For process safety engineers, there is far more to risk assessment than the simple explanations given to most managers at work. For example, the author provides the basic equation: risk analysis + risk evaluation = risk assessment, suggesting that for engineering purposes there is a long but measurable road to travel before arriving at a working assessment of risk.
Aven sets about explaining how to plan and use risk analysis, its varied applications and limitations, with an explanation that is aimed mainly at those who understand the basic mathematical approaches involved. He also makes necessary forays into basic probability theory and statistics.
Some of the techniques he outlines, such as HAZOP, failure modes and effects analysis (FMEA) and fault tree analysis will be known to many qualified safety professionals, but his weighing of their strengths and weaknesses is helpful. FMEA, for example, can give a systematic overview of a system's possible failure points and encourages designers to focus in system reliability, but it does not necessarily identify all the sources of critical failure, or human or other non-technical factors. Similarly, techniques such as HAZOP and SWIFT (structured "what if?" technique) can require considerable time, skilled teams and other resources. Increasingly, such resources can be hard to find.
One of the main reasons for carrying out risk analysis is to describe risk clearly to others. Aven usefully outlines how to convey an overall "risk picture" and covers factors such as risk tolerability. Anyone engaging with risk analysis needs to understand the limitations of the processes and outputs.
Risk Analysis is highly instructive and well presented. The main audience is likely to be those who need to quantify process and other engineering risks and explain them to colleagues and contractors, and those who need to understand the numerical approaches and risk analysis techniques. This might include policymakers and senior managers who deal with engineering-related decisions, as well as engineering practitioners.