Societal Risk

The PLL is a group risk measure that represents the maximum number of fatalities in a single accident, expressed in terms of the F-N curve for offsite personnel (i.e. societal risk to adjacent facilities/ surrounding residential areas). The F-N curve plots the cumulative frequency (F) of various accident scenarios against the number (N) of casualties associated with the modelled incidents.

The F-N curve for offsite personnel due to release scenarios from the HGN plant is illustrated in Figure 12.2a.