Vulnerability of industrial facilities to attacks with improvised explosive devices aimed at triggering domino scenarios

• Improvised explosives possibly used for terrorist attacks were described.
• The TNT efficiency of ANFO and TATP was characterized.
• Domino effects caused by an attack with improvised explosive were analyzed.
• Domino scenarios induced by an attack were compared to conventional scenarios.

Process- and chemical plants may constitute a critical target for a terrorist attack. In the present study, the analysis of industrial accidents induced by intentional acts of interference is carried out focusing on accident chains triggered by attacks with home-made (improvised) explosives. The effects of blast waves caused by improvised explosive devices are compared with those expected from a net equivalent charge of TNT by using a specific methodology for the assessment of stand-off distances. It is demonstrated that a home-made explosive device has a TNT efficiency comprised between 0.2 and 0.5. The model was applied to a case study, demonstrating the potentiality of improvised explosives in causing accident escalation sequences and severe effects on population and assets. The analysis of the case-study also allowed obtaining suggestions for an adequate security management.