The SMR Competition is part of the UK government’s plan to revive nuclear power in the face of a global race to deliver cleaner and more secure energy. Though debate continues whether nuclear can be considered ‘clean’ or be defined as ‘renewable energy’ in certain countries (such as Austria), there is a lot of confidence in the sector about the potential of SMRs, designs which are based on well-established technology with a high safety factor.

Currently there are no SMRs operating anywhere in the world, but plenty of R&D programmes are underway.

The UK government’s ambition is to ensure that up to 25% of all UK electricity capacity (about 24 GW) will be generated by nuclear power by 2050 – quadruple the country’s current nuclear energy capacity.

The designs chosen by the UK government and GBN are considered to be those most able to deliver operational SMRs by the mid-2030s. Conventional nuclear reactors that are built on site are proving far more costly and time-consuming to bring online than originally expected. EDF’s twin-reactor 3.2 GW Hinkley Point C plant in Somerset is likely to cost up to £35bn for completion in 2031, against an original expectation of £18bn for completion by 2017. Sizewell C is due to begin construction this year with the same design of European pressurised water reactor (EPR) as Hinkley Point. The plant is projected to cost £21bn.

Unlike these, SMRs are smaller, can be made largely in factories and installed on site, and could transform how power stations are built by making construction faster and less expensive.

According to the International Atomic Energy Agency (IAEA), SMR designs are generally simpler and safer than large nuclear plants, relying more on passive systems and inherent safety characteristics, such as low power and operating pressure. SMRs also require less frequent refuelling, every three to seven years, in comparison to one and two years for conventional nuclear plants. Some SMRs are designed to operate for up to 30 years without refuelling.

What do the six contractors offer? 
The six companies selected for the next stage of the process are Rolls-Royce SMR, EDF, GE-Hitachi Nuclear Energy International, Holtec Britain, NuScale Power and Westinghouse Electric UK.

The plan is to announce in spring 2024 which of the six companies the government will support, with initial contracts awarded by summer 2024. This is an ambitious timetable, given the looming UK general election and the need for significant private investment. According to Gwen Parry-Jones, CEO of GBN: ‘The target for the final investment decision is 2029.’

At the SMR Competition announcement in October 2023, Energy Secretary Claire Coutinho enthused that: ‘Small modular reactors will help the UK rapidly expand nuclear power and deliver cheaper, cleaner and more secure energy for British families and businesses, create well-paid, highly skilled jobs and grow the economy… putting the UK at the front of the global race to develop this exciting, cutting-edge technology.’

At the same event, Tom Sansom, CEO of Rolls-Royce SMR, estimated that deploying a fleet of SMRs in the UK would create up to 40,000 jobs.

In January, GBN Chairman Simon Bowen told World Nuclear News that sites had been earmarked at existing nuclear sites such as Oldbury, Gloucestershire; Wylfa, Wales; Heysham, Lancashire; Hartlepool, County Durham and others ‘where we can build on at scale… to deliver on energy security and on the journey to net zero’. Installing new reactors at existing nuclear sites would remove the need for an additional licensing process.

Momentum gathered and at the Spring Budget, UK Chancellor Jeremy Hunt revealed an agreement by the government to buy the Hitachi-owned sites for new nuclear at Wylfa and Oldbury-on-Severn for £160mn, to expand nuclear capacity.

‘Small modular reactors will help the UK rapidly expand nuclear power and deliver cheaper, cleaner, and more secure energy for British families and businesses, create well-paid, highly-skilled jobs and grow the economy.’ – UK Energy Secretary Claire Coutinho

Before nuclear power plant construction can begin, the reactor designs must be approved by the government’s nuclear regulator in a multi-year, three-step process called Generic Design Assessment (further reviews, including environmental impact, follow after). In this six-horse race, Rolls-Royce SMR seems to be winning, having started in April 2022, and is expected to complete step two in July.

Rolls-Royce SMR has short-listed three sites in the UK to host its first factory for producing components for a fleet of SMRs – in Sunderland, Redcar in Teesside, and Gateway, Deeside in north Wales. Its SMR is designed to produce 470 MWe – the largest of the six UK SMR contenders – and is based on the Gen III+ pressurised water reactor (PWR). Here again, the plant is designed in a number of modular sub-assemblies which will be manufactured in factories (with 78% UK content planned), then transported to site for rapid assembly inside a weatherproof canopy.

‘Rolls-Royce SMR’s factory-built power plant has been built around affordability, repeatability, deliverability and minimising project risk,’ comments Rolls-Royce SMR spokesperson Dan Gould. ‘At 470 MW, using conventional well-understood PWR fuel and technology, the vast majority of the components are available within the supply chain. Building the modules in a factory environment and transporting to site for assembly significantly reduces construction time and the potential for on-site delay.’

