Probabilistic Natech risk analysis in the defence sector

Natural hazard-triggered technological (Natech) accidents refer to releases of hazardous substances due to natural hazard impacts to technological systems, leading to toxic emission, fire, or explosion events. While relevant EU policy and legislation (e.g., SEVESO III Directive 2012/18/EU) exist for industrial facilities, military installations are usually excluded from their scope. Nonetheless, Natech accidents could also occur in military facilities that store, process, or transport hazardous substances (e.g., explosives), potentially leading to severe consequences, which can be of vital importance for the national security, the safety of citizens, the environment, and the economy.

Recent EU military policy acts address the issue of the resilience of defence infrastructure or defence-related critical energy infrastructure under climate-related impacts, but Natech risks are not explicitly covered therein. This technical report aims to complement existing EU policies and increase the awareness on Natech risks in military facilities by providing scientific evidence. In this respect, a detailed methodology is presented for quantitative (probabilistic) Natech risk analysis for the defence infrastructure, offering a template methodology for similar risk analyses due to natural hazard impacts. Site-specific case studies are carried out, considering three Natech scenarios of increasing complexity. Earthquakes and cascading tsunamis are selected as triggering natural hazards that impact a fictitious military facility, which comprises a diesel oil tank farm and a magazine with explosives. Two Natech accident mechanism are analysed, which involve the direct mechanism due to immediate physical damage to defence assets, and the propagation mechanisms due to domino effects. Natech risk analyses are conducted for a reference period of one year, considering the risk metric of human health impacts. Thus, the annual individual risk of death or severe injuries is computed due to the physical effects of heat radiation in the event of fire, or blast overpressure in case of explosions.
For the examined scenarios, the derived individual risks are mapped in contour plots, showing the risk occurrence rate and the associated impact zones. Recommendations are also provided for all examined scenarios towards Natech risk reduction measures and mitigation of adverse consequences.

The developed case-studies could also support the scenario-building initiative of the Union Civil Protection Mechanism (UCPM) for disaster management planning at Union level.