Modéliser des scénarios Natech par le dépliage des réseaux de Petri

The multirisk can be defined as a complex system made up of different hazards (natural and/or technological),which can act in combination - with or without coincidence in time - and have an impact on potentially dependent issues andtheir vulnerability. Indeed, under certain conditions, different combinations of risks are likely to occur. Smaller events canalso lead to cascades of events that are highly damaging to communities. To better understand and prevent this type of event,a major challenge lies in formalism knowledge and in particular to provide a representation of scenarios. The scientificchallenges mainly concern the representation of interactions between the many components of this complex system andunderstanding the dynamics of the system. To meet these challenges, approaches based on Petri nets and their unfolding are arelevant solution. Petri nets and their unfolding can be used to represent a dynamic between hazards and their effects. In thispossibilistic approach, an event statistically improbable (often the most destructive) is represented as much as the mostoccurable events. In this paper, we look at the case of a NaTech event caused by a forest fire. The aim is to understand thedynamics and interactions of the variables involved in a forest fire in order to prevent and possibly avoid major impacts. Thisfeasibility study is carried out on a simplified but realistic system, using the ECCO and Ecofolder tools. Beyond the industrialaspects characteristic of NaTech events, we also consider the impacts on the forest. In terms of multi-hazard management, thePetri nets process has made it possible to identify scenarios with damaging outcomes. This makes it possible to prevent thesteps leading to devastating events.