Event underscores delay by NRC in revising understated seismic risks to nuclear plants

^{Indian Point nuclear power plant's containment silos rise above the skyline along the Hudson River.  Julie Jacobson / Associated Press}

The Nuclear Regulatory Commission said two reactors were taken off line near Lake Anna in central Virginia, near the epicenter of Tuesday's earthquake, which shook buildings up and down the east coast. Eight other plants, including some in Pennsylvania , Maryland and New Jersey, declared "unusual events" requiring further scrutiny.

The NRC, in an April inspection meant to identify potential risks from an earthquake at the North Anna Power Station, noted earthquake "vulnerabilities" found there. Specifically, the NRC report notes that portions of water and gaseous suppression systems and hose stations "are not seismically designed."

The report noted that "potential leakage can occur through penetrations following seismic event."

In the report, the NRC said the company would “evaluate the issues above in order to determine if additional mitigation strategies are required.”

The NRC stated in a May 13  letter that it was trying to "promptly assess" the capabilities of the nuclear plant "to respond to extraordinary consequences similar to those that have recently occurred at the Japanese Fukushima Daiichi Nuclear Station."

The results from such inspections around the country, regulators continued, "will be used to evaluate the U.S. nuclear industry's readiness to safely respond to similar events."

U.S. reactors, including the four plants operated by Dominion Resources Inc. in Virginia, are supposed to be shut down in the event of a major earthquake such as the one that struck Japan in the spring of 2011. The Nuclear Energy Institute, an industry organization, noted Tuesday that "all U.S. companies have completed inspections of systems that protect nuclear energy facilities against these extreme events. Necessary changes to these systems are being undertaken by individual companies where warranted."

Exelon's Limerick plant near Philadelphia, Oyster Creek plant near Toms River, N.J., Peach Bottom plant near Lancaster, Pa., and Three Mile Island Unit 1 plant near Harrisburg, Pa., declared "unusual events."

At mid-afternoon, top advisors including NRC chairman Greg Jaczko told President Obama in a conference call that there had been no initial reports of major infrastructure damage from the quake, including at airports and nuclear plants. Obama asked them to let him know of any developments.

Since the Fukushima earthquake and tsunami, energy companies in the U.S. already were dealing with heightened investor anxieties over the status of nuclear power in the U.S.

Following the disaster, Robert S. Harris, a specialist in corporate finance and dean of University of Virginia's Darden School of Business, testified on behalf of Virginia Electric and Power Co. (Dominion Resources) before Virginia's State Corporation Commission on the company's cost of equity and general financial condition.

He noted that possible policy changes and heightened scrutiny of the industry have led to re-pricing of utility stocks and added "new uncertainties to the complicated challenge of finding a reliable, cost-effective and safe mix of power generation." And he added that "utilities with nuclear exposure have been harder hit" in the markets.

While hard to predict, Tuesday's earthquake along the east coast might add to the aftershocks on Wall Street.

What are the chances of an earthquake beneath a reactor near you? See this map.

As iWatch News has reported , regulators have been aware for years of understated seismic risks to nuclear plants -- but have dawdled on fixes to make reactors more secure. Despite six years of study, industry collaboration and a missed deadline, the NRC is still months from a decision. Read more here .

More information about the nuclear plants at Lake Anna is here.

The day of the east coast quake, the nuclear industry issued a list of steps it had been taken to learn lessons from the Japanese disaster. More information here.