ABSTRACT
Risk analysis is a technique for identifying, characterizing, quantifying, and evaluating hazards. Risk analysis, also called risk assessment, consists of two distinct phases: a qualitative step of identifying, characterizing, and ranking hazards; and a quantitative step of risk evaluation, which includes estimating the likelihood and consequences of hazard occurrence. The estimation of likelihood or frequency of hazard occurrence depends greatly on the reliability of the system's components, the system as a whole, and human-system interactions. This chapter discusses how the reliability evaluation methods are used, collectively, in a risk-analysis process. The risk-assessment process is primarily one of scenario development, with the risk contribution from each possible scenario that leads to the outcome or event of interest. Preparing for a probabilistic risk analysis (PRA) begins with a review of the objectives of the risk analysis. A critical building block in assessing the reliability and availability of items in complex systems is the failure data on the performance of items.
