Iran to upgrade nuclear centrifuges at Natanz Such a step could enable Iran to refine uranium faster than it can at the moment and increase concerns in the West and Israel about the goals of Tehran nuclear programme. The diplomat who declined to be identified, said Iran had informed the International Atomic Energy Agency of the plan in a letter dated Jan 23. The letter said that Iran would use the new centrifuges - a model called IR-2m - at a unit in the Natanz plant where Iran is enriching uranium to a fissile concentration of up to five per cent. Iran says it refines uranium to power a planned network of nuclear power stations. But the West fears that the material, if enriched much further to 90 per cent, could be used for weapons. Iran says its nuclear programme has only peaceful goals. The Islamic republic has for years been trying to develop more centrifuges that are more efficient than the 1970s IR-1 models it now uses for production, which are prone to breakdown.