Wylfa SMR by Rolls-Royce Holdings plc: status and timeline

Wylfa SMR

Three 470 MWe Rolls-Royce SMRs at the decommissioned Wylfa site in Anglesey, North Wales. Will provide 1.4 GW of baseload capacity to power approximately 3 million homes.

PilotStage 3 of 5

Site work started in 2026. Three reactors under Generic Design Assessment; mid-2030s operational target.

Updated 13 Apr 2026Checked 10 Oct0 updates this week

Milestones

Next · Site work starts at Wylfa

Generic Design Assessment beginsApr 2022Complete.
Contract with GBE-N signed13 Apr 2026Complete.
Site work starts at WylfaTarget Apr 2026Current milestone.
Generic Design Assessment completionTarget 2027+12 mo~~originally 2026~~Not yet reached.
Final Investment DecisionTarget 2029Not yet reached.
First units operationalTarget 2033Not yet reached.

Most important updates

Rolls-Royce SMR and GBE-N sign contract for three reactors at Wylfa, Anglesey13 Apr 2026

Upcoming

Apr 2026Site work starts at Wylfa (next)
2027Generic Design Assessment completion+12 mo~~originally 2026~~
2029Final Investment Decision
2033First units operational

Current obstacles

Design assessment timingGeneric Design Assessment must complete before units can enter final investment decision; every delay pushes operational dates into the next decade.
Cost controlBudget estimates have climbed to £2–3B per unit; keeping costs below traditional reactors while meeting UK manufacturing and safety standards is critical.

Physics limits

Total site capacityThree units at Wylfa provide only 1.4 GW; typical coal plants were 1–2 GW single units. Multiple sites are needed for meaningful scale.
Factory assembly bottleneckEven at 500 days per unit, building multiple sites in parallel requires multiple factories; the first factory can only produce a few units per year.

How it works

3 parts

Reactor design

Light-water PWR from Westinghouse design

UO₂ fuel in compact design. Coolant and moderator share one loop.

Manufacturing

Modules shipped and assembled onsite

Factory building reduces field time and weather risk.

Siting

Decommissioned coal plant sites reused

10-acre footprint, transmission and cooling systems shared.

Spec sheet

Spec	Wylfa SMR
Capacity per reactor	470 MWe^R (reported)
Total Wylfa capacity	1.4 GW^R (reported)
Site footprint	10 acres per unit^R (reported)
Target assembly time	500 days^R (reported)
Estimated cost per unit	£2–3 billion^E (estimated)
Homes powered	3 million^R (reported)

^R reported by the company · ^E our estimate

Update log

1 update

Mon 13 Apr

Major: Rolls-Royce SMR and GBE-N sign contract for three reactors at Wylfa, AngleseyPressCommercial

About Rolls-Royce Holdings plc

The team behind Wylfa SMR

Rolls-Royce Holdings plc

aerospace, defense, power systems, nuclear SMR

Rolls-Royce is a British multinational engineering company that designs and manufactures power and propulsion systems. Its Power Systems division develops small modular reactors (SMRs) as clean energy alternatives, with the first project at Wylfa in North Wales contracted in April 2026.

Light-water PWR, 470 MWe each, assembles under a canopy in ~500 days.
April 2026 contract: £599M from UK Wealth Fund plus £2.6B from 2025 Spending Review.
Three units at Wylfa targeted for mid-2030s; 3,000 jobs at site, 5,000 in supply chain.

rolls-royce.com (opens rolls-royce.com)Company profile →

Founded: 1906120 yrs
Headquarters: United Kingdom
Status: Public
Valuation: public
Works in: EnergyFission
Coverage: 1 program · 1 updatelatest 13 Apr 2026checked 10 Oct
Customers: Great British Energy–Nuclear (GBE-N) (opens gov.uk)

Spec

Wylfa SMR

Capacity per reactor

470 MWe^R (reported)

Total Wylfa capacity

1.4 GW^R (reported)

Site footprint

10 acres per unit^R (reported)

Target assembly time

500 days^R (reported)

Estimated cost per unit

£2–3 billion^E (estimated)

Homes powered

3 million^R (reported)