Iran’s nuclear deal with major powers says Tehran can only use first-generation IR-1 centrifuges, which are less efficient VIENNA: Iran has told the UN nuclear watchdog it plans to install three more cascades, or clusters, of advanced IR-2m centrifuges at its underground uranium enrichment plant at Natanz, the agency told member states on Friday in a report obtained by Reuters. “Iran informed the Agency that the operator of the Fuel Enrichment Plant (FEP) at Natanz ‘intends to start installation of three cascades of IR-2m centrifuge machines’ at FEP,” the agency wrote, adding that the three cascades were in addition to one of IR-2m machines already used for enrichment there. Iran’s nuclear deal with major powers says Tehran can only use first-generation IR-1 centrifuges, which are less efficient, at the underground plant and that those are the only machines Iran can accumulate enriched uranium with.