Use of risk analysis in safety decisions

Evaluation of risks from a major energy system such as coal, nuclear and oil is receiving increasing attention. However, the best use of risk results in safety decisions must take into consideration many factors and still unresolved limitations. For example the different kinds of risks, the time periods when risk is manifested, occupational risks versus public risks, comparability of risk results, assessment of uncertainties and completeness. Even when the uncertainties are adequately assessed, methods for including them in quantitative comparisons are not well formulated. Likewise the uncertainty problem may prevent valid conclusions regarding the relative ranking of significant contributors to risk. In addition insights based on risk analysis performed on a global or national basis can significantly deviate the conclusions of a site specific analysis. Based on the results of a comparative study of risks of energy from coal, oil, gas, LWR, and solar power (STEC-system) this paper will explore the sensitivity of the results to the various parameters describing the risks and the limitations of the conclusions which can be drawn. The paper also suggests that it is more useful for societal decisions to incorporate risk analyses into cost-effectiveness analysis. Cost-effectiveness analysis allows identification of those energy systems and areas within an energy system where a given expenditure will produce the greatest reduction in risk. This is facilitated by the fact that risks cannot be reduced to zero and each incremental reduction in risk costs increasingly more. This paper will also suggest that there is a limit to continually reducing the risk because excessive expenditures on risk reduction will actually increase the risk to society. The paper will identify and investigate parameters which the results of cost-effectiveness studies are sensitive to