NPR

A giant donut-shaped machine just proved a near-limitless clean power source is possible


By Danya Gainor and Angela Dewan, CNN

Updated 1500 GMT (2300 HKT) February 9, 2022
The core of the JET tokamak machine in the English village of Culham, near Oxford.
The core of the JET tokamak machine in the English village of Culham, near Oxford.

(CNN)There's no silver bullet to the climate crisis, but nuclear fusion may be the closest thing to it. In the quest for a near-limitless, zero-carbon source of reliable power, scientists have generated fusion energy before, but they have struggled for decades to sustain it for very long.

On Wednesday, however, scientists working in the United Kingdom announced that they more than doubled the previous record for generating and sustaining nuclear fusion, which is the same process that allows the sun and stars to shine so brightly.
Nuclear fusion is, as its name suggests, the fusing of two or more atoms into one larger one, a process that unleashes a tremendous amount of energy as heat.

Nuclear power used today is created by a different process, called fission, which relies on splitting, rather than fusing, atoms. But that process creates waste that can remain radioactive for tens of thousands of years. It's also potentially hazardous in the event of an accident, such as Japan's 2011 Fukushima disaster, triggered by an earthquake and tsunami.

Fusion, on the other hand, is much safer, can produce little waste and requires only small amounts of abundant, naturally-sourced fuel, including elements extracted from seawater. This makes it an attractive option as the world transitions away from the fossil fuels driving climate change.

Nuclear fusion: The end of our energy problem? (2018)
Nuclear fusion: The end of our energy problem? (2018) 03:30

In a giant donut-shaped machine known as a tokamak, scientists working in the English village of Culham, near Oxford, were able to generate a record-breaking 59 megajoules of sustained fusion energy over five seconds on December 21 last year. Five seconds is the limit the machine can sustain the power before its magnets overheat.

A magnetic field is required to contain the high temperatures needed to carry out the fusion process, which can be as high as 150 million degrees Celsius, 10 times hotter than the center of the sun.

"Our experiment showed for the first time that it's possible to have a sustained fusion process using exactly the same fuel mix planned for future fusion power plants," Tony Donné, CEO of EUROfusion, said at a press conference.

EUROfusion, a consortium that includes 4,800 experts, students and staff from across Europe, carried out the project in partnership with the UK Atomic Energy Authority. The European Commission also contributed funding.

Ymx wrote: Wed Feb 09, 2022 9:37 pm 150 million degrees. WTAF?

I’m guessing kit might start vapourising pretty quickly at those temps.

How does it work, design wise trying to manage that heat ?

Guy Smiley wrote: Wed Feb 09, 2022 11:06 pm It’s pretty small. I’d have to Google fu that up but from memory it’s almost a countable number of atoms involved in the reaction.

Guy Smiley wrote: Wed Feb 09, 2022 10:02 pm From what I’ve read, the magnets suspend a ‘cloud’ of superheated plasma that contains the fusion reaction.

I also think I’ve read that a Chinese lab has managed a longer reaction, out around the 17 seconds mark.

Seventeen Seconds. One of the best albums from The Cure. Coincidence? I think not.

Marylandolorian wrote: Thu Feb 10, 2022 2:22 am

Guy Smiley wrote: Wed Feb 09, 2022 10:02 pm From what I’ve read, the magnets suspend a ‘cloud’ of superheated plasma that contains the fusion reaction.

I also think I’ve read that a Chinese lab has managed a longer reaction, out around the 17 seconds mark.

Seventeen Seconds. One of the best albums from The Cure. Coincidence? I think not.

FFS, what can go wrong?

Ymx wrote: Thu Feb 10, 2022 5:58 am Nerd physics question.

With all this sub nuclear batshit(*) crazy testing, this and smashing particles together in Switzerland, are there any risks of creating dangerous chain reactions? Ripping a freakin’ hole in space time?

Obviously for fusion we have the Sun and probably know the limits of what can happen, can only affect certain elements??

But for the particle accelerators are there known natural equivalents to know what might happen?




(*) see what I did there.

Ymx wrote: Thu Feb 10, 2022 5:48 am UK seems to have a habit of claiming dubious firsts lately.

There was that “first detected Omicron” by Sajid Javid, when SA. Uk Parliament

The alleged record of this, when Chinese have said they have for longer. CNN (mind you)

The first country to remove all Covid restrictions (when Denmark did it a couple of weeks back). Daily fail.

….

Anywho, this is all going a bit PR

Guy Smiley wrote: Thu Feb 10, 2022 2:33 am Highlight some text in the whole paragraph that specifically refers to China and suggest there's a risk of things going wrong?

That looks like casual racism. Perhaps you'd like to take your turn explaining now?

Guy Smiley wrote: Thu Feb 10, 2022 2:33 am Highlight some text in the whole paragraph that specifically refers to China and suggest there's a risk of things going wrong?

That looks like casual racism. Perhaps you'd like to take your turn explaining now?

China's "artificial sun" has set a new world record after superheating a loop of plasma to temperatures five times hotter than the sun for more than 17 minutes, state media reported.

