Browns Ferry Nuclear Plant Scrammed (Shut Down)

Event Year: 2006 Reliability: Confirmed
Country: United States
Industry Type: Power and Utilities

Operators manually scrammed Browns Ferry, Unit 3, following a loss of both the 3A and 3B reactor recirculation pumps. The root cause was the malfunction of the Siemens Perfect Harmony VFD controller due to excessive traffic on the plant ethernet based integrated computer system (ICS) network.

From NRC report dated April 17, 2007:

The licensee determined that the root cause of the event was the malfunction of the VFD controller because of excessive traffic on the plant ICS network.


A manual scram or shutdown.

Action Description: Unit 3 VFD controllers were disconnected from the plant ICS network before restart. Unit 2 VFD controllers were also disconnected.