Iran began construction of the Uranium Conversion Facility (UCF) at Esfahan in 1999 based on design information provided by China. [1] Tehran had received the required documents and training before China cancelled a contract to construct two UCFs in Iran under intense diplomatic pressure from the United States. [2] Construction of the first process line ended in 2004 and production started in 2005.

Of the several process lines Iran plans to install at the facility, only the production line for converting natural uranium to UF6 is complete and operational. [3] Iran has sent some of the UF6 to the enrichment plant at Natanz. The total amount of UF6 produced at the plant stands at 371 tons, and as of November 2010 Iran had not produced any additional UF6 since August 2009. [4]

Iran also stores a considerable amount of heavy water at the UCF and has denied repeated requests by the IAEA to take samples of the material.[5] Iran has constructed underground tunnels below the plant for, as of yet, unknown purposes. In order to protect the UCF and other nuclear related facilities from aerial attack, Tehran has deployed several anti-aircraft missile batteries around Isfahan (Esfahan). [6]

In March 2010, Iran informed the IAEA of its intent to produce fuel for the Tehran Research Reactor (TRR) and allocate part of the UCF for research and development activities in this regard.[7] In August 2010, Iran informed the Agency that it would begin the installation of equipment for the conversion of the UF6 enriched up to 20% U-235 to U3O8 for TRR fuel fabrication in November 2010, but according to the November 2010 IAEA report, such an installation had not yet commenced.[8]

Sources:
[1] John W. Garver, China and Iran: Ancient Partners in a Post-Imperial World (Seattle: University of Washington Press, 2006), p. 153.
[2] John W. Garver, China and Iran: Ancient Partners in a Post-Imperial World (Seattle: University of Washington Press, 2006), p. 152.
[3] Other process lines include the production of UO2 for the IR-40 heavy water reactor at Arak and the production of low enriched UO2 as light-water reactor fuel. For a complete list see: "Implementation of the NPT Safeguards Agreement in the Islamic Republic of Iran," International Atomic Energy Agency (IAEA), 18 February 2010, www.iaea.org.
[4] "Implementation of the NPT Safeguards Agreement in the Islamic Republic of Iran," International Atomic Energy Agency (IAEA), 23 November 2010, www.iaea.org.
[5] "Implementation of the NPT Safeguards Agreement in the Islamic Republic of Iran," International Atomic Energy Agency (IAEA), 23 November 2010, www.iaea.org.
[6] "Nuclear, Iran - Proliferation," Jane's CBRN Assessments, 27 May 2010, www.janes.com.
[7] "Implementation of the NPT Safeguards Agreement in the Islamic Republic of Iran," International Atomic Energy Agency (IAEA), 31 May 2010, www.iaea.org.
[8] "Implementation of the NPT Safeguards Agreement in the Islamic Republic of Iran," International Atomic Energy Agency (IAEA), 6 September 2010, www.iaea.org; "Implementation of the NPT Safeguards Agreement in the Islamic Republic of Iran," International Atomic Energy Agency (IAEA), 23 November 2010, www.iaea.org.