An Analysis of the Cumulative Uncertainty Associated with a Quantitative Consequence Assessment of a Major Accident

The accident consequence estimation for a particular hazardous installation consists of source term estimation, dispersion simulation, and an assessment of the effects on the people, buildings and equipment. In the article the typical range of the uncertainty of each separate step is assessed and then combined and analysed with the view to understand their cumulative influence on the uncertainty surrounding the resulting consequence value. Certain assumptions and a simple error calculation formula have been applied to produce the analysis of influence of individual error estimates on the final consequence assessment. The data used are partially taken from past benchmarking exercises conducted by the Major Accident Hazards Bureau (MAHB) of the European Commission's Joint Research Centre, and partially from literature sources. The methodology for combining the separate uncertainty values together and the results of the analysis of the combined influence of the uncertainties associated with each step are described.