Darhovin Nuclear Power Plant

Darkhovin Nuclear Power Plant (also known as the IR-360 Reactor or the Karun Nuclear Power Reactor), is a nuclear power plant under construction in Khuzestan Province, on the banks of the Karun River and near the Iraqi border in southwestern Iran. The plant has been announced as Iran’s first nuclear power reactor designed and constructed using its own engineering capacity. The project has been a point of ongoing dispute between the International Atomic Energy Agency (IAEA) and Iran regarding safeguards obligations, due to delays in design and construction processes. During the night of 19–20 July 2026, the under-construction facility was targeted in a military strike conducted by the United States of America.

Plans for a nuclear power plant at the Darkhovin site date back to before the 1979 Iranian Revolution. During the reign of Shah Reza Pahlavi, a contract worth approximately $2 billion was signed in October 1977 with the French company Framatome for the construction of two 910 megawatt-electric (MWe) pressurized water reactors (PWRs) at the site, with construction beginning in January 1979. After the revolution, the project was canceled in April 1979; the engineered components produced for the reactors were retained in France and later used in the C unit (units 5 and 6) of the Gravelines nuclear power plant, which entered service in 1985.^【1】

In 1992, the Islamic Republic of Iran signed an agreement with China for the construction of two 300 MWe reactors at the Darkhovin site, similar in design to China’s Qinshan and Pakistan’s Chashma plants. This agreement was reached during then-President Akbar Hashemi Rafsanjani’s visit to Beijing, despite objections from the United States, but China withdrew from the project before construction began.^【2】

In May 2007, the Atomic Energy Organization of Iran (AEOI) announced plans to construct a 360 MWe light water reactor at the Darkhovin/Darkhovain area near the Karun River in Khuzestan Province, using domestic capabilities. Officials from the Nuclear Power Production and Development Company (NPPD) stated that the new project would not use Chinese technology and announced in October 2008 that design work would begin shortly and be completed within six years.^【3】

The institutional structure for the project was established as follows: SURENA Company, a subsidiary of AEOI, was appointed as the general contractor. SURENA designated Nuclear Power Plant Construction Company (MASNA), established in 2006 and 49 percent owned by AEOI, as the construction contractor. Responsibility for the procurement of key equipment was assigned to ESNICO (Equipment Suppliers for Nuclear Industries), a subsidiary of SURENA.^【4】

According to MASNA’s April 2018 presentation titled "Iran Intermediate Nuclear Power Plant (IR-360)", the reference reactor for the project was identified as the Beznau nuclear power plant in Switzerland; this plant is a Westinghouse-type pressurized water reactor. The same presentation noted that the reference plant’s (Beznau) preliminary design was classified as “Generation II,” while the IR-360’s safety systems had been significantly enhanced to reach “Generation III” standards.^【5】

The design process was planned in three phases: conceptual design, basic design, and detailed design. Conceptual design work began in 2005, and the 15-part design package was reviewed and approved by the Swiss consulting engineering firm Colenco. This phase was completed in 2006 (Colenco was acquired in 2007 by the Swedish company ÅF, becoming AF Colenco). The basic design phase lasted three years; approximately 65 percent of the package, developed across 22 engineering disciplines with technical support from the Swiss engineering firm IPD, was reviewed and approved by AF-Colenco. The detailed design phase began in 2008, and by 2012 approximately 33 percent had been completed; by 2018, approximately 54 percent had been completed.^【6】

According to the Nuclear Power Production and Development Company’s (NPPD) internal report dated 2012, the main causes of delays in the detailed design phase were: inability to maintain cooperation with foreign companies due to international sanctions, difficulties in preparing technical specifications for equipment, procurement problems, lack of experienced human resources, and absence of a suitable reference nuclear power plant.^【7】

The Darkhovin project received technical support from foreign companies at various stages of its design process. However, these collaborations could not be sustained due to international sanctions. In 2009, following approval by the Swiss government and initiatives by the U.S. government, the Swiss-based engineering firm AF Colenco terminated its cooperation with MASNA and Iran. According to the U.S. government, AF Colenco provided documents containing detailed reactor core design characteristics derived from outputs of a Dutch-origin computer code marked as "secret data", in addition to non-public analyses. AF Colenco also provided training to MASNA personnel in Switzerland on probabilistic safety analysis.

