Initiating Event

Definition:
An Initiating Event is the first occurrence that can lead to a hazardous event if not properly managed. It is a key component in a HAZOP, typically documented in the first (far left) column. Ties into the “guide words” that a HAZOP uses.

Key Points:

• Used to calculate initial event frequencies in risk assessment.
• Triggers the on demand safety functions.

Example:
Loss of cooling to a reactor jacket is an initiating event.

See Also: H&RA, HAZOP

Cited Source:

• CCPS Guidelines for Chemical Process Quantitative Risk Analysis.