Arms Control Wonk flagged this WaPo analysis a few days ago:
Once the uranium is enriched above 20 percent, it is considered highly enriched uranium. The uranium would need to be enriched further, to 60 percent and then to 90 percent, before it could be used for a weapon. “The last two steps are not that big a deal,” [David Albright, president of the Institute for Science and International Security in Washington] said. They could be accomplished, he said, at a relatively small facility within months.
ACW parses today's news and the WaPo reports today that Iran's nuclear program has encountered various technical set backs. Earlier skepticism of Ahmadi's statement here.