In December, Holtec entered the GDA process. US-based Holtec and South Korea’s Hyundai Engineering and Construction have teamed up with Balfour Beatty and Mott McDonald to cooperate on Holtec’s bid to construct an SMR in the UK. Holtec’s 160 MWe SMR is a pressurised light-water reactor. The company has also applied for a GDA of the SMR-160 in the UK. Under a recent co-operation agreement, Holtec’s SMR is also being considered for use in Ukraine by 2029 (with plans for up to 20 SMRs), as well as in other countries.

Holtec Dual-Unit SMR-160 – CGI rendering
Photo: Holtec

In January, GE Hitachi Nuclear Energy signed up its BWRX-300 boiling water reactor SMR to GDA, having won £33.6mn from the UK Future Nuclear Enabling Fund. The company already has another design approved: the 1.35 GWe UKABWR (a different technology to all of the other SMRs, which are known as pressurised-water reactors). GE Hitachi Nuclear is developing a UK supply chain which includes a memorandum of understanding with Sheffield Forgemasters. The BWRX-300 has also been selected for SMR programmes in Canada, Poland and the US.

The BWRX-300 boiling water reactor has an electrical capacity of 300 MWe and uses natural circulation and passive cooling isolation condenser systems. Using a combination of modular and ‘open-top’ construction, the SMR can be constructed in two to three years, occupying about 90% less volume than a conventional large-scale nuclear plant.

CGI rendering of GE Hitachi Nuclear Energy’s BWRX-300 SMR design
Photo: GE Hitachi 

Meanwhile, in February Westinghouse submitted an application to enter GDA for its AP300 SMR. Earlier that month, the company signed an agreement with Community Nuclear Power to build up to four AP300s in north-east England, as a privately-financed SMR fleet.

The 300 MWe reactor is based on Westinghouse’s 1.1 GWe AP1000 technology, which is already licensed in the UK and is in operation in China and the US. Westinghouse Energy Systems President David Durham says: ‘We are very optimistic that DESNZ [Department for Energy Security and Net Zero] will approve our GDA application as UK regulators are already very familiar with the AP300 SMR’s underpinning technology.’

EDF’s SMR is the NUWARD, a 340 MWe SMR with two independent reactors (170 MWe each) housed in a single nuclear building to optimise the use of mutual equipment. This is an integrated Gen III+ pressurised water reactor, compliant with IAEA safety standards and WENRA Nuclear Regulators’ Association requirements.

Lastly, Shearwater Energy, a UK-based hybrid clean energy company, is intent on developing an innovative wind-SMR-hydrogen production energy project in north Wales. Under a memorandum of understanding, Shearwater has selected SMR technology being developed by US company NuScale. The project is designed to provide 3 GWe of zero-carbon energy and over 3mn kg/y of green hydrogen for use by the transport sector under proposals submitted to GBN.

In Russia and beyond 
Although no land-based SMRs are operating currently in the world, SMRs have been running in various guises for many years. For example, Rolls-Royce manufactures nuclear reactors for propulsion of submarines. The Russian RITM-200N 55 MW MR has been adapted from the RITM-200 series used to power Russia’s latest fleet of nuclear-powered icebreakers. It is being built in Yakutia (also known as Sakha) in Russia’s Arctic north, for commissioning by 2028.

Russia’s Akademik Lomonosov, the world’s first floating nuclear plant, began commercial operation in May 2020, and is producing energy from two 35 MWe SMRs. Other SMRs are under construction or in the licensing stage in Argentina, Canada, China, Russia, South Korea and the US.

There are more than 80 commercial SMR designs under development around the world, with varied outputs and different applications, such as electricity, hybrid energy systems, heating, water desalination, hydrogen production and steam for industrial applications. It is worth noting that, according to the IAEA: ‘Though SMRs have lower upfront capital cost per unit, their economic competitiveness is still to be proven in practice once they are deployed.’ 

However, SMRs offer unique attributes in terms of efficiency, economics and flexibility, as they can adjust output according to electricity demand, compared to the variability and intermittency of renewables sources like wind and solar energy.

On an election note 
In the UK, faced with a pending election, is there a likelihood of more enthusiasm for nuclear energy developments by one party than another?

In Rolls-Royce SMR Gould’s opinion: ‘There is cross-party support for new nuclear, with equal commitment on both sides. We anticipate contractual negotiations with GBN by mid-2024.’ Furthermore, he continued: ‘Building on sites of former nuclear power stations, like west Moorside and adjacent to Sellafield, which are owned by the Nuclear Decommissioning Authority, means the right infrastructure will be available for quick deployment, with an engaged workforce and an existing supply chain.’

Small nuclear looks ready for power up. The race is truly on, and the homegrown Rolls-Royce SMR option appears to be a leading contender.

• Further reading: ‘Global nuclear SMR project pipeline expands to 22 GW’. A recent report by Wood Mackenzie suggests that the current SMR project pipeline would require an investment of close to $176bn.
• ‘Is nuclear energy back?’ Comment from the World Nuclear Association in November 2023 (spoiler alert: the answer is yes).