At the State Scientific Centre–Research Institute of Atomic Reactors (SSC RIAR) site in Dimitrovgrad, Ulyanovsk Region, a unique project is underway: the building of the Multipurpose Fast Neutron Research Reactor (MBIR). The plant is in its final stages of construction as of January 2026, with a 2028 commissioning date set. With scientific and technological capabilities intended to enable nuclear research for decades to come, MBIR will be among the most powerful and cutting-edge fast-neutron research reactors in the world once it is operational.
Background History and Strategic Significance
As part of Russia’s long-term plan to create a cutting-edge experimental facility for materials science and nuclear energy, construction of MBIR started in 2015. In order to build infrastructure for fourth-generation nuclear reactor technologies—systems that are safer, more effective, and able to function inside a closed nuclear fuel cycle—the project is part of a national program.
The world-renowned BOR-60 research reactor, which has been in operation at SSC RIAR for more than 50 years, is set to be replaced by MBIR. Although BOR-60’s operating life is almost up, it has been significant in testing nuclear fuels, materials, and reactor technology. MBIR is a significant technological advancement that will take over as the main fast-neutron research platform.
MBIR is intended to accommodate a far greater variety of experimental programs than its predecessor. The scope and speed of reactor-based research will be greatly increased by its sophisticated core, adaptable experimental channels, and state-of-the-art infrastructure.
Design of Reactors and Integrated Facilities
MBIR is a comprehensive scientific complex rather than just a reactor. Its main component is a 150 MW thermal-power fast neutron reactor with three steam-water circuits and two sodium coolant circuits. A steam turbine unit, a transportation and technology system, vertical and horizontal experimental channels, scientific labs, and state-of-the-art testing apparatus are also included in the complex.
Both in-core and out-of-core experimentation are made possible by this integrated setup. Within the same facility, researchers will be able to carry out post-irradiation studies, neutron beam tests, and direct material irradiation in the reactor core.
The existence of distinct loop channels, a crucial component of MBIR’s architecture, enables researchers to model reactor core operating conditions with various coolants. These consist of gaseous media, sodium, lead, and lead-bismuth eutectic. Because of its adaptability, MBIR provides a versatile experimental platform for evaluating various reactor ideas and thermal-hydraulic regimes.
Provision of Essential Equipment and Advancements in Technology
Essential parts for MBIR’s transportation and technology systems were delivered, according to SSC RIAR specialists, in January 2026. These included the steam-water washing sockets for waste fuel assemblies and the fuel handling system. A crucial precondition for finishing the reactor’s control assembly phase is the delivery of this equipment.
The gasoline handling mechanism is a sophisticated electromechanical device that is about 10 meters long and weighs over 3.3 tons. It is made to precisely withdraw and reposition fuel assemblies. The system makes it possible to precisely monitor extraction forces during refueling operations, rotate assemblies to the necessary angles, and sample gas to confirm the integrity of the fuel cladding.
The variable-diameter pipe that serves as the steam-water washing socket has a bellows compensator, thermal insulation, and shut-off valves. Its purpose is to contain and remove leftover coolant from spent fuel assemblies, other detachable cores, and side-reflector components. Additionally, it makes fuel integrity inspection and verification possible. Each washing plug will weigh roughly 2.2 tonnes and be 5.5 meters long when it is fully completed on-site at the MBIR reactor building.
In order to facilitate final assembly and subsequent commissioning activities, the installation of this entirely domestically produced technological equipment is planned for 2026.
Research Mission and Scientific Capabilities
Replicating extreme working conditions, such as extremely high temperatures, intense neutron radiation, and high pressures, is one of MBIR’s main goals. Tests of next-generation fuels and structural materials for sophisticated nuclear systems require such conditions.
Comprehensive research on new fuel compositions, structural alloys, coolant technologies, and core components will be made possible by the reactor. By simulating actual operating and even emergency conditions in advanced reactors, MBIR will enable researchers to examine material behavior under irradiation levels and thermal loads.
The creation of technology for a closed nuclear fuel cycle is a key component of MBIR’s research agenda. This strategy lowers the amount and long-term radiotoxicity of nuclear waste while greatly increasing resource efficiency through the reuse of fissile elements recovered from spent fuel.
Global Collaboration and Research Center
In order to provide access to its experimental capabilities to international research institutes, universities, and corporate partners, MBIR is anticipated to act as the basis for an International Research Centre (IRC MBIR). The center will support extensive international research initiatives and improve international collaboration in nuclear engineering and science.
A number of nations, including China, Belarus, Uzbekistan, and others, have already shown a keen interest in taking part in MBIR-based research initiatives. It is believed that having access to such a potent fast-neutron facility would be extremely beneficial for developing national nuclear programs and producing highly skilled experts.
The project’s regional and global importance is further highlighted by the approval of a coordinated research program based on MBIR for the years 2029–2040 by the Interstate Commission of CIS Member States for the Use of Atomic Energy.
Impact on the Future of Energy and Nuclear Science
Building MBIR is a critical step in laying the experimental groundwork needed for the upcoming generation of nuclear energy technologies. The reactor will drastically reduce research timelines and enable materials to reach target irradiation levels far more quickly than in current facilities because of its high neutron flux and power level.
The capabilities of MBIR will speed up basic research as well as applied development, influencing the development of improved reactor designs, fuel cycles, and nuclear safety systems in Russia and around the world.
In conclusion
One project of international significance is the Multipurpose Fast Neutron Research Reactor, or MBIR. It will enable research on materials, fuels, closed fuel cycle technologies, and fourth-generation reactor systems when it is commissioned in 2028. It is expected to become a key component of advanced nuclear research.
With its unparalleled experimental versatility, high power, and robust global interest, MBIR is well-positioned to become a premier scientific center that will shape nuclear science and technology for many years to come.