Equipment vulnerability models for the assessment of domino effect caused by fire

Domino effect is considered one of the principal potential harms for major accident scenarios in chemical and process industry. It can be defined as a propagation of the primary event due to escalation vectors, generated by the physical effects of the primary scenario, resulting in an overall scenario more severe than the primary event that triggered the escalation. Over the last years, this growing concern leads to introduce the assessment of domino effect in the Quantitative Risk Analysis, as can be read in the Seveso Directives. This thesis work focused on the definition of a new vulnerability models for equipment exposed to fire, capable to take into account not only the characteristics of the targets but also the space and time evolution of the heat radiation. In particular, two probit equations, one for atmospheric tanks and one for pressurized tanks, have been developed. The first part of the study is dedicated to the definition of the dose and of the probit coefficients, using data sets derived from previous publications. Subsequently, some accidental scenarios were chosen in order to evaluate the validity of these equations and then, results obtained with the new method were compared to those ones obtained with a threshold values approach. In the final part of the work, the procedure developed has been applied to a case study.