Small modular reactors (SMRs) potentially offer significant opportunities to manufacturers. If the UK can take an international lead in technology development, the UK supply chain could produce SMRs for the global market.

Small modular reactors (SMRs) are advanced reactors that can be largely built in factories as modules to minimise costly on-site construction. The International Atomic Energy Agency defines SMRs as producing up to 300MW of electric power, but the term is applied to some larger designs – though all are smaller than the current generation of gigawatt-scale reactors.

SMRs are generally based on Gen III+ technologies which are relatively close to commercial readiness. The term advanced modular reactor (AMR) usually refers to a variety of Generation IV reactor technologies which are at an earlier stage of development.

SMRs should be much more affordable to build, by avoiding the huge upfront costs and decade-long development times of current reactors. An initial SMR power station would be a fraction of the cost of a gigawatt-scale new build, could be built in four or five years and, once operational, will generate revenue to help finance additional units. Rolls-Royce SMR is now targeting a delivery price of £40–60/MWh for its power station.

Because SMRs are designed to be largely made in factories, manufacturers will be able to use lessons learned from other sectors such as aerospace to drive down costs, and exploit advanced manufacturing techniques which aren’t approved for current reactor designs.

With the UK’s net-zero commitments likely to require a quadrupling of low-carbon electricity generation by 2050, SMRs have a vital role to play in the energy mix. They are intended to complement the current generation of gigawatt-scale reactors, rather than be a substitute.

In March 2023, the UK government announced a new competition to select the best SMR technologies for development in the UK. The process is managed by Great British Nuclear, and aims to select a number of technologies (likely between two and four) by autumn. Government will co-fund the selected technologies through their development, and work with successful bidders on financing and site arrangements.


Rolls-Royce SMR

The Rolls-Royce SMR is a compact power station design, producing 470MWe from a Gen III+ pressurised water reactor (PWR).

Around 90 per cent of a Rolls-Royce SMR power plant will be built or assembled in factory conditions, and around 80 per cent could be delivered by a UK supply chain. Much of the venture’s investment is expected to be focused in the North of the UK, where there is significant existing nuclear expertise

A single Rolls-Royce SMR power station will occupy the footprint of two football pitches and power approximately one million homes. It can support both on-grid electricity and a range of off-grid clean energy solutions, enabling the decarbonisation of industrial processes and the production of clean fuels, such as sustainable aviation fuels (SAF) and green hydrogen, to support the energy transition in the wider heat and transportation sectors.

By 2050, a full UK programme of up to 16 of these power stations could create up to 40,000 jobs and £52 billion of value to the UK economy. Developing an SMR in the UK could also create an estimated £250 billion of exports.

The entire plant is being designed as a number of modular sub-assemblies which will be manufactured in factories then transported to site for rapid assembly inside a weatherproof canopy. That will cut costs and project risks by avoiding weather disruption, and also secure efficiency savings by using streamlined and standardised manufacturing processes for all its components.

Development is led by a dedicated business, Rolls-Royce SMR Ltd, supported by up to £210 million government match-funding from the Industrial Strategy Challenge Fund. Rolls-Royce Group, BNF Resources UK Limited and Constellation Energy (formerly Exelon Generation) will invest £195 million across three years from November 2021. The company announced a further £85 million investment from the Qatar Investment Authority in December 2021.

Initial development was carried out by the UK SMR Consortium, a collaboration of Assystem, Atkins, BAM Nuttall, Jacobs, Laing O’Rourke, NNL, the Nuclear AMRC, Rolls-Royce and TWI. The 18-month first phase was backed by an initial £18 million match-funding investment from the government’s Industrial Strategy Challenge Fund, and ended in early 2021.

The Nuclear AMRC demonstrated how a range of advanced manufacturing techniques can reduce capital costs and production time. The centre’s work focused on key manufacturing technologies which could be deployed in SMR factories across the UK.

In the second phase launched in November 2021, the Nuclear AMRC is carrying out manufacturing capability delivery projects in areas including fixed and portable machining, post-process cleanliness, measurement process development, welding, cladding, and digital manufacturing.

Rolls-Royce SMR aims to have its first power station in operation around 2030, with its reactor entering the UK generic design assessment (GDA) in April 2022. It entered the second phase in April 2023, and is now inviting comments and questions.

To register your interest in supplying the programme, visit the Rolls-Royce SMR supplier portal.


Other SMR developers

More than 70 designs of small modular reactor are in development in 18 countries, according to the IAEA.

