Table of Contents

• Introduction
• Table 1: Iran's fuel cycle facilities
• Table 2: Iran’s undeclared facilities suspected of a connection to its nuclear weaponization effort

Introduction

Iran operates a number of facilities that carry out the different steps of the nuclear fuel cycle. This infrastructure includes the mines where Iran extracts natural uranium, the mill that processes uranium ore into a concentrate known as "yellowcake," and the plant that converts this yellowcake into uranium hexafluoride (UF6) gas. This gas is the feedstock for centrifuges that enrich uranium. Iran operates several gas centrifuge plants and accumulates enriched uranium that can be used to manufacture fuel for nuclear reactors or nuclear weapons. It also operates reactors for the purpose of generating electricity and conducting research for medical and industrial applications. Because of the dual-use potential of many of these facilities, however, the international community has long raised concerns that Iran could use this infrastructure and expertise to develop nuclear weapons.

Iran has declared the above facilities to the International Atomic Energy Agency (IAEA), and they have been subject to some form of inspection by the Agency, although Iran has curtailed much of the expanded access that it had allowed during the five years following implementation of the Joint Comprehensive Plan of Action (JCPOA) in 2016.

Other developments highlight the importance of accessing facilities that Iran has not declared to the IAEA. In 2018, for example, the IAEA became aware of a site in Turquzabad, near Tehran, that had allegedly been used to store nuclear material and equipment. In 2019, Agency inspectors visited the site, took environmental samples, and detected uranium particles of anthropogenic origin there.

The IAEA subsequently identified three additional undeclared sites where nuclear-related activities might have occurred: Lavisan-Shian, Varamin, and Marivan. Iran ultimately granted the IAEA access to Varamin and Marivan to investigate the possible presence of nuclear material or activity, but such access took months to negotiate. As of February 2024, the Agency had closed its investigations into Lavisan-Shian and Marivan but had not resolved outstanding issues related to Turquzabad and Varamin due to a lack of cooperation from Iran. Of the closed investigations, the IAEA decided not to seek access to Lavisan-Shian after determining that there would be no verification value because the site had “undergone extensive sanitization and levelling.” The Agency accepted a “possible” explanation from Iran for the presence of nuclear material at Marivan while standing by its assessment that explosive testing had occurred there.

These incidents echo past access challenges for the Agency: before the implementation of the Joint Comprehensive Plan of Action (JCPOA), the IAEA sought to understand the "possible military dimensions to Iran's nuclear program," referring to an Iranian effort to design nuclear weapons (“weaponization”) that is understood to have mostly taken place before 2003. However, the Agency was often thwarted in its investigation by a lack of access to locations and key individuals.

Below, Iran’s nuclear sites are divided into two tables: the facilities relating to its nuclear fuel cycle and undeclared facilities suspected of being connected to its nuclear weaponization effort. Each table gives the facility’s purpose, location, and, where known, its operating status and the status of applicable IAEA verification efforts or investigations.

Table 1: Iran's fuel cycle facilities

Table 2: Iran’s undeclared facilities suspected of a connection to its nuclear weaponization effort

[1] In January 2022, Iran informed the IAEA that it planned to produce centrifuge rotor tubes and bellows at a new location “in Esfahan” rather than at the TESA Karaj complex, which had been heavily damaged during an incident in 2021. Then, in April 2022, Iran told the IAEA that it had moved production equipment from the decommissioned Karaj facility to a location “at the Natanz site.” The Agency installed cameras at both workshops but was forced to remove them in June 2022. Eleven months later, in May 2023, the IAEA reported that it had reinstalled cameras in centrifuge “workshops at one location” in Esfahan. Thus it is not clear how many total workshops there are, where exactly the workshops “in Esfahan” are located, or whether the Natanz workshop is among those described as being “in Esfahan.” The IAEA has not explicitly confirmed whether any of the workshops is in operation. However, in the case of the Natanz workshop, the IAEA removed its seals from the equipment on April 12, 2022, and Iran informed the Agency that it would begin operation the following day, making it likely that at least that workshop is operational. See IAEA documents GOV/INF/2022/10,  GOV/INF/2022/11, GOV/2022/39 (para. 48), GOV/2023/24 (paras. 9 and 74, and footnote 10).

[2] Iran renamed the IR-40 at Arak (commonly known as the Arak Heavy Water Reactor) as the Khondab Heavy Water Research Reactor in April 2017. The original design of the IR-40 reactor was for a power of 40 megawatts thermal (MWt); the JCPOA requires that the reactor be redesigned with a power not exceeding 20 MWt.

[3] Satellite imagery indicated activity as late as 2013 at the Pilot Uranium Laser Enrichment Plant, prompting the IAEA to visit the facility in March 2014. The JCPOA (Annex I, Section S, Paragraph 81) requires Iran to only enrich uranium using gas centrifuge technology, thereby prohibiting laser enrichment. The IAEA has made no subsequent mention of the Pilot Uranium Laser Enrichment Plant since 2014, suggesting that the facility is inactive.