The Quantitative Risk Assessment (QRA) of major toxic hazards: Dissertation

During the last 20 years there has been a considerable increase in the use of Quantitative Risk Assessment (QRA). QRA identifies those areas where operations, engineering, or management systems may be modified to reduce risk, and may identify the most economical way to do it. It can be applied to the investigation of the siting and design options before deciding of the further management actions. In QRA, a variety of predictive models is employed. The results can contain uncertainties which arise from the approximations inherent in the model or the assumptions and judgments that are necessary to perform risk analysis. This work presents the estimation of source term, dispersion, consequences and individual risks arising from toxic hazards (development of RISKIT program) and some special areas in QRA considers such as: - effect of relative humidity - effect of ventilation and chemical reactions - application of fuzzy method to the selection of appropriate computer model - experiences of consequence and risk assessment in process design. The results of this work show that the deviation of the results due to using different models for specific situations in QRA cam be large; therefore, more experimental work is required in order to better validate the models. The experimental work of dispersion in certain areas, such as the effect of relative humidity, and the effect of ventilation and chemical reactions, has been very sparse. Proposals for improving the reliability of the models in QRA on the basis of the results of this work are presented. These concern, for example, the development of models and expert systems, and the use of QRA and its results. Because of the wide scope of this held and the scarcity of experimental data, the results of this work and the proposals presented should be considered only as a basis for further research and development.