Guy Smiley wrote: Thu Feb 10, 2022 7:35 am Ummmm…

https://www.livescience.com/chinas-1-tr ... an-the-sun

China's "artificial sun" has set a new world record after superheating a loop of plasma to temperatures five times hotter than the sun for more than 17 minutes, state media reported.

mat the expat wrote: Thu Feb 10, 2022 6:02 am

Ymx wrote: Thu Feb 10, 2022 5:58 am Nerd physics question.

With all this sub nuclear batshit(*) crazy testing, this and smashing particles together in Switzerland, are there any risks of creating dangerous chain reactions? Ripping a freakin’ hole in space time?

Obviously for fusion we have the Sun and probably know the limits of what can happen, can only affect certain elements??

But for the particle accelerators are there known natural equivalents to know what might happen?




(*) see what I did there.

Halflife probably

Guy Smiley wrote: Thu Feb 10, 2022 6:19 am Well, I guess if fusion experiments get out of hand and someone ends up with another sun growing in their backyard, the good folk at CERN could always whip up a black hole to devour it.

Ymx wrote: Thu Feb 10, 2022 5:58 am Nerd physics question.

With all this sub nuclear batshit(*) crazy testing, this and smashing particles together in Switzerland, are there any risks of creating dangerous chain reactions? Ripping a freakin’ hole in space time?

Obviously for fusion we have the Sun and probably know the limits of what can happen, can only affect certain elements??

But for the particle accelerators are there known natural equivalents to know what might happen?




(*) see what I did there.

Biffer wrote: Thu Feb 10, 2022 8:26 am

Guy Smiley wrote: Thu Feb 10, 2022 7:35 am Ummmm…

https://www.livescience.com/chinas-1-tr ... an-the-sun

China's "artificial sun" has set a new world record after superheating a loop of plasma to temperatures five times hotter than the sun for more than 17 minutes, state media reported.

The two groups are working on different things. The Chinese group are working on maintaining high temperatures for long periods, but haven’t yet got those temperatures high enough, at those lengths of time, to maintain fusion. They’ve maintained temperatures of 70million centigrade for up to about 15 minutes. The JET reactor runs at over 150 million degrees centigrade, which is the temperature needed to create a fusion reaction.

So one group is working on the tech to maintain high temperatures for long times, one is working on the fusion reaction. Both are doing tremendous work, and the outputs from both will be needed (alongside all sorts of other things being worked on across Europe, North America, China, Russia and India) to channel into the ITER reactor to produce a sustained, energy producing fusion reaction.

S/Lt_Phillips wrote: Thu Feb 10, 2022 11:23 am Question (for Biffer, probably, as he seems to be the only one who actually knows much on this):

The plasma has to be kept contained in a really strong magnetic field because it's so hot if it touches anything it'll melt it. So, how do they get the heat out to generate electricity (presumably via raising steam to drive turbines)? You can't exactly run a heat exchanger through the plasma bit, because, well, it'll melt.

Do enough photons leak out of the magnetic field to warm up the inner walls of the reactor? If so, how do you control that? Can you manipulate the magnetic field to make it more 'leaky' for the photons?

Or is there something fundamental that I've not spotted?

tabascoboy wrote: Thu Feb 10, 2022 11:56 am My basic understanding, probably wrong, is that it is neutrons that heat the reactor and having no charge are not affected by magnetic containment

Biffer wrote: Thu Feb 10, 2022 12:20 pm

tabascoboy wrote: Thu Feb 10, 2022 11:56 am My basic understanding, probably wrong, is that it is neutrons that heat the reactor and having no charge are not affected by magnetic containment

That's basically right as far as I understand it. What they're doing is to mush (technical term) two hydrogen atoms together to make helium. But instead of using normal hydrogen which has one proton in it, they use deuterium and tritium, which are forms of hydrogen which have, respectively, one proton and one neutron, and one proton and two neutrons. Helium usually has two protons and two neutrons, so when you add deuterium and tritium, you have a neutron left over. Neutrons are stable and chargeless so pass through the magnetic field, and they'll be moving pretty fast, as they take the excess energy from the reaction (which comes from the changes in binding energies of the atomic nuclei, but that's starting to get complicated). They're then absorbed by the water, and the kinetic energy they had (their speed) is turned into heat. So the water heats up and you use that to generate your electricity through a normal turbine.

Biffer wrote: Thu Feb 10, 2022 12:20 pm

tabascoboy wrote: Thu Feb 10, 2022 11:56 am My basic understanding, probably wrong, is that it is neutrons that heat the reactor and having no charge are not affected by magnetic containment

That's basically right as far as I understand it. What they're doing is to mush (technical term) two hydrogen atoms together to make helium. But instead of using normal hydrogen which has one proton in it, they use deuterium and tritium, which are forms of hydrogen which have, respectively, one proton and one neutron, and one proton and two neutrons. Helium usually has two protons and two neutrons, so when you add deuterium and tritium, you have a neutron left over. Neutrons are stable and chargeless so pass through the magnetic field, and they'll be moving pretty fast, as they take the excess energy from the reaction (which comes from the changes in binding energies of the atomic nuclei, but that's starting to get complicated). They're then absorbed by the water, and the kinetic energy they had (their speed) is turned into heat. So the water heats up and you use that to generate your electricity through a normal turbine.

Dinsdale Piranha wrote: Thu Feb 10, 2022 12:36 pm Worth adding that extracting any useable power from fusion is outside the scope of ITER. It's there to demonstrate a sustainable fusion reaction.