Above: Soviet PWR technology initially developed for icebreaker vessels such as the Yamal is the design origin of the RITM series

With an over 80% market share, Rosatom has secured an almost unassailable position in the world’s new-build exports of GW-scale reactors. Now it is working towards extending its market reach with in the small- and medium-capacity reactor segment too.

The development of small modular reactors (SMRs) is one of the key components of Russia’s nuclear energy strategy to 2050. The main role of SMRs in the context of future deployment in Russia is to power remote regions, including the vast and scarcely populated lands of Siberia and the Russian Far East, which lack extensive power transmission lines. They are also expected to provide electricity for energy-intensive industries like mining and to serve as emergency autonomous power sources for larger grids, thereby enhancing energy security. For export markets Russian SMRs would also target potential on-grid applications for countries and regions with smaller size grids, as well as regions currently heavily dependent on coal for electricity supply, as well as district heating, which are moving towards decarbonisation of their grids.

Portfolio approach

Rosatom has developed a portfolio of designs both for use in Russia and potential export, covering a broad spectrum of applications and market segments. It includes the RITM series of reactors for plants with the total capacity ranging from 50 to 600 MWe, Shelf-M reactors for off-grid installations covering less than 10MWe to 50 MWe, and the generation-IV SVBR-100 lead-bismuth-cooled fast reactor.

The RITM-200 series, based on an evolutionary generation III+ integral PWR design, is already in series manufacturing. Already 10 RITM-200 reactors have been manufactured and installed on nuclear-propelled icebreakers and up to 20 more are expected to become operational by 2030, including the RITM-200N modification for the pilot onshore plant in Yakutia and the RITM-200S reactors for the floating plant to power the Baimskiy mine. The first-of-a-kind Shelf-M-based plant is scheduled to be operational by 2030 supplying power to the Sovinoye mine in Chukotka, while the demonstration unit of SVBR-100 is expected to be started up in the early 2030s in Dmitrovgrad. Additionally, Rosatom is working on two other major reactor projects, which are planned to be in series deployment from the middle of 2030s: a mobile transportable micro-reactor of about 1 MWe (based on Russian space and defence microreactor technologies) and high temperature gas-cooled reactors for industrial process heat applications, and first of all, hydrogen production.

RITM-200, the flagship SMR

The RITM series design is based on Soviet PWR technology initially developed for icebreaker vessels with several hundreds of reactor-years of service. This series marks a transition from the old loop-type (OK-150 reactors) through the multi-unit configuration (OK-900, KLT-40 series) to an integral layout, where the key components, including the steam generators, are all housed within the same reactor vessel. The introduction of innovative technological solutions has led to a reduction in the overall reactor weight, an extension of the continuous operational period, and an increase in the service life of replaceable components, thereby improving both efficiency and reliability.

The RITM-200 series concept aims to reconcile the idea of standardised modular manufacturing –enabling SMRs to achieve significant cost reductions over time – with a wide spectrum of diverse needs requiring different features and characteristics. Its philosophy revolves around the principle of modifications and add-ons to the same basic design of the series, utilising standard key components.

It enables RITM reactors to serve three interconnected market areas: marine transport applications (nuclear icebreakers and nuclear propelled cargo vessels), small-capacity land-based nuclear power plants, and floating nuclear power units.

The RITM series design boasts a number of significant advantages. Unlike most evolutionary PWR designs, it utilises accident-tolerant fuel based on high assay low enriched uranium (HALEU), which offers enhanced safety features. It also allows for an extended refuelling interval of up to seven years, and characteristics that enable higher reactor manoeuvrability (10 to 100% at 6% of nominal power per minute, compared with typical PWRs capable of changing electric output at an average rate of 30-50% per hour). For applications in grids with a high share of variable renewables, the load-following capabilities of the RITM-200 plant could be further enhanced by utilising the flexibility of the steam turbine unit, with additional features based on cogeneration or heat storage systems.

Turbine units of this kind are equipped with a high-speed reduction gear, which redirects excess steam away from the turbine to cogeneration devices, such as heating or heat storage systems, or dumps steam into the condenser. The Akademik Lomonosov floating power plant, for example, is equipped with TK-35/38-3.4 steam turbine units. Turbine of that design have three steam extraction lines: the first and third are non-adjustable and are used for feedwater heating. The second is an adjustable extraction though and can direct steam for feedwater heating and for heating water in the intermediate circuit which is used for district heating in Pevek.

