Quantitative assessment of risk due to NaTech scenarios caused by floods

Floods may cause severe damages to chemical and process facilities, triggering major accidents (fires, explosions, and toxic release). Such cascading events are termed as NaTech scenarios. In the present study, a specific methodology for the implementation of Quantitative Risk Assessment (QRA) of NaTech scenarios triggered by floods was further developed and applied to the assessment of different flood events and equipment categories. Specific vulnerability models allowed estimating the failure probability of both atmospheric and pressurized equipment, and the estimation of NaTech-induced release frequencies. A case-study representative of an industrial installation was discussed, comparing the risk due to conventional internal causes to that deriving from NaTech scenarios and identifying possible specific safety barriers. The case-study demonstrated that a significant risk increment may be associated to industrial facilities located in flood-prone areas when flood-triggered NaTech scenarios are considered.