The gun is supposed to be on a nuclear powered naval ship. Would an EMP knock out a reactor? I second the call for someone with a bigger brain.
"Would an EMP knock out a reactor?"
No, an EMP would not knock out the reactor.
However, any electronic components associated with either the control of the reactor or the transmission/switching of the power would get fried unless it were properly shielded.
"The gun is supposed to be on a nuclear powered naval ship. Would an EMP knock out a reactor? I second the call for someone with a bigger brain."
Depends on the shielding -- it is fairly easy to shield against EMP. Basically just put a metal cage ("Faraday shielding" I believe it's called) around the sensitive parts or the whole ship interior for that matter. Remember, EMP is not designed to take out military assets or kill people, it's intended to crush a civilian high-tech economy. (And yes, we could shield practically everything, but the sheer volume of stuff that would have to be shielded makes this prohibitively expensive.)
If a modern ship's electrical and/or electronic systems get knocked out, there are no weapons of any kind that will work, beyond the crew members' model 1911s.
In regard to the claim about the railgun being only for nuclear wessels, I don't see why. If you do the math, even conventional steam powered ships can be designed to come up with enough juice to run the gun.