Development of generic scenarios of industrial accidents triggered by floods: a first step toward decreasing the vulnerability of industrial facilities

Interactions between natural events and industrial installations may lead to dangerous phenomena such as: fires, explosions, or toxic dispersions. The industrial sector is often unprepared for these Natech events, increasing its vulnerability. The final purpose of this study is to help industrial facilities to decrease their vulnerability to accidents triggered by floods. In order to attain this objective, the present article deals with the development of reference bowties that reconfigure the scenarios of these accidents. According to bibliographical research, Natech events are mainly caused by the releases of hazardous materials. This means that flood water can affect numerous parts of an industrial installation but only equipment in which hazardous substances can be found, are critical: storage units, process units and pipe networks. It is their damage that causes the LOC (Loss of Containment), responsible for generating dangerous phenomena. Studies on past accidents also showed that depending on the levels of flood severity, flood water can cause different categories of structural damage to critical equipment and thus affect the intensity of the LOC. Consequently, for each critical equipment identified, a list of structural damages (critical events) is associated depending on three levels of flood severity. Then, for each critical event, a bow-tie is elaborated. The development of nine generic bow-ties is the first step of a three step methodology of risk assessment aiming at the development of a checklist to be used in order to decrease the vulnerability of facilities to accidents triggered by floods.