Explainer: Iran’s Key Nuclear Facilities Targeted by Israel

By Francois Murphy

VIENNA – Following Iran’s missile attack on Israel on Tuesday, there is growing speculation that Israel may act on its long-standing threats to attack Iran’s nuclear facilities.

Here is an overview of some of Iran’s key nuclear facilities.

URANIUM ENRICHMENT AT ITS CORE

Iran’s nuclear program is distributed across multiple sites. While the risk of Israeli airstrikes has been a concern for decades, only a few of these sites have been constructed underground.

Both the United States and the U.N. nuclear watchdog believe Iran once operated a coordinated and secret nuclear weapons program, which it claims to have halted in 2003. The Islamic Republic denies ever having pursued such a program or having plans to do so.

In 2015, Iran accepted restrictions on its nuclear activities in exchange for relief from international sanctions. This agreement collapsed after former President Donald Trump withdrew the U.S. in 2018, prompting Iran to start retracting its commitments the following year.

Since then, Iran has expanded its uranium enrichment, significantly reducing the time it would need to produce enough weapons-grade uranium for a nuclear bomb to just weeks, compared to the previous timeframe of at least a year set by the 2015 agreement.

Although it would require more time to actually fabricate a bomb from this material, the exact duration is unclear and subject to debate.

Currently, Iran is enriching uranium to levels of up to 60% fissile purity, which is close to the 90% needed for weapons-grade uranium. According to the International Atomic Energy Agency (IAEA), the country theoretically possesses enough material enriched to this level—if further processed—for nearly four nuclear bombs.

NATANZ

Natanz is central to Iran’s enrichment program and is located on a plain near the mountains, south of Tehran and adjacent to the Shiite Muslim holy city of Qom. This site includes the underground Fuel Enrichment Plant (FEP) and the above-ground Pilot Fuel Enrichment Plant (PFEP).

The existence of Natanz was disclosed in 2002 by an exiled Iranian opposition group, leading to a prolonged diplomatic standoff over Iran’s nuclear intentions.

The FEP was designed for large-scale enrichment with capacity for 50,000 centrifuges; currently, about 14,000 centrifuges are installed, with approximately 11,000 operational and enriching uranium to 5% purity.

Reports suggest the FEP is located roughly three floors underground, igniting discussions about the potential effectiveness of Israeli airstrikes on the facility. Past incidents have caused damage there, including an explosion attributed by Iran to Israeli actions in April 2021.

The PFEP, while equipped with only a few hundred centrifuges, is enriching uranium up to 60% purity.

FORDOW

Fordow, situated across from Qom, is an enrichment site built into a mountain, providing it with greater protection against possible airstrikes compared to the FEP.

Under the 2015 agreement, Iran was prohibited from enriching uranium at Fordow, but it now operates over 1,000 centrifuges there, including advanced IR-6 models enriching up to 60%. Recently, Iran doubled the number of centrifuges at this site, with all of the new additions being of the advanced type.

In 2009, the U.S., Britain, and France revealed that Fordow was being constructed secretly, and former President Barack Obama remarked at the time that the facility’s size and configuration were inconsistent with peaceful purposes.

ISFAHAN

On the outskirts of Isfahan, Iran’s second-largest city, there exists a significant nuclear technology center. This facility includes the Fuel Plate Fabrication Plant (FPFP) and a uranium conversion facility (UCF) that creates uranium hexafluoride to be fed into centrifuges.

Notably, Isfahan also has equipment for producing uranium metal, which poses a proliferation risk due to its use in constructing nuclear bomb cores. The IAEA has identified machinery for manufacturing centrifuge parts at Isfahan, labeling it a "new location" in 2022.

KHONDAB

The Khondab site, initially known as Arak, features a partially constructed heavy-water research reactor. Such reactors pose proliferation concerns as they can generate plutonium, which, like enriched uranium, is usable in nuclear bomb cores.

The 2015 agreement led to a halt in construction, with the reactor’s core removed and replaced with concrete to prevent its use. Plans were set to redesign the reactor to minimize plutonium production. Iran has indicated to the IAEA that it aims to bring Khondab online by 2026.

TEHRAN RESEARCH CENTRE

Iran’s nuclear research facilities in Tehran include a research reactor.

BUSHEHR

Lastly, Iran operates its only nuclear power plant on the Gulf coast, which uses Russian fuel that is returned to Russia when spent, thereby reducing proliferation risks.