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A new method to quantify the leakage scenarios (frequencies andu flowrates) on hydrogen high pressure components
No full textInternational audienceThis work is part of the MULTHYFUEL E.U. research program [1] aiming at enabling the implementationof hydrogen dispersers in refuelling stations. One important challenge is the severity of accidentsdue to a leakage of hydrogen from a dispenser in the forecourt. The work presented in this paper dealswith the quantification of the leakage scenarios in terms of frequencies and severities.The risk analysis exercise, although performed by experts, showed very large discrepancies betweenthe frequencies of leakages of the same categories and even between the consequences. A large part ofthe disagreement comes from the failure databases chosen as shown in the paper. The mismatch betweenthe components on which the databases have been settled and the actual hydrogen components may beresponsible for this situation. However, as it stands, limited confidence can be laid on the outcome ofthe risk analysis.A new method is being developed to calculate the frequencies of the leakage and the flowrate based onan accurate description of each component and of each hazardous situation. For instance, the possibilityfor a fitting to become untight due to pressure cycling is modelled based on the contact mechanics.Human errors can also be introduced by describing the tasks. In addition of the description of the method,the application to a disperser is proposed with some comparison to experiments. One of the outcomesis that leakage cross sections can be much larger than expected
Application of the Fpg-modified comet assay on three-spined stickleback in freshwater biomonitoring: toward a multi-biomarker approach of genotoxicity
No full textInternational audienceAquatic species are exposed to a wide spectrum of substances, which can compromise their genomic integrity by inducing DNA damage or oxidative stress. Genotoxicity biomarkers as DNA strand breaks and chromosomal damages developed on sentinel species have already proved to be relevant in aquatic biomonitoring. However, these biomarkers do not reflect DNA oxidative lesions, i.e., the 8-oxodG, recognized as pre-mutagenic lesion if not or mis-repaired in human biomonitoring. The relevance to include the measure of these lesions by using the Fpg-modified comet assay on erythrocytes of the three-spined stickleback was investigated. An optimization step of the Fpg-modified comet assay considering enzyme buffer impact, Fpg concentration, and incubation time has been performed. Then, this measure was integrated in a battery of genotoxicity and cytotoxicity biomarkers (considering DNA strand breaks, DNA content variation, and cell apoptosis/necrosis and density) and applied in a freshwater monitoring program on six stations of the Artois Picardie watershed (3-week caging of control fish). These biomarkers allowed to discriminate the stations regarding the genotoxic potential of water bodies and specifically by the measure of oxidative DNA lesions, which seem to be a promising tool in environmental genotoxicity risk assessment
The variability of mass concentrations and source apportionment analysis of equivalent black carbon across urban Europe
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Functional safety assessment of an AI sensor according to IEC 61508
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Valeurs toxicologiques de référence (VTR) par voie respiratoire pour les particules de l’air ambiant extérieur - Recommandation de VTR long terme pour les PM2,5 et extrapolation aux PM10 - Faisabilité d’élaboration de VTR pour le carbone suie et pour les particules ultrafines
No full textCitation suggérée: Anses. (2022). VTR par voie respiratoire pour l’exposition à long terme aux particules de l’air ambiant extérieur (PM2,5 et PM10) et à la faisabilité d’élaborer des VTR pour les particules de carbone suie et les particules ultrafines. (saisine 2019-SA-0198). Maisons-Alfort : Anses, 274 p.Une valeur toxicologique de référence, ou VTR, est un indice toxicologique qui permet de qualifier ou de quantifier un risque pour la santé humaine. Elle établit le lien entre une exposition à un agent toxique et l’occurrence d’un effet sanitaire indésirable. Les VTR sont spécifiques d’une durée d’exposition (aiguë, subchronique ou chronique) et d’une voie d’exposition (orale ou respiratoire). La construction des VTR diffère en fonction des connaissances ou des hypothèses formulées surles mécanismes d’action des substances. Actuellement, l’hypothèse par défaut est de considérer une relation monotone entre la dose d’exposition (ou la concentration d’exposition) et l’effet (ou la réponse). En l’état