Modular nuclear reactors sound great, but won’t be ready any time soon

The UK government has unveiled ambitious plans to construct over a dozen small nuclear reactors nationwide, marking what officials are dubbing a new “golden age” for nuclear energy. This initiative aims to significantly reduce the nation’s dependence on Russian energy within the next three years. However, the efficacy and feasibility of deploying these small reactors remain subjects of debate.

As part of a prelude to President Trump’s visit to London on September 16, a collaborative energy security agreement has been announced between UK firm Centrica and US startup X-Energy. This partnership aims to establish twelve small modular nuclear reactors to power data centers, as well as a “micro modular nuclear power plant” at DP World’s London Gateway port, spearheaded by Last Energy, another US-based startup.

Despite the announcements, details about timelines for project initiation were notably absent, and the Department for Energy Security and Net Zero has yet to respond to inquiries from New Scientist for additional information.

This latest announcement aligns with a growing trend toward smaller nuclear reactors. Dr. Bruno Merk at the University of Liverpool highlighted that Russia’s state nuclear enterprise, Rosatom, has recently completed construction on several small reactors intended for specific applications, such as nuclear-powered icebreakers. Their continued production hints at either emerging demand or a strategic gamble by Rosatom to demonstrate commercial viability amidst international sanctions following its actions in Ukraine.

China has also entered the fray with its construction of the Linglong One small nuclear reactor; however, its commercial viability remains unproven. Meanwhile, major technology firms, including Amazon, Google, and Microsoft, have started investing in these nuclear technologies.

David Dye from Imperial College London expresses doubt about the practicality of utilizing small nuclear reactors to fulfill the demands of tech giants, noting that it’s simpler to site data centers near existing energy supplies. “For tech billionaires who have already made their fortunes, investing in ‘cool’ technologies might seem appealing, but it often lacks serious scrutiny of practicality,” he remarks.

Conversely, Michael Bluck, also from Imperial College London, notes that data centers require high reliability, suggesting that establishing control over energy resources through small nuclear plants could provide advantages. “They need to function continuously, thus having priority access to electricity becomes essential,” he explains.

Despite the high-level engineering discussions surrounding tiny nuclear reactors, Bluck asserts that their construction is feasible. Historical context shows that smaller experimental reactors have been successfully operational, including many that serve in military vessels and research institutions worldwide.

“The challenge isn’t related to size; it’s about modularity and assembling reactors on production lines with standardized components,” Bluck elaborates, noting the practicality of standard engineering in this realm.

Nevertheless, significant concerns surround the trend toward miniaturization. Merk points out that larger reactors yield cost- and energy-efficient benefits due to their scale. Both small and large reactors necessitate equal shielding thickness for safety, and larger reactors generally provide more energy output for the same amount of fuel due to the physical principles governing neutron fission and chain reactions. “It’s a matter of physical laws, not magic,” he stresses.

Merk also highlights that the high costs associated with traditional nuclear plants can make smaller reactors appear attractive. “These large facilities have become extremely expensive to develop. Thus, there may be merit in seeking smaller alternatives,” he suggests.

Exploring Innovative Reactor Designs

Bluck outlines two distinct approaches in the latest governmental announcements: X-Energy’s Xe-100, a gas-cooled reactor featuring unique design elements and fuel types that may take a decade for regulatory approval, and Last Energy’s PWR-20. The latter employs familiar pressurized water reactor technology akin to England’s Sizewell B facility using standard fuel types, which may expedite its entry into the market.

However, Bluck estimates that Last Energy could require up to five years to construct even a prototype reactor in the UK, emphasizing the difference between public enthusiasm for immediate results and the realistic timeline for energy projects.

A crucial factor for the successful production and distribution of these small reactors will be the acquisition of regulatory approvals on a country-by-country basis. Bluck believes the recent US-UK partnership could be pivotal in this regard, potentially accelerating the approval process through mutual recognition of certifications. For instance, should Rolls Royce’s larger small modular reactor receive UK approval, it could subsequently be marketed in the US without redundant evaluations.

Despite these advancements, Bluck reminds stakeholders of the associated political risks. Opponents of nuclear energy may leverage apprehensions about the safety and reliability of these technologies. However, he observes that this collaboration is unprecedented for significant manufacturing nations and could mitigate some of those concerns.