There’s a mission where you have to launch one on Monongah Mine. You must’ve missed that. I got that mission when I was level 18 and I’m now 80 and still haven’t been able to launch it dammit.
In subreddit r/fo76
In a post titled:
Congratulations, Helvetia Nukers. For your overwhelming acts of villainy, the nuclear silo robots have adjusted the nuke protection zone on the PTS.