The aim of the paper is to present Ammonia pressure station from the major accident prevention point of view. This object, located in the SEVESO establishment, present a significant source of risk which can cause serious consequences to human health and the environment in case of major accident. Ammonia, classified as a named dangerous substance, is stored in 500 kilograms pressure vessel, which is inside of the pressure station placed. The highest risk for surroundings presents transport of ammonia pressure vessel from the storage to the pressure station and transport to the storage naturally.
For purposes of completion of approved SEVESO documentation, new risk assessment had to be processed. This paper focuses in particular on the possible negative impact on the environment in case of extraordinary release of ammonia from the pressure vessel. For calculation of consequence categories of the impact on the environment was selected methodology “Hazard & Vulnerability Index”. The H&V index methodology is a Czech, official and frequently used methodology recommended especially for the environmental risk analysis in the SEVESO establishments. The benefit of this methodology is in its options to evaluate the impact to different parts of the environment, i.e. surface waters, underground waters, soil medium and biota considering diverse vulnerability of these components.
Risk analysis via the H&V index methodology follows up on the determination of accident scenarios, a stage describing different transfer routes of ammonia release to the environment occurred in the establishment. The pressure vessel is to a steel pallet attached so that it can transported in the establishment by a forklift or truck. Four different places in the establishment was determined as the worst in terms of the environmental endanger (i.e. direct and indirect endanger of the environment, transport via sewer system etc.). Consequence categories were for closed surface water and biotic environmental compartments calculated.
In conclusion, risk acceptability of determined scenarios is estimated in acceptable level. Results are presented via risk matrix recommended by H&V Index methodology. Visualization of scenarios is created by GIS. Proposed preventive measures including the way of liquidation of ammonia accidental release close this paper.