Besides, what could be safer than being in an LCCC in the middle of a nuclear attack?
My bet was on the CMC.
Lots of good info in this thread. Indeed, there is no way in hell the bomb in Megaton would work after a decade, much less two centuries. The power supply alone would have made it a dead deal. I'll cut them some slack on the form factor. Yes, it looks like fatman (even fatter), but in a world with vacuum-tube computers, they wouldn't have had what we needed to make the bombs smaller. EMP would not have been a problem for bombers. However, they would have been carrying maybe two of these huge beasts and likely heading for urban and industrial targets, since counter-force would have been long off the target list by this point. So, putting a bomber carried bomb in the vicinity (but not directly on top) of DC isn't out of the question.
What I can't figure out is how satcom facilities were let untouched. Particularly those with uplink to mini-nuke dropping platforms. I'm thinking that goes pretty high on my frag list.