You’ve probably seen the dome. If you’ve ever walked the shingle beaches near Aldeburgh or Thorpeness, that massive, white pressurized water reactor housing of Sizewell B looms over the horizon like something out of a 1970s sci-fi flick. It’s iconic. It’s controversial. Honestly, it’s a bit of a localized obsession for people living in East Anglia. But the story of the Sizewell nuclear power stations isn't just about one building or even one era of technology. It’s actually a decades-long saga of British energy policy, massive engineering gambles, and a tiny fishing hamlet that became the center of a national shouting match.
Most people think "Sizewell" is just one plant. It isn't. It’s a lineage.
We are talking about a site that has seen the rise and fall of Magnox technology, the transition to American-style pressurized water reactors (PWR), and now, the grueling birth pains of the European Pressurized Reactor (EPR) with Sizewell C. It’s a lot to wrap your head around, especially when the headlines are usually just screaming about costs or "the birds." Let's actually look at what’s happening on that patch of Suffolk sand.
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The ghost of Sizewell A and the reality of decommissioning
Sizewell A is the one people forget. It’s the twin-reactor Magnox station that started huffing and puffing back in 1966. For about 40 years, it just did its job. It produced enough electricity to power a city like London for decades before finally being switched off in 2006.
But here’s the kicker: turning a nuclear plant off doesn’t mean it’s gone.
Walking past the site today, you’d still see the massive rectangular blocks. Decommissioning is a slow, methodical, and frankly expensive dance. According to the Nuclear Decommissioning Authority (NDA), we are looking at a process that won’t be "done" in the way most people think until the next century. They’ve already cleared the ponds and removed the fuel—that happened around 2014—but the structures remain in a state of "care and maintenance."
It’s weirdly quiet there now. The humming of turbines has been replaced by the sound of gulls and the occasional van from Magnox Ltd. It serves as a stark reminder that when we build these things, we are making a commitment that lasts longer than most countries' political systems.
Why Sizewell B is still the heavy hitter
Then you’ve got the B station. This is the star of the show. Sizewell B is the UK’s only pressurized water reactor, and it’s been the backbone of the grid since 1995.
While the rest of the UK’s aging fleet of Advanced Gas-cooled Reactors (AGRs) like Hinkley Point B or Hunterston B have been hitting their "use-by" dates and shutting down, Sizewell B just keeps trucking. It produces about 1,200 megawatts of power. That’s enough to keep the lights on in over 2 million homes. It’s reliable. It doesn’t care if the wind isn’t blowing or the sun is tucked behind a thick layer of British clouds.
Wait, there’s a catch.
The plant was originally supposed to retire around 2035. EDF Energy, the French giant that runs the place, has been looking into life extension. They’ve invested heavily—we’re talking tens of millions—in outages and maintenance to see if they can push that date further back. It makes sense. Replacing that much low-carbon baseload power is a nightmare for the National Grid. If you’ve ever wondered why your electricity bill is so volatile, it’s partly because the "boring" reliable stuff like Sizewell B is becoming a rarer breed.
The tech inside the dome
Inside that famous white dome is a four-loop Westinghouse design. It’s basically a massive kettle. The water is kept under such intense pressure that it can't boil, even when it’s screamingly hot. That heat is transferred to a secondary circuit to make steam, which spins the turbines. Simple in theory. Terrifyingly complex in practice.
The safety protocols are insane. I’ve spoken to engineers who describe the "defense in depth" approach—multiple redundant systems that are designed to fail-safe. Even the concrete of the containment building is reinforced with steel tendons that could probably withstand a plane crash.
The Sizewell C drama: Why is it taking so long?
If Sizewell B is the reliable veteran, Sizewell C is the ambitious, expensive, and polarizing new recruit. This is where the conversation gets heated. The plan is to build a twin-reactor plant that would basically be a carbon copy of Hinkley Point C, which is currently under construction in Somerset.
The logic? "Copy-paste."
The UK government and EDF argue that by building the same design twice, they can avoid the massive cost overruns and delays that have plagued Hinkley. They call it the "fleet effect." If you know how to build the first one, the second one should be cheaper and faster.