Depending on the variability of the load and the demand for cogeneration, RITM-200-based plants can be equipped with a broad range of add-ons. For instance, in hotter climates, excess steam could be used for cooling (particularly for data centres) with the help of absorption chillers thus bypassing the need for electricity generation and its consumption by electric air conditioners. Excess steam could also be utilised for seawater desalination (Russian engineers pioneered nuclear-powered seawater desalination using a small fast-neutron reactor, BN-350, in the town of Aktau in Kazakhstan in the 1970s), as well as for pulp and paper production, the manufacturing of polymers, and the production of ammonia and urea.

The flexibility of the team turbine unit, combined with the versatility of the reactor unit, enables a combined system flexibility that effectively matches the capabilities of fossil fuel-fired peaking power plants. At the same time, flexible cogeneration improves capacity utilisation rates, which, given RITMs’ higher overall availability factors, leads to a lower levelised cost of electricity (LCOE) and cost of heat. Additionally, as Rosatom expands further into the wind energy business and wind turbine manufacturing through its fully owned subsidiary NovaWind, it can offer ‘one-stop-shop’ solutions for hybrid, wind-plus-SMR, off-grid installations with a complete net-zero profile for industrial electricity and heat users.

Similarly, following the same principle of add-ons, other parameters of the RITM-based plant would be tailored and fine-tuned to meet the specific needs and opportunities of a given location and application. For instance, the standard configuration of a terrestrial RITM power plant is designed with a seismic profile that enables the facility to withstand earthquakes with peak ground acceleration of 0.3g. However, for more seismically active areas, it could be strengthened to withstand accelerations of up to 2g. Similarly, cooling modules could be based on water cooling systems or adapted to air cooling for arid regions.

Making progress

In 2023, Rosatom began manufacturing equipment for the first small-capacity, land-based plant based on the modified RITM-200N. The RITM-200N reactor (N stands for ‘nazemniy’, the Russian word for ‘land-based’) has a slightly higher capacity (190 MWt versus 175 MWt in the basic model for icebreakers). The first RITM-200N unit will be built in Ust-Kuyga, in the Yakutia region of Eastern Russia, and will serve as a vital power generation hub for local mining operations. Construction is planned to begin in 2024 and is scheduled to be completed in 2028, when the plant is expected to start generating power.

While the Ust-Kuyga project involves a single RITM-200N unit, the modular principle of the RITM line allows for the assembly of plants with capacities up to 600 MWe, suitable for regions with more advanced power grids. Rosatom is currently conducting feasibility studies for a number of potential projects for RITM-based small-capacity onshore plants, both in Russia and for export. The Russian plans include power and heating supply for the Norilsk area, meeting the needs of the city of Norilsk and the mining and smelting operations of Nornickel, the world’s largest manufacturer of battery-grade nickel. For export, Rosatom is actively engaging with prospective customers in Sri Lanka, India, Kyrgyzstan, Myanmar, and other countries interested in this technology.

For floating nuclear power plant projects, a Rosatom subsidiary OKBM Afrikantov, is completing technical designs for floating power units based on the RITM-200S, RITM-200M and RITM-400M reactors. The first customer for a series of four floating power units will be the Baimskiy Mining and Processing Plant in Chukotka. Over a dozen floating power units are planned to be built for Rosatom’s new subsidiary, Energoflot, which will offer its customers in coastal areas in countries of Africa, South Asia, and Latin America turnkey power supply solutions based on a build-own-operate scheme, without the transfer of ownership or the need for the countries to invest in their own nuclear infrastructure.

Both the RITM-200N and RITM-200S modifications have been included in the list of 21 SMR projects in the SMR Dashboard by the NEA OECD in its 2023 edition. A recent report by the London-based think tank New Nuclear Watch Institute (NNWI), projects that the RITM series will have the largest market share in the global SMR fleet by installed capacity by 2025. It has also included the series in the list of the five ‘front-runners’ in the SMR race.

Other designs

The Shelf project, developed since 2010 by the Moscow-based NIKIET institute, also part of Rosatom, offers an integral water-water reactor of up to 10 MWe capacity. The entire unit, known as the Shelf-M, is housed in a protected energy capsule, with a six-year fuel campaign and a 60-year operational life.

