Each LOPA incident sequence begins with which of the following?

Each LOPA incident sequence begins with an initiating event because this event marks the starting point of a potential risk scenario that could lead to undesirable consequences. The initiating event is typically an upset or failure that disrupts normal operations, such as a equipment malfunction, human error, or external factors. Understanding this event is crucial as it sets off a chain of events that can lead to a consequence if not adequately controlled or mitigated by protective measures.

The accuracy of identifying initiating events is essential in LOPA, as it allows risk analysts to systematically evaluate layers of protection that are in place to prevent the scenario from escalating. This analysis guides the assessment of whether the existing safety layers are sufficient to manage the risks associated with the potential consequences that follow. Therefore, starting the incident sequence with the initiating event aligns with the fundamental principles of LOPA, ensuring that subsequent evaluations can appropriately focus on the effectiveness of protection layers and risk mitigation strategies.