What should be done first if a fire detector fails during testing?

When a fire detector fails during testing, the priority action is to replace the defective unit. Fire detection systems are critical for the safety of a powerplant, as they provide early warning of potential fire hazards. A non-functional detector compromises the ability to detect fires effectively, which can lead to dangerous situations.

Replacing the defective unit immediately ensures that the system remains operational and capable of responding to a fire threat. This action directly addresses the problem at hand, restoring the integrity of the fire detection system without delay.

While it is essential to conduct investigations, inform the maintenance team, and possibly reset the alarm system as part of ongoing safety procedures, the immediate focus is to ensure that the fire detection capability is fully restored by replacing any non-functional components. Each of these subsequent actions plays a role in a larger safety protocol but should occur only after the defective unit is addressed.