Secretive, undeclared or public, Iran is littered with nuclear sites and facilities - See list in wake of Israel attack

Israel's attack targeting Iran's nuclear programme on Friday (June 13) shed the limelight on its key nuclear facilities. Iran’s nuclear programme began under the US-backed Atoms for Peace initiative in the 1960s. The programme saw significant growth in the 1990s with assistance from Russia, China, and the AQ Khan network of Pakistan. Iran ran a nuclear weapons programme, the so-called Amad Plan, from late 1990s to around 2003, with facilities like Fordow, Varamin, and Parchin playing key roles. But that programme was reportedly stopped in 2003. Iran continued undeclared nuclear programme activities since then, raising concerns in the global community, particularly Israel, its arch rival in the region.

The 2015 nuclear deal, formally known as Joint Comprehensive Plan of Action (JCPOA) imposed limits on the Iranian nuclear programme, in return for the easing of sanctions. The deal capped the uranium enrichment at 3.67 per cent, and imposed other restrictions, like limiting uranium stockpiles to 300 kg and allowing monitoring by IAEA, the UN nuclear watchdog. But after the US withdrew from the Iran nuclear deal under President Donald Trump's first term in 2018, Iran resumed enrichment beyond limits imposed on the pact.

Since then, its uranium stockpiles are thought to have exceeded 30 times the agreed limit and enrichment is thought to have reached anywhere between 60 to 83.7 per cent. Note that 90 per cent enriched uranium is considered weapons-grade, but nuclear weapons can be made even with 20 per cent enrichment, with some effort.

Iran has had a tense history with IAEA monitoring, with the nuclear agency reporting on Thursday it had violated several norms. Iran often restricted access to IAEA monitors, particularly since 2021, and failed to resolve issues at undeclared sites like Turquzabad and Varamin.

The IAEA has also accused Iran of non-compliance with safeguards of the Non-Proliferation Treaty or NPT , which Iran had ratified. There are specific fears regarding the undisclosed nuclear facilities of Iran.

At this juncture, here is a detailed look at the key Iranian nuclear facilities and allied concerns, including those that are publicly known or inactive, as well as research facilities and universities.

Natanz Fuel Enrichment Complex

Located 322 km south of Tehran amid mountains outside Qom, Natanz is the primary uranium enrichment facility of Iranian nuclear programme.

Natanz produces most of Iran’s enriched uranium and is at the heart of its nuclear programme.

It has a Fuel Enrichment Plant (FEP), a vast underground facility designed for commercial-scale enrichment. The FEP can house up to 50,000 centrifuges. This facility is possibly beyond the reach of even US-made bunker buster bombs. As of 2025, approximately 16,000 centrifuges are installed, out of which some 13,000 are believed to be operational, enriching uranium to 5 per cent purity.

Above ground, there is a Pilot Fuel Enrichment Plant (PFEP) that conducts research and smaller-scale enrichment.

Fordow Fuel Enrichment Plant (FFEP)

Fordow was once a covert uranium enrichment facility and part of the Amad Plan for weapons-grade uranium production. Under the 2015 JCPOA, Fordow was redesigned for non-enrichment research, but enrichment resumed after 2018.

Located Near Qom and dug into a mountain approximately 80–90 metres underground, Fordow is reported to have 1,000 centrifuges, including advanced IR-6 models, which are enriching uranium to 60 per cent. In 2023, uranium enriched to 83.7 per cent was detected in Fordow, which is very close to weapon-grade.

Fordow, to which IAEA monitoring access is restricted, is deep underground, making it Iran’s best-protected nuclear site. It is difficult to target with military strikes.

Arak (Khondab) Heavy Water Reactor (IR-40)

Arak is a 40 MW heavy-water research reactor designed to produce plutonium that can be used for nuclear weapons. The core of the reactor, located near Arak in Markazi province, was removed after the Iran nuclear deal. It was filled with concrete to stop production of weapons-grade plutonium and the reactor was redesigned to use natural uranium fuel. In 2015, it was reported that Arak was being modified with Chinese assistance to prevent large-scale plutonium production. Iran has frequently denied IAEA monitoring of Arak.

