QRA will postulate a number of failure events resulting in loss of contaminant of a hazardous material. Typically this failure event consists of leaks from pipe work and vessels, assumed to occur under otherwise normal operating condition for the system under the study. It is unusual for QRA to consider explicitly accidents occurring during the abnormal or process upset conditions.
QRA is done based on the ALOHA software for the maximum area to be covered in case of undesired events.