Except, "cheaper" is a relative term in the nuclear world. We are talking about a project estimated to cost north of £20 billion.
Money, money, money
Funding has been a mess. For a long time, the UK tried to use the "Contract for Difference" model, but that put all the construction risk on the developer, which scared off investors. Now, they’ve switched to the Regulated Asset Base (RAB) model.
Basically, you—the taxpayer and billpayer—start paying for the plant while it’s still being built. It lowers the cost of borrowing for the developers, but it’s a tough pill for the public to swallow during a cost-of-living crisis.
In late 2022, the UK government became a 50% shareholder in the project, effectively nationalizing a huge chunk of the risk. They even set up a company called Sizewell C Ltd. It’s a massive bet on the future of the UK’s energy security.
The environmental tug-of-war
You can't talk about the Sizewell nuclear power stations without talking about the RSPB Minsmere reserve. It’s right next door. It’s one of the most important wildlife sites in Europe, home to rare birds like the bittern and the marsh harrier.
Environmentalists aren't just worried about "glowing fish"—that’s a myth. The real concerns are:
- Water Usage: The plant needs a staggering amount of water for cooling. There are ongoing debates about where that water comes from and what happens to the tiny fish sucked into the intake pipes.
- Coastal Erosion: The Suffolk coast is basically made of sugar. It erodes fast. How do you protect a nuclear site for 100 years when the sea is trying to eat the land?
- Construction Chaos: Building this thing requires thousands of workers, new roads, and massive amounts of concrete. For a quiet area of Suffolk, that’s a tectonic shift.
Groups like "Stop Sizewell C" have been fighting this in the courts for years. They argue that the money would be better spent on renewables and battery storage. On the flip side, the GMB union and local chambers of commerce are desperate for the jobs. It’s the classic "environment vs. economy" deadlock, but with radioactive stakes.
Is nuclear actually "green"?
This is the big one. Depending on who you ask, Sizewell is either the savior of the planet or a toxic legacy.
From a carbon perspective, nuclear is incredibly clean. Over its lifecycle, it produces about the same amount of CO2 per kilowatt-hour as wind power. If the UK wants to hit Net Zero by 2050, most experts—including the Climate Change Committee—say we need a "firm" base of nuclear to back up the intermittent renewables.
But then there’s the waste. We still don’t have a Geological Disposal Facility (GDF) in the UK. This means the high-level waste from Sizewell B and eventually C has to be stored on-site in "dry casks" or cooling ponds for decades. It’s a temporary solution that feels very permanent.
What’s next for the Suffolk shore?
Construction prep for Sizewell C has actually started. If you drive past the site now, you’ll see the early works—fencing, vegetation clearance, and the beginning of the haul roads. It’s no longer just a "plan." It’s happening.
But challenges remain. The final investment decision (FID) is always the big hurdle. The government needs to bring in private investors to dilute their 50% stake, and in a world of high interest rates, that’s a tough sell.
Actionable insights for the curious
If you’re trying to make sense of the Sizewell situation for your own energy bills or just out of interest, keep these things in mind:
- Watch the RAB model: Look at your energy bill’s "policy costs" in the coming years. This is where the funding for Sizewell C will eventually show up. Understanding this helps you see the real cost of "energy security."
- Check the "Life Extension" news: Keep an eye on Sizewell B's status. If EDF gets the green light to run it until 2055, it significantly changes the UK's energy outlook for the next two decades.
- Visit the Discovery Centre: If you’re actually in Suffolk, the Sizewell B Visitor Centre is genuinely worth a look. You can't just wander into the reactor (obviously), but they have massive exhibitions on how the cooling systems work and the history of the site. It’s a great way to see the scale of the engineering without the political filter.
- Monitor the coastal defense plans: If you live nearby, pay close attention to the "soft coastal defense" strategies proposed by Sizewell C Ltd. These plans involve moving thousands of tonnes of shingle and will likely change the shape of the local beaches more than the power station itself.
Nuclear energy is never simple. It’s a mix of high-stakes physics, multi-billion pound finance, and local heritage. Whether you love the "big white dome" or hate the idea of another one next to it, the Sizewell nuclear power stations are going to be the heart of the UK's energy debate for at least another eighty years. That's just the reality of the atom.