With the implementation of the 2015 Joint Comprehensive Plan of Action (JCPOA), the agreement’s Annex III anticipated that the E3/EU+3 parties would facilitate Iran’s acquisition of light water research and power reactors. Accordingly, in June 2016, a six-member delegation from AF Consult and IPD conducted a five-day visit to Tehran to meet with the Atomic Energy Organization of Iran (AEOI) regarding the IR-360 and IR-40 reactors. In 2018, following the United States’ withdrawal from the JCPOA and the re-imposition of sanctions, European companies largely ceased cooperation with the project. Since then, the main institutions providing technological and engineering support to the project have been MASNA, Shahid Beheshti University Faculty of Engineering, Islamic Azad University Department of Nuclear Engineering, Amir Kebir University Faculty of Energy Engineering and Physics, Shiraz University School of Mechanical Engineering, and Shiraz University Center for Security Research.^【8】

IAEA, in its quarterly safeguards report on Iran dated 26 February 2024, criticized the initiation of construction of the Darkhovin Nuclear Power Reactor, arguing that Iran had violated its notification obligations under the Comprehensive Safeguards Agreement (CSA), specifically the provisions of Modified Code 3.1. This regulation requires a state to notify the IAEA in advance of any decision to construct or approve a new nuclear facility and to provide design information on the facility.

According to the report, AEOI President Mohammad Eslami announced in November 2023 that excavation work for the planned 360 MWe IR-360 reactor’s main building would begin “in the coming days.” AEOI also announced on its official website that construction had been initiated by presidential directive. In December 2023, the IAEA reported that analysis of satellite imagery confirmed the commencement of excavation work at the reactor site.

Iran, however, rejects the applicability of Modified Code 3.1, asserting that only the obligations under the original Code 3.1—which requires notification no later than six months before nuclear material enters a facility—are legally binding. In its response dated 7 February 2024 to the IAEA’s request for updated design information dated 5 February 2024, Iran reiterated its position that the application of Modified Code 3.1 has been suspended and that the only legally binding obligation under the CSA is the original Code 3.1.

IAEA stated that the Director General has repeatedly reminded Iran that the application of Modified Code 3.1 constitutes a legally binding obligation, but that Iran has terminated cooperation aimed at reaching a mutually acceptable resolution on this matter. The report also noted that this dispute is not new in relation to the Darkhovin project. In 2007, the IAEA requested preliminary design information on the project; Iran provided such data in September 2009, indicating that construction was planned to begin in 2011 and the reactor to become operational in 2015. Iran refused to provide additional information until the JCPOA entered into force in 2015–2016, at which point it committed to fully implementing Modified Code 3.1. However, after Iran began reducing its JCPOA nuclear commitments in 2019, it also ceased cooperation regarding this provision.^【9】

In December 2022, a cornerstone-laying ceremony was held at the Darkhovin site. AEOI President and Presidential Advisor Mohammad Eslami told journalists that the project, also known as the "Karun" plant due to its proximity to the Karun River, represents a significant investment for southwestern Khuzestan. Eslami stated that work had begun with site preparation for the 300 MWe plant; the project would be built entirely by Iran on a 59-hectare site using pressurized water reactor (PWR) technology, completed in approximately eight years at a cost of approximately $2 billion.^【10】

In October 2023, AEOI held a ceremony symbolizing the commencement of site development work. Commercial satellite imagery confirms the progress of construction activities. Imagery from 23 August 2022 showed no site preparation, while imagery from 7 August 2023 showed the land cleared and prepared for concrete pouring. On 22 February 2024, Mohammad Eslami revisited the site and announced that the first phase of excavation work had been completed.

During the night of 19–20 July 2026, the under-construction Darkhovin Nuclear Power Plant was targeted in a military strike conducted by the United States of America. The attack was carried out as part of the eighth consecutive night of U.S. air strikes against Iran, occurring despite a ceasefire agreement brokered by Pakistan in June 2026 and amid renewed Iran-U.S. hostilities.^【11】

Atomic Energy Organization of Iran (AEOI), in its statement issued in the early hours of 19 July 2026, reported that U.S. military forces had targeted the construction site of the Darkhovin Nuclear Power Plant with “a series of munitions.” In a statement broadcast on state television, Iran condemned the strike as a violation of international law, asserting that the United States had attacked the under-construction facility with an “unlawful, aggressive, and barbaric act.”

The attack was part of a broader military operation targeting elements of the Islamic Revolutionary Guard Corps (IRGC), which the United States holds responsible for attacks that killed two U.S. servicemembers in Jordan. The U.S. military stated that the operation also aimed to degrade Iran’s capacity to threaten commercial maritime traffic in the Strait of Hormuz.

Details regarding the extent of damage caused by the attack have not been disclosed by either Iranian authorities or the IAEA.

International Atomic Energy Agency (IAEA), in its statement issued on 20 July 2026, confirmed it had reviewed reports of the nighttime attack on the Darkhovin Nuclear Power Plant construction site. The Agency noted that construction was still in a very early stage and that during its most recent inspection, IAEA inspectors had confirmed that no nuclear material was present at the site.

IAEA, in its official statement on X, stated that it did not believe the reported attack posed any radiological risk; it reiterated Director General Rafael Grossi’s call for all nuclear facilities to be kept out of military operations. The Agency also confirmed that it had contacted Iran following the media reports and would continue to inform the public as new information became available.