Natech accidents triggered by cold waves

Natural events are a widely recognized hazard for industrial sites where relevant quantities of hazardous sub-stances are handled, due to the possible generation of cascading events resulting in severe technological acci-dents (Natech scenarios). To date, research efforts were mainly dedicated to the study of Natech scenarios triggered by earthquakes, floods, and hurricanes. However, a number of recent events evidenced the potential hazard of Natech scenarios triggered by cold waves and winter storms. The present study aims at providing a comprehensive analysis of past accidents involving hazardous substances triggered by cold waves affecting the industrial infrastructure. A dataset of over 740 Natech events was collected from specialized sources. A detailed analysis of the primary events and damage modes of the equipment items involved was carried out, highlighting that most of the accidents were linked to the phase transition from the liquid to the solid state of the process fluid or of atmospheric water. The analysis of the events allowed the identification of several aspects of the cause -consequence chains, such as the technological scenarios and the equipment items more frequently involved. A specific focus was also on the vulnerability and failure modes of safety barriers. The lessons learned derived from the analysis of the accidents provide key elements to prevent similar accidents from happening in the future. These were used to suggest specific safety barriers integrating winterization and freeze protection programs.