In January 2023, BEIS confirmed that six developers have submitted their designs to the UK GDA process:

  • GE Hitachi’s BWRX-300 is a 300MWe water-cooled, natural circulation SMR, with passive safety systems adapted from the US-licenced ESBWR. GE Hitachi says it will achieve construction and operating costs which are substantially lower than traditional nuclear technologies, and could be deployed by 2028.
  • Holtec’s SMR-160 is a 160MWe pressurised water reactor, developed in collaboration with Mitsubishi Electric of Japan and Hyundai Engineering and Construction of Korea. US-based Holtec proposes to deploy 32 SMR-160s (5.1 GWe total) in serial production in the UK by 2050.
  • X-energy is developing a high-temperature gas reactor for industrial decarbonisation as well as electricity generation. X-energy says its first units will be deployed in the US from 2027, with the UK to follow. The US-based firm is working with Cavendish Nuclear on UK development.
  • Newcleo is developing a lead-cooled fast reactor. The UK-Italian company is aiming to commercialise a 30MWe micro-reactor by 2030, followed by a 200MWe reactor fuelled by waste from existing nuclear plant.
  • UK Atomics, a subsidiary of Danish business Copenhagen Atomics, is developing a containerised thorium molten salt reactor, and aiming for deployment in 2028.
  • GMET is developing a reactor called NuCell, but is yet to release details. The UK engineering group says it will base production at TSP Engineering’s factory in Workington, Cumbria.

For the latest information on the pre-GDA assessment, see the DESNZ/BEIS page on advanced nuclear technologies.

A number of other SMR developers have stated their interest in UK deployment, including:

  • MoltexFlex is developing a thermal neutron moderated version of Moltex Energy’s stable salt reactor technology, designed for cogeneration and industrial applications. Each Flex module will produce 16MWe or 40MWt. The Nuclear AMRC is working with Moltex on manufacturability and supply chain studies.
  • Westinghouse’s AP300 is a 300MW PWR based on the established AP1000 technology. The Nuclear AMRC is engaged with Westinghouse on potential UK development, and completed a detailed manufacturing study on an early version of the design.
  • Ultra Safe Nuclear is developing a micro modular reactor using the established Triso encapsulated fuel technology. Each cell will generate 5–10MWe (15–30MWt) per unit for industrial applications and off-grid power. The Nuclear AMRC has worked with Ultra Safe Nuclear on projects covering manufacturability, modularisation and supply chain.
  • Last Energy is developing a 20MWe (60MWt) PWR for industrial and grid-balancing applications. The PWR-20 is designed for rapid scalable deployment with up to 10 reactors per site.
  • NuScale is developing the Power Module, a 77MWe pressurised water reactor and generator, designed to be deployed in clusters of up to 12 per site. The Nuclear AMRC worked with US-based NuScale on potential UK development at an early stage of development.


Key manufacturing technologies

Driving down production costs is the key to making SMRs economically viable. SMRs offer the nuclear industry the opportunity to become more like other high-value low-volume manufacturing sectors such as aerospace or oil and gas, where the UK has proven expertise. To achieve this, the SMR design must allow economies of volume when making 50 or 100 units, and manufacturers will need to demonstrate high learning rates as production ramps up.

UK manufacturers in other high-value sectors already use a range of processes which have not yet been approved by the UK nuclear regulator. By working with manufacturers, technology providers and researchers, SMR developers will be able to include new processes into the safety case for their new designs, and use techniques such as design for manufacturing and modularisation to build in production efficiencies.

Manufacturing processes which could be exploited for SMRs include a range of machining techniques such as robotic machining, single-platform machining and cryogenic cooling, as well as supporting technologies such as intelligent fixturing and on-machine inspection. Advanced joining and near-net shape manufacturing processes such as electron beam welding, diode laser cladding, automated arc welding, bulk additive manufacturing and hot isostatic pressing also offer significant savings in cost and lead time.

Many of these technologies are already being developed for civil nuclear applications by the Nuclear AMRC. The centre’s advanced machine tools and fabrication cells have been specified to work on representative-size parts for gigawatt-scale reactors, which means that they could also produce full-size prototypes for SMRs.

Since 2017, the Nuclear AMRC has worked with US-based EPRI to develop new manufacturing and fabrication methods for SMR pressure vessels. The project aims to reduce the total time needed to produce a vessel, based on NuScale’s Power Module design, from three to four years to less than 12 months. The project is funded by the US Department of Energy, and involves industrial partners on both sides of the Atlantic including Sheffield Forgemasters. Find out more about our work with EPRI on electron beam welding.