The Islamic Republic of Iran first began to explore uranium enrichment in 1985. The program limped along for close to fifteen years, before Iranian scientists successfully introduced uranium hexafluoride into IR-1 centrifuges sometime in 1999. Iran began enrichment at Natanz in 2007. And now, Iran has some 20,000 IR-1’s under vacuum, with close to 10,000 actually enriching uranium to 3.5%.
As part of the recently concluded Joint Plan of Action (JPOA), the P5+1 and the Islamic Republic agreed that “a comprehensive solution would involve a mutually defined enrichment program with practical limits and transparency measures to ensure the peaceful nature of the program.” The two sides are now haggling over the number of centrifuges, as part of a concerted American effort to decrease Iran’s capacity to enrich uranium, so as to lengthen the time in which Iran could reenrich its current stockpile of low-enriched uranium to weapons grade in a so-called “breakout” scenario. (Iran would then have to fashion that weapons-grade uranium into a usable weapon.)