Weapon Program: 

  • Nuclear



 Satellite image of Natanz on September 20, 2002 (Satellite imagery courtesy of Space Imaging Middle East)

Location of a previously clandestine uranium enrichment facility, the existence of which was first acknowledged by Iran in February 2003; allegedly overseen by the Atomic Energy Organization of Iran (AEOI); facility consists of a Pilot Fuel Enrichment Plant (PFEP) and a large commercial-scale Fuel Enrichment Plant (FEP), both under construction; the FEP is scheduled to start accepting centrifuges in late 2006; one thousand P-1 type centrifuges are planned for the PFEP and over 50,000 P-1 type centrifuges are planned for the FEP; location of the third phase of Iran's centrifuge enrichment program.

Enrichment research, development and assembly activities were moved to Natanz in 2002; according to Iran, the Natanz facility is designed to produce nuclear fuel for power plants using low enriched uranium of around 3% to 5% U-235, including the Bushehr power plant; the P-1 machines at the PFEP are of an early European design, allegedly based on Urenco design information stolen by Pakistan in the 1970s and provided to Iran by the A.Q. Khan procurement network; Pakistani individuals and companies allegedly provided centrifuge blueprints, technical guidance and equipment; the P-1 machines are allegedly based specifically on the CNOR and SNOR centrifuge models; the CNOR model reportedly has a throughput of about 3 SWU/year.

First visited by inspectors from the International Atomic Energy Agency (IAEA) February 21-22, 2003; at that time more than 100 centrifuge casings had already been installed at the PFEP; the IAEA took baseline samples at the PFEP between March and June 2003, allegedly before any nuclear material was introduced; samples taken from chemical traps during this time period revealed the presence of highly enriched uranium particles; further environmental sampling revealed the presence in Iran of at least two other types of highly enriched uranium, as well as low enriched uranium and natural uranium; the presence of highly enriched uranium indicates that Iran may have undeclared nuclear material in its inventory; results among samples taken from the surfaces of the centrifuge casings installed for single machine tests differed, suggesting differences in their manufacturing history.

Uranium hexafluoride gas (UF6) was introduced into the first centrifuge at the PFEP on June 25, 2003 and into a ten-machine cascade on August 19, 2003; as of October 2003, the installation of a 164-machine cascade was being finalized; the IAEA visited the PFEP between September 14-18, 2003, October 13-22 2003, and on October 31, 2003; on October 31, inspectors observed that no UF6 gas was being fed into the 164-machine cascade but that construction and installation work continued.

Enrichment Suspension

On November 10, 2003 Iran announced that it had decided to suspend all enrichment and reprocessing activities; on November 12, all centrifuges located in the cascade hall of the PFEP were shut down, the feed cylinder was removed from the autoclave and inspectors sealed feed and withdrawal stations and chemical and cold traps; ad hoc inspections and design information verifications (DIV) were carried out between December 8-16, 2003; inspectors finished sealing all declared UF6 feed material in November and December 2003; safeguard inspections and DIV were carried out between January 10-28, 2004; DIV were also conducted at the FEP on December 10, 2003; inspections confirmed that there was no operation or testing of centrifuges at the PFEP and that no new centrifuges had been installed at the PFEP.

However, between November 2003 and mid-January 2004, Iran assembled approximately 120 centrifuges in addition to the 800 centrifuges produced prior to November 2003; these and any centrifuges produced since mid-January 2004 were to be placed under IAEA seal; IAEA inspections of the PFEP planned for March 13-18, 2004 were postponed by Iran until March 29, 2004; between May 14-23, 2004, the IAEA carried out verification and sealing activities of centrifuge components; at that time, the IAEA sealed 392 of the 402 assembled rotors; ten assembled rotors and some key centrifuge components were left unsealed in order to allow for ongoing research and development centrifuge work at Natanz and Kalaye Electric Company; on May 31 and June 1, 2004, mandrels and moulds used to manufacture centrifuge components along with maraging steel, high strength aluminum, balancing machines, centrifuge test pits, engineering jigs and gauges were sealed by the IAEA at Natanz; IAEA inspections of the PFEP were conducted between June 22-30, 2004.

