nuclear-news

World’s largest nuclear fusion reactor promises clean energy, but the challenges are huge

ABC Science ,By Carl Smith for Strange Frontiers on the Science Show, 19 Mar 23,

“……………………………… 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.

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…………………………………………………………………………………………………….

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.

……………………………………………………………… 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.

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……………………..

….. thousands of scientists will be hoping this massive experiment pays off. https://www.abc.net.au/news/science/2023-03-19/nuclear-fission-iter-experiment-france-construction/102050226

March 20, 2023 - Posted by Christina Macpherson | Uncategorized