Methods along with PWR Measurements
No full textInternational audienceNuclear power plants safety relies partly on predictions from numerical simulations. Their uncertainties must therefore be evaluated. In PWR reactor physics, the simulations' uncertainties are nowadays estimated on the basis of the differences between existing measurements and the corresponding simulations. This approach leads to weaknesses in the estimation of uncertainties. For example, a novelty can induce more deviations than those seen in the past. Moreover, in some (common) cases, these uncertainties are based on differences between measurements and adjusted simulations, i.e. carried out after the measurements and by forcing the simulations as close as possible to the measurements. The residual deviation thus leads to consider compressed uncertainties. This method of evaluating uncertainties can therefore be improved. To further increase robustness, the approach proposed in a recently published Ph.D. thesis is to return to the fundamentals : the sources of errors in the simulations. The two main types discussed in this paper are the following. On the one hand, physical and numerical approximations introduce deterministic biases, which can be evaluated as the difference with Monte-Carlo. On the other hand, the nuclear data uncertainties, that arise from the limited human understanding of nuclear physics, are propagated in this article with a Total Monte-Carlo approach
Mass log-stable distribution of fragments in liquid–liquid jet fragmentation based on a two-step cascade between viscous Kelvin-Helmholtz instability and Rayleigh-Taylor instability
No full textInternational audienceThis work is devoted to the study of liquid–liquid fragmentation. It contains both an experimental part and a theoretical part. In the experimental part, a low-melting point liquid metal jet is injected into a water pool. High-speed shadowgraph method is used to measure the jet velocity and to observe the dynamics of the fragmentation. Thereafter, the solidified fragments are sieved and weighted allowing to measure their mass distribution according to their size. The mass Probability Density Function (PDF) is then fitted using log-stablelaws, generalization of log-normal laws. In the theoretical part, it is shown how it is possible to compute the shift parameter of the stable law considering that the droplets are mainly generated by a boundary layer stripping mechanism. Actually the computation relies on a viscous shear instability mechanism (different fromclassical Kelvin–Helmholtz instability) sometime called ‘‘gradient instability’’. The width of the distribution (or more precisely its scale parameter) is computed assuming a cascade mechanism between this first wave instability and a secondary Rayleigh–Taylor mechanism applied on the generated wave. The model is then compared to present experimental results and previously published results obtained in the field of nuclear safety studies (Fuel-Coolant Interaction or FCI). Two fitting parameters are then identified. The agreement is goodwhen phase change and solidification effects can be neglected and qualitatively good (i.e. fitting parameters need to be modified) when these effects cannot be neglected
A two-scale approach to widen a predictive blast propagation model around a hemicylindrical obstacle
No full textInternational audienceThe aim of the present paper was to report on an experimental study of the characterization of a blast wave initiated by a solid explosive and its interaction with a rigid obstacle in the form of a hemicylinder. Pressure transducers located along the path of the blast wave and high-speed imaging allow (1) the measurement of the overpressure at different locations and (2) the characterization of the blast wave inception, propagation, and reflection off the hemicylinder. The scaling effect has been investigated by performing experiments in two different facilities, where one is at twice the scale of the other
Dysfonctionnements salivaires et lacrymaux après un traitement par radioiode pour un cancer de la thyroïde : résultats du suivi à 6 mois de l'étude START
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Etude expérimentale de la faisabilité de piégeage des gaz rares (Xe, Kr) par des matériaux poreux innovants de type Metal-Organic Framework (MOF)
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Systemically delivered adipose stromal vascular fraction mitigates radiation-induced gastrointestinal syndrome by immunomodulating the inflammatory response through a CD11b+ cell-dependent mechanism
No full textInternational audienceBackground Stromal vascular fraction (SVF) treatment promoted the regeneration of the intestinal epithelium, limiting lethality in a mouse model of radiation-induced gastrointestinal syndrome (GIS). The SVF has a heterogeneous cell composition; the effects between SVF and the host intestinal immunity are still unknown. The specific role of the different cells contained in the SVF needs to be clarified. Monocytes-macrophages have a crucial role in repair and monocyte recruitment and activation are orchestrated by the chemokine receptors CX3CR1 and CCR2. Methods Mice exposed to abdominal radiation (18 Gy) received a single intravenous injection of SVF (2.5 × 10 6 cells), obtained by enzymatic digestion of inguinal fat tissue, on the day of irradiation. Intestinal immunity and regeneration were evaluated by flow cytometry, RT-PCR and histological analyses. Results Using flow cytometry, we showed that SVF treatment modulated intestinal monocyte differentiation at 7 days post-irradiation by very early increasing the CD11b + Ly6C + CCR2 + population in the intestine ileal mucosa and accelerating the phenotype modification to acquire CX3CR1 in order to finally restore the F4/80 + CX3CR1 + macrophage population. In CX3CR1-depleted mice, SVF treatment fails to mature the Ly6C − MCHII + CX3CR1 + population, leading to a macrophage population deficit associated with proinflammatory environment maintenance and defective intestinal repair; this impaired SVF efficiency on survival. Consistent with a CD11b + being involved in SVF-induced intestinal repair, we showed that SVF-depleted CD11b + treatment impaired F4/80 + CX3CR1 + macrophage pool restoration and caused loss of anti-inflammatory properties, abrogating stem cell compartment repair and survival. Conclusions These data showed that SVF treatment mitigates the GIS-involving immunomodulatory effect. Cooperation between the monocyte in SVF and the host monocyte defining the therapeutic properties of the SVF is necessary to guarantee the effective action of the SVF on the GIS
Chapter 3.5 - Anthropogenic and natural radionuclides in the Mediterranean atmospheric system
No full textInternational audienceTo better understand the transport of pollutants and nutrients by atmospheric particles in the Mediterranean area, there is a need to use and develop independent geochemical tracers in order to determine particle origins and mechanisms of deposition and uplift. Radionuclides, either natural or anthropogenic, are specifically adequate for this issue. When released in the atmosphere, some of them are rapidly bound to submicronic aerosols, also carriers of atmospheric pollutants like heavy metals or S and N oxides. Here, we discuss the sources and sinks of artificial and natural radionuclides as tracers of atmospheric processes in the Mediterranean area. This region is highly sensitive to climate change, which will favor already marked featured processes encountered in this area: dust resuspension, wildfires, and biogenic emissions. Such processes play a major role in the Mediterranean aerosol features and can be tracked using radionuclide-labeled aerosols. Naturally occurring radionuclides such as 22Na and 7Be, which are produced in the upper troposphere and lower stratosphere can also be used to track downdrafts and stratosphere-to-troposphere exchanges. Primordial radionuclides (uranium, thorium and their decay products) originating from the earth crust and mantle can enter the atmosphere as particles and their isotopic or activity ratios can help discriminate between source locations. Additionally, formerly deposited anthropogenic radionuclide-labelled aerosols whose deposition map are rather well known at large scale, can be re-emitted to the atmosphere by soil particle resuspension on a regular basis at short scale and at large scale during (i) paroxystic dust resuspension outbreaks, (ii) wildfires and biomass burning, especially during droughts periods, and (iii) seasonal biogenic emissions (pollens)