Development of fragility models for process equipment affected by physical security attacks

The vulnerability of chemical and process facilities toward physical security attacks depends on the equipment resistance against such attacks and on the performance of Physical Protection Systems (PPS) in place. To enhance the protection against intentional attacks, the development of quantitative vulnerability metrics is essential, nevertheless current standard approaches only offer qualitative or semi-quantitative evaluations. The aim of the present work is to develop a quantitative methodology for the assessment of chemical and process facilities vulnerability towards external acts of interference. The proposed methodology is based both on the evaluation of equipment structural integrity in response to different types of specific impact vectors characterizing intentional attacks and on the quantitative performance assessment of related PPS. In particular, specific fragility models were developed for impact vectors associated with improvised explosive devices, firearms, and incendiary weapons. The novel fragility models were implemented in a comprehensive security vulnerability assessment (SVA) based on Bayesian Networks, in which the contribution of PPS performance was also considered. A case study was defined and analyzed to exemplify the application of the proposed approach. The results obtained allowed for the identification of the most critical security-related escalation scenarios and thus for an improved quantitative SVA.Seventh Framework Programme (FP7)LIFE20 ENV/IT/000436Security and Global Affair

Dynamic vulnerability assessment of process plants with respect to vapor cloud explosions

Vapor cloud explosion (VCE) accidents in recent years such as the Buncefield accident in 2005 indicate that VCEs in process plants may lead to unpredicted overpressures, resulting in catastrophic disasters. Although a lot of attempts have been done to assess VCEs in process plants, little attention has been paid to the spatial-temporal evolution of VCEs. This study, therefore, aims to develop a dynamic methodology based on discrete dynamic event tree to assess the likelihood of VCEs and the vulnerability of installations. The developed methodology consists of six steps: (i) identification of hazardous installations and potential loss of containment (LOC), (ii) analysis of vapor cloud dispersion, (iii) identification and characterization of ignition sources, (iv) explosion frequency and delayed time assessment using the dynamic event tree, (v) overpressure calculation by the Multi-Energy method and (vi) damage assessment based on probit models. This methodology considers the time dependencies in vapor cloud dispersion and in the uncertainty of delayed ignitions. Application of the methodology to a case study shows that the methodology can reflect the characteristics of large VCEs and avoid underestimating the consequences. Besides, this study indicates that ignition control may be regarded as a delay measure, effective emergency actions are needed for preventing VCEs.Safety and Security Scienc