The military does not oversee the decommissioning of a nuclear power plant. Since most nuclear power plants since the 1950s have actually been privately owned, a private company would perform the task including security. The story is likely inspired by the 2011 Japanese Fukushima disaster after which there was an increase of nuclear plants shutting down.
As the team arrives at Marks House. Sylvester corrects Gen. Walker out that they only have 2 minutes and 12 seconds to avert a meltdown. It take the team a total of 2 minutes and 29 seconds to upload the signal to the reactor.
In the beginning, a subtitle says, "1 mile east of Montero Nuclear Reactor". The guy keeps heading south-east with his compass. If you are east of somewhere, and keep heading east, you will get farther away, not closer.