The present paper illustrates the results of a Quantitative Risk Analysis (QRA) case study of a refinery. The main purpose of a QRA is to evaluate the risk levels (both individual and societal risk) of a process due to Loss Of Containment scenarios (LOCs). A QRA can be used to optimize the risk reduction measures to be implemented to comply with a given tolerable risk level. Moreover, the development of a detailed QRA is the best opportunity to perform a specific analysis addressing structural response due to overpressure impacts caused by explosions and also estimating the Time To Failure (TTF) of structures and equipment due to thermal radiation of fires.
Part I of this paper is focused on illustrating how a detailed analysis of QRA results can provide valuable information for characterizing the blast phenomena parameters for a given location. The analysis gathers three key sources of information: (1) peak overpressure, maximum and minimum positive phase durations and impulses as a function of the cumulative frequency of occurrence; (2) total number of LOC scenarios which contribute to the impact of explosions (including vapor cloud explosions due to both immediate and delayed sources of ignition); and (3) the identification of each LOC scenario and associated individual frequency of occurrence. This information is valuable for ensuring the blast loading function for a subsequent structural response analysis (e.g., equivalent elasto-plastic Single Degree Of Freedom analysis), and also provides specific information regarding which LOCs contribute most on overpressure impact.