Christian M. 7 min read

Sizewell C: Nuclear dawn or dusk?

Sizewell C is the second nuclear power station to be constructed in the UK since 1995. It will add about 25,000 GWh of electricity to the national grid (~8% of national annual consumption) using the latest generation of EPR reactors, which are safer, cleaner, and more efficient than any of its predecessors. Construction is due to begin as early as 2024.

However, significant delays and excessive costs at Hinkley Point C (another UK nuclear power station currently under construction) are leaving Sizewell in an awkward position. This is not only because Sizewell is a near-exact replica but also because consumers will finance any cost overruns through future electricity bills.

This article provides a comprehensive rundown of Sizewell C, covering all essentials and its pros and cons, allowing you to form your own informed opinion. Is this a revival, the end, or a subtle continuation of nuclear energy in the UK?

💡 Contents:

Sizewell C essentials

Here’s all the fundamental information you need to understand the current situation at Sizewell:

What is Sizewell C?

Sizewell C is a planned nuclear power station to be built at the Sizewell site on the coast of Suffolk, in the East of England. Upon completion, it will be the second fission reactor since Sizewell B in 1995, following its blueprint Hinkley Point C in Somerset, which is currently under construction.

Sizewell C is expected to produce 3.2 gigawatts (GW) of electricity using the latest generation of reactors. This is enough to power around 6 million UK homes with low-carbon, baseload electricity.

Where is Sizewell C located?

The Sizewell nuclear power site, which encompasses Sizewell A, B, and C, is next to the small fishing hamlet of Sizewell on the Suffolk coast. One mile inland is the ‘nuclear town’ of Leiston, whose economy has relied heavily on the power stations since the commissioning of Sizewell A in 1966.

The nuclear site is next to the shore because it uses North Sea water as coolant for its reactors. It’s an environmentally sensitive area known for its natural beauty and ecological significance, with the Minsmere Reserve only 4 miles due north. The Suffolk coast is an eroding coastline, rendering any infrastructure vulnerable to subsidence and flooding.

Who owns Sizewell C?

As of April 2024, Sizewell C is owned by EDF Energy (50%) and the UK government (50%), although this was not the case initially.

At first, Sizewell C was a joint venture between EDF Energy and China General Nuclear Power Group (CGN), with both companies acting as owners and co-developers with an 80%/20% split.

However, due to legislation passed in March 2022, worsening UK-China relations and national security concerns, CGN sold its stake in 2023 to the UK government.

Has Sizewell C been approved?

After much planning and deliberation, Sizewell C received the necessary approvals to proceed on July 20, 2022. The UK government granted the Development Consent Order (DCO), a crucial regulatory approval required for any project to move forward with construction. The project is undertaking its final preparation stages before construction can begin.

Is Sizewell C under construction?

The project is expected to begin construction in 2024 and finish in the mid-2030s. Development largely depends on the progress at Hinkley Point C in Somerset, which remains under construction and is led by EDF. Hinkley is to serve as a blueprint for Sizewell C, with the new power station relying on its workforce, expertise, and any lessons learned to make it a success.

Who is funding Sizewell C?

The funding for Sizewell C involves a mix of government investment and private sector and consumer financing through energy bills. The latter is being done through the new Regulated Asset Base (RAB) model, specifically brought into law in March 2022 for this project in reaction to Hinkley’s spiralling costs.

This model allows developers to charge consumers a regulated price, similar to Contracts for Difference (CfDs) introduced to finance renewable business energy projects. However, instead of a fixed price per kWh of electricity, the RAB model allows project investors to recover their investment and earn a return through variable charges added to consumer energy bills over time.

This encourages companies like EDF to keep investing in the UK by providing certainty on their returns at the expense of energy consumers, making it controversial but a necessary step after the failures at Hinkley.

Besides this, the government has pledged up to £700 million in direct funding to help develop the project in 2023, with EDF having already made sizeable financial commitments.

When will Sizewell C be ready?

Estimates suggest a construction period of nine to twelve years from the start of building, putting the earliest possible commissioning date in the mid-2030s, assuming construction starts in 2024-25 and progresses without significant delays.

