Risk analysis in safety reports required by the Seveso Directive

The Seveso Directive of the EC requires the operators of certain industrial installations deemed to present a ‘major hazard’ to produce and submit to the appropriate National Regulatory Authority a report (notification) giving information relevant to the safety of the installation. In particular, information has to be given with regard to the quantity and nature of dangerous substances handled, the circumstances under which a major accident might occur and the measures to prevent such accidents and to mitigate their consequences. In effect, this requires some form of risk analysis to be carried out. The laws introduced by Member States have specified to greater and lesser extents how that should be done, in particular the extent to which the consequences and likelihood of possible accidents should be quantified. That, together with the general view of industry that there are real limitations as to how far meaningful quantification of those aspects is possible, has resulted in some differences in the style of reports prepared. When considering the question of risk analysis it is important to recognise that it comprises a number of elements from the identification of causes of possible accidents, through evaluation of their consequences and likelihood to, in the limit, an evaluation of the risk of harm to people. In general, industry takes the view that the identification stage, which is largely qualitative, is the most important and is necessary for the preparation of a safety report. It is also generally accepted that some evaluation of the consequence of possible accidents in quantitative terms is necessary to indicate that management appreciates the potential for harm. But that has to take account of the uncertainties in the analysis procedure. Such uncertainties also limit the extent to which a meaningful quantification can be made of the probability or likelihood of accidents and, even more so, of the probability of harm to people. Hence, industry is largely opposed to the general use of those elements of quantified risk analysis (QRA) in a safety case for reasons discussed by CEFIC in its position paper ‘CEFIC Views on the Quantitative Assessment of Risks from Installations in the Chemical Industry’.