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The FBI has joined the TVA and the Nuclear Regulatory Commission investigating a trespasser who exchanged gunfire with a security officer on the property of the Watts Bar Nuclear Plant early Sunday morning.
It is unclear why the intruder -- who escaped -- was there, and investigators are saying little.
But the nuclear plant, like all federal facilities, remains under high security alert in the aftermath of the Boston bombings last week, and investigators combed the area -- even with helicopters and surveillance aircraft -- for well over 12 hours Sunday.
"It's been a long day," FBI Special Agent Ed Galloway said Sunday evening. "All I can say is that we are devoting our resources and we are committed to resolving any issues here."
TVA officials said there was no threat to public safety or the security of the plant as the shots were fired well away from the plant's "protected area."
Jim Hopson, a TVA spokesman stationed at Watts Bar, said the incident occurred about 2 a.m. when a TVA security officer patrolling the plant's perimeter encountered the intruder near the Tennessee River, about 200 yards away from the cooling towers in territory clearly marked as a restricted area.
"The officer challenged that individual, and the individual fired at the officer," Hopson said. "The officer returned the fire, and as the officer was calling for backup as well as switching to a higher-powered weapon [he] had in the vehicle, the individual fled the site."
The officer was not injured, though his truck was struck, he said, and both the intruder and the officer fired multiple shots.
Hopson said he did not know how the person escaped -- by river or land. There was no indication that the intruder was injured.
He said investigators -- along with Rhea and Meigs County officials -- spent hours combing the riverbanks around the plant and across the Chickamauga Reservoir on the Meigs County side.
"A very detailed search of the site [including the plant's protected area] ... did not turn up any threats, which was why we exited out of the 'unusual event' notification," Hopson said.
The incident occurred about two football fields away from what TVA refers to as the plant's "protected area" where the reactors and power production equipment sits. But the river side is where water intakes are located that carry cooling water into the plant. The water that has circulated in enclosed pipes around the plant and through cooling towers is returned to the river.
NRC spokesman Roger Hannah said inspections of the protected area, the river area and that intake pumping station were made before the unusual event alert was ended.
"The plant staff has notified the NRC that it will continue to maintain security at higher than normal levels," Hannah said, adding that two security inspectors from NRC's Atlanta office will review the incident and TVA's response.
The Watts Bar plant is near Spring City and about 48 miles northeast of Chattanooga. One reactor there is at 100 percent power, and a second reactor is under construction.
TVA has had security problems at Watts Bar before, and two contractors have been convicted of falsifying records about inspections of nonexistent electrical cable that would have served the newest reactor's cooling system.
The NRC in 2011 placed Watts Bar under a security safety flag for several months, but neither TVA nor NRC would discuss why.
U.S. District Attorney William "Bill" Killian said he could not comment Sunday about this newest security investigation.
Contact staff writer Pam Sohn at psohn@timesfree press.com or 423-757-6346.