One of the primary objectives of the developers of the Shelf-M was to eliminate the need for all nuclear-specific and radiation-hazardous operations at the site of the plant to the greatest extent possible. Thanks to its integral design and transportability, that objective has been achieved.

The reactor requires a very small operating crew with no exposure to radiation-related works. The Shelf-M module is manufactured, assembled, and tested at a factory, after which it will be transported to the customer as a sealed capsule with the fuel already loaded. There will be no refuelling outages and in situ refuelling since for refuelling, the module will be replaced by another module, fully loaded with fresh fuel, while the existing module is returned to a specialised facility. Future modifications of Shelf-M will also include the option of fully remote satellite operation control with no operating personnel present on site.

The small capacity of Shelf-M defines its consumer base. Primarily, it is intended for remote and hard-to-reach areas with decentralised power supply, such as off-grid industrial sites currently powered with diesel generators, as well as mini- and micro grids for remote communities. In Russia, the first Shelf-M is expected to be operational by 2030 in Chukotka to provide electricity to the Sovinoye gold mine with four more Russian mining site projects in the pipeline.

Unlike the RITM and ‘Shelf’ series, the SVBR-100 reactor uses a lead-bismuth eutectic mixture as the coolant. A fundamental advantage of the lead-bismuth coolant is the absence of a large accumulation of potential energy, which, in certain scenarios, could cause the destruction of a nuclear reactor’s protective barriers. Additionally, unlike PWRs, the SVBR-100 does not have any internal pressure, meaning there are no internal forces capable of causing structural damage. Finally, the exclusion of water means that under no circumstances will explosive gaseous hydrogen be generated in the SVBR-100.

The design utilises operational data gained from the operation of the Soviet Lyra-class submarines that also used lead-bismuth reactors. For the SVBR-100, the outlet temperature is set to be below 500°C. However, in subsequent projects, the temperature will be significantly increased, enabling the SVBR-100 reactors to generate process heat of 500-700°C, suitable for higher temperature industrial needs such as petroleum refining and methanol synthesis. For applications requiring very high temperatures, such as steam methane reformingfor hydrogen production, Rosatom is developing a series of high-temperature gas-cooled reactors. These reactors have outlet temperatures starting from 800°C and, in later modifications, this will rise to over 1,000°C. Although the heat from the reactors themselves would not be suitable for some industrial applications their use could be further extended to on-site hydrogen supply for sectors such as steelmaking, cement, and glass manufacturing, which require temperatures above 1,200°C.

Additionally, Rosatom is also working on a mobile microreactor to be deployed in the early 2030s. One of these projects is the GREM microreactor which is being developed by NIKIET institute in conjunction with other Rosatom’s design bureaus and research labs. GREM is being designed as a single-circuit power unit featuring a high-temperature fast gas-cooled reactor and a closed-cycle gas turbine with a cogeneration heat exchanger and an air-end cooler, boasting a power of 2.5 MWth and approximately 1 MWe. Its core is based on nanostructured carbonitride fuel, developed as part of the Russian space energy development programme. This design will allow the reactor to operate in a capsule format for 20–25 years without fuel reloading.

Rosatom’s portfolio plans

Rosatom and its predecessor companies have accumulated extensive experience in small-capacity nuclear power, going back to the Soviet era and its broad range of the research and engineering developments. In addition to reactor installations on icebreakers and submarines, a number of small capacity nuclear power plants and reactors have already been developed and operated to supply electricity and heat for remote sites and communities. In Chukotka, for example, the Bilibino Nuclear Power Plant with four EGP-6 reactors, each with a capacity of 11 MWe, has been successfully operating for nearly 50 years. In Kazakhstan, the BN-350 fast-neutron reactor with an actual capacity of 150 MWe supplied electricity, heat, and fresh water to the city of Aktau. Russian nuclear engineers have also developed a wide range of microreactor models for space and defence needs. Capitalising on this heritage, Rosatom considers the SMR segment one of its priorities and is committing significant resources, both human and financial, to developing a full product portfolio for complex ‘one-stop-shop’ energy transition solutions. This portfolio strategy would make Rosatom the only nuclear vendor in the world capable of meeting demand for plants from under 1 MWe to several GWe of capacity.

Author: Leo Kaplan et al

All images courtesy of Rosatom