Research On Environmental Risk Assessment Of Hazardous Gas Release Accident Based On Uncertainty Analysis

In recent years, catastrophic accidents of atmospheric pollution caused by chemical gas leak have happened more and more frequently, causing significant loss of social properties and human health. In such context, the environmental risk management (ERM) has become a critical part of social management. As the basis of ERM decision making, environmental risk assessment (ERA) has been playing an important role in the environmental risk mitigation and reduction. Scientific ERA can support the ERM with necessary risk information; in addition, environmental risk assessment can also be used for land use planning, prevent the environmental risk by optimizing the spatial arrangement.The ERA theory and methodologies have been developed for decades, but the inherent uncertainty of risk hasn't been widely recognized and solved, so the current ERA is not scientific and reliable. so the current ERM is poorly risk-informed. To assure the risk decision-making are fully risk-informed, the uncertainty should be fully considered and analyzed in the process of ERA, to cover all the potential accidental scenarios, extract as much risk information from the somewhat unknown risk system as possible.In this article, the objective is to establish a new ERA system by the integration of the uncertainty analysis and the traditional ERA. The process of traditional ERA is thoroughly scoped and the uncertainties in each state are identified. The uncertainties have been considered as important factors that reduce the reliability of quantitative risk assessment (QRA), Monte Carlo analysis is used to assess the effects of six epistemic uncertainties sources on the result of vapor release modeling, and the result of uncertainty analysis is integrated into the final result of QRA. In geographic information system (GIS), the result of QRA are characterized in terms of individual risk and societal risk, and based on which the tolerability of risk is judged. A case study of application of the improved method of QRA on a chlorine release accident was carried out. It showed that the societal risk of the accident was not tolerable, some recommendations on environmental risk management were proposed for risk mitigation. It is concluded that the integration of Monte Carlo analysis with QRA is a more complete, scientific and reliable measure of risk assessment.