Its iconic white dome is one of the most famous - if controversial - landmarks on the Suffolk coast.
And today, with an exclusive tour, we can reveal what really goes on behind the scenes at one of Britain's most important power stations.
Opened in 1995, Sizewell B - run by EDF Energy - has long faced criticism from its neighbours for the effects many believe it has on one of most beautiful parts of the country.
As well as the visual impact of a large industrial powerhouse near an area of outstanding natural beauty (AONB), environmentalists fear the radioactive waste it leaves behind for decades.
Despite the incredibly low statistical chances of a major nuclear accident, the fear of a devastating catastrophe - heightened by the television series Chernobyl - is also never far from many people's minds.
Yet those on the inside, from the technical apprentices starting out in their careers right up to the station director, are unrepentant about what they see as its benefits - a reliable, cost-effective way of meeting Britain's energy needs which provides valuable, much-needed skilled jobs and contributes millions of pounds to Suffolk's economy.
Without it, they don't believe Britain - let alone Suffolk - could survive. Are they right?
How does Sizewell B work?
The inner workings of a nuclear power station are notoriously complex, with its intricate technical design taking years of training to understand.
Essentially though Sizewell B, the UK's only pressurised water reactor, works by splitting uranium atoms in a process called fission to create nuclear energy.
The steam created by this intense reaction enters two massive turbines with shafts rotating at 3,000rpm at a temperature 282C, turning it into electricity.
Huge power lines transport that electricity directly to the people, powering 2.2million homes. Indeed, Sizewell B powers much of East Anglia.
For station director Paul Morton, who worked his way up through coal and gas power stations before joining Sizewell B, said: "It's a very different technology.
"The science of making heat from nuclear fission is something completely different and I've thoroughly enjoyed learning the technology."
What is it like inside?
When she first saw the two turbines, fourth year mechanical maintenance apprentice Beth Gant described her "amazement" at the sheer scale and technical detail of what are effectively Sizewell B's 'engine rooms'.
The tips of the large turbine blades travel at twice the speed of sound, creating a deafening noise and vibrations you can feel through your feet.
When she first stepped inside, Miss Gant said: "I was shocked at how big it was. It was very loud, very big and very hot.
"My first thought was: 'How am I going to help maintain all of this?'"
The sight of the nuclear reactor itself, inside the famous white dome and above almost glowing blue water, is equally jaw-dropping.
But Miss Gant said: "When you look at the turbine it's huge, but I was shocked at how small the reactor is itself.
"To create so much power I thought it had to be huge, but it's really not."
The reactor control room: Sizewell B's 'nerve centre'
Katie Bannister works in a room which perhaps more resembles a science fiction movie than an office.
Sitting inside a console in the centre of the space, almost as if she is controlling the Starship Enterprise, the reactor control room operator is responsible for monitoring dozens of screens and dials.
To you and me, what is on those screens might look like gobbledegook - but they contain crucial and sensitive technical information about the performance of the plant.
A lay-person wouldn't even know where to look, yet the three people on shift have to keep an eye on it all and spot in an instant when something doesn't look quite right.
It is an extraordinarily challenging job which requires operators to memorise literally thousands of buttons and switches.
Yet to Miss Bannister and her colleagues, it is a rare privilege.
"Our primary job is making sure we're maintaining a safe and reliable generation of power," said Miss Bannister, who studied chemical engineering at university.
"We control and supervise all the activities in the power station. We do routine testing of emergency equipment, routine checks of all our key parameters and make sure temperatures are right."
It is certainly not a job you can just start straight away.
The accredited reactor control room training programme takes 18 months, much of it in an exact carbon copy replica Sizewell B has built as training ground, and much of it supervised.
Even once that is completed, an authorisation panel has to meet to decide who is given approval to work there full-time.
To become a shift supervisor, even more training is required.
And you can't just walk into this highly secretive area - even the station director has to stand behind a red line and wait to be given permission to enter by the shift supervisor.
"You spend weeks in the simulator," Miss Bannister said.
"You have to learn every single switch. Then you look at all those systems and how they hang together.
"It's a very layered training programme."
Reassuringly, several weeks during the training is devoted to what to do in "abnormal situations" - not that they are expected to occur, since Miss Bannister says Sizewell B is "one of the best designed power stations in the world".
Amazing attention to detail is also given to creating the calmest working environment, with even the lights designed so that buttons and switches aren't obscured by shadows.
Why is Sizewell B needed?
Travel round east Suffolk's most picturesque towns and villages - from Leiston to Saxmundham and Framlingham, from Theberton to Thorpeness and even Sizewell itself - and you will see several posters decrying any nuclear expansion in Suffolk.
But Mr Morton, who took charge of EDF Energy's Sizewell B nuclear power station in 2016, is clear: "I don't believe the lights will stay on without it."
The station's director is in some ways relatively new to the world of nuclear energy.
