Cyber Incident Blamed for Nuclear Power Plant Shutdown

Weiss said unplanned, automatic shutdowns such as what happened at the Hatch plant are costly, forcing utilities to purchase power from other parts of the grid to the tune of about $1 million a day. But more importantly, Weiss said, automatic shutdowns unnecessarily challenge nuclear safety systems.

"Anytime you have to shut down, especially with an automatic shutdown, you're challenging the safety systems," he said. "What happened [at Hatch] was absolutely what the plant was designed to do, but there's always that chance that something could go wrong."

The NRC has for years had regulations in place that require that all plants be able to defend against cyber attacks. But the agency is still in the final stretch of implementing more specific cyber-security regulations that would require plants to detail their plans for defending their digital networks as a condition of maintaining their operating license, said Scott Morris, deputy director for reactor security at the NRC.

"The plants are expanding their use of digital technology to put more megawatts on the grid, and because of that these lessons are going to occur," Morris said. "But our expectation is that when these types of events happen, that [plant operators] correct the problem and share the information broadly with the rest of the industry."

Unplanned nuclear plant shutdowns used to be a fairly common event, but not anymore, Weiss said. In fact, he said, another shutdown of a U.S. nuclear plant was also precipitated by a cyber event. In August 2006, Unit 3 of the Browns Ferry nuclear plant went into a shutdown after two water recirculation pumps failed. An investigation found that the controllers for the pumps locked up due to a flood of computer data traffic on the plant's internal control system network.

Weiss said many people in charge of SCADA systems have sought to downplay the threat that hackers pose to these complex networks. But he cautioned that internal, accidental cyber incidents at control system networks can be just as deadly as a carefully planned attack from the outside.

In June 1999, a steel gas pipeline ruptured near Bellingham, Wash., killing two children and an 18-year-old, and injuring eight others. A subsequent investigation found that a computer failure just prior to the accident locked out the central control room operating the pipeline, preventing technicians from relieving pressure in the pipeline.

"To people in the IT world, cyber means 'attacks,' but what I tell people is that in our world the predominant cyber events are unintentional," he said. "The flip side of that is if it can happen unintentionally, it can probably be caused intentionally and be a whole lot worse."

News of the Hatch incident also comes as the cyber-security posture of the electric and nuclear power industry is coming under increasing scrutiny from Congress and government investigators. Last month, the Government Accountability Office issued a scathing report about cyber security weaknesses at the Tennessee Valley Authority, the nation's largest public power company and operator of three nuclear plants, including Browns Ferry.

The GAO found that TVA's Internet-connected corporate network was linked with systems used to control power production, and that security weaknesses pervasive in the corporate side could be used by attackers to manipulate or destroy vital control systems. The agency also warned that computers on TVA's corporate network lacked security software updates and anti-virus protection, and that firewalls and intrusion detection systems on the network were easily bypassed and failed to record suspicious activity.