The second round of talks between Iran and six world powers over Iran’s nuclear program ended Wednesday with all parties expressing satisfaction with the discussions, which were the most detailed so far on each of the main issues dividing them. Both Catherine Ashton, the European Union ’s foreign affairs chief and the chief negotiator for the six powers, and Mohammad Javad Zarif, the Iranian foreign minister, described the talks as “useful and substantive.” Although neither offered details, a senior American official described the sessions as “intense” and said there were discussions of Iran’s uranium enrichment program, the construction of a heavy water reactor at Arak that could be used to make plutonium into a fissile material, civilian cooperation on nuclear power and sanctions. The talks, which started on Jan. 20 and are expected to last until July 20, are aimed at reaching a permanent agreement intended to […]