Dominion’s North Anna Nuclear Plant Loses Power After Quake
August 23, 2011, 8:17 PM EDTSTORY TOOLS
By Julie Johnsson and Brian Wingfield
(Updates with comment from regulator on earthquake damage in third paragraph.)
Aug. 23 (Bloomberg) -- Dominion Resources Inc.’s North Anna nuclear power plant was operating on backup diesel generators after a 5.8-magnitude earthquake knocked out its offsite power.
North Anna’s twin nuclear reactors automatically shut down during the earthquake, whose epicenter was less than 15 miles (24 kilometers) from the plant, about 85 miles southwest of Washington, according to the U.S. Geological Survey.
One of the plant’s four diesel generators, which are powering the reactors’ cooling systems during the blackout, stopped working as a result of a coolant leak, Roger Hanah, a spokesman for the U.S. Nuclear Regulatory Commission, said in an interview. Dominion Resources Inc. called a fifth standby generator into service to replace the broken unit, Ryan Frazier, a spokesman for Richmond-based Dominion, said in an e-mail.
“It’s not critical at this point,” Hanah said. “They are able to operate all safety systems off the generators they have.”
Workers at North Anna were trying to determine whether the generator was damaged during the earthquake or as the result of a mechanical failure, Hanah said.
North Anna, which generates 1,806 megawatts of power, enough to power 450,000 homes, is designed to withstand a 6.2 earthquake, William Hall, another Dominion spokesman, said in an interview. Following today’s earthquake, the station declared an “alert,” the second-lowest of four emergency classifications set by the nuclear oversight agency.
‘Conservative’ Restart
Hall said a damage inspection was still underway at 6 p.m. New York time. He said he did not know when the plant would restart.
“We will be conservative,” he said.
The earthquake was felt from Richmond, Virginia, to Toronto and as far west as Columbus, Ohio, and prompted power companies across the region to inspect pumps, motors and valves for damages. Twelve nuclear plants, including two as far west as Michigan, declared “unusual events,” the lowest of the four emergency designations set by the Nuclear Regulatory Commission, said Joey Ledford, a spokesman for the nuclear agency.
The incident provided a test of the U.S. nuclear industry’s earthquake preparedness at a time when regulators and industry operators are studying the lessons of the disaster at Japan’s Fukushima Dai-Ichi plants in March.
Response as Planned
“Based on all information we have thus far, the systems at every U.S. nuclear energy facility where the earthquake’s effects were felt responded as designed,” Tony Pietrangelo, senior vice president and chief nuclear officer at the Nuclear Energy Institute, a Washington-based industry group, said in a statement today.
The earthquake shows why the industry shouldn’t wait to implement safety improvements to guard against such events, said Bob Alvarez, a senior scholar at the Institute for Policy Studies, a group that pushes for tighter regulation on nuclear power.
“We don’t need to wait for earthquakes to fix safety weaknesses that have been lingering for several years,” Alvarez, 64, said.
After four Exelon Corp. nuclear plants in Pennsylvania and New Jersey declared “unusual events,” operators were performing “walk-downs” to scout for damage from the seismic activity, Chicago-based Exelon said in a statement.
Local Outages
PJM Interconnection LLC, which manages the electric grid for all or parts of 13 states and the District of Columbia, said about 2,700 megawatts of power generation was lost in Virginia and another 500 megawatts were lost in Pennsylvania and Ohio.
“There were outages, but they are local outages,” said Ray Dotter, spokesman for PJM, based in Valley Forge, Pennsylvania, in a telephone interview. “It wasn’t because the grid was unstable.”
U.S. nuclear plants are required to have batteries capable of powering a plant for four hours and diesel generators protected by a hardened structure. The power is necessary to keep nuclear fuel cool at the site, preventing a meltdown and a radioactive release.
Japan’s Fukushima reactors lost offsite power after a magnitude 9 earthquake struck in March. The tsunami that followed the quake wiped out its diesel generators, which weren’t secured, leading to a meltdown and the worst nuclear accident since Chernobyl.
Cooling the Core
“The reactors need power to cool the operating cores and spent fuel,” Chris Gadomski, a nuclear analyst for Bloomberg New Energy Finance, said in an e-mail. “If we lose the backup diesel generators at North Anna, you can have a similar situation as Fukushima developing there. Virginia Power should try to restore offsite power as soon as possible.”
North Anna has a seven-day supply of diesel fuel on site and more can be brought in, Dominion’s Frazier said in an e- mail. The plants’ backup generators “can cool the reactor indefinitely,” said the nuclear agency’s Ledford.
The Nuclear Regulatory Commission inspected North Anna earlier this year to evaluate whether it’s prepared to withstand disasters and blackouts as part of a survey conducted in Fukushima’s aftermath at all 104 nuclear plants in the U.S.
In a May 13 letter to David Heacock, president and chief nuclear officer of Dominion subisidary Virginia Electric and Power Co., the nuclear agency said its inspector hadn’t identified “any significant issues” with the station blackout diesel generator room and related equipment.
Seismic Design Lacking
However, the agency noted that a study by North Anna of the plant’s fire and flood protection structures had identified vulnerable areas that were “not seismically designed.”
“The licensee will evaluate the issues above in order to determine if additional mitigation strategies are required,” the letter stated.
When North Anna was built, some of these systems were not required to be designed to seismic standards, Hall said.
“We will do everything that needs to be done,” he said.
--With assistance from Mike Lee in Dallas, Zachary Mider in Chicago, Aaron Clark and Christine Buurma in New York, and Richard Heidorn in Washington. Editors: Susan Warren, Charles Siler
To contact the reporter on this story: Julie Johnsson in Chicago at jjohnsson@bloomberg.net
To contact the editor responsible for this story: Susan Warren at susanwarren@bloomberg.net
