Risk Assessment: Theory, Methods, and Applications

CHAPTER 8

RISK ASSESSMENT PROCESS

We never analyze a system—we analyze only a conceptual model of a system.

—P. L. Clemens

8.1 INTRODUCTION

Part II of the book presents a number of methods that can be used as part of a risk analysis. The part is divided into nine chapters and each method is presented in the chapter where it is most relevant. Some methods are very specialized, while others have a wider scope and therefore span several aspects of a risk analysis. This makes it difficult to get a stringent classification, and some methods could therefore have been presented in more than one chapter.

The order of Chapters 9–11 is according to the main structure of a risk analysis as illustrated in Figure 8.1. Barriers are important in all risk analyses and the barrier concept is therefore discussed thoroughly in Chapter 12, and several methods for barrier analysis are presented. Human errors are claimed to be a major factor in many major accidents. Human errors and human reliability are therefore discussed in Chapter 13 and several methods for human reliability assessment are presented. Another important factor in many accidents is common-cause failure. Such failures are discussed in Chapter 15. The uncertainty of risk analysis results and the sensitivity of input parameters are discussed in Chapter 16. The two remaining chapters in Part II deviate a bit from the main structure. Chapter 14 presents job safety analysis and contains elements from several of the other chapters. Chapter ...