UK Watchdog Flags Sizewell C Uncertainty as Europe Revisits Nuclear Orthodoxy

UK Watchdog Flags Sizewell C Uncertainty as Europe Revisits Nuclear Orthodoxy Britain's spending watchdog says Sizewell C won't break even until 2064, a verdict landing as European governments scramble to reassess nuclear capacity. Britain's government spending watchdog has found that the 3.2 GW Sizewell C nuclear plant could save consumers GBP 18 billion on energy bills, but that those benefits would not outweigh costs until 2064, with significant uncertainties remaining over the project's viability, Montel reported.⁷ That verdict lands at an uncomfortable moment for UK energy policy. Across Europe, governments that spent the past decade treating nuclear as a legacy technology are reconsidering, driven by two energy price crises in four years and the growing realisation that intermittent renewables alone cannot deliver baseload security. Analysts told Montel that mindsets must change to release the EU from the grip of its second energy price crisis, with Italy already delaying its coal phase-out and Germany's economy minister publicly raising nuclear.² The watchdog's 2064 breakeven date encapsulates the core tension in UK energy planning: nuclear delivers certainty on decarbonisation and supply security that gas and renewables cannot match, but the capital commitment is enormous and the payoff horizon extends well beyond any political cycle. The problem for investors is that "significant uncertainties" is not a phrase that invites capital at scale.⁷ France is navigating a sharper version of the same debate. French renewable energy investment is beginning to stall as a contest between nuclear and green technologies intensifies ahead of next year's presidential election, analysts told Montel, with energy policy at risk of becoming ideological rather than technical.³ Ireland sits at the other end of the spectrum. Cornwall Insight told Montel this week that small modular reactors risk becoming a "distraction" from Ireland's existing decarbonisation strategy, despite growing political discussion around nuclear. The warning reflects a pattern across smaller European markets: nuclear discussion is rising, but without the grid scale, regulatory infrastructure or supply chain to back it up, the debate runs well ahead of reality.⁸ Globally, the nuclear revival has more substance. Japan's latest energy plan envisages nuclear providing 20% of the electricity mix by 2040, up from under 10% today. Japan currently has 15 operational reactors; three more have received safety clearances but remain idle, with 18 others still awaiting regulatory approval. To reach the 20% target, the Economist reported, nearly all 21 eligible reactors would need to restart.⁵ In the United States, Donald Trump has called for a quadrupling of domestic nuclear capacity to 400 GW by 2050.⁶ The IEA's Electricity 2026 report projects that coal's share of the global generation mix will erode as nuclear, renewables and natural gas gain ground, with those two clean sources together reaching 50% of the world's power mix by the end of this decade.⁴ The AI data centre buildout is adding urgency to the demand side of that equation. Capital has been rotating into energy companies capable of supplying reliable baseload for hyperscalers, illustrated by Fluence Energy's shares rising 98.2% in a single week in early May after the company disclosed master supply agreements with two hyperscalers and reported a record $5.6 billion backlog.¹ For UK energy traders, the Sizewell C watchdog report matters less as a final verdict than as a marker of where the policy risk sits. The project's economics depend on financing terms the government has not locked in, a construction timeline that spans governments, and a regulatory environment still being defined.⁷ The next signal to watch is whether the UK government responds to the watchdog findings by tightening Sizewell C's financial structure or allowing the project to drift — with every month of delay adding to the gap between Britain's stated nuclear ambitions and any timeline that would actually matter for the energy transition.^7,2