Off-site Consequence Analyses
Note that there are specific requirements for the Offsite Consequence Analysis (OCA). For the “worst case scenario”, a scenario must be analyzed which addresses the complete loss of largest amount of ammonia (held in a single vessel) over a period of 10 minutes. For the Alternative Case Scenario, a more likely scenario is to be analyzed which represents a ‘more likely’ scenario than the worst case scenario. Examples of alternative release scenarios include (but are not limited to) relief valve discharge, pipe leak, or pipe and fitting leak.
There are computer technologies available for performing these calculations which should define the threat radius (where the ammonia concentration would not exceed 200 ppm), the population within the radius, any relevant populations/receptors (schools, hospitals, etc.), and any environmental issues such as navigable streams, parks, etc.
For further information regarding Offsite Consequence Analyses (OCAs) and/or other PSM related questions, please contact CECI.