Isfahan Nuclear Technology Centre

Ishfahan is a nuclear research centre that hosts a Uranium Conversion Facility (UCF). The UCF converts yellowcake into uranium hexafluoride (UF6) for enrichment. The UCF produced 550 tonnes of natural UF6 by 2015, with about one-third transferred to Natanz.

Located on the outskirts of Isfahan, Iran’s second-largest city, the centre reportedly engages in centrifuge component manufacturing, and produces parts for IR-1 centrifuges. The centre was relocated to Isfahan in 2022 after an attack on the TESA Karaj complex.

It contains small research reactors, ostensibly for medical and industrial isotope production.

It is believed that China provided Iran with the blueprints for UCF, in spite of a 1997 agreement to halt nuclear cooperation.

Isfahan is critical for the nuclear fuel cycle and plays a crucial role in Iran’s enrichment programme.

Bushehr Nuclear Power Plant

This is Iran’s only operational nuclear power reactor. The Russian-designed VVER-1000 unit, located in the Gulf coast near Bushehr, has been generating electricity since 2011. Russia supplies the fuel, and spent fuel is returned to Russia.

Two additional units are planned, and construction of the first started in 2019.

Tehran Nuclear Research Centre (TNRC)

This is Iran’s largest nuclear research facility, hosting a small research reactor and laboratories for plutonium separation and purification as well as uranium conversion. Note that polonium production has dual-use potential for nuclear weapons triggers.

Located in the capital Tehran, TNRC houses some 3,000 scientists.

Parchin Military Complex

Located 20 miles southeast of Tehran, Parchin is a multi-purpose military complex involved in missile and ammunition development, with suspected nuclear weapons research involvement. It houses Taleghan 2, part of the Amad Plan, and was used for nuclear weapons-related research until at least 2018. This was attacked and destroyed by Israel in 2024.

The complex also has an underground tunnel complex linked to the Amad Plan, which was operational as recently as 2018.

There had been reports in the past of high-explosive testing for hydrodynamic experiments, potentially related to nuclear warhead development, in the complex.

Iran has consistently opposed IAEA monitoring access to the complex.

Lavisan-Shian undeclared nuclear site

Located near Tehran, this was a suspected site of undeclared nuclear activities by Tehran. It is believed that Iran conducts neutron detector development and testing for nuclear weapons from this site. Subject of an investigation, it was allegedly sanitised and destroyed in 2004 to remove evidence.

Varamin secret unarium conversion site

This was a secret pilot uranium conversion site operating between 1999 and 2003. Codenamed the New Tehran Plant, this site processed uranium ore into yellowcake, UF4, and UF6 during the Amad Plan. It was overhauled in 2004 and has been inactive since then.

Turquzabad storage site

This is a suspected storage site for nuclear material and equipment, identified in 2018 by the IAEA. Environmental samples in 2019 detected uranium particles in the site, located near Tehran, which is thought to have been a warehouse for Amad Plan.

Marivan suspected explosive testing site

Located in western Iran, Marivan was a suspected high-explosive testing site for nuclear weapons under the Amad Plan. Iran is believed to have conducted neutron detector experiments at this site. While linked to Iran’s historical weapons programme, there is no evidence of current activity at Marivan.

Ivanaki (Rangin Kaman or Rainbow Site)

Located in the Semnan Province, southeast of Tehran, Ivanaki is a suspected covert site of the Organization of Defensive Innovation and Research (SPND). Since 2009, this place, publicly known as Diba Energy Sina Company's chemical plant, has reportedly focused on tritium extraction for boosted nuclear warheads and hydrogen bomb development. If confirmed, this could be a site of ongoing nuclear weapons research, but nothing has been said to this extent by the IAEA.

Gorgan (Neka) alleged nuclear research site

Gorgan in northern Iran allegedly hosted a secret nuclear research facility, possibly for weapons development, in the 1990s. It is thought to have hosted scientists from Iran, Ukraine, Russia and Kazakhstan. There have been reports of military applications at this site, but authentic data is not available.

Sharif University of Technology

This university in Tehran is the centre of Iran's nuclear research and is allegedly involved in uranium centrifuge development. It has helped in the development of small research reactors at the University of Tehran.