The problem is that the UK has achieved a terrible track record for executing large projects.

Hinkley Point C, EDF’s flagship nuclear project, finally got underway in 2016 with a budget of £24 billion and was expected to be completed in 2025. Fast-forward to 2024, and the most recent estimate has it that it will cost £46 billion and not be ready until 2031, making it the second most expensive nuclear power station in the world!

How much electricity will Sizewell C generate?

The electrical output of Sizewell C can be quantified in two ways:

  • Power Output (i.e. the maximum energy it can generate when reactors are working at full capacity, in GW) or,
  • Annual Energy Output (i.e. the total electrical energy it can supply over a year, in GWh).

Sizewell C will have a Power Output of 3.2 GW once its reactors go live. This is equivalent to around 3% of the UK’s maximum power output, which assumes all power stations are operating at full capacity at a given time (which never actually happens; usually enough is produced to meet demand).

EPR nuclear power stations can generate this output about 90% of the time (note: This % is known as the capacity factor), as reactors have some downtime for refuelling and routine maintenance operations.

Using these two figures, the Annual Energy Output of Sizewell C is 25,229 GWh or about 8% of the UK’s typical electricity consumption over a year. This is a significant contribution of low-carbon energy to the grid!

What are the pros and cons of Sizewell C?

Here is a summary of the advantages and disadvantages of Sizewell C that will be addressed in more detail:

Nuclear power is a source of large-scale, baseload, low-carbon electricityHigh construction costs and long delivery times provide uncertainty
Having nuclear power is essential for diversification and energy securitySizewell C siting may prove problematic in the long-run due to risk of flooding
Sizewell C helps with the economic development of Suffolk and the UKNuclear waste remains a long-term problem and significantly adds costs
Will use the latest, safest, most efficient nuclear power technologyNuclear power is a sensitive public opinion subject, often unpopular
Nuclear power becomes cheaper with repetitive buildsIt will rely on long, global supply chains for operation, making it vulnerable to geopolitics

The advantages of Sizewell C

Here are the main reasons why building Sizewell C would be advantageous to the UK’s energy security and economy:

Sizewell C will generate baseload, low-carbon electricity

Sizewell C will feature two European Pressurised Reactors (EPRs) and is expected to produce 3.2 gigawatts (GW) of electricity. In terms of design and technology, it will be a near-exact replica of Hinkley Point C, which is currently under construction. This approach aims to reduce construction and financial risks by applying the lessons learned and efficiencies from Hinkley to Sizewell C.

EPR is an advanced type of nuclear reactor (Generation III+) that represents a significant evolution in nuclear reactor technology, offering enhanced safety features, greater efficiency and a longer lifespan compared to older reactor designs:

CharacteristicEPR (Gen III+)Older Reactors (Gen II)
SafetyAdvanced safety systems including double containment, core catcher, and passive safety systems.Basic safety systems with reliance on active measures and external power for accident management.
Efficiency~37% thermal efficiency~33% thermal efficiency
Power output~1.65 GW per reactor~1 GW per reactor
Operational life60 years40 years
ConstructionComplex. Often experiences significant delays and cost overruns.Simpler. Generally less complex, but still prone to cost overruns and delays.

It’s the same tried-ad-tested technology used in new reactors in Finland, India, South Korea and China.

If all goes well, Sizewell C will generate a reliable stream of GW-scaled, baseload green energy that will keep churning electricity during its 60-year lifespan, regardless of whether the sun is shining or the wind is blowing. It’s a blessing for national grid operators who must juggle supply and demand to keep a stable grid.

Sizewell C will diversify the UK’s power generation

Intermittent renewables like wind and solar power are the fastest-growing sources of electricity in the UK because the technology keeps scaling and becoming cheaper.

Both are key to the UK’s net zero plans but have the major flaw of relying on weather conditions and requiring large amounts of space to scale.

Technologies like floating solar, floating offshore wind and scalable energy storage (i.e. flow batteries, pumped storage hydro, and gravitational batteries) are continuously being developed to provide stable electricity generation, but their success remains uncertain.

