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International audience; Serious games and environmental computer-based simulations can be useful training tools for people who have to act in emergencies. Currently, stakeholders who deal with crises have to make decisions under stress, for example in order to mitigate consequences or avoid negative impacts on high-stake elements. Many factors are critical in a training environment for ensuring that effective learning occurs, principally: experience improvement, engagement and immersion, and realism. This paper aims to identify the limits of existing learning systems for emergency stakeholders within a crisis cell and then to propose a set of recommendations in order to specify a system to improve the effectiveness of peoples' actions in case of a major crisis. The development of this approach requires the pooling of information concerning varied and multidisciplinary skills. The paper first focuses on the classical difficulties of crisis management, after which the notion of experience in decision-making is defined. The issue is studied from three points of view: the educational approach, the simulation system, and the training environment. The last section of this paper contributes to establishing a set of enhancements which can lead to the specification of simulation based learning systems for further development. More particularly, we specify the needed characteristics of our learning approach and teaching strategy. Finally, we propose a model with the main steps that have to be implemented in order to design a new learning system: a semi-virtual training environment for strategic crisis management.

Dispersion models are mostly validated on the basis of historical dispersion experiments. The latter imply large quantities of hazardous products (flammable or toxic gases), and are dedicated to study the dispersion of the resulting clouds on great distances from the source to reach a better knowledge of the different phases of gas dispersion (slumping, creeping, passive dispersion…). However, dispersion models have hardly been validated on small releases and therefore require more validation on small plumes of dangerous gases. Indeed, what is their reliability in case of accidents involving small amounts (e.g., chlorine leakages at swimming pools’ installations), and for small distances downwind the gas source? This information is of prime interest in so far as small releases are more likely to occur than larger ones. This paper reports on chlorine small-scale dispersion experiments and deals with the comparison between experimental data of ground level concentrations in the plume and predicted concentrations obtained from several dispersion models.

The mitigation of the consequences of accidental releases of dangerous toxic and/or flammable cloud is a serious concern in the petro-chemical and gas industries. Nowadays, the water-curtain is recognized as a useful technique to mitigate a heavy gas cloud. The paper presents a research methodology, which has been established and undertaken to quantify the forced dispersion factor provided by a water-curtain with respect to its configuration. The method involves medium-scale field tests, Wind-Gallery tests and numerical simulations. These different approaches are discussed and exemplified by typical results emphasizing the observed concentration reduction due to the water-curtain.

Numerous accidents involving dangerous substances may unfortunately occur, namely because of the importance of the transport of dangerous materials, of the storage and use of dangerous products on industrial sites. Several kinds of barriers can be used to protect or reduce the consequences of these accidents, such as the water curtains which mitigate the atmospheric dispersion of toxic clouds. Nevertheless, few studies assessing their effectiveness exist and models predicting the concentrations downstream of water curtains are scarce. In this context, a new concept, based on the representation of the water curtain as a Discontinuous Virtual Source is proposed. From this concept, the DVS model aims to predict on one hand the influence of the ‘peacock tail hose’ (vertical and upwards water curtain) on the dispersion of a toxic cloud, on the other hand, to predict the concentrations downwind of the water barrier. The bases of the model are set out and the results of the simulation, are presented and compared with experimental values of an ammonia plume dispersion in presence of the peacock tail spray.

The objective of this paper is to increase current knowledge on the dispersion of a small plume of chlorine using medium scale field experiments. An experiment using a peacock tail spray was undertaken to study the mitigation of the chlorine cloud.

This paper presents the results of some dispersion experiments of liquefied ammonia in the presence of peacock tail water curtains. The aim of this paper is to evaluate the effectiveness of water barriers to counteract a weak release of ammonia under pressure (0.25 kg/s). The dissolution of ammonia in the water curtain is rather poor (about 15%), but at 10 m behind the curtain the effectiveness can reach levels as high as 90%. The results of the effectiveness obtained with ammonia releases of 0.25 kg/s are compared with results from those obtained from a release of ammonia half the size.

International audience; We have studied the sequence of events that occurs when a high-speed projectile (from 960 m s−1 to 1480 m s−1) penetrates a vessel filled with toxic liquid. We find that prior to liquid ejection several well-defined phases occur, including the phenomenon known as the “hydraulic ram.” Then a catastrophic tank failure leads to liquid ejection and fragmentation. This paper focuses on this phenomenon and explains how it can be related to the initial conditions of the target.

International audience; Since the events of September 11, 2001, the possibility of an intentional act targeting the chemical process industry has become realistic. It is, therefore, a great concern to be able to predict the immediate consequences of such an act. This study is intended to improve our knowledge about the sequence of events that occurs when a high-speed bullet (>1000 m s−1) penetrates a vessel filled with toxic liquid. We find that, prior to liquid ejection, several well-defined phases occur, including the phenomenon known as the “hydraulic ram.” This paper focuses on projectile–target interactions and explains how the decay of projectile velocity is related to the initial conditions of the target.

International audience; This work has been carried out in the framework of the ARAMIS project, which aims at developing a comprehensive procedure for assessing the risk level associated to an industrial site with respect to the surrounding environment. To this end, an index is defined which consists of the contribution of three terms, expressing the severity of the scenario consequences, the efficiency of the safety management and the vulnerability of the surrounding environment. The present work focuses on this last aspect concerning the determination of the vulnerability, of the area in the vicinity of an industrial site, of human, environmental (or natural) and material stakes. The applied methodology consists in identifying and quantifying the targets by the means of a geographical information system (GIS) and in assessing the contribution of each target on the basis of a multicriteria decision approach (Saaty method). The result is an operational tool allowing competent authorities, industrialists and risk experts to assess the vulnerability of the area surrounding an industrial site.

