Under the U.S. parameters for Iran’s uranium enrichment program announced in Lausanne on April 2, Tehran will decrease its stock of about 19,000 installed centrifuges to just 6,104, with only 5,060 of these designated for enriching uranium. This arrangement will last for ten years, and all of the centrifuges will be first-generation IR-1s. The parameters also state that “Iran will not use its IR-2, IR-4, IR-5, IR-6, or IR-8 models to produce enriched uranium” during this period, and that it will “engage in limited research and development with its advanced centrifuges, according to a schedule and parameters which have been agreed to by the P5+1.” In addition, the amount of low-enriched stock that Iran can retain is capped at 300 kilograms of 3.67 percent-enriched uranium for the next fifteen years (i.e., uranium that contains 3.67 percent of the fissile isotope U-235).

The technical details underlying these parameters raise several concerns that go to the heart of the proposed deal’s efficacy. For one thing, the 1,044 centrifuges designated only for non-nuclear enrichment will remain installed, so they could potentially be reconverted to enriching uranium in a short time regardless of technical or monitoring arrangements. More important, no details have been revealed about the agreed “schedule and parameters” for R&D on more advanced centrifuges. Iran’s current timeframe for acquiring enough high-enriched uranium to make a nuclear bomb — known as breakout time — is around two or three months, and the United States wants a deal that extends that period to at least one year (see “Iran’s Nuclear Breakout Time: A Fact Sheet,” PolicyWatch 2394). In Washington’s view, a full year would provide enough time to detect noncompliance and take diplomatic or military action if Tehran seems poised to make an illegal dash for a nuclear weapon. Yet the use of more efficient centrifuges would shorten that time, so Iran’s determination to develop more advanced machines is as much a concern as, for example, its continuing retention of large low-enriched uranium stockpiles despite a commitment in the parameters that they be converted into less contentious forms (see David Albright and Serena Kelleher-Vergantini’s June 5 article “State Department Explanation of Iran’s Newly Produced 3.5 Percent Enriched Uranium Falls Short”). Using partially enriched feedstock could also reduce breakout time substantially.

Read the article in full at the Washington Institute.