What is Sizewell C and what does it mean for Suffolk?

The government has said the Sizewell C project would cost £38bn

Plans for the Sizewell C nuclear power station are set to go ahead after the government signed off on the final investment decision for the project. But what exactly is Sizewell C, and what are the arguments for and against it?

What is Sizewell C and where will it be built?

The site for Sizewell C is near existing nuclear buildings on the Suffolk coast

French energy company EDF wants to build a new two-reactor nuclear power station on the east Suffolk coastline that could generate 3.2 gigawatts of electricity.

It claims Sizewell C could power the equivalent of about six million homes and will generate electricity for 60 years.

The power station will sit right next to Sizewell B, which has been operating since 1995, just off Sizewell beach, close to the town of Leiston.

The decommissioned Sizewell A site, which first opened at the same site in 1967, stopped generating electricity in 2006.

What is nuclear and is it safe?

To generate nuclear power in non-military reactors, uranium atoms are bombarded by much smaller neutron particles.

This causes the atoms to break down in a process called nuclear fission, which releases huge amounts of energy as heat.

The heat is used to boil water, producing steam, which drives turbines and generates electricity.

According to the International Atomic Energy Agency, the plants are among the "safest and most secure facilities in the world" and are subject to strict international safety standards.

When was Sizewell C first proposed?

In 2008, the then Labour prime minister, Gordon Brown, said the UK needed to increase its nuclear power capacity.

Two years later during the coalition government between the Conservatives and Liberal Democrats, Sizewell was identified as a site suitable for a new power station.

In November 2012, EDF launched its first public consultation to get the feedback of local people ahead of any formal planning application.

Three other public consultations were held, with the final one finishing in September 2019.

Sizewell C said more than 10,000 East Suffolk residents had been involved in the consultations.

Does Sizewell C have planning permission?

Sizewell C will stand alongside the existing Sizewell A and B plants

In May 2020, EDF submitted an application for a development consent order to build the power station.

This is a legal document that grants permission for large-scale and nationally significant projects in England and Wales.

This was granted by the government in July 2022 despite the Examining Authority recommending it was not approved over water supply and nature concerns.

The site has also had its nuclear licence granted too in May 2024.

While both these have been given, there were still questions over how it would be funded.

How much will Sizewell C cost?

In July 2025, it was announced that the cost of building the power station would be £38bn, despite EDF previously rejecting claims from some energy experts that the project would cost about £40bn.

Prior to this, in 2020, EDF had estimated the cost of the power station to be about £20bn, but the joint managing director of Sizewell C, Julie Pyke, said earlier estimates did not account for inflation or risk.

What investment has the government already committed to?

Chancellor Rachel Reeves said Sizewell C would "kickstart" economic growth

The government said in June 2025 it would be investing £14.2bn to build Sizewell C - this figure included £2.7bn announced in November last year, a spokesperson for the Department for Energy Security confirmed.

It means £17.8bn has been invested in the project in total.

This included some funding from a subsidy scheme called Devex.

Who else has a stake in the project?

In early July 2025, it was announced that EDF would take a 12.5% stake.

Several weeks later, the government announced the other companies that would have holdings in the project in exchange for funding.

La Caisse, a global investment group, would take a 20% stake, and Centrica, an electric services company, would take 15%.

Amber Infrastructure would also have a stake of 7.6%.

What is the argument for Sizewell C?

No new nuclear power plant has opened in the UK since 1995 when Sizewell B began operating.

According to the government, all existing nuclear stations with the exception of Sizewell B, are likely to be phased out by the early 2030s.

The government has previously said it was on a "mission" to deliver clean power by 2030 and reach its net zero target.

Nuclear power stations do not produce greenhouse gases like carbon dioxide or methane while in operation and therefore it could be key to help with this goal.

The government also said this "clean, homegrown power" could play a part in building economic growth, improve its energy security and reduce the country's dependency on fossil fuels.

Another key argument around the project is the jobs it could create for the surrounding areas.

While in construction, the project could employ up to 10,000 people and once in operation there will be 900 people employed at Sizewell C.

What do campaigners say?

Alison Downes from Stop Sizewell C has hit out at the cost of the project

There has been strong opposition against Sizewell C since it was announced.

Campaign groups Stop Sizewell C and Together Against Sizewell C both fear the plant could have negative effects across a range of different areas.

Both have significant worries over the environmental impact and the Royal Society for the Protection of Birds has similarly protested in the past over this fear.

Sizewell C has argued it has worked to protect the wildlife around the site by rehoming displaced animals in new nature reserves it has created.

The campaign groups also argue the project is "too slow" to combat climate change and is too expensive.

Alison Downes, director of Stop Sizewell C, said the government would come to "regret" its investment and felt the money could be spent elsewhere.

When could Sizewell C be operational?

The Sizewell C reactor is expected to be operational in the mid to late 2030s.

Sizewell C also recently announced plans to open a post-16 college in Leiston, which it hoped would help train up its future workforce.