Operator Manual Action

Operator Manual Action or Manual Operator Action is part of a pre-planned sequence in response to an event. Its specific to a required step when a person needs to perform an action. This is in contrast to an automatic action which is when an instrument detects and activates something.

Discussion on manual action vs automatic action

Automatic is generally more reliable then a human action. So if a plant uses a manual action to accomplish a safety function it receives scrutiny that its trained, practiced, and validated. In regard to a change per 50.59, changing an automatic to manual operator action will normally require NRC approval.

The reason to use manual action instead of automatic is because automatic could result in unnecessary automatic actuation. If time permits, it may be preferred for a person to interpret the plant conditions as valid prior to system actuation. For example, preventing scrams in response to invalid signals.