In an interview with Iranian television, Ali Akbar Salehi, head of the Atomic Energy Organization of Iran (AEOI), stated Iran would need a minimum uranium enrichment capacity of 190,000 separative work units (SWUs) once Russia's contract to provide fuel for the Bushehr reactor expires in eight years.  Salehi said that this figure takes into account the annual fuel needs of the Tehran Research Reactor and the Arak Heavy Water Reactor.  The number of centrifuges Iran would need to operate would depend on the capacity of each machine.  According Salehi, the first generation IR-1 has a capacity of less than two SWUs per machine; the IR-2m and the IR-4 have a capacity of nearly six SWUs; and the IR-6 has a capacity of 10 SWUs.  Iran is only enriching uranium in IR-1 centrifuges.