Even though he has worked in power stations his whole working life, the vast majority of his career has been in coal and gas.
He had never even been to a nuclear power station before first visiting Sizewell when the top job became vacant more than three years ago.
Yet he quickly reached the view that nuclear power is essential to the future.
"Where I started out my career, it became clear it wasn't technology you could rely on in the long-term," he said.
Fossil fuels are a finite resource, with many predicting coal, oil and gas could run out in anywhere between 50 and 100 years.
Yet the demand for electricity grows, with cars increasingly relying on electric as fuel runs out.
"We need to ensure we provide sustainable energy for the long-term and nuclear is one of the answers to that," said Mr Morton.
"The electrification of our lives is very clearly a direction we're going to go.
"We've burned fossil fuels to create electricity and we've burned them to heat our houses. Over the next few decades, that's going to change.
"We need to be able to produce bigger volumes of electricity in a clean, sustainable way.
"Renewables will play a big part - but that will get nowhere near being able to fulfil the needs of the nation.
"When the wind doesn't blow and the sun doesn't shine, we still need to be able to power our homes, pump our water, produce our food.
"Nuclear technology can fill that gap at the moment."
Future plans to build Sizewell C next to its sister stations attract major debate, just as the B station did before construction began in 1988.
Many of the objections centre on entirely separate issues, such as the effect on the nearby Minsmere nature reserve which the RSPB says could be catastrophic.
Whatever the benefits or national importance of nuclear power, these are issues that deserve the highest consideration.
EDF Energy is adamant it is going above and beyond to protect wildlife in its proposals for Sizewell C, for example with the creation of a wetland habitat at nearby Aldhurst Farm.
Groups like the RSPB and even celebrities such as Bill Turnbull beg to differ.
But although its lifetime could be extended, Sizewell B's current lifespan is only currently due to last until 2035.
EDF believes that could potentially leave a huge gap in the UK's energy needs, at the very time demand is rising.
"The renewal of our current assets is a national imperative," said Mr Morton.
"We have to do it and we have to do it now to continue to supply the nation with the energy it will need."
Reactor control room operator Katie Bannister added: "Having the opportunity to work in an industry that is so important to energy mix of the country in the future is a privileged position to be in."
What about safety?
The television series Chernobyl has seared into people's minds the risks of a nuclear accident, as well as the devastating consequences should the worst ever happen.
But station director Paul Morton is prepared to be as blunt as saying that at Sizewell B: "It's just not going to happen."
Safety is certainly a constant watchword wherever you go at Suffolk's nuclear power station.
In every corridor and workshop, there are signs warning you to watch where you're going, potential hazards and what you can and can't carry.
Even as you walk up and down the stairs, signs tell you to always have one hand on the bannister should you slip or fall.
The most junior staff are also allowed - and indeed encouraged - to challenge their superiors on anything related to safety, from whether they are wearing the correct protective clothing to if their working methods are the safest.
Electrical technician Gary Jackman described how staff are encouraged to think through the potential consequences of their work before turning a single spanner.
"It's our over-riding priority," Mr Morton said.
"Safety is everything. It's our ticket to the game."
Sizewell B has never suffered a serious or minor nuclear incident. The UK as a whole has only had a handful in the last 70 years.
Globally, the statistical chances of a nuclear accident are rated as very low. Mr Morton also points out that external assessors from across the world assess Sizewell's safety.
When asked if he could put a figure on the likelihood of a nuclear accident at Sizewell B, he said: "It's just not going to happen.
"With the levels of design, attention to detail, the way in which the plant is operated and the level of legislation, it's not going to happen."
Mr Jackman is even one of the few who last year benefited from a rare opportunity to visit the site of the 1986 Chernobyl disaster.
It had a lasting effect him and others, teaching them about the potential consequences should safety guidelines not be adhered to.
What about security?
Even the tiniest amount of nuclear material is known to lethal, so one could imagine that Sizewell B could be a target for terrorists.
If it is, Mr Morton is confident they would not get very far.
Mr Morton is unable to go into the specific details of how Sizewell B is kept safe because those security protocols are, by their very nature, secret.
But he said: "There are scenarios which we test ourselves against to satisfy ourselves that we're robust."
He added that: "The material we use here is not material you could use to make a bomb - it's not of that nature."
And he pointed out that as well as security guards and cameras, the most sensitive areas can only be accessed by highly qualified and accredited staff - something which takes years to acquire.
"You'd have to go through so many barriers to even get near it," he explained.
Even Sizewell B's famous white dome, which houses the crucial reactor core, is built with the strength to withstand an aeroplane crash should it be targeted from the air.
The apprentices' story
As universities battle for the best and brightest students, there might be one competitor they are overlooking.
Sizewell B prides itself on not just being a nuclear power station but giving its workers the chance to train, earn qualifications while they are paid and - provided they work hard - improve their career prospects.
