The installation of the third ring of the internal containment for the reactor building at the second unit of Bushehr NPP has been completed “with the efforts of domestic experts”, according to the Public Diplomacy and Information Centre of the Atomic Energy Agency of Iran (AEOI).
The installation of the 12 components of the third ring was completed after four weeks, in line with safety regulations, despite adverse weather conditions such as rain and strong seasonal winds, AEOI said.
Work is now underway to connect and weld the 12 sections. This increased the height of the reactor building by 14 metres to 40 metres. The airlock for transferring the equipment into the reactor building is located in this ring, and this component was installed with special care and special safety measures due to its weight – 140 tonnes compared with about 60 tonnes for the other components. The fourth ring of the inner containment is scheduled to be installed during 2026.
The first unit at the Bushehr plant, on the Persian Gulf coast, was connected to the grid in 2011. It is a Russian-designed VVER unit with a capacity. Two further units featuring VVER-1000 units are under construction. At an event at the International Atomic Energy Agency’s General Conference in September 2024, Iran suggested unit 2’s target date for operation was 2029. According to Russia’s Rosatom, unit 3 is also under construction.
Russia is assisting with the construction of units 2&3 at the Bushehr NPP, where the first unit with a 915 MWe VVER reactor has been in operation since 2011. Construction of the Bushehr NPP began in 1975 with a West German company but stopped in 1979 after the start of the Islamic revolution. In 1992, Russia and Iran signed an agreement to continue construction of the station using Russian VVER-1000 technology. Unit 1 was officially transferred to Iran in September 2013. First concrete for unit 2 was poured in 2019 and the core catcher was installed in 2024.
In September 2025, a $25bn deal was agreed in Moscow expanding the existing strategic partnership between Iran and Russia and paving the way for the construction of four NPPs in southern Iran. The agreement between Iran’s Hormoz Company and Russia’s Rosatom Project Company formalises plans to build four NPP units in the coastal town of Sirik, in Hormozgan province.
The project, to be situated on a 500-hectare plot in the Kuhestak district, will have a total capacity of 5,020 MWe. It is based on an existing intergovernmental agreement on the peaceful use of nuclear energy, with site selection and preliminary engineering studies already completed.
This came two days after a memorandum of understanding on cooperation in construction of small-scale nuclear power plants (SMRs) was signed by Rosatom Director General Alexey Likhachev and AEOI head Mohammad Eslami.
Alexander Efimov, Russia’s temporary trade representative to Iran, said in early January that the development of SMRs with Russian participation is in demand in Iran. “The construction of small nuclear power plants is being considered in Iran. This is a new and popular solution, especially for remote regions and industrial clusters that do not need large power plants but need a reliable and environmentally friendly source of electricity,” he told RIA Novosti.
In an interview with WANA News in December 2025, Behrouz Kamalvandi, AEOI Spokesman & Deputy Head, said Iran’s cooperation with Russia in nuclear technologies, particularly in the power generation sector, is extensive and continues to grow, as Tehran moves toward building nuclear power plants independently.
“Our cooperation with Russia is strong in various fields, especially in nuclear power plants,” Kamalvandi said, noting that collaboration also extends to other areas such as radiopharmaceuticals. Commenting on technological cooperation with China, Kamalvandi said Iran had cooperation with Beijing in the past but currently maintains no significant engagement. “At present, our main focus is on cooperation with Russia, particularly as we seek to develop domestically built power plants,” he said.
He confirmed that Iran is currently building a 300 MWe nuclear power plant in Darkhovin, stressing that the country’s industrial capabilities fully support such projects. “The construction of a power plant requires equipment such as steam generators, boilers, pressure vessels, and turbines, all of which can now be produced domestically,” he said.
He emphasised that Iran’s strategic objective is to become a fully competent in NPP construction. “We are working intensively to integrate all necessary components so that we can build our own power plants, while continuing cooperation with various countries,” he said. He stressed that Iran already manufactures key power plant components domestically and carries out maintenance operations independently. “Our industrial sector enables us to produce major and critical equipment ourselves,” he said. “With these capabilities, we see a promising future for Iran’s nuclear power plants.”
