Approach for Domino Effects On Quantitative Risk Analysis

Domino effect is the propagation of an accident originated from a specific equipment or inventory to adjacent equipment or areas from an industrial site. Normally the propagation of fires or explosions from one area to others is not very representative for the risk of external population. This is due to the fact that, as a secondary effect, it will necessary be a localized event, with potential to increase damage to assets, but with few impact for people outside the limits of the instalation. The energy released from the first event pratically exclude the possibility of a new cloud dispersion from a flammable material, since the release due to domino effect will be immediately ignited from the energy of the first event.

Toxic materials that can be envolved or release due to domino effect as well as the possibility of reaching flammable storage areas of liquified products have a different relation to process areas, since these two specific events can lead to greater vulnerabilities areas and so reach a part of population that were not affected from the first event.

This work intends to present a methodology to calculate the domino effect and shows the results of it in terms of Societal Risk and Individual Risk in a Quantitative Risk Analysis Study. The definition of which events to consider for the domino effect, how to screen the equipment that will be affected, calculate the frequency for domino effects and incorporate it on the risk calculation. This model is implemented in Phast Risk software. In this paper we also show how the domino effects influence the risk for both internal and external populations, comparing to national and international acceptability criterias.