There's a fascinating online publication about underground testing at
the Nevada Test Site called, "The Containment of Underground Nuclear
Explosions".  It was written in October 1989 before testing ended at
the NTS in 1992,  The document runs 85 pages and contains lots of good
diagrams of the tunnel complexes.  It also talks about radiation
monitoring systems throughout Nevada in case of accidental release.
No mention of the shady neighbor to the northeast though.

It's in pdf files.  The download of the entire document is about 3
megs, although you can download sections if you prefer.

http://www.princeton.edu/~ota/disk1/1989/8909_n.html