"Data storm" blamed for nuclear-plant shutdown

During the incident, which happened last August at Unit 3 of the Browns Ferry nuclear power plant, operators manually shut down the reactor after two water recirculation pumps failed.

An investigation into the failure found that the controllers for the pumps locked up following a spike in data traffic -- referred to as a "data storm" in the NRC notice -- on the power plant's internal control system network.

"Conversations between the Homeland Security Committee staff and the NRC representatives suggest that it is possible that this incident could have come from outside the plant," Committee Chairman Bennie G. Thompson (D-Miss.) and Subcommittee Chairman James R. Langevin (D-RI) stated in the letter. "Unless and until the cause of the excessive network load can be explained, there is no way for either the licensee (power company) or the NRC to know that this was not an external distributed denial-of-service attack."