It is impossible to win the great prizes of life without running risks.

—Theodore Roosevelt


Any risk analysis has to be based on a careful consideration of the hazards and threats that are relevant for the study object in its operating context. This chapter defines, explains, and gives examples of typical hazards and threats. Hazards are most often linked to some type of energy, and energy sources are therefore highlighted. Generic lists of hazards, threats, and energy sources are valuable tools for the identification of potential hazardous events. Examples of such lists are provided in this chapter. The possibility of technical failures is a special category of hazards, and the concepts failure and failure modes are therefore defined and briefly discussed.


A hazard is defined as:

image Hazard: A source of danger that may cause harm to an asset.

A “source of danger” is a property, a situation, or a state. It is not an event but a prerequisite for the occurrence of a hazardous event that may lead to harm to an asset. A hazard is often, but not always, related to energy of some kind.

Some examples of hazards are:

  • Ice on a sidewalk is a hazard, because you could slip, fall, and hurt yourself.
  • Drunk driving is a hazard, because you have a reduced alertness and may harm yourself and others.
  • Exposure to asbestos is a hazard, because ...

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