Instead of asking sensationalist questions designed to create fear...why not look into it?
https://www.sciencedirect.com/science/article/pii/S173857331...
The studies have already been done, crashing a jet into a nuclear power plant wont do much.
I'm more familiar with Canada's designs and the walls are several M thick of reinforced concrete. Not exactly material known for being easy to break into.
This is from the power plant close by me :
https://www.google.ca/maps/@43.8122465,-79.0744714,3a,48.2y,...
warning that you may be shot for entering has a tendency of keeping people away