In a June 23 letter to the IAEA, Iran announced that as of June 29 it would resume "manufacturing of centrifuge components and assembly and testing of centrifuges," under IAEA supervision; Iran subsequently removed 40 seals from material, equipment and centrifuge components located at Natanz, Pars Trash and Farayand Technique and returned the seals to the IAEA during its visit to Iran from July 6-18, 2004; despite Iran's actions, the IAEA had continued to monitor the suspension of enrichment activities at the PFEP on a monthly basis, covering both the cascade hall and the previously declared UF6 feed material; by October 10, 2004, Iran had assembled 135 new centrifuge rotors, bringing the total number of assembled rotors at Natanz to 1,274; Iran has so far refused the IAEA's request to seal all tested rotors.

On November 14, 2004, Iran declared that it would voluntarily resume its suspension of all enrichment related and reprocessing activities under an agreement reached with Britain, France, Germany and the European Union; specifically, Iran pledged to cease the production and import of gas centrifuges and components as well as the assembly, testing and use of gas centrifuges already in place; Iran invited the IAEA to verify the suspension as of November 22, 2004.

In January 2006, Iran informed the IAEA of plans to resume uranium enrichment related activities and requested the removal of seals at Natanz, Pars Trash and Farayand Technique; these seals covered P-1 centrifuge components, maraging steel, high strength aluminum, centrifuge quality control and manufacturing equipment, process equipment and two cylinders of UF6; on January 10 and 11, Iran removed these seals in the presence of IAEA inspectors; the cylinders of UF6 were placed under IAEA containment and surveillance on January 29; since the removal of seals, Iran has begun renovations of the gas handling system and conducted quality control of components and rotor testing at the PFEP; on February 8, the IAEA received updated design information for the PFEP and the FEP; equipment, including process tanks and an autoclave, are being moved into the FEP; on February 11, enrichment tests resumed by feeding a P-1 machine with UF6; on February 15, UF6 was fed into a 10-centrifuge cascade; vacuum testing of a 20-centrifuge cascade began February 22; at Iran's request, IAEA containment and surveillance measures were limited to those of the standard inspection agreement.


Iranian officials claim that enriched uranium contamination found during environmental sampling came from imported centrifuge components; the IAEA took samples from both imported and domestically manufactured components in August 2003, and again in October 2003; analysis of samples revealed predominantly low enriched uranium contamination on domestically manufactured components and both low and highly enriched uranium contamination on imported components; samples taken from imported components used in manufacturing workshops and now stored at Natanz showed high enriched uranium contamination of up to 70% U-235, with almost no depleted uranium; a cluster of about 54% U-235, with U-236 contamination, was found on the surface of imported centrifuge components as well as on samples from chemical traps at the PFEP; the samples were taken before the PFEP began operation; according to the IAEA, sample results suggest that "most" of the high enriched uranium contamination found at Natanz "correlates reasonably" with high enriched uranium found on imported components; however, based on information provided by the state that supplied most of Iran's imported centrifuge components, it does not appear that all of the high enriched uranium particles found in Iran came from that state; samples taken at a location in another IAEA member state where Iran has said centrifuge components were stored prior to arrival in Iran did not reveal any traces of nuclear material; therefore, though sample results so far suggest that imported centrifuge components may have been the source of some enriched uranium contamination, the IAEA continues to investigate other possible explanations.

After initial denials, Iran admitted in October 2003 that it had used 1.9 kg of UF6, secretly imported in 1991, to test centrifuges at the Kalaye Electric Company; tests achieved an enrichment level of 1.2% U-235; the 1.9 kg of UF6 used in enrichment experiments at Kalaye is currently declared as hold-up in dismantled equipment stored at PFEP; the IAEA collected 650g of uranium from the dismantled equipment during its visit on July 10-11, 2004; the remaining UF6 imported in 1991 is also stored at Natanz.

Farayand Technique, a subsidiary of Kalaye, is reportedly the Quality Control Center for the centrifuge components manufactured for use in Natanz; it also has the capacity to test and assemble centrifuges.

According to the National Council of Resistance of Iran (NCRI), Natanz is allegedly run by an engineer named Nobari; located 158 miles south of Tehran; according to the NCRI the project occupies 100,000 square meters with two large 25,000 meter halls, has underground facilities, and is protected by two concrete walls; construction of the buildings allegedly began in 2000.

Date Entered: 

January 26, 2004

Date Last Modified: 

October 18, 2007