Enter Sizewell C, which would power six million homes in one swoop with proven technology. Even if storage technology makes fully distributed grids cheaper and more efficient, there is always room for more clean energy generation.

Recall that interconnector capacity with Europe is at record levels, and any excess can be sold abroad. Alternatively, cheap electricity can be used for many useful applications, like powering heat pumps, heavy industry with electric-arc furnaces, and increased electric vehicle charging.

The only concern is its cost. If the price of nuclear electricity from Sizewell C is significantly higher than that of renewables, who will want to buy it?

Sizewell C will support local and UK economies

Sizewell C is poised to substantially impact Suffolk’s economic development and the broader UK economy during all project stages: construction, operation, and decommissioning.

Assuming construction takes ten years, the operational lifespan is sixty years. With ten years of decommissioning and another ten waiting for the remaining spent fuel to cool down for transport, the result is ninety years of guaranteed jobs.

Will Sizewell C create jobs?

The project will employ around 25,000 people during the construction phase alone. While experienced staff from Hinkley Point C will make up a significant portion, new local and national staff will also be required.

Once operational, the plant will need a permanent workforce to manage and maintain the facility, providing long-term employment opportunities. Locals are already at an advantage here, having one of the most nuclear-experienced populations in the UK, with the Sizewell site existing since the 1960s.

What skills are needed to work at Sizewell C?

The success of Sizewell C would mark a re-birth of nuclear power in the UK, encouraging educational establishments like universities and technical colleges (both local and UK-wide) to offer courses directly linked with the industry.

This includes nuclear, mechanical and civil engineering, specialised machine operators, drone pilots, and environmental and social scientists, just to name a few. Any project of this size requires a wide spectrum of skills involved in direct and indirect employment across the supply chain.

What are the other economic benefits of Sizewell C?

Large projects force infrastructure upgrades that can benefit everyone. Public infrastructure development like new roads, upgraded rail lines, new hospitals, and schools are required to support the relocated workforce.

Additionally, increasing the proportion of low-carbon energy in the UK power mix will make it more attractive for investors because it helps them more easily fulfil their ETS and carbon credit obligations. Whether it will be churn cheap energy remains to be seen, and it will largely depend on how much the project overruns its budget.

The disadvantages of Sizewell C

Let’s flip the coin and see Sizewell C’s potential dark side, including a potential increase in energy bills and the dangers of building a sensitive facility on a receding coastline.

Sizewell C may be expensive

The UK is becoming well-known for its inability to deliver big infrastructure projects. The perpetual discussion of a third runway at Heathrow Airport, the cancelling of HS2, and the collapse of Britishvolt are notable examples. However, they appear minimal compared to the precedent being set by Hinkley Point C.

Hinkley is essentially the blueprint for Sizewell C, a near-exact replica. However, as of 2024, its construction costs have doubled the original budget, taking six years longer than initially planned. This may prove a disaster for households and businesses that will bear the costs of increased energy bills due to the RAB model passed into law in 2022.

To put the scale of this failure into perspective, Taishan Nuclear Power Plant in China, which has an extra 300MW power capacity and uses the same EPR technology as Hinkley, took just over 4 years to build and cost about £6.4 billion. In other words, it was built in a third of the time and cost 86% less than current estimates at Hinkley, which remains under construction.

While Sizewell C offers an opportunity to apply the lessons learned from the failure at Hinkley Point C, history quickly dampens any optimism. It remains to be seen what the costs per MWh of Hinkley’s power will be, but renewable costs breaking record lows may ultimately result in a price hike for consumers.

How much will Sizewell C cost?

The estimated cost for the Sizewell C nuclear power project ranges significantly, from about £20 billion to as high as £35 billion. While this is significantly less than the current estimates for Hinkley Point C, the final costs will only be known upon completion.

Will Sizewell C increase energy bills?

With the introduction of the Regulated Asset Base (RAB) model into law in 2022, some of the costs of building Sizewell C will be reflected in a rise in both domestic electricity prices and business electricity prices.

