Will earthquake affect plans for third nuclear reactor?

Anthony J. Crone knew central Virginia's history of earthquakes when he toured the North Anna nuclear plant in 2004 with a delegation of federal geologists and nuclear regulators studying the site's suitability for a third and, potentially, fourth reactor.

Four months earlier, on Dec. 9, 2003, a magnitude-4.5 earthquake had shaken the region from an epicenter in Powhatan County.

It was a "light earthquake" by seismological standards and not unusual for a broad swath of Piedmont known as the Central Virginia Seismic Zone. It wasn't even the first earthquake in the area that year — a magnitude-3.9 quake had shaken Goochland County in May.

But now the seismic stakes are much higher in Virginia after a magnitude-5.8 earthquake rattled the East Coast on Aug. 23 from an epicenter in Louisa County, just 11 miles from the North Anna Power Station operated by Dominion Virginia Power.

The earthquake's vibrations shut down both reactors, which is the first time that has happened to a nuclear plant in the United States. And it happened less than six months after a magnitude-9 quake in Japan triggered a tsunami that crippled the Fukushima Dai-ichi nuclear plant and forced the evacuation of 59,000 people.

Now, geologists are studying the lessons of the Louisa earthquake, along with the nuclear industry, its regulators and opponents, including those against construction of a third reactor at North Anna.

"The latest central Virginia earthquake is going to be a windfall of valuable new information," said Crone, a research geologist at the U.S. Geological Survey's Geologic Hazards Center in Denver.

"It's going to offer us a tremendous amount of insight, not only for central Virginia, but to a large part of the central and eastern United States," he said.

Dominion officials say the August earthquake will have no effect on its plans for a third nuclear reactor at North Anna, currently being considered for licensing by the U.S. Nuclear Regulatory Commission.

The company already has an early site permit for the project, issued by the NRC in late 2007 after a four-year review that included a detailed analysis of the geology and seismic risks in the region, including a controversial fault confirmed beneath North Anna in 1973.

"The faults we see are not correlated to any (seismological) events we are seeing," said Eugene S. Grecheck, vice president of nuclear development at Dominion. "The faults we see are relics of the distant past."

Louis A. Zeller sees the lessons much differently as science director of the Blue Ridge Environmental Defense League, a longtime critic of the North Anna nuclear plant and opponent of its plan to expand.

The August earthquake shook the plant well beyond the level of vibration it was designed to withstand. Dominion found no significant damage to the plant or its critical safety systems, but Zeller said the potential danger became clear.

"It was a bad earthquake … which the power company and others said couldn't happen here," he said. "The fact that they dodged the bullet doesn't make me feel any better."

His organization has formally asked the Atomic Safety and Licensing Board, a quasi-judicial arm of the NRC, to consider the August earthquake as fresh seismological evidence that must be considered in the proposed licensing of North Anna Unit 3.

Dominion officials said the earthquake proved just how safe Unit 3 would be, given a design standard for ground vibration that's more than four times the standard used at North Anna Units 1 and 2.

The earthquake vibration at the most damaging, low frequencies was 1.5 times lower than the level from which the proposed unit is designed to protect, Grecheck said.

However, the ground vibrations were more than twice the standard for the existing reactors at a high frequency, according to the NRC. At the lower frequencies, the vibrations exceeded the standard for the units by 12 to 21 percent, Dominion said. That standard assumes the most damaging vibrations would last five times longer than they did Aug. 23, the company said.

David Lochbaum, director of the Nuclear Safety Project for the Union of Concerned Scientists, said the earthquake "reconfirmed our knowledge" about seismic hazards in central Virginia.

His concern is less about North Anna Unit 3 than the plant's other two units, which are among 27 existing reactors already identified by the NRC as facing greater threats from earthquakes than had been expected east of the Rocky Mountains.

The rules for proposed new reactors stiffened 15 years ago, but the NRC is still grappling with what criteria should apply to existing nuclear units.

"The earthquake isn't going to bypass the old reactors and focus its fury on the new reactor just because it's better protected," Lochbaum said.

* * * * *

Dr. Jane Pendleton Wootton's family has owned the house known as Cuckoo for seven generations. Built in 1818 on the site of the tavern where, in 1781, Jack Jouett began his famous ride to warn Gov. Thomas Jefferson of raiding Redcoats, the house has withstood the Civil War, hurricanes and fire.

The August earthquake was centered roughly 2 miles from Cuckoo. The vibrations shifted the roof, toppled four chimneys, and left a large crack down one side of the house.

"It's stood over all these years, but now it's pretty pitiful-looking," Wootton said.

Unbeknownst to Wootton, the house also had withstood many earthquakes within the Central Virginia Seismic Zone, including one in Goochland in 1875 that is estimated now as magnitude-4.8, the largest in the region until Aug. 23.

"Historically, it's been recognized as an area where there has been above-average earthquake activity," said Martin Chapman, director of the Virginia Tech Seismology Observatory.

It's also an area riddled with underground faults, most of them caused by the wracking of the Earth's crust during the formation of the Atlantic Ocean hundreds of millions of years ago.

In 1973, the Virginia Electric & Power Co., as it was known then, confirmed that it had discovered a fault in the excavation of the North Anna site. Three Virginia geologists testified that they had observed the fault in 1970.

In 1976, the NRC fined the company for 12 material misstatements of fact in not disclosing discovery of the fault sooner.

But the power company got the permit, also upheld in federal court, because geologists concluded the fault hadn't moved in millions of years. (Today, geologists say evidence of inactivity is more like tens of thousands of years.)

"Finding a fault isn't a real revelation," the USGS' Crone said. "The fundamental question is: What's the ability of that fault to generate earthquakes?"

The nature of seismic hazards in the region aren't the same as those in California or Japan, where the slipping of massive tectonic plates cause earthquakes of the magnitude that led to the disaster at Fukushima on March 11.

There aren't obvious major faults and ground folds in central Virginia as there are on the West Coast, geologists say, but that doesn't mean the region isn't a hive of seismic activity.

"Believe me, we have active faults in central Virginia," said Chapman, an associate professor of seismology at Virginia Tech. "That's what this earthquake demonstrates."