In 1946, few if any could have imagined the dramatic effects technological change would bring. At the time, the prevailing image of uranium enrichment was the gaseous-diffusion plant built at Oak Ridge: a facility of such enormous scale that it employed at its wartime peak some 12,000 people, enclosed forty-four acres under a single roof, and by 1945 consumed nearly three times the electricity of the heavily industrialized city of Detroit. By the 1960s, the enrichment challenge had changed completely. Using centrifuges, a handful of engineers and a few dozen technicians could build a plant capable of enriching uranium for one bomb per year. It would fit in a high-school cafeteria, and could be powered by a single diesel generator. In 2014, such a centrifuge plant might be had for as little as $20 million.
Kemp, R. Scott. “The Nonproliferation Emperor Has No Clothes: The Gas Centrifuge, Supply-Side Controls, and the Future of Nuclear Proliferation.” International Security (2014) 38 (4): 39–78.
This is very interesting. It seems that much technology decreases in size over time. I remember using a computer at the World Bank in 1981 that filled up a large room. There was almost a sacred quiet in this room.
On the significance of uranium centrifuges to nuclear weapon proliferation, see: Nuclear Weapon Risks Briefing, p. 2
Kemp is explaining that it’s not much of a barrier to proliferation anymore, and can even plausibly be done in secret by moderately well resourced organizations.