United Kingdom - World Nuclear Outlook Report
Current operations
The UK has nine operable reactors at five sites, with a net capacity of about 5900 MWe: eight advanced gas-cooled reactors (AGRs) and the Sizewell B pressurized water reactor. Two EPRs are under construction at Hinkley Point C, with start-up of the first unit expected around 2030.
Gradual cracking of the graphite bricks in the AGR moderators limits their operating lifetimes. All eight AGRs (two reactors each at Hartlepool, Heysham I, Heysham II and Torness) are due to close in March 2030. EDF has said it aims to run Heysham II and Torness beyond 2030 if inspections allow.
Table Uk.1 Nuclear capacity status (as of 1 October 2026)
| Operable reactors | Operable reactors net capacity (MWe) | Operable reactors gross capacity (MWe) | Reactors under construction | Reactors under construction gross capacity (MWe) | Cumulative carbon dioxide emissions avoided 1970-2025 (cf. coal) (MtCO2) |
|---|---|---|---|---|---|
| 9 | 5883 | 6534 | 2 | 3440 | 2870 |
Nuclear policy and outlook
A goal of up to 24 GWe of nuclear capacity was set by the previous government in 2022. The current Labour government, in office since July 2024, has not formally recommitted to it.
Hinkley Point C, in Somerset, is under construction under a contract for difference, with EDF now scheduling the first of the two EPRs to start up in 2030.
Sizewell C, in Suffolk, which will also consist of two EPRs, reached a final investment decision on 22 July 2025 and uses a regulated asset base model.
Rolls-Royce SMR was selected as preferred bidder in June 2025 to deliver the UK’s first SMR, and in November 2025 the government named Wylfa, on Ynys Môn (Anglesey), as the site for up to three 498 MWe units, forming the Gwyndod Power Station. Great British Energy - Nuclear (GBE-N) - the UK’s state nuclear delivery body - assesses the site as able to host up to eight. First grid connection is targeted for the mid-2030s.
Centrica and X-energy plan up to 6 GWe of Xe-100 high temperature gas-cooled reactors in the UK, with Hartlepool the preferred first site for a 12-unit, 960 MWe plant. The Xe-100 entered the UK’s Generic Design Assessment process in September 2026.
Table Uk.2 Contributions to total capacity projection in 2050 (gross)
| 60 year operation (MWe) | 80 year operation (MWe) | Currently under construction capacity (MWe) | Planned capacity (MWe) | Proposed capacity (MWe) | Potential capacity (MWe) | Government capacity target (MWe) | Additional capacity* required to meet government target (MWe) | Total capacity (MWe) |
|---|---|---|---|---|---|---|---|---|
| 1250 | - | 3440 | 3838 | 2796 | - | 24,000 | 12,676 | 24,000 |
| *Capacity additional to operable, under construction, planned, proposed and potential capacities required to meet the government target. | ||||||||
Readiness Assessment
The UK has a funded new build programme: Hinkley Point C is under construction; Sizewell C has reached FID; and contracts for pre-construction development work are in place for up to three SMR units at Wylfa.
| Country Category | Expander |
|---|---|
| Policy Framework Readiness | High The UK has a delivery body (GBE-N) for new nuclear, a financing model for the Sizewell C project, a development contract for the Wylfa SMR programme, an advanced nuclear framework, a fuel strategy and substantial committed public investment. |
| Institutional & Infrastructure Readiness | High The UK has an experienced regulator and plant operators, the state-owned nuclear delivery vehicle GBE-N, an active new build workforce, extensive engineering and fuel cycle capability, national laboratories, and established waste and decommissioning institutions. |
| Programme & Project Development Readiness | Moderate-High Two EPRs are under construction, Sizewell C has reached FID with substantial site works underway, and site development work at Wylfa has begun. |
| Target Achievability | Low-Moderate The path to significantly more nuclear capacity is now credible, but a substantial proportion of the prior administration’s target of up to 24 GWe remains uncommitted. (Assessed on the basis of the previous government's target.) |
