Support WBURBlocking Iran With A Global Game Of Nuclear 'Keep Away'Play09:02Download AudioNPR StaffFebruary 07, 2013 ShareIranian President Mahmoud Ahmadinejad (center) visits a uranium enrichment facility in Natanz, Iran, in 2008. Enriching uranium requires many fast-spinning centrifuges, arranged in what's called a cascade. (AP)