It is an offer that proved too good to turn down for 24-year-old Beth Gant, currently a fourth year engineering maintenance apprentice, when she weighed up the option of going to university.
"I did A-levels and all of my friends were going off to uni," she said.
"I was in the year that they put up uni fees and I didn't want to get into debt."
She also thought a hands-on job suited her learning style much better than lecture-based higher education.
"I always played with stuff and picked stuff up when I was young," she said.
"I've always done it at home, so I thought it was something I could learn about properly."
Gary Jackman, 23, likewise decided that he "thought an apprenticeship was the best route to take, because you're getting paid to learn" when arriving in the UK from Zambia.
Would-be technical maintenance apprentices need five GCSEs at grade C or grade four and above, including English, maths and two science or technical subjects.
They start on £11,200 a year, with accommodation and meal costs covered in the first two years, along with a number of paid return journeys home.
Those on the nuclear engineering and civil engineering degree courses start on £17,335 but ideally need three A-levels at grade C or above, or the equivalent BTech qualifications.
But the programme does not just stop at teaching apprentices the technical skills needed for the job.
There are a whole range of classroom-based sessions on crucial life skills, such as working in teams and challenging colleagues in a constructive way.
In her first week, Miss Gant and her new colleagues even visited Alton Water to build team building skills on an outdoor course.
"It's no good having someone who's excellent technically who can't work with the rest of the team," Mr Jackman said.
Many industries are criticised for being inaccessible to people without the financial support to go to university and do unpaid work experience.
But while station director Paul Morton said that about half of the jobs at Sizewell B require a higher education level qualification, many of those can all be completed during employment.
"It's a much broader thing and then just learning hands on skills," he said.
"They've learned life skills, lived away from home and learned how to look after their own finances."
It's not all about nuclear power...
Sizewell B is home to some of the country's cleverest nuclear scientists.
Yet while they may help keep Britain's power running, there are a whole range of other people who keep Suffolk's nuclear plant going 24-7.
Whether they are security guards, cleaners, administrators, chemists or cooks, all are part of what could be described as Sizewell's nuclear family.
One is chef manager Stuart Bayford, who leads a team preparing breakfasts and lunches for nearly 800 workers - 505 permanent EDF staff, the rest contractors.
Having worked in restaurants across Suffolk and Essex, a nuclear power station might seem an unusual place for a top chef to be serving up culinary delights.
Yet he sees his role as crucially important to the running of Sizewell B.
"From our perspective, it's a reason to come to work," he says of his team's range of cooked meals provided each day, often using Suffolk produce.
"It's quite easy to throw sarnies in a box, but people won't be inspired. We can produce a nutritious meal that they want to eat.
"These guys can be doing 12-hour shifts and we don't want them to be doing something really critical and then have a lull during the day.
"This gives people energy to get up and do their job."
The future
Nuclear power stations have always been controversial.
Mr Morton himself admits that "they're expensive to build", even though their lifespan of decades makes the cost more economical in the long-term.
The impact they leave behind is often huge, with hundreds of workers - thousands during construction periods - living in the area, adding to the existing pressures of housing and roads infrastructure.
Mr Morton believes the amount of radioactive waste Sizewell B leaves behind is relatively small - but said: "It's a small volume but does need to be managed over the long-term, and that's something as a nation we have to work our way through."
No more is there evidence of that than at the B station's neighbour Sizewell A, which was shut down in 2006 but has to be kept secure to allow radiation levels to decay before final site clearance.
That is a process that could reportedly take 100 years.
But Mr Morton said: "I can understand that it will be an impact on the local area.
"But there are also a lot of people who will benefit from these power stations being here.
"The apprenticeships are highly valued by the local population. There is a tremendous level of interest."
He also said Sizewell B contributes about £20million a year to the local economy, which can rise to £40million in a year when there is an outage - when the plant stops generating power to allow for round the clock maintenance.
Mr Morton is keen that young people within the 25-mile radius that Sizewell requires its workers to live, in case they are needed in an emergency, benefit from those advantages.
It talks to children aged as young as six or seven about future careers in energy, visiting schools and inviting pupils in to see science in action.
Miss Gant and Miss Bannister take time out of their day jobs to particularly encourage young girls, in what has perhaps traditionally been seen as male-dominated industry.
Mr Morton, who started his career with the old Central Electricity Generating Board (CEGB) at High Marnham Power Station in Nottinghamshire, says the goal is "catching their imagination".
"I went into a power station with my dad when I was a kid and remember walking round thinking: 'This is enormous.'
"It certainly interested me and I do everything I can to encourage young people into the industry.
"I think we've got a lot to be proud of."
Sizewell B in numbers
? 2.2million - homes powered
? 1 - pressurised water reactor
? 520 - full-time staff
? 1,198 - MW supplied to national grid
? 40 - lifespan of the plant
? £20million - amount contributed to local economy
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