According to the IAEA, Iran is believed to have about 440kg (970lbs) of uranium enriched to 60 percent – enough to theoretically build 10 or 11 low-technology atomic bombs if refined to 90 percent. The effort it takes to enrich uranium is measured in separative work units (SWU).
Ted Postol, professor emeritus of science, technology and international security at the Massachusetts Institute of Technology (MIT), told Al Jazeera that before the US attack on Iran’s nuclear facility at Fordow, the country had at least 10 cascades of 174 IR-6 centrifuges in operation – meaning 1,740 IR-6 centrifuges. Postol has calculated that Iran’s cascade of centrifuges could produce 900 to 1,000 SWUs annually.
“Getting from natural uranium to 60 percent enrichment, which Iran has already achieved, takes roughly five years, and about 5,000 SWUs using Iran’s cascades.” “If I want to go from 60 to 90 percent, I only need 500 SWUs. So, instead of five years, [by] starting with the 60 percent here, this might take me four or five weeks. Because I am already very enriched,” Postol said.
Using an analogy of a clock, Postol explained: “Let’s say it takes seven minutes to get 33 percent enrichment, and then eight minutes to get to 50 percent enrichment. It only takes me one minute to get to total [90 percent] enrichment.”