There is a news that it has been found a document in Iran by IAEA that one European diplamat described as a "cookbook" for the the enriched uranium core of a nuclear weapon. The document has been seen by Reuters and it is "on the casting and machining of enriched, natural and depleted uranium into hemispherical forms".
But a U.S. nuclear expert, David Albright of the Institute for Science and International security, said it was far from a step-by-step guide to producing a bomb core.