The UK is investing in small modular reactors (SMRs) to meet rising energy demands, reduce carbon emissions, and improve energy security. SMRs offer quicker, cheaper, and safer nuclear power. While still in early development, they promise economic growth, job creation, and long-term cost benefits despite challenges around waste, safety, and public acceptance.
The UK is investing in a new generation of nuclear technology known as small modular reactors (SMRs), with Rolls Royce chosen to lead their development. These compact nuclear reactors are expected to play a key role in helping the country meet rising electricity demand, reduce carbon emissions, and support economic growth. But what are they, and why the growing interest?
Small modular reactors (SMRs), often nicknamed “mini nukes”, are smaller versions of traditional nuclear power stations. Like full-sized reactors, they generate electricity using nuclear fission—splitting atoms of fuel to release heat, which turns water into steam that drives turbines.
However, SMRs are much smaller and produce about a third of the electricity of a standard large reactor. For example, while a large reactor can power over 3 million homes, an SMR can supply electricity for roughly 970,000 homes—producing around 7.2 million kilowatt-hours (kWh) per day.
Their modular design means key components can be built in factories and assembled on-site like a kit, potentially reducing construction time and costs compared to traditional nuclear plants.
The UK is investing in small modular rectors for the following reasons:
As older nuclear and fossil fuel plants are retired, the UK faces growing electricity demands. In 2024, nuclear power made up around 14% of the UK’s electricity generation. To secure future energy supplies, the government sees SMRs as a critical part of a low-carbon, reliable energy mix.
Large nuclear plants like Hinkley Point C are massive projects—currently running years behind schedule and billions over budget. SMRs, in contrast, are designed to be quicker and cheaper to build, though early models may still be costly until production becomes routine.
By supporting SMRs, the UK hopes to create thousands of skilled jobs and revive industrial sites, such as old coal plants or former nuclear facilities. In 2025, the government said it would cut planning red tape to help SMRs be built at more sites across the country—excluding airports, flood-prone areas, and wildlife reserves.
The UK joins over 30 countries in a global pledge to triple nuclear capacity by 2050. While only China and Russia have operating SMRs so far, the UK aims to be a leader in this emerging field. US tech giants like Google and Microsoft are also backing the technology for powering energy-intensive data centres.
The challenges of implementing small modular reactors involve high initial costs, nuclear waste, and matters concerning safety and security.
Although SMRs are meant to be cheaper in the long run, early models are expected to be expensive to build. Cost savings won’t be fully realised until designs are standardised and factory production scales up.
Radioactive waste remains a major issue. The UK’s main waste facility at Sellafield is running out of space, and clean up costs have soared. A 2024 advisory report warned that future SMR projects must have clear waste management plans to avoid repeating past mistakes.
Modern SMRs are designed with advanced safety features, including passive cooling systems. Experts, including Dr Simon Middleburgh from Bangor University, describe UK SMR designs as “incredibly safe”.
Still, the spread-out nature of SMRs—likely to be built closer to populated or industrial areas—raises new security concerns, according to civil nuclear security expert Dr Ross Peel. Protecting more sites could increase the burden on the Civil Nuclear Constabulary.
The UK originally earmarked eight sites for large reactors (e.g. Sizewell, Bradwell, Hinkley Point). Now, with SMRs on the horizon, more sites—including former industrial locations—are being considered. A final decision is expected by the end of 2025, with the first SMR possibly operating by the mid-2030s.
Rolls Royce beat two American consortiums and a Canadian company in a government-run competition to develop the first UK SMR.
Eventually, SMRs could help reduce electricity prices by providing a stable, low-carbon energy source. However, costs will remain high in the short term, especially for early models and nuclear waste handling.
Public support may hinge on price: a 2024 government survey showed 78% of people would support energy infrastructure near their homes if it came with discounted bills. While such discounts have been promised near pylons, no similar commitment has yet been made for SMRs.
The UK’s rollout of small modular reactors (SMRs) could indirectly impact Ireland through shared electricity infrastructure. While Ireland does not generate nuclear power, it is connected to the UK via the Single Electricity Market (SEM) and the East–West Interconnector. As the UK adds SMRs to its energy mix, Ireland may increasingly rely on electricity partially sourced from nuclear, even as it maintains a non-nuclear policy. This could prompt policy discussions about energy sourcing, emissions goals, and energy security.
Proximity is also a concern. If SMRs are built in western England or Wales, they could be located relatively close to Ireland’s east coast. Ireland has previously raised environmental and safety concerns about UK nuclear facilities like Sellafield. Similar concerns may arise around SMRs—particularly around waste transport and emergency preparedness—potentially straining cross-border environmental cooperation and public confidence.
Economically, there may be opportunities for Irish companies in engineering, compliance, or high-tech manufacturing to contribute to the UK’s nuclear supply chain. However, if SMRs prove cost-effective and reduce UK electricity prices, Irish industry may face competitiveness pressure. Longer term, success of SMRs across the Irish Sea could influence public debate or policymaking in Ireland, even if nuclear energy remains politically off the table for now.
Small modular reactors are central to the UK’s future energy plans. If successful, they could offer faster, safer, and more flexible nuclear power—helping the country cut emissions, secure supply, and support green industry.
But the challenges—cost, waste, regulation, and public trust—must be addressed carefully. As the UK presses forward, SMRs may reshape not just how we power homes, but how we think about nuclear energy altogether.
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