Assuming the maximum expected cost of £35 billion, we can make a very rough RAB estimate as follows:

  • Annual cost recovery: Approximately £583.33 million per year over the operational lifespan of 60 years.
  • Annual cost per GWh: Approximately £23,121.72 per GWh.
  • Additional cost per kWh: Approximately 2.31 pence per kWh.

Assuming a typical medium-sized home in the UK uses an average of 2,900 kWh per year, Sizewell C would add £66.99 to its annual electricity bill in 2024.

This premium would increase yearly with inflation and essentially become perpetual for current households and businesses, assuming it is paid over its operational life of 60 years.

💡 You can play around with these costs by using our electricity bill calculator, which lets you add different costs per kWh to your bill.

Sizewell is dangerously prone to flooding

The previous generation of nuclear power stations in the UK never suffered any safety or environmental concerns based on location. However, with worsening climate change and the precedent set by the Fukushima disaster in Japan, the siting of Sizewell C appears significantly more complicated.

Is Sizewell prone to coastal erosion?

Sizewell C is located on the Suffolk coast and is historically renowned for its exposure to erosion. The village of Dunwich, 4 miles north of the site, was once the capital of the Kingdom of East Anglia but diminished to its current size due to long-term coastal erosion.

Unlike Dunwich, Sizewell is protected from erosion and frequent storm surges by large underwater sandbanks. Still, these dynamic features are not guaranteed to remain perpetually in place. So far, the Sizewell site has never had issues, but this was before climate change.

Is sea-level rise a problem for Sizewell C?

Global warming is expected to cause more frequent and intense storm surges on the Suffolk coast. Their impact is compounded by sea-level rise, which will bring the average sea level closer to the exposed nuclear facility.

The Sizewell site must remain protected from flooding for at least 90 years to support its entire life cycle. Current IPCC estimates predict a significant sea-level rise of 0.6 to 1 meter by 2100, severely complicating the risk of catastrophic flooding at Sizewell.

💡 Tsunami risk: The Suffolk coast might not be prone to earthquake-triggered tsunamis like Fukushima, but geological evidence shows that tsunamis triggered by underwater landslides on the North Sea have occurred in the past and could also threaten Sizewell.

Does Sizewell C have coastal defences?

The Fukushima flooding disaster caused by the Japanese 2011 tsunami raised concerns for all seaside nuclear power stations worldwide.

Sizewell C is designed to withstand the flooding risk highlighted earlier. The power station will be constructed on an elevated platform approximately 7 meters above the current mean sea level. A sea defence structure standing more than 14 meters above mean sea level will provide additional protection.

In theory, the infrastructure is designed to withstand up to one in 100,000-year surge events and can adapt and enhance its defences if future sea-level rise exceeds current expectations. However, there is always a risk.

Sizewell C will generate nuclear waste

Using the European Pressurized Reactor (EPR) design, Sizewell C is expected to generate significantly less radioactive waste than existing UK nuclear power stations. EPRs use enriched Uranium that generates three different kinds of radioactive wastes:

Type of Waste% volume (% radioactivity)Description
Low-Level Waste (LLW)90% (1%)Materials contaminated with low levels of radioactivity. Managed through containment and disposal in designated low-level waste facilities.
Intermediate-Level Waste (ILW)7% (4%)Higher levels of radioactivity but does not generate heat. Contained and stored securely until a long-term disposal solution is available.
High-Level Waste (HLW)3% (95%)Highly radioactive, heat-generating spent fuel. Requires cooling and shielding on-site, before permanent storage.

How much nuclear waste will Sizewell C generate?

If you extend these yearly nuclear waste tonnage estimates to its 60-year life cycle, Sizewell C will generate between 19,200 and 38,400 tonnes of low-level radioactive waste and between 3,840 and 5,760 tonnes each of intermediate-level waste and critical high-level spent fuel from the reactor.

At best, this is 26,880 tonnes of radioactive waste.

Is nuclear waste a problem?

Radioactive waste is one of the main pain points of nuclear energy. While highly regulated and strictly managed, it is a significant expense for any nuclear operation and has numerous safety concerns.

