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Two nuclear reactors in Virginia were shut down and so-called “Unusual Events” were being monitored at a dozen other nuclear power plants in the wake of Tuesday’s earthquake in the Eastern U.S.
No damage was immediately reported at any of the plants, and safety inspections were underway.
The U.S. Nuclear Regulatory Commission said it was monitoring an Alert at the North Anna nuclear power plant, seven miles northeast of the quake’s epicenter at Mineral, VA.
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Dominion Resources Inc. |
| The North Anna Power Station in central Virginia is one of four nuclear power stations operated by Dominion. Tuesday’s quake shut down two reactors at the plant. |
The quake—the strongest in Virginia’s history—measured 5.8 at its center; the North Anna plant, operated by Dominion Power, is built to withstand a quake of 5.9 to 6.1, the company has said.
No significant quake damage to bridges, tunnels, highways or infrastructure was immediately reported, but inspections throughout the affected states were continuing.
Automatic Shutdown
The two North Anna reactors shut down automatically after the earthquake struck Tuesday afternoon, the NRC said.
The reactors also lost their offsite power connection, and the plant declared an Alert, the second-lowest of the NRC’s four emergency classifications.
Four on-site diesel generators provided power to run basic plant functions, including the pumps that cool spent nuclear fuel stored at the plant, “and the plant’s safety systems are operating normally,” NRC said. “Plant personnel and NRC resident inspectors are continuing to examine plant conditions.”
Offsite power was restored Wednesday, and the NRC announced late Wednesday that the emergency declaration had been canceled.
NRC staff at the agency’s headquarters in Rockville, MD, felt the quake tremors and immediately began checking with nuclear power plants throughout the U.S., the agency said.
Global anxiety over the possibility of a nuclear meltdown triggered by a natural disaster have been running high since a catastrophic earthquake and tsunami destroyed the reactors at Japan’s Fukushima Daiichi nuclear power plant in March.
‘Vulnerabilities’ Reported
In April, an NRC inspection noted earthquake “vulnerabilities” at North Anna, according to the Center for Public Integrity. The NRC found that portions of water and gaseous suppression systems and hose stations “are not seismically designed,” the center reported.
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Nuclear & Industrial Safety Agency |
| Anxieties over nuclear plants’ vulnerability to natural disasters have been running high since an earthquake and tsunami hit Japan’s Fukushima Daiichi plant in March. |
The NRC report said that “potential leakage can occur through penetrations following a seismic event” and that the company would “evaluate the issues above in order to determine if additional mitigation strategies are required.”
Unusual Events
In addition to the North Anna shutdowns, the NRC was monitoring “Unusual Events”—the lowest emergency classification—at 12 other nuclear plants from North Carolina to Michigan after this week’s quake.
Unusual Events “indicate a potential decrease in plant safety,” the NRC said in a statement. It did not elaborate but said the plants that reported “Unusual Events” continued to operate while they were being inspected.
“In accordance with agency procedures, the NRC’s regional offices in King of Prussia, PA, and Atlanta have activated their incident response centers,” the NRC said in a release. “NRC resident inspectors at the affected nuclear power plants will continue to monitor conditions for the duration of the event.”
The plants declaring Unusual Events were:
• Peach Bottom, Three Mile Island, Susquehanna and Limerick in Pennsylvania;
• Salem, Hope Creek and Oyster Creek in New Jersey;
• Calvert Cliffs in Maryland;
• Surry in Virginia;
• Shearon Harris in North Carolina; and
• D.C. Cook and Palisades in Michigan.
Those events were later canceled and the plants were operating normally, NRC said late Wednesday.
Just hours before Tuesday’s quake, the nuclear industry issued a list of steps it had taken since the Japanese disaster to improve its readiness.
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