US civilian nuclear facilities, on the other hand, tend to be secured by the lowest bidder: desperately undermanned and underpaid, with lots of cameras and other sensors so that they can show off the shiny security control room to the shareholders. (With a huge false alarm rate, so any real alarm will probably be dismissed until a bunch of others start going off.)
And of course they all have the usual problem of forces like this, which is that there are approximately zero real threats, so even with the best will in the world they get complacent. In the military you can fix that to some extent with intense training.
And again, they don't know what an actual attack would look like. They can plan for what they think the bad guys might do, but chances are if it happens they'll do something else.
Remember Y-12 in 2012 (a DoE uranium enrichment facility run by a private contractor). If any of those people had actually wanted to get at the HEU, they wouldn't have had any problem.
https://en.wikipedia.org/wiki/Y-12_N...clear_protests
Some of the first-hand accounts and incident reports I found while doing research for
Meltdown & Fallout were frankly terrifying, and if I can find them so can bad guys. But for reasons which should be obvious I'm not going to cite my sources.