T
he NRC requires all nuclear power plants to consider the effects of possible earthquakes in their area – designing, operating and maintaining safety-related structures and equipment to ensure that they can endure a seismic event and still function.
Two events in 2011 only a few months apart highlighted the importance of the NRC’s seismic regulations.
In March 2011, a strong earthquake off the coast of Japan caused a tsunami that disabled power supplies and cooling to several nuclear reactors at the Fukushima 
Daiichi nuclear station. Important safety structures and equipment were largely undamaged by the earthquake’s ground motion, but flooding created major problems.
Months later, In August 2011, a much smaller earthquake occurred near Mineral, Va., close to the North Anna nuclear station.
The quake exceeded some levels for which the plant was designed and licensed, but detailed reviews and inspections by Dominion, the plant operator, and the NRC confirmed there was no damage to safety equipment. Both North Anna units remained offline until November of that year when the NRC was certain they could be restarted safely.
NRC seismologists have worked closely with NRC inspectors, license reviewers and others within the agency to apply the real-world lessons of Fukushima and North Anna to all other U.S. nuclear plants. The NRC is working to ensure potential earthquake hazard information for each nuclear plant site accurately reflects what might be expected, and the agency is requiring nuclear plants to reanalyze those risks over the next several years.
Fortunately, the seismic risk for most U.S. nuclear plants is very low, but the NRC continues to examine information from actual earthquakes, review improved predictive models and inspect plants to be certain that people living near U.S. nuclear plants are adequately protected if an earthquake does occur in that area.
We’ll be posting a new YouTube video on the subject soon, and please join our Chat, tomorrow, with NRC seismic expert Dr. Annie Kammerer. She’ll be “chatting” about how the NRC makes sure plants can withstand any earthquakes they may experience. She can also talk about the Mineral, Va., earthquake but won’t be able to address specific questions about designs or risk at other sites.
Note: The Chat is now closed. To view the archive, go here: http://chat.nrc-gateway.gov/2013/07/31/earthquakes-and-nuclear-power-plants-this-chat-is-closed/
U.S. NRC Blog 
High levels of radioactive tritium, far exceeding the EPA acceptable levels in one onsite well at North Anna ….for years NOW and Dominion still doesn’t know where the leak is coming from.
Click to access ML15105A080.pdf
I read that cooling pipes were broken by the quake even before the tsunamis hit.
I also want to say that In a simple odds-versus-stakes analysis, the reactors at Fort Calhoun and Cooper should never have been built.
If the odds of something are very low, but the stakes are the Corn Belt, then the stakes are too high for the bet.
Then after the dam water “tsunami”, there would little to no water for cooling and that could spell DISASTER, if emergency electrical generation was lost…
RE: Fortunately, the seismic risk for most U.S. nuclear plants is very low…
They said that about Fukushima, until 3/11/11 happened now they have a Trillion Dollar Eco-Disaster!
FACT: A once in a hundred year or even a thousand year event is just as likely to happen tomorrow as many years in the future; then what?
This is where the NRC and the nuclear Industry fails the public trust because they live in Nuclear Denial* because they believe nothing BAD will happen to any Nuclear Power Plants (NPP’s).
Example:
French Nuclear Disaster Scenario Was So Bad The Government Kept It Secret http://www.businessinsider.com/potential-cost-of-a-nuclear-accident-so-high-its-a-secret-2013-3 via @bi_contributors
snip
Catastrophic nuclear accidents, like Chernobyl in 1986 or Fukushima No. 1 in 2011, are, we’re incessantly told, very rare, and their probability of occurring infinitesimal.
But when they do occur, they get costly. So costly that the French government, when it came up with cost estimates for an accident in France, kept them secret.
But now the report was leaked to the French magazine, Le Journal de Dimanche. Turns out, the upper end of the cost spectrum of an accident at the nuclear power plant at Dampierre, in the Department of Loiret in north-central France, amounted to over three times the country’s GDP.
* http://is.gd/XPjMd0
The illogical belief that Nature cannot destroy any land based nuclear reactor, any place anytime 24/7/365!
Are dams upstream of nuclear power plants analyzed for earthquake protection adequacy? An example would be those dams along the Missouri River upstream the Fort Calhoun and Cooper nuclear stations. A catastrophic failure of these dams would result in a tsunami for these plants.