Aggregation of hazardous phenomena

The regulatory changes initiated by French law no. 2003-699 of July 30, 2003 have had the effect of encouraging manufacturers to carry out exhaustive analyses of the various accident scenarios likely to occur at their facilities. For example, the inclusion of different sizes of equipment breach, or the systematic consideration of the functioning and non-functioning of risk control measures (RCMs), has led to an "explosion" in the number of hazardous phenomena included in the risk assessment grid. To comply with the acceptability rule set out in the circular of May 10, 2010, manufacturers are proposing aggregations of phenomena. It can therefore be observed that, for equivalent facilities, the number of hazardous phenomena presented in the risk assessment grid may differ. This raises three main questions:

• Are there any rules specifying the nature of possible aggregations?

• How does aggregation work?

• What are the most common aggregations?