Too many inaccuracies in the way a nuclear plant and nuclear reactor work to list.
In the scene with Jake pulling Ashley from the car, you can see the wire that is pulling the car further once he has her free.
When Jake and his mum are running toward the cellar and the power line falls on top, The struts holding up the wires disappear when they begin to run.
The tornado siren shown does not produce the sound that was dubbed in for the siren in the movie.
Wind Machines visible in 16:9 release of the film.