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

The task of the article is to quantify the uncertainty of the possible results of the accident consequence assessment of the chemical production plant and to provide some description of potentional problems with literature references and examples to help to avoid the erroneous use of available formulas. Based on numbers presented in the article we may conclude, that the main source of uncertainty in the consequence analysis of chemical accident assessment is surprisingly not only the dispersion simulation, but also the source term assessment, as it is strongly influenced by subjective factor, and the probit analysis, because of the weak knowledge of the hazardous material on man effect. The error in the source assessment influences the concentration and probit analysis. The concentration analysis relative error may reach 200% and the probit error depends strongly both on the absolute value of the concentration and on its error. Decrease of the final uncertainty could be reached by the quality assurance and independent result validation, what removes the subjective factor, so in the end we may finally decrease the probit result relative error from the common 250%. This consideration is but only valid for the flat unobstructed terrain, when the latest standard simulation tools are used.

JIRSA Pavel; 

2007-05-22

INST CHEMICAL ENGINEERS

JRC30797