When it comes to the effects of a massive failure of the U.S. power grid, one of the most worrisome questions is what would happen to the nation’s nuclear power plants. We already have a disturbing example of what can go wrong: The March 2011 disaster at the Fukushima Daiichi nuclear plant in Japan. After an earthquake that knocked out grid-supplied electricity to run the cooling pumps, and the backup generators were also damaged by a subsequent tsunami, the plant was forced to rely upon battery backups, which proved unequal to the task. As a result, officials were helpless to prevent three of the plant’s reactors from overheating and ultimately releasing radioactive material into the atmosphere and the Pacific Ocean.
Charles Ferguson, President of the Federation of American Scientists, warns that many U.S. nuclear plants may be similarly inadequately prepared for a lengthy grid failure that would force them to rely upon backup power sources to keep their reactors cooled and avoid nuclear mishaps. “In the U.S., we've got 20 or so older reactors with that same design…some of them have a reliable 72 hours of backup power, some don’t,” he says.
According to a 2011 New York Times article, nearly all nuclear facilities have backup diesel generators in place to enable operators to keep circulating coolant and prevent the reactors from overheating. But if those generators are damaged somehow or run out of fuel, operators would be forced to rely upon backup batteries, which only are designed to last for four to eight hours—just long enough for technicians to restore grid or generator power, the Times reported. But in the event of a lengthy disruption of the grid, those backups would be insufficient.
A 2011 Nuclear Regulatory Commission task force report recommended that nuclear plant operators beef up their redundancy power sources so that they could go up to 72 hours without grid power, and that they have replacement equipment stored at an offsite location that could be delivered and installed in that time, even factoring in the sort of transportation slowdowns foreseeable in a disaster. The nuclear industry has since developed a strategy for adding more backup systems. But even with these improvements, nuclear plants might still remain vulnerable to a blackout that lasted for several weeks or longer.