If anything good came out of the Fukushima Daiichi nuclear disaster that began last March, it is that regulators in the U.S. and elsewhere are paying more attention to the hazards of aging nuclear reactors. The unnerving outcome of this greater scrutiny is the knowledge that U.S. nuclear plants, especially reactors in the central and eastern U.S. are far more susceptible to earthquakes than previously thought. 

Plants built west of the Mississippi were built to withstand earthquakes because the risk was clear, but facilities in the Midwest and east were built when it was assumed that earthquakes in these regions were infrequent and minor.  However, today scientists aided by computers and satellites know that there have been many massive earthquakes in the past in the central and eastern regions of the country.

As a result of a new seismic map announced today by the U.S. Nuclear Regulatory Commission (NRC), nuclear-plant operators will be required to conduct new seismic studies for 96 reactors east of the Mississippi River to determine if their plants could withstand the shaking predicted by the government's new seismic model. They have four years to conduct their studies, which critics rightfully argue is too long. Even when the studies are complete, it is unlikely that many reactors will be upgraded to withstand bigger quakes because it would be costly and could force some to close.

The lesson here is that you should be prepared to deal with the horrible consequences of the "low probability/high consequence" meltdown of a nuclear reactor if one is located within 200 miles of your home, which if you live east of the Mississippi, there almost certainly is. 

Below is a map showing the location of operational U.S. reactors:

The official U.S. NRC map of active nuclear reactors allows you to zoom in and provides the names and other important information about each facility. 

At the very least, to deal with the meltdown of a nearby plant your material preparations should include Potassium Iodide pills, quality NBC masks and suits, and plenty of plastic sheeting and duck tape to seal off living spaces. You might consider additional gear if the risk you face is critical, i.e., there is a nuke plant next door. Contingency plans should cover sheltering in place (sealing your house, providing clean water, food, etc.) and evacuating outside the hazard zone.

It might seem unlikely you will face a meltdown, but then again, that is what the folks in Fukushima thought.