Atypical Scenarios Identification by the DyPASI Procedure: Application to LNG

Several severe accidents in the chemical and process industry were caused by “atypical scenarios”, that may be defined as unexpected scenarios which were not identified by conventional hazard identification processes. The accidents that took place in Buncefield, Tolouse and Seveso were characterized by atypical scenarios. Within the European Commission FP7 iNTeg-Risk project a specific tool, named DyPASI (Dynamic Procedure of Atypical Scenarios Identification), was developed. The aim of DyPASI is to make easier and systematic the inclusion of atypical incident scenarios in Hazard Identification (HAZID) processes, which are often unable to capture low probability or little known events. The method is based on a systematic review of the relevant past accidents and near misses. The aim of the present study was the analysis of the atypical scenarios in liquefied natural gas (LNG) regasification terminals by the DyPASI procedure. LNG is expected to play an increasingly important role in the natural gas industry and global energy markets in the next years. New technologies, mainly related to advanced floating and off-shore LNG terminals are now tackling the market of the new regasification plants proposed both in Europe and in the US. The four main categories that basically mirror the available regasification terminal lay-outs have been considered and analysed in the study: on-shore terminals, off-shore gravity based structures, off-shore floating storage and regasification units, and off-shore transport and regasification vessels. The application of the DyPASI methodology resulted in the comprehensive identification of potential risks of each lay-out, also taking into account uncommon events.