Our ace FAS researcher, Lucas Royland, has developed a simple calculator that allows prediction of when Iran will first have enough highly enriched uranium to build a simple gun-assembled nuclear bomb. We must emphasize that the calculator gives the best case (from the Iranian point of view, the worst case from the rest of the world’s point of view). In other words, the user enters, for example, the rate at which Iran can produce centrifuges. The calculator assumes those are used to best efficiency as produced. There are never any management errors, supply problems, or misallocation of resources, that is, the things that always slow down any real-world construction project. So, for the parameters entered, the calculator gives the “not before” date.
The President of Iran, Mahmoud Ahmadinejad , announced on Tuesday that Iran has successfully enriched uranium to levels useable in a nuclear reactor. The calculator shows that the announcement is important but not quite as momentous as it might first appear. Certain events really are “milestones.” The day before the United States exploded the first nuclear bomb or the day before the Soviets launched Earth’s first artificial satellite, no one could be absolutely certain the feat was possible but the day after we knew it was possible. The Iranian announcement is not in this category.
The Iranians had built some centrifuges using plans and parts bought from Pakistan. The world knew they had some experience operating individual centrifuges. But no centrifuge can enrich uranium to reactor grade; the output from one centrifuge is passed on as the input to the next, and so forth through several layers in what is called a “cascade.” Optimizing a cascade is a complex business and the Iranians linked their 164 centrifuges together to study the problem. Using this small experimental cascade, the Iranians were able, they claim, to enrich some small quantity of uranium from a natural concentration of 0.7% U-235 to 3.5% U-235. This is an important accomplishment but not a Sputnik-like milestone. It is one step in a long engineering and production process that eventually will lead to the capability to produce significant quantities of bomb-grade uranium and, perhaps, the material itself if the Iranians chose to go that route.