Highly radioactive material has to be stored and contained over geological timescales. It must be stored in secure conditions as it could potentially be targeted by terrorists seeking materials for radiological dispersal devices (dirty bombs).

There are no permanent, long-term spent fuel storage facilities anywhere in the world. In the UK, low-level waste is stored in a facility in Drigg, Cumbria; intermediate-level waste is encapsulated in cement and stored in stainless steel containers at UK nuclear sites, and spent fuel is stored at nuclear power plant sites in vitrified form within stainless steel canisters until they cool down.

💡 Huge premiums: According to various industry estimates and regulatory reports, nuclear waste management can add between 5% and 10% to the overall costs of generating nuclear power!

Sizewell C is unpopular

Like any nuclear power station, promoting Sizewell C to the public has been challenging for EDF and the government, for the same arguments listed in this section of the article, including:

Public opposition is local and national-scale, with various actors, such as NGOs, environmental groups, political figures, and even entire parties, opposing it. The Stop Sizewell C website gives a glimpse of this and largely capitalises on the failures at Hinkley Point C.

Nevertheless, the recent energy crisis and the need for the UK to reach net zero by 2050 have been key push factors to keep the project on track despite its many issues.

💡 Not THAT unpopular: A recent 2024 survey mentioned in The Economist shows that, in fact, most people in Suffolk and across the UK are actually for the development of Sizewell C.

Sizewell C increases the UK’s geopolitical risk

Sizewell C  is exposed to geopolitical risks because of the global nature of its supply chain. Because uranium is not mined in significant quantities in the UK, all British reactors rely on imports.

The leading suppliers of uranium include Canada, Australia, Kazakhstan, and Russia. While the first two are friendly commonwealth nations, countries like Russia are renowned for using their control over natural resources as a bargaining chip.

On the other hand, Sizewell C reduces dependence on imported fossil fuels, which are even more susceptible to geopolitical disruptions as the re-fuelling of the UK’s power station is more immediate than that of a nuclear power station like Sizewell C, which requires more sporadic supplies.

Conclusion: Finish Sizewell C, but keep building renewables

Three things are certain:

  1. The UK must produce more electricity. The world is electrifying fast, with EV charging, cloud applications and AI on the rise. Excess electricity only brings advantages, as it can attract high-tech industries and, at worst, be sold abroad through interconnectors.
  2. The UK needs clean energy. We’re entering the challenging part of the net zero by 2050 strategy, having experienced the easy gains from removing coal power from the grid and replacing it with gas and wind power.
  3. The UK must improve energy security. The world is changing, and the UK must become resilient. This means diversifying electricity generation by recuperating the large-scale nuclear power capacity lost over the years.

Given these three pillar truths about the UK’s energy sector, building Sizewell C will be beneficial, even if its price tag and siting are not ideal. Countries like South Korea, France and China have proven that nuclear gets cheaper with established expertise and ‘cookie-cutter’ builds, and pulling the plug on nuclear now would break all momentum.

On the other hand, the UK would be unwise to put all of its eggs in the nuclear basket. Combined with energy storage, wind, geothermal and solar technologies are poised to become equally robust at a much lower price while providing full independence from Uranium suppliers and the nagging worry of nuclear safety and waste management.

This leaves us with a clear conclusion. Yes, build Sizewell C and another handful of ‘cookie-cutter’ reactors to ensure ample baseload nuclear energy. The remaining effort should go to renewables, which are already significantly cheaper and poised to be equally robust and even more efficient with the rise of cheap energy and distributed grid technologies.

Sizewell C – FAQs

Our business energy experts answer commonly asked questions on Sizewell C.

What would happen if Sizewell C blew up?

Like any other nuclear power station, Sizewell C can’t possibly blow up like a nuclear weapon. However, while extremely rare, severe nuclear accidents are possible. This includes a damaged core or radioactive material released into the environment, which poses health risks to humans and wildlife.

Depending on the severity of the accident and the extent of the radioactive release, a temporary or permanent evacuation of the population in the surrounding areas might be necessary. Besides the health and environmental damage, the cost of cleanup and decommissioning, as well as the loss of power to the grid, would likely cripple both local and national economies.

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