PURPOSES : This study analyzes the accident damage scale of hazardous material transportation vehicles not monitored in real time by the Hazardous Material Transportation Safety (HMTS) management center. METHODS : To simulate hazardous-material transportation vehicle accidents, a preliminary analysis of transportation vehicle registration status was conducted. Simulation analyses were conducted for hazardous substance and flammable gas transportation vehicles with a high proportion of small- and medium-sized vehicles. To perform a spill accident damage-scale simulation of hazardous-substance transportation vehicles, the fluid analysis software ANSYS Fluent was used. Additionally, to analyze explosion accidents in combustible gas transportation vehicles, the risk assessment software Phast and Aloha were utilized. RESULT : Simulation analysis of hazardous material transportation vehicles revealed varying damage scales based on vehicle capacity. Simulation analysis of spillage accidents showed that the first arrival time at the side gutter was similar for various vehicle capacities. However, the results of the cumulative pollution analysis based on vehicle capacity exhibited some differences. In addition, the simulation analysis of the explosion overpressure and radiant heat intensity of the combustible gas transportation vehicle showed that the difference in the danger radius owing to the difference in vehicle capacity was insignificant. CONCLUSIONS : The simulation analysis of hazardous-material transportation vehicles indicated that accidents involving small- and medium-sized transportation vehicles could result in substantial damage to humans and ecosystems. For safety management of these small and medium-sized hazardous material transportation vehicles, it is expected that damage can be minimized with the help of rapid accident response through real-time vehicle control operated by the existing HMTS management center.

This paper analyses the effect of parameters on the consequences of the unconfined vapor cloud explosion accident (UVCE) by the release of heavy gas (xylene vapor). Simulation results showed that the overpresure was increased with the increase of the release hole diameter and with the decrease of the interested distance and the wind speed. While, the overpresure was not nearly affected by the release height, weather and environmental conditions. From the results of the consequence analysis and analysis of affecting the consequences of UVCE, the emergency plan should be established taking into account these parameters.

For the unconfined vapor cloud explosion accident by the continuous release of gas-liquid flow of various saturated liquids in a vessel at ground level, overpressures were estimated and analyzed with various release conditions and materials by TNT equivalency model with vapor dispersion. We found that at same release conditions, overpressure showed n-heptane > xylene > n-hexane > toluene > n-heptane > benzene, respectively and that overpressure was increased with increasing the hole diameter and the storage pressure, but it was increased with decreasing the wind speed, the interested distance, and the vessel thickness.

In this case study, results of the explosion accident at MEK-PO factory were analysed by using the consequence analysis of quantitative hazard assessment and the explosion energy, the burst pressure of vessel, and overpressures at the explosion center and at 300m distance from the explosion center were estimated, respectively. As a result, we found that a cause of accident was the runaway reaction of product(MEK-PO) because of the molecular expansion in vessel and that the possibility of the runaway reaction was classified the mechanical failure(the obstacle of refrigerator or the shutdown valve), design error, and operating error by lack of thermochemical knowledge. Also, the evasive action to prevent accident was suggested.

The consequence analysis for the unconfined vapor cloud explosion(UVCE) accident by the continuous release of butane vapor was performed and effects of process parameters on consequences were analyzed in standard conditions. For the case of continuous release(87.8 kg/s) of butane vapor at 8 m elevated height in the debutanizing process of tile naphtha cracking plant operating at 877 kPa ＆ 346.75 K, we found that combustion ranges of dispersed vapor estimated by HMP model were 11.2~120.2 m and overpressures estimated by TNT equivalency model at 200 m were about 37.35~55.1 kPa. Also, overpressures estimated by Model UVCE I based on advective travel time to XLFL were smaller than those estimated by Model UVCE IIbased on real travel time between XUFL and XLFL. At the same time, damage intensities at 200 m and effect ranges by overpressure could be predicted. Furthermore, simulation results showed that effects of operating pressures on consequences were larger than those of operating temperatures and results of accidents were increased with increasing operating pressures. At this time, sensitivities of overpressures for UVCE accident by the continuous release were about 5 kPa/atm.