actuel des connaissances et par défaut, on considère généralement que, pour les effets non cancérogènes, la toxicité ne s’exprime qu’au-delà d’un seuil de dose (ou de concentration) (Anses 2017b).A l'issue de l'expertise de l'Anses visant à sélectionner les polluants à prendre en compte dans les évaluations des risques sanitaires réalisées dans le cadre des études d'impact des infrastructures routières, l'agence rappelait l'intérêt des études quantitatives des risques sanitaires (EQRS) dans une approche prospective pour estimer les impacts et permettre d'informer la population des risques potentiels sur la santé (Anses 2012). Pour réaliser une telle évaluation des risques en lien avec la source « trafic routier », la prise en compte des particules en suspension apparaît indispensable, impliquant la nécessité de disposer de valeurs de référence (telle qu’une VTR). De même, l’utilisation des VTR s’inscrit dans le cadre de la réalisation d'études d'impact pour des installations classées pour la protection de l'environnement (ICPE).D’après une enquête par questionnaire en ligne menée en 2018 par l’Anses auprès d’un échantillon non représentatif d’utilisateurs de VTR sur le territoire national (n=26), une majorité de répondants (61,5 %) rapportait le besoin d’une VTR pour les particules de l’air ambiant dans des contextes variés, pour les motifs suivants :- pouvoir évaluer des particules en cohérence avec les substances chimiques,- pouvoir évaluer les risques liés à des particules de sources variées ou parfois très spécifiques (ex : incendie de déchetterie) et en fonction de la omposition/granulométrie des particules,- pouvoir se référer à des valeurs plus protectrices pour la santé au regard de l’écart entre les valeurs existantes pour la gestion de la qualité de l’air (valeurs réglementaires) et les valeurs guides de la qualité de l’air.En l’absence de VTR, la méthode la plus simple, et employée jusqu’à présent, était de comparer les données de concentration dans l’air ambiant à des valeurs réglementaires ou de référence sanitaire comme celles établies par l’OMS. Ces valeurs apportent des points de repères mais ce ne sont cependant en aucun cas des VTR. Les valeurs réglementaires ne correspondent pas à des concentrations sans risque sanitaire au regard des études épidémiologiques montrant qu’il existedes effets sanitaires pour des concentrations atmosphériques inférieures à ces valeurs. Dans le domaine environnemental, les conventions métrologiques actuelles concernent la mesure de la matière particulaire en suspension dans l’air, c’est-à-dire les « PM » (particulate matter en anglais), en concentration massique pour les fractions de PM de diamètre aérodynamique médian inférieur ou égal à 10 μm (PM10) et à 2,5 μm (PM2,5). Ainsi, l'Anses se propose d’étudier la faisabilité d'élaborer des VTR pour les particules PM10 et PM2,5 en suspension dans l’air ambiant et de les construire le cas échéant.Au regard des nouvelles connaissances sur la question de la composition et de la granulométrie en lien avec les effets sur la santé (Anses 2019a), ces travaux d’expertise incluent également la pertinence et la faisabilité d’élaborer des VTR pour le carbone suie (BC) et les particules ultrafines (PUF).L’élaboration des VTR suit une approche structurée et exigeante qui implique des évaluations collectives par des groupes de spécialistes
Coupling and complexity at the global scale: flows, networks, interconnectedness and synchronicity (e.g. Covid-19)
No full textInternational audienceThe argument of this paper is that the notions of coupling and complexity introduced by Perrow to discuss high-risk technologies need to be scaled up from their original scope to a wider, global one considering the evolution of the operational landscape of safety–critical systems. One value of Perrow in the 1980 s was to trigger core debates, contributing to a new form of causal reasoning. It provided a way of thinking about causality within a context of expanding sociotechnical systems such as nuclear power plants, civil commercial aviation or petroleum infrastructures. In the 2020 s, high-risk technologies do not only represent potential for single catastrophic events anymore but are also the sources of wider problems associated with globalised flows (systemic risks) and ecological degradation known as anthropocene (leading to existential risks). In this context, the scope, scale and timeframe of high-risk systems is extended in comparison to Perrow’s original work. In these new circumstances, coupling and complexity categories apply to a much wider spectrum of issues than initially conceived by Perrow and notions such as flows, nodes, networks, interconnectedness, and synchronicity should be incorporated to illustrate a move to the global stage. After a presentation and discussion of Perrow’s coupling and interaction, the “global turn” in research is discussed, using sociology and history as examples. It is followed by the contribution by Guillén on the “architecture of collapse” characterising our contemporary era. Its implications for safety science research are then explored using Covid-19 as an example
