We go behind the scenes at the world’s largest nuclear fusion device attempting to harness energy from the same reaction that powers the Sun and stars.
ADVERTISEMENTIn the heart of Provence, some of the brightest scientific minds on the planet are setting the stage for what is being called the world’s largest and most ambitious science experiment.
“We are building arguably the most complex machine ever designed,” confides Laban Coblentz.
The task at hand is to demonstrate the feasibility of harnessing nuclear fusion – the same reaction powering our Sun and stars – at an industrial scale.
To do this, the world’s largest magnetic confinement chamber, or tokamak, is under construction in the south of France to generate net energy.
The International Thermonuclear Experimental Reactor (ITER) project agreement was formally signed in 2006 by the US, EU, Russia, China, India, and South Korea at the Elysée Palace in Paris.
There are now more than 30 countries collaborating on the effort to build the experimental device, projected to weigh 23,000 tonnes and withstand temperatures of up to 150 million°C when complete.
“In a way, this is like a national laboratory, a big research institute facility. But it’s the convergence of the national laboratories, really, of 35 countries,” Coblentz, ITER’s head of communications, told Euronews Next.
How does nuclear fusion work?
Nuclear fusion is the process by which two light atomic nuclei fuse to form a single heavier one, generating a massive release of energy.
In the case of the Sun, hydrogen atoms at its core are fused together by the sheer amount of gravitational pressure.
Meanwhile, here on Earth, two main methods are being explored to generate fusion.
“The first, you might have heard at the National Ignition Facility in the US,” Coblentz explained.
“You take a very, very tiny bit – the size of a peppercorn – of two forms of hydrogen: deuterium and tritium. And you shoot lasers at them. So, you’re doing the same thing. You’re crushing pressurisation as well as adding heat and you get an explosion of energy, E = mc². A little amount of matter is converted to energy”.
ITER’s project is focused on the second possible route: magnetic confinement fusion.
“In this case, we have a very large chamber, 800 m³, and we put a very tiny amount of fuel -2 to 3 g of fuel, deuterium, and tritium – and we get it up to 150 million degrees through various heating systems,” Laban said.
“That is the temperature at which the velocity of these particles is so high that instead of repelling each other with their positive charge, they combine and fuse. And when they fuse, they give off an alpha particle and they give off a neutron”.
In the tokamak, the charged particles are confined by a magnetic field, except the highly energetic neutrons which escape and hit the wall of the chamber, transfer their heat and thereby heat water running behind the wall.
Theoretically, energy would be harnessed by the resulting steam driving a turbine.
“This is, if you like, the successor of a long line of research devices,” Richard Pitts, the section leader of ITER’s science division, explained.
ADVERTISEMENT“The field has been investigating tokamak physics for around 70 years, since the first experiments were designed and built in Russia in the 1940s and 50s,” he added.
According to Pitts, early tokamaks were small, tabletop devices.
“Then bit by bit, they get bigger and bigger and bigger because we know – from our work on these smaller devices, our scaling studies from going small to bigger to bigger – that in order to make net fusion power out of these things, we need to make one as big as this,” he said.
Advantages of fusion
Nuclear power plants have been around since the 1950s exploiting a fission reaction, whereby the atom is split in a reactor, releasing a massive amount of energy in the process.
Fission has the clear advantage of already being the established tried and tested method, with over 400 nuclear fission reactors in operation worldwide today.
ADVERTISEMENTBut while nuclear disasters have been a rare occurrence in history, the catastrophic meltdown of reactor 4 at Chernobyl in April 1986 is a potent reminder that they are never entirely risk-free.
Moreover, fission reactors also have to contend with the safe management of vast amounts of radioactive waste, which is typically buried deep underground in geologic repositories.
By contrast, ITER notes that a fusion plant of a similar scale would be generating power from a much smaller amount of chemical inputs, just a few grams of hydrogen.
“The safety effects are not even comparable,” Coblentz noted.
“You’ve only got 2 to 3 g of material. Moreover, the material in a fusion plant, deuterium and tritium, and the material coming out, non-radioactive helium…
Read More: Inside the world’s first reactor that will power Earth using the same nuclear