Risk Assessment, 2nd Edition

Chapter 12 Development of Accident Scenarios

12.1 Introduction

An accident scenario is defined in Chapter 2 as a sequence of events – from an initiating event to an end event – with undesired consequences. This sequence may be regarded as a pathway from the initiating event to the vulnerable assets. Development of potential accident scenarios means to identify and describe the possible pathways from an initiating event until a suitable end event is reached. Identification of relevant hazards and hazardous events is discussed in Chapter 10.

An initiating event may in practice lead to a wide range of consequences to assets (see Chapter 2). Which assets to consider depend on the objectives of the study. The analysis may focus on a single asset or several assets at the same time. Some authors prefer to use the term target instead of asset, and the development of accident scenarios is also called accident sequence analysis.

12.1.1 Objectives of the Development of Accident Scenarios

The objectives of developing accident scenarios are to:

1. (1) Determine the possible accident scenarios (event sequences) that can possibly take place after a specified initiating event has occurred.
2. (2) Identify existing and possible reactive barriers that can stop or mitigate the various accident scenarios.
3. (3) Identify external events or conditions that can influence each accident scenario.
4. (4) Determine and describe the possible end events of each accident scenario.
5. (5) Determine the consequences ...