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), as defined by the International Atomic Energy Agency, are advanced reactors producing up to 300MW of electric power that can be largely built in factories as modules to minimise costly on-site construction.

Initial cost modelling suggests that SMRs will not be significantly cheaper, in terms of capital cost per megawatt output, than the current generation of gigawatt-scale reactors. A 2014 SMR feasibility study led by the National Nuclear Laboratory gave a best estimate of over £80/MWh – not far from the strike price agreed for Hinkley Point C. Rolls-Royce is now targeting a price of £60/MWh for its SMR design.

SMRs should however 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.

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 new manufacturing techniques which aren’t approved for current reactor designs.

The 2014 NNL report predicts a potential global SMR market of 65–85GWe by 2035, valued at £250–400 billion; and a UK market of around 7GWe.

UK government support

The UK government expressed support for domestic SMR development in the 2016 Budget, and launched a competition to identify the best-value design for the UK. The competition considered SMR designs which generate up to 300MWe, and which are able to achieve in-factory production of modular components or systems amounting to a minimum of 40 per cent of the total plant cost. That competition was closed in December 2017, with the publication of a series of techno-economic assessments of SMRs. The government also commissioned an Expert Finance Working Group on Small Reactors which published its final report in July 2018.

In November 2019, the government confirmed that it is investing £18 million match funding in the UK SMR consortium led by Rolls-Royce through the Industrial Strategy Challenge Fund.

The government is also offering a range of targeted support for advanced nuclear technologies, including small reactors, as part of the nuclear sector deal. BEIS is investing up to £44 million in the Advanced Modular Reactor (AMR) Feasibility and Development project, with eight developers now producing feasibility studies for their modular reactor designs (including some larger modular reactors). These AMRs are based on a variety of Generation IV reactor technologies – SMRs are generally based on Gen III+ technologies which should be closer to commercial readiness.


A number of SMR developers have publically expressed interest in UK development. The following developers have released information about their proposals.

Rolls-Royce is developing a modular reactor capable of providing 220-440MWe, depending on configuration, and compact enough to be transported by truck, train or barge. The reactor will use proven technology with a high degree of commercial or standardised components, and is designed specifically for factory manufacture and commissioning. Over 75 per cent of the design by cost is modular, opening up opportunities for UK supply chain companies to enter into volume manufacturing. The Nuclear AMRC is working with Rolls-Royce to support development as part of the UK SMR consortium.

Westinghouse is developing a 225MWe pressurised water reactor, largely based on technologies deployed in its AP1000 design. The Nuclear AMRC is engaged with Westinghouse on potential UK development, and has completed a manufacturability study which showed that the UK supply chain has the capabilities to effectively manufacture the reactor pressure vessel. The study determined that Westinghouse’s use of UK advanced manufacturing techniques offers a potential 50 per cent reduction in delivery lead times and offers substantial cost savings to SMR manufacturing.

NuScale Power is developing the Power Module, a 50MWe pressurised water reactor and generator, designed to be deployed in clusters of up to 12 per site. US-based NuScale is working with the Nuclear AMRC to collaborate on UK development, and is actively seeking potential UK suppliers. In July 2016, the Nuclear AMRC hosted NuScale’s UK suppliers day. NuScale has launched a supplier registration page at

Urenco is working with Wood and Atkins on an ultra-small design called U-Battery. Based on pebble bed technology, each reactor will produce just 4MWe plus 10MWt. Target markets include back-up power, desalination plants and smart cities. Urenco is working with the Nuclear AMRC to support development.

China National Nuclear Corporation (CNNC) is also adapting Westinghouse AP1000 technology for its ACP100 SMR, with an output of 100MWe plus 310MW thermal power which can be used in district heating schemes. CNNC is preparing a demonstration site with two units in Fujian province, and is engaged with the Nuclear AMRC on potential UK development.

Moltex Energy, a privately-held UK company, is developing a 150MWe stable salt reactor, designed for modular deployment in clusters of up to 10 units per site. It is engaged with the Nuclear AMRC on potential development.

GF Nuclear is an independent power generation company which aims to develop the South Korean 100MWe Smart reactor in the UK. GF Nuclear says it will give UK engineering firms every opportunity to supply elements of the reactor’s core and other critical nuclear systems.

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.

Technology roadmapping

In May 2016, the Nuclear AMRC brought together eight reactor developers – plus representatives from utility companies, research institutions and manufacturers along the supply chain – for an SMR technology roadmapping event.

The technology roadmapping event aimed to identify and prioritise the advanced manufacturing capabilities required for SMR development in the UK, as well as the challenges facing local supply chains.

The need for innovative technologies to reduce lead time emerged as a common theme, with a variety of processes, technologies and services identified as potentially benefiting SMR manufacturing. Other issues included conformance of new designs to multiple standards used worldwide, and the opportunity for new codes and regulatory assessment methods to allow greater use of innovative manufacturing techniques.

Full roadmapping results have been shared with participants.