Iran is escalating its uranium enrichment further by preparing to use advanced IR-6 centrifuges at its underground Fordow site that can more easily switch between enrichment levels, a U.N. nuclear watchdog report seen by Reuters showed on Monday.
The cascade, or cluster, of 166 machines is the second IR-6 cascade installed at Fordow, a site buried inside a mountain, and it is the only cascade with so-called "modified sub-headers" that make it easier to enrich to different purities.
The confidential report to member states said Iran had informed the International Atomic Energy Agency that it had begun passivation, a process that is carried out before enrichment, but Tehran had not clarified which level the cascade would enrich to, which the IAEA confirmed in a statement.
(Reporting by Francois Murphy; Editing by Sandra Maler)
