Nuclear Sites


The Natanz Fuel Enrichment complex is the primary site of Iran’s gas centrifuge program. It contains two primary facilities:  the Pilot Fuel Enrichment Plant (PFEP) and the Fuel Enrichment Plant (FEP).  It also houses a centrifuge assembly area.  The two primary facilities, as well as other buildings at the Natanz site, can be seen in satellite imagery below.

On March 30, 2005, then President Mohammad Khatami toured the Natanz site accompanied by the media.  This tour produced the first publicly available ground images of Natanz.  A subsequent visit by President Mahmoud Ahmadinejad in 2008 led to many images of the complex and centrifuges in the pilot plant. 

The Natanz facility was first publicly identified by the National Council for Resistance of Iran (NCRI) in August 2002.  At that time, NCRI identified the facility as a nuclear fuel fabrication plant.  In December 2002, ISIS released satellite photos of the facility for the first time and correctly identified the site as a gas centrifuge enrichment facility.

Natanz Fuel Enrichment Plant

The Natanz Fuel Enrichment Plant (FEP) is Iran’s largest gas centrifuge uranium enrichment facility. It consists of three large underground buildings, two of which are designed to be cascade halls to hold 50,000 centrifuges.  The buildings started as 70 foot deep holes, and satellite imagery showed the construction of thick concrete walls. The FEP began operating in February 2007, and construction on centrifuge cascades is ongoing. The FEP ostensibly exists to produce enriched uranium for light water reactors in Iran, including the Bushehr facility and others that Iran has not yet built.

Iran uses the FEP to produce 3.5 percent low-enriched uranium (LEU) for its nuclear program. Until early 2013, it installed only IR-1 centrifuges in single 174- and 164- machine cascades. Iran announced to the IAEA on January 23, 2013 that it intended to install IR-2m advanced centrifuges at the FEP.

Natanz Pilot Fuel Enrichment Plant

The Pilot Fuel Enrichment Plant (PFEP) is Iran’s centrifuge research and development facility which uses uranium hexafluoride.  Iran has other facilities, mostly unknown publicly, which conduct important tests of centrifuges without introducing uranium hexafluoride.  More is known about the PFEP than other centrifuge manufacturing facilities because its use of uranium hexafluoride requires inspections by the IAEA, which then reports publicly on activities there.

In 2002, Iran moved gas centrifuge research, development, and assembly operations to this facility from Kalaye Electric, its then secret site near Tehran. The PFEP is an above-ground building at the Natanz Fuel Enrichment complex. 

Iran tests centrifuges of various models, including its deployed IR-1 and IR-2m, but also more advanced designs, in single machine, small cascades, and production-scale cascades at the PFEP. Typically, in the test cascades, Iran recombines the product and tails from these cascades, so no enriched uranium is produced.

Since February 2010, Iran has produced 19.75 percent enriched uranium in a set of two, 164-machine IR-1 cascades oriented in tandem, ostensibly for the Tehran Research Reactor (TRR).  One of these cascades enriches from 3.5 percent LEU to almost 20 percent low enriched uranium (LEU), while the second one takes the tails from the first and outputs roughly 10 percent LEU and a tails of natural uranium.  The ten percent material is fed into the first cascade in addition to 3.5 percent LEU.  This process allows Iran to more efficiently use its 3.5 percent LEU stock.

For more information check: Related Reports