ABSTRACT
A multi-step approach for the deterministic estimation of the domino effects due to the projection of fragments was proposed by the Centre for Chemical Process Safety (CCPS, 2000). Such method consists in computing: (i) the explosion energy; (ii) the number and size of missiles produced by the vessel fragmentation; (iii) the initial velocity and angle of departure for each fragment; and (iv) the distance of fallout. Afterwards, by analyzing the plant layout, facilities located in the range of potential fallout of missiles are identified; these could be the potential sources of the accident escalation. To include the quantification of such domino effects into the QRA, the consequence and the frequency of the scenario must be estimated, their probabilistic implementation is necessary to extend studies such as those of Baesi et al. (2013) and Milazzo et al. (2010). The frequency of the domino scenario is the product of the frequency of the primary event and the probability of the following sequence of events (given the occurrence of the primary event). This probability is obtained by multiplying the probabilities of the fragmentation, of impact on a target and of damage given the occurrence of the impact (Nguyen et al., 2006). In this frame Holden and Reeves (see Lees 1996) developed models for the estimation of the fragmentation probability. Approaches to the modelling of the impact probability based on the
1 INTRODUCTION
The term domino effect denotes a chain of accidents generated by an initiating accident, which occurs in an industrial unit and causes more severe events in other units (accident escalation), either in the same establishment or in neighbouring industries (Delvosalle, 1996). The literature provides some relevant examples, i.e. see the survey performed by Fabiano & Currò (2012), however a complete inventory of domino effects was given by Abdolhamidzadeh et al. (2011). According to Khan & Abbasi (2001), a domino effect may be initiated by several events: (i) fires (pool fire, flash fire, fireball, and jet fire); (ii) explosions (vapour cloud explosions VCE, boiling liquid expanding vapour explosion BLEVE, vented explosion, confined vapour cloud explosion, dust explosion); (iii) toxic release (instantaneous or continuous release of toxic lighter and heavier than air gases, release of toxic liquids and dust), in this latter case aspects of the emergency management are involved.
