Given the incredibly organic nature of anti-nuclear (power) sentiment during its heyday (the 70s-80s), when everyone was freaked out over TMI and Chornobyl; and the fact that so far, there've been no "revelations" of the Soviets or their latter counterparts having funded or infiltrated any of these groups (apart from attempting to influence the disarmament issue) --

Occam's Razor would seem to cut the other way, actually.