Modélisation de la qualité de l’air : vers l’évaluation de l’exposition atmosphérique aux pesticides
No full textInternational audienceDetermining atmospheric exposure is critical to assess the health impact of pesticides, but few tools currently exist to map pesticide concentrations at the national scale. One possible method would be to use air quality models such as the CHIMERE model to simulate pesticide atmospheric concentrations. This type of model represents the physicochemical processes occurring in the atmosphere to calculate concentrations of various chemicals. A method has recently been developed in the CHIMERE model to simulate pesticide concentrations by incorporating a volatilization flux model to calculate emissions to air from treated surfaces. Using such a method would require knowledge of the spatial and temporal distribution of pesticide applications. While data from the Banque nationale des ventes de produits phytopharmaceutiques par les distributeurs agréés spatialisée (BNVD-S) provides a good indication of the spatial distribution of applications, little information exists on treatment schedules. Although such models operate at resolutions of a few kilometers (which would not allow a reliable determination of exposure), it would be possible to determine high-resolution pesticide maps over the whole France using downscaling approaches combined with results from local-scale dispersion models. Such a method would eventually provide maps of pesticide concentrations for epidemiological studies.La détermination de l’exposition atmosphérique est critique pour évaluer l’impact sanitaire des pesticides mais peu d’outils permettent actuellement de réaliser une cartographie des concentrations à l’échelle nationale. Une méthode possible consisterait à utiliser des modèles de qualité de l’air comme le modèle CHIMERE pour simuler les concentrations de pesticides. Ce genre de modèle représente les processus physico-chimiques intervenant dans l’atmosphère pour calculer les concentrations de diverses substances. Une méthode a été récemment développée dans le modèle CHIMERE pour simuler les concentrations de pesticides en intégrant un modèle de calcul de flux de volatilisation afin de calculer les émissions dans l’air depuis les surfaces traitées. Utiliser une telle méthode exigerait de connaître la distribution spatiale et temporelle des applications de pesticides. Si la spatialisation des données de la Banque nationale des ventes de produits phytopharmaceutiques par les distributeurs agréés spatialisée (BNVD-S) fournit une bonne indication sur la distribution spatiale des applications en France, peu d’informations existent sur les calendriers de traitement. Bien que ce genre de modèles fonctionne à des résolutions de quelques kilomètres (ce qui ne permettrait pas une détermination fiable de l’exposition), il serait possible de déterminer des cartographies à haute résolution de pesticides sur l’ensemble de la France en utilisant des approches de descente d’échelle combinées à des résultats de modèles de dispersion à l’échelle locale. Une telle méthode permettrait à terme de fournir des cartographies de concentrations de pesticides pour les études épidémiologiques
Safety of cryogenic liquid hydrogen bunkering operations - The gaps between existing knowhow and industry needs
No full textInternational audienceHydrogen plays an important role in the global transition towards Net-Zero emission. While pipelinesare a viable option to transport large quantities of compressed hydrogen over long distances, it is notalways practical in many applications. In such situations, a viable option is to transport and deliver largequantities of hydrogen as cryogenic liquid. The liquefaction process cools hydrogen to cryogenictemperatures below its boiling point of -259.2 0C. Such extreme low temperature implies specifichazards and risks, which are different from those associated with the relatively well-known compressedgaseous hydrogen. Managing these specific issues brings new challenges for the stakeholders.Furthermore, the transfer of liquid hydrogen (LH2) and its technical handling is relatively well knownfor industrial gas or space applications. Experience with LH2 in public and populated areas, such astruck and aircraft refuelling stations or port bunkering stations for example, is limited or non-existent.Safety requirements in these applications, which involve or are in proximity of untrained public, aredifferent from rocket/aerospace industry.The manuscript reviews knowhow already gained by the international hydrogen safety community; andon such basis elucidate the gaps, which are yet to be filled to meet industry needs to design and operateinherently safe LH2 operations, including the implications for regulations, codes, and standards (RCS).Where relevant, the associated gaps in some underpinning sciences will be mentioned; and the need tocontextualise the information and safety practices from NASA1/ESA2/JAXA3 to inform risk adoptionwill be summarised
