Risk assessment and risk contour mapping

Abstract

This paper presents a brief overview of risk assessment methodologies, focusing on safety in design and the different methods which can be combined for a full quantitative risk analysis (QRA). The results of a QRA are normally presented as individual risk and group or societal risk. The calculated individual risks are often presented in the form of an individual risk graph (IRG) or individual risk contours (IRC). The IRGs and IRCs are calculated for an example accident scenario: a release of ammonia at 2 kg s −1 for 1800 s, during different types of meteorological conditions. These examples clearly illustrate the development of the graphs and curves. Finally, it is concluded that a QRA (inclusive risk contour mapping) can be a useful tool, for example in land use planning. However, for the safety of a chemical plant, other methods for risk assessment are also available, and are indispensable.