Depends. Does it have to be peaceful?I'm wondering how many "South Africas" you could get WRT nukes (building functional bombs and then dismantling everything).
And the ex-SSRs with their effectively unusable warheads don't count.
I could see Brazil doing it after the fall of the military junta if it obtains nukes during the seventies or eighties. Maybe Argentina in a “the junta survives after 1983 and gets nukes” scenario.