The use of Natural Gas Vehicles in underground facilities: Application to the PARIS-LA-DÉFENSE underground network
No full textInternational audienceConsidering the current strong development of natural gas vehicles and their use in many underground infrastructures, this paper focuses on the corresponding risk induced in such situations. It consists in applying the analysis of the consequences of the huge and complex underground network of the La Défense business center, in the suburbs of Paris. The different types of natural gas vehicles were considered, compressed natural gas (CNG) and liquified natural gas vehicles (LNG). Based on existing knowledge in risk analysis, the main dangerous phenomena that can occur for those vehicles, jet fire, vapor cloud explosion, and tank burst, were all considered and modeled for each technology. To evaluate the release source term, the very beginning for both jet fire and flammable cloud characterization, the classic gas release model was used while considering the pressure decrease in the tank to get the mass release time variation. This was mainly interested in estimating the resulting jet fire heat release rate and duration and the corresponding impact on the global heat release curve. As far as vapor cloud explosion (VCE) is concerned, the worst-case situation, more precisely the largest flammable mass is obtained in the first seconds following the release beginning. The specificity for VCE represents the tunnel confinement's influence on the pressure wave propagation. In such an environment, the commonly used multi-energy approach, based on semi-spherical wave propagation is inappropriate, reflexion phenomena should be introduced to provide a better prediction. The consequence modeling shows that, for both technologies, the worst dangerous phenomena remain the tank burst, especially for LNG where the lethal effect may affect most of the people present in the tunnel, for CNG lethal effect should reach 30 m and more for the same tank burst scenario. This huge consequence highlights the importance of preventing its occurrence through the efficiency of dedicated safety measures but also fire prevention since such a tank burst is induced by a fire in the surrounding of the tank. For the jet fire case, the consequences are a global vehicle heat release rate increase, during the gas release, while this could influence the efficiency of the tunnel ventilation, this does not significantly modify the thermal consequences for people. Regarding the vapor cloud explosion, lethal overpressure would affect passengers of the few closest vehicles for LNG and users in an area of 4 to 20 m centered on the vehicle for CNG
Experimental study of the mitigation of hydrogen-air explosions by inhibiting powder
No full textInternational audienceThe development of hydrogen production technologies and new uses represents an opportunity toaccelerate the ecological transition and create a new industrial sector. However, the risks associated withthe use of hydrogen must be considered. Mitigation of a hydrogen explosion in an enclosure is partlybased on prevention strategies such as detection and ventilation and protection strategies such asexplosion venting. Even if applications involving hydrogen probably are most interesting for ventedexplosions in weak structures, the extreme reactivity of hydrogen-air mixtures often excludes the use ofregular venting devices, such as in highly constrained urban environments. Thus, having alternativemitigation solutions can make the effects of the explosion acceptable by reducing the flame speed andthe overpressure loading or suppressing the secondary explosion. The objective of this paper is to presentexperimental studies of the mitigation of hydrogen-air deflagration in a 4 m3 vented enclosure byinjection of inhibiting powder (NaHCO₃). After describing the experimental set-up, the mainexperimental results are presented for several trial configurations showing the influence of inhibitingpowder in the flammable cloud on flame propagation. An interpretation of the mitigating effect ofinhibiting powder on the explosion effects is proposed based on the work of Proust et al