This research employed computational fluid dynamics (CFD) fire and explosion simulation software, FLACS, to evaluate the possible hazards of different worst-case scenarios within a petrochemical plant After the effect factors (overpressure. pressure impulse, and thermal radiation temperature) were calculated, the results of interest were, in turn, adopted to a self-developed risk analysis module to estimate the corresponding 3D individual risk value The latter value can further be utilized as an index for assessing suitable preventive action against specific hazard before any accident happens The whole procedure was realized by applying a preliminary consequence analysis on a naphtha-cracking plant site. The simulation results can assist the relevant personnel in understanding all the varied conditions during an accident and can also be used as a reference for emergency response planning. According to the results, the size of the vapor cloud has great influence on the hazard consequence Furthermore, a water spray system alone has limited potential on a disastrous accident and its mitigation effect can be observed via the corresponding 3D risk values. With the aid of the 3D dynamic consequence simulation and QRA (quantitative risk assessment) technique, the plant site safety can be effectively improved by means of implementing the preliminary hazard assessment and Suitable preventive control strategies. Crown Copyright (C) 2009 Published by Elsevier Ltd All rights reserved.