We can all breath a sigh of relief that this tree didn't cause a meltdown, only a shut down of the reactors.
From the Chattanooga Times Free Press: Felled Tree causes shutdown at TVA's Watt's Bar Nuclear Plant
Tennessee Valley Authority spokeswoman Gail Rymer says automatic shutdown procedures began at the Watts Bar plant when the electrical fault was detected on Friday afternoon.
Rymer says a homeowner cut down the tree that fell onto a 500 kilovolt transmission line close to the plant located near Spring City, about 55 miles southwest of Knoxville. All six reactors were back online by Sunday afternoon.
P.S. Don't blame Obama. It isn't his fault.