The UK's uncertainty around a disposal option for nuclear waste critically undermines its grand ambitions to deploy fleets of small modular reactors (SMRs), campaigners have told NCE.
Activists from across the spectrum of anti-nuclear groups and environmentalists raised concerns ranging from waste disposal to reliance on Russian uranium, and the high costs associated with building nuclear reactors, as reasons why the SMR programme should not be pursued.
The reactions came as the UK Government announced the intention to sign agreements with the US Government and have US-based companies deploy their SMR reactor designs in England and Wales, ahead of Trump's visit to the UK this past week (16 to 18 September 2025).
Nuclear developers then told NCE that they plan to deploy approximately 20 or more SMRs, including advanced modular reactors (AMRs) and micro-modular reactors (MMRs) by the mid-2030s.
Uncertainty over GDF delivery 'casts doubt on credibility of SMR programme'
Nuclear Information Service research manager Okopi Ajonye told NCE that the Treasury's National Infrastructure and Service Delivery Authority's (Nista's) assessment of the geological disposal facility as appearing to be "unachievable" undermined the credibility of new nuclear.
"Waste is a critical factor here, especially as this development quickly follows on the heels of the geological disposal facility recently receiving a 'Red' rating in the latest Nista report," he said.
Ajonye also pointed out: "Small modular reactors have been described as 'miniaturised versions of the larger reactors' and hence capable of producing broadly similar volumes and types of radioactive waste.
"Given that the Nuclear Industry Association recently stated that the existence of a GDF is 'key to the credibility and sustainability of the UK's nuclear programme', then, by extension, the uncertainty over whether a GDF can even be delivered casts doubt on the credibility of this SMR programme."
Anti-nuclear groups warn about Russian uranium and 'toxic waste problem'
Nuclear Free Local Authorities secretary Richard Outram told NCE: "It is nonsense for ministers to insist that nuclear power brings energy security when it is dependent on accessing Russian uranium products.
"It is also wholly hypocritical for ministers to support proposals to apply secondary sanctions to nations continuing to purchase fossil fuel products from Russia, whilst Britain continues to import Russian uranium fuel products."
It is likely that some of the uranium powering the UK's nuclear reactors is sourced from Russia. Hamad Bin Khalifa University's Qatar Environment and Energy Research Institute scientist Sa'd Shannak told NCE in February 2025 that nuclear plant operators like EDF will likely know the provenance of the uranium in their reactors.
CND general secretary Sophie Bolt told NCE: "Keir Starmer talks about a 'golden age of nuclear,' but what he really means is a gold rush for nuclear companies and their investors with untested technologies - all paid for with public money.
"This government is using the same rhetoric to justify the colossal hikes in military spending, with many of the same companies set to make billions in profit. Like with military spending, most of this money will flow to companies outside of Britain and away from the communities they claim to be helping.
"This effort to push nuclear power as the answer to our energy concerns also ignores the radioactive elephant in the room - that building more nuclear reactors will only add to Britain's toxic waste problem.
"Ultimately, Britain's civilian nuclear programme is about building up Britain's deadly nuclear weapons programme."
University of Surrey NPL (National Physical Laboratory) professor of nuclear metrology Patrick Regan previously told NCE in October 2024 that "the reason we have nuclear power in the UK was to make plutonium for the nuclear weapons programme".
Bolt continued: "The government must reverse this disastrous direction and instead channel investment into genuinely self-reliant renewables like wind, solar, and tidal energy. Rather than ensuring Britain's energy independence, we're locking ourselves into further reliance on the whims of Donald Trump."
Anti-Sizewell C campaigners say SMRs will face local opposition and proliferation risks
Together Against Sizewell C (TASC) chair Jenny Kirtley said: "In TASC's view, this is yet more gaslighting from Starmer and Miliband - the truth is nuclear is not cheap, not clean and certainly not homegrown, requiring overseas uranium to operate.
"History is littered with assertions about future benefits from nuclear power which have never materialised - Sizewell C's £40bn build cost (it was originally projected to cost £20bn) and French government-owned EDF's €50bn of debt is evidence of that.
"SMRs carry substantial risks, namely security, safety, weapons proliferation and storage of radioactive waste, with a recent Treasury report advising the proposed storage facility is unachievable and unaffordable.
"Events in Ukraine demonstrate, littering the UK with nuclear reactors will be a huge risk to national security."
Russia has repeatedly increased the risk of a nuclear incident due to its invasion of Ukraine and occupation of the Zaporizhzhia Nuclear Power Plant.
Kirtley continued: "As for deregulation, there is no 'change' from Labour here - they are parroting the rhetoric promulgated by the Tories right-wing thinktank advisors blaming delays on regulators and blockers - ignoring the reality of high costs, safety concerns, lengthy construction times, and that nuclear will be a climate change casualty, not a solution due to drought, flooding and sea level rise."
Stop Sizewell C executive director Alison Downes said: "The government is on a collision course with communities over its plans to expand nuclear energy.
"The Prime Minister's inflammatory rhetoric directed at those who express concern about new nuclear plants, coupled with plans to allow developers to select their own sites and threats of a 'bonfire of regulations', are hardly the way to build public confidence.
"We need assurances of strong, independent regulators and affected communities to be allowed to actively engage, not be insulted."
Nuclear not the answer to climate breakdown and too expensive - environmentalists
Friends of the Earth head of policy Mike Childs told NCE: "For decades we've seen governments across the political spectrum promise a new golden age of nuclear.
"But each time their hopes have been dashed as the stark economic realities bite - nuclear energy is extraordinarily expensive. It also produces a legacy of radioactive waste that we don't have a solution for.
"The Hinkley Point C nuclear project costs have soared from £18bn to almost £50bn today, and it is years behind schedule. It would be far quicker and more cost-effective to capitalise on the UK's enormous renewable power resources and invest in energy storage.
"Clean solar and wind energy will bring down bills, whereas nuclear power will keep them high for decades to come."
Greenpeace UK chief scientist Douglas Parr said: "While the US blocks the effective, clean technologies that are successfully cutting carbon emissions around the world, they are pushing projects that will actively obstruct tackling climate change.
"If these proposals for new reactors scattered around Britain really materialise, the net effect will be higher bills from nuclear's relentlessly spiralling costs, and more CO2 as we wait for the builders to overcome their inevitable construction delays.
"Anyone curious about which technologies are actually going to replace fossil fuels can find the answer by looking for the technologies the fossil fuel industry spends its money lobbying against. It does not lobby against nuclear.
"Britain is a world leader in offshore wind, battery technology and other genuinely clean, affordable tech - we should be focusing there, rather than slow, costly reactors which produce waste we still have no plan to handle after 60 years of trying. There is no evidence that small modular reactors have changed any of that."