Donald Trump’s recent visit to the UK saw a so-called “landmark partnership” on nuclear energy. London and Washington announced plans to build 20 small modular reactors and also develop microreactor technology – despite the fact no such plants have yet been built commercially anywhere in the world.

The UK prime minister, Keir Starmer, promised these plans will deliver a “golden age” of nuclear energy that will also “drive down bills”. Yet the history of nuclear power has been decades of overhype, soaring costs and constant delays. Around the world, the trends point the wrong way.

So why the renewed excitement about going nuclear? The real reasons have less to do with energy security, or climate change – and far more to do with military power.

At first sight, the case may seem obvious. Nuclear supporters frame small modular reactors, or SMRs, as vital for cutting emissions, meeting rising demand for electricity from cars and data centres. With large nuclear plants now prohibitively expensive, smaller reactors are billed as an exciting new alternative.

But these days even the most optimistic industry analyses concede that nuclear – even SMRs – is unlikely to compete with renewables. One analysis in New Civil Engineer published earlier this year concluded that SMRs are “the most expensive source per kilowatt of electricity generated when compared with natural gas, traditional nuclear and renewables”.

Independent assessments – for instance by the formerly pro-nuclear Royal Society – find that 100% renewable systems outperform any energy system including nuclear on cost, flexibility and security. This helps explain why worldwide statistical analysis shows nuclear power is not generally linked to carbon emissions reductions, while renewables are.

Partly, the enthusiasm for SMRs can be explained by the loudest institutional voices tending to have formal pro-nuclear remits or interests: they include the industry itself and its suppliers, nuclear agencies, and governments with entrenched military nuclear programmes. For these interests, the only question is which kinds of nuclear reactors to develop, and how fast. They don’t wonder if we should build reactors in the first place: the need is seen as self-evident.

At least big nuclear reactors have benefited from economies of scale and decades of technological optimisation. Many SMR designs are just “powerpoint reactors”, existing only in slides and feasibility studies. Claims these unbuilt designs “will cost less” are speculative at best.

Investment markets know this. While financiers see SMR hype as a way to profit from billions in government subsidies, their own analyses are less enthusiastic about the technology itself.

So why then, all this attention to nuclear in general and smaller reactors in particular? There is clearly more to this than meets the eye.

The hidden link

The neglected factor is the military dependence on civil nuclear industries. Maintaining a nuclear armed navy or weapons programme requires constant access to generic reactor technologies, skilled workers and special materials. Without a civilian nuclear industry, military nuclear capabilities are significantly more challenging and costly to sustain.

Nuclear submarines are especially important here as they would very likely require national reactor industries and their supply chains even if there was no civil nuclear power. Barely affordable even vessel by vessel, nuclear submarines become even more expensive when the costs of this “submarine industrial base” is factored in.

Rolls-Royce is an important link here, as it already builds the UK’s submarine reactors and is set to build the newly announced civil SMRs. The company said openly in 2017 that a civil SMR programme would “relieve the Ministry of Defence of the burden of developing and retaining skills and capability”.

Here, as emphasised by Nuclear Intelligence Weekly in 2020, the Rolls-Royce SMR programme has an important “symbiosis with UK military needs”. It is this dependency that allows military costs (in the words of a former executive with submarine builders BAE Systems), to be “masked” behind civilian programmes.

By funding civil nuclear projects, taxpayers and consumers cover military uses of nuclear power in subsidies and higher bills – without the added spending appearing in defence budgets.

When the UK government funded us to investigate the value of this transfer, we put it at around £5 billion per year in the UK alone. These costs are masked from public view, covered by revenues from higher electricity prices and the budgets of supposedly civilian government agencies.

This is not a conspiracy but a kind of political gravitational field. Once governments see nuclear weapons as a marker of global status, the funding and political support becomes self-perpetuating.

The result is a strange sort of circularity: nuclear power is justified by energy security and cost arguments that don’t stand up, but is in reality sustained for strategic reasons that remain unacknowledged.

A global pattern

The UK is not unique, though other nuclear powers are much more candid. US energy secretary Chris Wright described the US-UK nuclear deal as important for “securing nuclear supply chains across the Atlantic”. Around US$25 billion a year (£18.7 billion) flows from civil to military nuclear activity in the US.

Russia and China are both quite open about their own inseparable civil-military links. French president Emmanuel Macron put it clearly: “Without civilian nuclear, no military nuclear, without military nuclear, no civilian nuclear.”

Across these states, military nuclear capabilities are seen as a way to stay at the world’s “top table”. An end to their civilian programme would threaten not just jobs and energy, but their great power status.

The next frontier

Beyond submarines, the development of “microreactors” is opening up new military uses for nuclear power. Microreactors are even smaller and more experimental than SMRs. Though they can make profits by milking military procurement budgets, they make no sense from a commercial energy standpoint.

However, microreactors are seen as essential in US plans for battlefield power, space infrastructure and new “high energy” anti-drone and missile weaponry. Prepare to see them become ever more prominent in “civil” debates – precisely because they serve military goals.

Whatever view is taken of these military developments, it makes no sense to pretend they are unrelated to the civil nuclear sector. The real drivers of the recent US-UK nuclear agreement lie in military projection of force, not civilian power production. Yet this remains absent from most discussions of energy policy.

It is a crucial matter of democracy that there be honesty about what is really going on.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Phil Johnstone, University of Sussex; University of Tartu; Utrecht University and Andy Stirling, University of Sussex

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Phil Johnstone is a Visiting Professor at the University of Tartu, Postdoctoral Researcher at the University of Utrecht, and Visiting Fellow at the University of Sussex. He is an unpaid member of the Sussex Energy Group, the Nuclear Consultation Group, a Patron of the Nuclear Information Service, and serves on the advisory board of the Medact Nuclear Weapons group. He and Andy Stirling previously received funding from the United Kingdom Foreign, Commonwealth, and Development Office (FCDO) for research that underpins some of the insights in this blog.

Andy Stirling is Emeritus Professor at the University of Sussex. Among many previous government and intergovernmental policy advisory appointments, he currently serves on the sociology sub-panel of the UK Research Excellence Framework 2029 and the Research Council for the Canadian Institute for Advanced Research. He is an unpaid member of the Sussex Energy Group, the Nuclear Consultation Group, a Patron of the Nuclear Information Service and Nuclear Education Trust and a trustee for Greenpeace UK. He served in 2022-3 as an expert advisor for the official UK Government review of the DESNZ Nuclear Innovation Programme and (with Phil Johnstone) received funding from the United Kingdom Foreign, Commonwealth, and Development Office (FCDO) for research that underpins some of the insights in this blog.