UK — Nuclear Fleet Overview

Operating Reactors (database): 0 tracked in platform Total Tracked Capacity: see fleet summary Under Construction (database): 2 Planned: 8 Regulatory Body: ONR (Office for Nuclear Regulation)

Fleet Summary

The United Kingdom pioneered civilian nuclear power with the opening of Calder Hall in 1956, becoming the first country to generate electricity on a commercial scale from nuclear energy. As of 2023, the UK operates 9 reactors across 5 sites, with a total net capacity of approximately 5.9 GWe, though this is down from a peak of 15 reactors due to progressive decommissioning of older Magnox and AGR (Advanced Gas-cooled Reactor) units. Currently, two EPR reactors are under construction at Hinkley Point C (3.26 GWe combined), with plans for additional capacity at Sizewell C and exploratory projects for Small Modular Reactors (SMRs). The fleet is transitioning from legacy gas-cooled designs to modern pressurized water reactors (PWRs), signaling a renewed commitment to nuclear as a low-carbon energy source.

Policy & Outlook

The UK government has reaffirmed nuclear power as a cornerstone of its net-zero ambitions, targeting 24 GWe of nuclear capacity by 2050 as outlined in the 2022 British Energy Security Strategy. Key legislation, such as the Nuclear Energy (Financing) Act 2022, supports new projects through regulated asset base (RAB) funding models, notably for Sizewell C, while the government has committed £700 million to nuclear development, including SMRs. SMRs are a priority, with Rolls-Royce leading a 470 MWe PWR design aiming for deployment by the early 2030s, backed by £210 million in public funding, alongside interest in other innovative designs like the BWRX-300 for Wylfa Newydd. This policy direction reflects a balance of large-scale reactors and modular technologies to meet energy security and decarbonization goals.

Key Sites

• Hinkley Point (Somerset): Hosts Hinkley Point C, where two EPR reactors (3.26 GWe total) are under construction by EDF Energy, marking the first new nuclear build in the UK in over 30 years, with completion expected in the late 2020s despite delays and cost overruns.
• Sizewell (Suffolk): Home to the operational Sizewell B (1.2 GWe PWR) and the planned Sizewell C project with two EPR reactors (3.26 GWe total), which received development consent in 2022 and is advancing under a government-backed funding model.
• Sellafield (Cumbria): A critical non-power site focused on nuclear decommissioning and waste management, formerly the Windscale facility, it handles legacy waste from the UK’s early nuclear programs and operates the Thorp reprocessing plant (now closed).

Historical Context

The UK’s nuclear journey began in 1956 with Calder Hall at Windscale (now Sellafield), the world’s first commercial nuclear power station, initially under the Magnox design program. The country expanded its fleet through the 1960s and 1970s with Magnox and later AGR reactors, peaking at 26 operational units by the 1980s, while also contributing to global nuclear technology through research at sites like Harwell. A notable incident occurred in 1957 at Windscale, where a fire in a reactor core released radioactive material, though it had no immediate fatalities and led to significant safety reforms. The privatization of the industry in the 1990s and a lull in new builds until Hinkley Point C reflect a complex history of policy shifts before the current nuclear renaissance.

Operating Reactors (Platform Database)

No reactors in database for this category.

Under Construction (Platform Database)

Reactor	Site	Type	Capacity (MWe)	Expected Operation
Hinkley Point C Unit 1	—	EPR	1630	TBD
Hinkley Point C Unit 2	—	EPR	1630	TBD

Sources

• IAEA PRIS — UK — IAEA Power Reactor Information System
• WNA Country Profile — World Nuclear Association
• ONR (Office for Nuclear Regulation) — National nuclear regulator

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Enriched by Grok · Second Atomic Age Nuclear Wiki · 2026-05-10