Natech Risk Assessment with Imprecise Probabilities

Natechs are technological accidents that are triggered by natural disasters. The increase in the frequency and severity of climatic natural disasters and the growth of industrialization demand the development of dedicated methodologies for risk assessment and management of Natechs. Due to the lack of accurate and sufficient data, the risk assessment of Natechs has largely been based on subjective assumptions and imprecise probabilities, making the assessed risks and the subsequent risk management strategies less cost-effective. In the present study, evidence theory, as an effective technique for dealing with imprecise probabilities, and Bayesian network, as an effective tool for reasoning under uncertainty, are combined to develop a methodology for risk analysis of Natechs. Flotation of oil tanks during floods has been considered to exemplify the methodology. It is demonstrated that replacing the interval probabilities with average probabilities can result in different yet consistent risk values.