Выражение встречается в следующем контексте:
These are industrial enclaves in a very backward region which has never been a nuclear region but rather a retreat for the tribal population.
Книга по истории.

Заранее спасибо

http://www.thefreedictionary.com/nuclear
Adj.
..........
4. nuclear - constituting or like a nucleus; "annexation of the suburban fringe by the nuclear metropolis"; "the nuclear core of the congregation"
central - in or near a center or constituting a center; the inner area; "a central position"