Communications address a significant part of the potential harms and risks associated with major crises (Ch. 1); they mitigate the potential negative reactions of stakeholders; they contribute to the resolution of conflicts; and they stimulate positive reactions for the manager's reputation, when the situation is appropriate (Ch. 2). However, the lack of formal evaluation of communications delivered to the public during major crises raises questions about the ability of managers to communicate effectively and to critically evaluate their communications, for example on Facebook (e.g., to maintain reputation and political activity, to respond to risks or to resolve conflicts, Ch. 3). In France, the Presidency of the Republic and journalists exploit Facebook continuously, and journalists increased their frequency of publication during a crisis of the Presidency's reputation (Ch. 4). Most of the French governmental offices ('Préfectures') use Facebook on a daily basis, and to alert the public about some risks - but they are not as visible as the Presidency (Ch. 5). Facebook is an important part of french people's information practices, but the manager must not lose focus of their other behaviors; their expectations of communications; and the purpose of communications, which is to trigger useful reactions, from the communicator's perspective (Ch. 6). In France, Facebook participates in reputational crises (e.g., spreading a scandal - Ch. 4); and Facebook helps maintain the reputation of the manager, if he or she plans to communicate and does not commit mistakes or 'faux-pas'. In parallel to the reputation management, managers sometimes have to communicate to support conflict management and/or to prevent the destructions of disasters preventively - if possible - and then respond continuously, as during the 2016 floods (Ch. 7); among other issues of crisis communication. Facebook is useful for responding to crises, but it does not solve management dilemmas, occurrence of natural disasters or the human factors leading to accidents and crisis management errors.; Les communications répondent à une partie non-négligeable des préjudices et des risques des crises majeures (Ch. 1); elles déjouent les réactions négatives des parties-prenantes; accompagnent la résolution des conflits; et elles attisent des réactions positives pour la réputation et l'activité du gestionnaire, quand la situation s'y prête (Ch. 2). Cependant, l'absence de bilan officiel autour des communications délivrées au public pendant les crises majeures questionne la capacité des gestionnaires à communiquer efficacement et à établir un bilan-critique de leurs communications, ne serait-ce que sur Facebook (e.g., pour maintenir la réputation et l'activité politique, répondre aux risques ou résoudre les conflits, Ch. 3). En France, la Présidence de la République et les journalistes exploitent Facebook en continu, et les journalistes accentuent leurs fréquences de publication pendant les crises de réputation de la Présidence (Ch. 4). La majeure partie des préfectures exploitent Facebook, y compris pour alerter le public au sujet de quelques risques - mais elles n'y sont pas aussi visibles que la Présidence (Ch. 5). Facebook occupe une place importante dans les pratiques informatives des populations, mais le gestionnaire ne doit pas perdre de vue leurs autres pratiques; leurs attentes en matière de communications; et la finalité des communications, visant à déclencher des réactions utiles, du point de vue du communicant (Ch. 6). Facebook participe aux crises de réputation (e.g., diffusion d'un scandale - Chap. 4); et cet outil permet également de maintenir la réputation du gestionnaire, si ce dernier envisage de communiquer et ne commet pas de faux-pas. En parallèle du maintien de sa réputation, le gestionnaire doit parfois communiquer pour accompagner la résolution d'un conflit et/ou pour déjouer les destructions des catastrophes à titre préventif - si possible - et y répondre ensuite en continu, comme pendant les crues de 2016 (Ch. 7); entre autres enjeux de la communication de crise. Facebook est appréciable pour répondre aux crises, mais ce réseau ne solutionne pas les dilemmes de gestion, l'émergence des catastrophes naturelles ou les facteurs humains conduisant aux accidents et aux erreurs de gestion.

Lessons learnt from past accidents emphasize that major crisis management’s limitations are mainly characterised by collective failures (organizational, behavioural and cognitive), absence and/or maladaptive training of actors. Indeed, the training exercises have limitations such as the assessment: it focuses on the technical skills of the group, not on non-technical skills mobilized, and it is not conducted in real time. The presentation of the results during the debriefing is also incomplete. The present work aims to present the EVADE method to assess trainees during crisis management training and feedback them. This method required the upstream creation of a typology of training objectives to be integrated into training and the identification of technical and non-technical skills of a crisis cell. The approach is based on behavioural markers which are used to identify mobilized skills of a group during exercise. The assessment tool is presented, through its construction and its functioning, and it is tested with trainees in crisis management exercises. Various examples of the results of restitution are then proposed for the debriefing., Les leçons tirées des accidents passés soulignent que les limites en matière de gestion de crise se caractérisent principalement par des dysfonctionnements collectits (organisationnels, comportementaux et cognitifs), l'absence et/ou la formation inadaptée des acteurs. En effet, les exercices de formation ont actuellement des limites telle que l'évaluation : cette dernière se concentre sur les compétences techniques du groupe, et non pas sur les compétences non techniques mobilisées, tandis qu'elle n'est pas effectuée en temps réel. La restitution des résultats lors du débriefing est également incomplète. Le présent travail vise donc à présenter la méthode EVADE afin d'évaluer les stagiaires au cours d'une formation de gestion de crise et de leur restituer les résultats obtenus. Cette méthode nécessite la création en amont d'une typologie des objectifs pédagogiques à intégrer dans la formation et l'identification des compétences techniques et non techniques d'une cellule de crise. L'approche est basée sur l'utilisation des marqueurs comportementaux utilisés pour identifier les compétences mobilisées d'un groupe pendant l'exercice. L'outil d'évaluation est présenté a été construit et testé avec différents publics de stagiaires dans des exercices de gestion de crise. Divers exemples de résultats de restitution sont ensuite proposés afin d'alimenter le débriefing.