ABSTRACT
The probabilistic approach is the most widely used method for characterizing both types of uncertainty. However, the purely probability-based approach to risk and uncertainty analysis can be challenged under the common conditions of limited or poor knowledge on the high-consequence risk problem, for which the information available does not provide a strong basis for a specific probability assignment (Zio & Pedroni 2013). This concern has sparked a number of investigations in the field of uncertainty representation and analysis which has led to the development of alternative frameworks that can be grouped in four main categories (Aven & Zio 2011): imprecise probability,
1 INTRODUCTION
Risk Analysis (RA) is a fundamental process to prevent accidents and other unwanted events possibly occurring during industrial process activities handling of hazardous materials. It is defined as the process of systematic use of available information in order to identify hazards and to estimate the risk (IEC 60300 1995). Depending on the accuracy required to the analysis, it can be qualitatively or quantitatively carried out. In qualitative methods no explicit quantification of the risk is obtained, whereas in the quantitative ones a numerical calculation of the risk level is addressed.
