Treatment of Uncertainty in Risk Based Regulations and Standards for Risk Analysis

The role of quantitative risk analysis as a foundation for decision making, regarding hazardous activities and establishments, has gained increased importance during the last decades. When performing a quantitative risk analysis, a wide range of uncertainties will inevitably be introduced during the process. The impact of these uncertainties must somehow be addressed if the analysis is to serve as a tool in the decision-making process. The objective of this report is to present a summary of how issues of uncertainty are dealt with in existing safety regulations, and in existing standards for risk analysis and management. Using this summary as a guide, various aspects of uncertainty are discussed. E.g. what role will uncertainty play in the decision-making process? Is there a need for identifying and separating different kinds of uncertainty (e.g. aleatory, or stochastic uncertainty, vs. epistemic, or knowledge based uncertainty) while creating the foundation for decision-making? Will we always be dependent on expert judgement while dealing with these issues?

The work behind this paper is the first step in a research project with the objective to produce the basis for a Swedish Standard regarding treatment of uncertainties in quantitative risk analyses. The project is to be completed by the end of the year 2001.