In which phase of the IEC safety lifecycle does likelihood analysis fit?

• A. Safety system installation and commissioning
• B. Hazards and risk analysis
• C. Overall scope definition
• D. Safety requirements allocation

Answer: (B)

Likelihood analysis is an important component of the hazards and risk analysis phase in the IEC safety lifecycle. This phase involves identifying potential hazards associated with a system and assessing the associated risks to determine how likely it is for these hazards to actually occur.

During this analysis, not only are hazards identified, but their potential to cause harm is evaluated based on the frequency or likelihood of occurrence and the severity of the consequences. By conducting likelihood analysis in this phase, engineers and safety professionals can prioritize risks and decide on appropriate safety measures and design approaches to mitigate them effectively.

The other options focus on different aspects of the safety lifecycle. Safety system installation and commissioning refers to the implementation phase, where systems are put into place. Overall scope definition is concerned with outlining the boundaries and context of the safety lifecycle project. Safety requirements allocation deals with specifying and assigning safety requirements once the risks have been identified and analyzed. Therefore, the likelihood analysis specifically aligns with the hazards and risk analysis phase, making it the correct answer.