Applied Study On Probability Risk Assessment Of Major Hazards

Probability Risk Assessment (PRA) is a quantitative evaluation and its advantages have been emerged when compared with other safety assessment methods. At present, this method has been applied in significant projects all over the world. However, PRA is not applied in the field of hazardous chemicals because of its deficiency.Based on the practices accumulation of PRA, some improvements have been proposed which point to the problems existed. Meanwhile, application range of PRA is wider than before to some extents. This has a positive effect to develop safety assessment in our country.Probability Risk Assessment can be classified into 5 parts, including Hazard identification, probability estimates, the accident consequence assessment, determine acceptable risk and the feedback on the evaluation of the structure. In this paper, it discussed and focused on probability estimates, the accident consequence assessment, the feedback on the evaluation of the structure. An example about fireworks warehouse as major hazards is quoted to demonstrate that it is scientific and effective to improve the traditional PRA. The main contents include:1. Fuzzy Mathematics solved deficiency of basic data and problems of obtaining data ineffectively because of its functions to convert single probability data into confidential interval. Thus, applied Fuzzy Mathematics into PRA can satisfy the precision of PRA and improve the assessment efficiency as well.2. The core of PRA is FTA, however, FTA has some defaults and limits the application of PRA to some extents. In this paper, Bayesian networks method (BN) and Event Sequence Diagram (ESD) can solve and correct 3 main contradictions, including multiple state of analyzing accident, relative effects of sub-event and process of accident development. All of these 3 parts cannot be analyzed by FTA.3. In this paper, effects of fire spread and shock are analyzed through an example. Cellular Automata (CA) and Fuzzy Mathematics simulation combined method is used to analyze the trend of fire spread when discussing fire spread. Effects of shock after exploration are analyzed by FEM. These methods solve the disadvantages of traditional one which it is disable to simulate.4. It is difficult to confirm acceptable Risk all over the world. In this paper, acceptable risk degree is calculated and determined by considering each factor. Based on the results, all of these acceptable risk degrees can satisfy the needs of practical assessment.