A Model for Probabilistic Seismic Risk Assessment of Process Plants

Abstract

Seismic vulnerability of industrial plants processing hazardous substances is widely documented, and thousands of such facilities are located in areas of medium to high seismicity near population centers. Nevertheless, with the exception of the nuclear industry, national or international standards do not establish any procedure for the overall seismic risk assessment of industrial process plants located in earthquake-prone areas. Moreover, existing Probabilistic Seismic Risk Assessment (PSRA) methods developed by the nuclear industry are not readily applicable to process plants. In order to overcome this limitation, in this paper a novel general-purpose PSRA method is presented, able to systematically generate potential starting scenarios, deriving from simultaneous interactions of the earthquake with each separate equipment, and to account for propagation of effects between distinct equipment (i.e. Domino effects) keeping track of multiple simultaneous and possibly interacting chains of accidents. This allows to dynamically generate damage scenarios, and to rank their risk levels determining the critical process units that can be involved.