A probabilistic risk-acceptance model for assessing blast and fragmentation safety hazards

There are many circumstances where decision-makers consider risks associated with explosions - from either natural or deliberate events - where the goal is clarity with respect to the actual safety and hazard risks posed to society and its people, systems and infrastructure. The paper describes how probabilistic safety and hazard modelling of blast and fragmentation can better inform a Quantitative Explosive Risk assessment (QERA). A QERA may be used to define an explosive safety distance based on the risk of explosive hazards being less than a societal acceptable risk. The concepts are illustrated with scenarios at a generic explosives ordnance (EO) site. In one scenario we demonstrate that current, deterministically based, regulations in Australia and internationally may be overly conservative. In other words, a deterministic based regulation may show that a building is located in an unsafe area, whereas a QERA can show, for the same building, that fatality risks are less than those deemed acceptable by society. Another example demonstrates the significant effect that uncertainty modelling, particularly that associated with post-detonation blast-loads, has on fatality risks.