Extract from ABC News
Provence in southern France is known for its rolling vineyards, fields of lavender, olive groves and idyllic villages.
But recently, the mood has shifted in this charming part of the world.
Eerie midnight convoys block off stretches of highway between Marseille, Avignon and Nice.
Semi-trailers slowly creep along deserted roads, ferrying enormous and mysterious-looking objects through the Provencal countryside.
These parts are headed for one of the biggest science experiments on the planet: the International Thermonuclear Experimental Reactor, or ITER.
At this complex, hidden behind rows of fences, forests, and fields, scientists are planning to create the reaction happening in the centre of the Sun.
The major goal of ITER, which is a multi-billion dollar collaboration between dozens of nations, is to show nuclear fusion can generate power at an industrial scale.
"Fusion energy is seen sometimes as the holy grail of energy," says Tom Wauters, a calm, slender and genial Belgian who works as a plasma physicist at ITER.
"The advantages of this technique — even though it's very complicated to achieve — is that you can have almost limitless energy."
Unlike nuclear fission, which generates electricity by splitting atoms, nuclear fusion harnesses the energy released when two atoms merge.
It mimics the reaction fizzing away at the centre of stars — and doesn't produce long-lived radioactive waste.
But as is often the case with power generation devices, there are a few catches.
The world’s largest fusion reactor
Everything at the vast ITER site — including the layers of security and a satellite city for staff — has been constructed around a huge, concrete, blocky building.
It houses an assembly hall, where 10 million components, manufactured in places as far-flung as South Korea, China and the Americas, are put together.
And right beside the hall is where the magic will (hopefully) happen: a chamber containing a hollow doughnut-shaped device, around 30 metres across and almost the same again tall, called a tokamak.
The tokamak will superheat heavy forms of hydrogen, breaking them into their component parts to create plasma — essentially a super-hot gas.
"Inside our 'doughnut' we will have temperatures of more than 100 million degrees Celsius — much hotter even than the centre of the Sun," Dr Wauters says.
"The electrons are stripped from the atoms, so you have actually a soup or a gas of positive-charged particles and negative-charge electrons that are swirling around."
To create this swirling soup, ITER's physicists will blast the hydrogen isotopes with powerful electromagnetic waves — a bit like how a microwave heats your leftovers, but at a much more impressive scale.
The tokamak also uses incredibly strong electromagnets to corral the super-hot gas in the centre of the doughnut-shaped vacuum.
Then to generate power, some of the heat can be siphoned off from the roiling plasma to create steam and spin a turbine.
There are several other fusion reactor experiments already up and running around the world using this and other techniques.
But so far, experiments using this technique have generated only a small amount of power compared to the energy that goes into kickstarting the fusion reaction.
ITER's goal is a 10-fold return on the energy that goes in.
"For fusion, size matters and based on the present experiments we have seen, if we scale it up, we will get to the conditions that are needed to make more energy than we put in," Dr Wauter says.
"It's never been done before on such a large scale, on an industrial scale.
"For the first time here at ITER, we are trying to accomplish this."
Sounds dangerous ... is it safe?
Nuclear fission power plants — the ones that produce energy when heavy atoms decay into lighter ones — run the risk of a runaway chain reaction if the reactor is damaged.
But there's no risk of that happening at ITER's tokamak, Dr Wauters says.
"If you drill a hole in the reactor, it means that you breach the vacuum.
"The reactor will be filled immediately with air and this will stop the reaction."
Another benefit of fusion compared with fission is that any breaches wouldn't leak massive amounts of radioactive material.
However, some of the fuel used to generate the fusion reaction is radioactive, and Dr Wauters says there could be situations where some subatomic particles in the fusion plasma may irradiate parts of the tokamak itself.
"The amounts that we are talking about are grams — nothing compared to tonnes of material in a similar case in a fission plant," he says.
"I don't think personally that it will come to this. And if it would come to this, the amounts are really, really small."
Even so, and just in case, there are layers of containment such as reinforced concrete in place around the tokamak, as there are at fission power plants.
So what's the hold up?
It's often wryly noted that fusion is always 10 to 20 years away.
ITER originally set the date for "first plasma" in late 2025, but recently announced that delays and the pandemic have pushed this back to a yet-to-be-determined date.
The tokamak will begin by fusing very small amounts of fuel in very small bursts, but will not send electricity into the grid.
The facility is just a test site to show that industrial-scale fusion power generation is possible.
If it proves successful, Dr Wauters says every member state involved in the project is able to use the blueprint, the "intellectual property, the knowledge, the know-how" to create their own reactors.
However, there are still hurdles the ITER team must jump first.
Perhaps the most crucial is finding a sustainable way to fuel the reaction.
The fusion reaction they're planning to create at ITER is dependent on having two unusual forms of hydrogen called deuterium and tritium, which, along with a proton and electron, also contain one and two neutrons respectively.
Deuterium is easy: It's abundant in seawater, Dr Wauters says.
"It's tritium, the second part, which is a bit more complicated."
It's rarely created naturally, and ITER estimates the total current global supply of stored tritium to be roughly 20 kilograms.
But the team at ITER hopes to use the fusion reactor itself to create more tritium as a kind of by-product of the reaction.
This is known as "tritium-breeding", and involves bombarding lithium on the inner wall of the tokamak with neutrons in the plasma to create more tritium.
"The idea is to have at least one tritium produced for one tritium consumed in the plasma to have a closed fuel cycle," Dr Wauters says.
"It should be possible, but there is a difference between doing these things on paper and actually doing it."
There's a bit riding on this.
If they can't find out how to replace the tritium they use, then it's likely game over for the dream of fusion power anytime soon.
"There is indeed a risk," Dr Wauters says.
"I'm quite confident that at some point we will manage it, and that it'll be ITER that does it."
In the meantime, the midnight convoys will keep shuttling through the quiet countryside, the shiny doughnut will be slotted together over coming years, and thousands of scientists will be hoping this massive experiment pays off.
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