A problem on the non-nuclear side of the plant caused Browns Ferry's unit 1 reactor to shut down automatically Tuesday.
The unit's turbine tripped at 5:30 p.m. on a generator neutral over voltage signal, according to a report filed with the Nuclear Regulatory Commission. This, in turn, tripped the reactor's safety systems and it shut down. Main turbine bypass valves controlled reactor pressure during the shutdown, three main steam relief valves opened, and feedwater pumps maintained reactor water levels. The high-pressure coolant injection and reactor core isolation cooling systems were not activated. The plant shut down safely and remained offline as of Wednesday morning.
Browns Ferry 1 is a boiling water reactor. It is currently in the NRC's multiple/repetitive degraded cornerstone oversight column, and the plant reported that it will initiate a service request in its current corrective action program.