Iran is meeting world powers in Vienna for talks over its nuclear programme. Negotiators hope to end a decade old dispute over the Islamic Republic's atomic activities. Western diplomats want the Iranians to stop high grade uranium enrichment in exchange for modest relief from punitive sanctions. The country's Arak heavy water reactor is a major point of contention for the diplomats attending, as Iran's parliament refused to accept any bans on the development of Arak or on enrichment. Al Jazeera's Tim Friend reports from Vienna.