At time 0252 EDT, the control room overhead
annunciators malfunctioned resulting in the inability to receive more than one station alarm input and could not be acknowledged using the normal station alarm acknowledge pushbutton.
This condition existed from time 0252 EDT until time 0516 EDT on 5/26/2014 at which time the system was restored. During the entire period, backup assessment capability was functional, dependent upon redundant assets as described in existing station documentation and/or functionality of the control room alarm typer. Additionally, the station computer alarms and Safety Parameter Display System remained functional during the entire time period.
The licensee will continue to investigate the annunciator system.
The licensee notified the NRC Resident Inspector.
The licensee will also notify State and local government agencies.
