
The Anhei tokamak is first in the world to generate 100M degrees Celsius - lelf
https://phys.org/news/2019-04-china-quest-limitless-energy.html
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ncmncm
What they never mention in these breathless articles is that your multi-
billion-dollar tokamak power-generation system will be bathing itself in high-
energy neutron flux, essentially destroying itself over only a few years,
leaving a multi-hundred-ton radioactive husk to be somehow disposed of, or at
least kept the rain from eroding and leaching radioactive slag into the water
table.

Probably they would need to be built underground to begin with, so they would
already be buried when they have been used up.

The pB reactor designs that emit mostly charged particles do not suffer from
this problem, much, but get overwhelmingly less investment. There is a reason:
the main purpose of the tokamak is a jobs creation program for high-neutron-
flux physicists, to maintain a population to draw upon for weapons work. There
was, and is, no intention ever to actually use tokamaks as an electrical-
energy source.

Many involved will not agree with this. It is easy to get caught up in the
technical challenge and leave worrying about practicalities and true
motivations to others.

~~~
DennisP
MIT's ARC design solves neutron flux by making the inner core of the reactor
easily replaceable. The superconducting coils are hinged, so once a year they
can just open up the reactor and lift out the core, which is 3D-printed. The
core is surrounded by molten FLiBe salt, which functions as coolant and
tritium breeder. The new superconductors allow the reactor to be much smaller
than ITER for the same power output.

MIT's project has been spun off into the startup Commonwealth Fusion Systems,
which has investment from an Italian oil company and Breakthrough Energy
Ventures. Neither party has an interest in physicist job creation or weapons
work.

There are at several pB efforts and one D-D/D-He3 (Helion, which says only 6%
of energy would be released as neutrons) but it's harder to get net power from
aneutronic fusion and we don't understand the plasma physics as well for the
designs they need, so it's more of a wildcard at the moment.

~~~
pfdietz
MIT's ARC design has an estimated cost of $29/W(e), an order of magnitude
higher than PV.

Each 170 MW(e) ARC reactor will use 40% of the world's annual production of
beryllium.

The "easily replaceable" in your description is quite a stretch. The
replacement will be much more demanding than the replacement of fuel elements
in a fission reactor. In the latter, the radioactivity is almost entirely
contained inside the fuel elements, and they are simply transfered, as fuel
bundles, to a cooling pool.

But the 86 tonne reactor vessel in ARC will have been permeated with tritium,
and the tungsten will have been loaded with activation products by the intense
neutron bombardment. It will be much larger than the rather compact
arrangement of fuel rods that makes up a PWR core (about 165 tonnes of fuel,
including structural material, in a typical 1000 MW(e) power reactor, which
has nearly six times the power output of the ARC design.) The reactor vessel
will take more space to remove. And then it will have to be crushed. The
workspace in which this happens will become inaccessible to people, as it will
become contaminated with tritium and radioactive tungsten dust. The overall
volume inside the reactor building where all this happens will be very large,
making the building expensive.

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jacob019
"Sometimes called an 'artificial sun' for the sheer heat and power it
produces" No, it's because the sun is also a fusion reactor.

~~~
Razengan
Very dumb but honest question: How are we certain that stars are fusion
reactors and not, say, the other ends of black holes?

~~~
moh_maya
I am not an astrophysicist (or a physicist even) but one piece of evidence
that may be useful here:

Based on our understanding of the nuclear fusion reactions, starting from
hydrogen, we expect to see, for a star of a given light / radiation spectrum
(viz. Young stars, old, white dwarfs, super giants, etc ), emit spectra lines
indicative of different elements such as H, He, O, C, etc. [1]. Young stars
may not have all the "heavier elements", older stars do. Their relative
abundance also changes with age.

Our models & predictions of stellar nuclear fusion (afaik) correspond very
well with the specific emission spectra we detect for different star types.
Which also corresponds very well to the size / lifetime of star, etc.

So, the data is very very consistent with nuclear fusion happening in stars.

Now, it may be possible that they are just the "other ends" of white holes.
But if it were so, then the model becomes far mode complex, plus, where are
all the black holes? While I do not know if the total number / mass of all
extant blackholes is as much as the total stellar mass, I would suspect it's
far far lesser. Probably wouldn't add up.

This is just the first explanation that came to my mind. I am certain there
are others.

Again, this is a non-physicist's lay analysis. Take it FWIW. :)

[1]
[https://en.m.wikipedia.org/wiki/Astronomical_spectroscopy](https://en.m.wikipedia.org/wiki/Astronomical_spectroscopy)

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IMTDb
I am always amazed by the (low) price of those projects, compared to the
potential benefits

$890 million for potentially giving a new clean energy source seems incredibly
low. I can't see a reason why we don't have at least 10 of those projects
being concurrently funded in the US, Europe and China. This is a fraction of a
percent of the annual budget of each region.

Whoever gets their hand on that first is going to have a massive economical -
and probably military - advantage over the others.

~~~
hannob
> I am always amazed by the (low) price of those projects, compared to the
> potential benefits

What would be the potential benefit?

In an optimistic scenario you'd end up with a technology that will likely have
very high capital costs for construction and also very high infrastructure
costs for transmission lines, because you create a lot of energy in one
location.

Even in that best case I don't see such a technology playing a huge role in a
future energy system. You end up competing with Wind, Solar and Storage
decades into the future (i.e. they'll be much cheaper than they already are
today).

Of course there's also the much more likely case: It just won't work.

Given that there are much more pressing needs in energy research (how do we
manage storage once we get to higher rates of renewables? how do we
decarbonize sectors outside of electricity?) there isn't that much in favor of
fusion imho.

~~~
jcoleh
The potential benefit is lots of electricity, which may be abundant that when
amortized over the "high capital costs" could be much more cost effective than
wind, solar, and storage, or may not be. We have to invest in these relatively
small projects to figure that out.

Furthermore, the highly geographically concentrated energy production from
fusion power could work really well for energy consumers with a similarly
localized nature. I'm thinking large scale carbon capture, energy intensive
materials manufacturing or processing, or large scale ocean water
desalination.

~~~
pfdietz
No, actually fusion is likely to be even more expensive than fission, and
fission already cannot compete with wind and solar. Fusion takes the biggest
problem of fission, high capital cost, and makes it worse, while reducing fuel
costs, which are only a minor part of the cost of fission. It's bass-ackwards
engineering.

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melling
“Unlike fission, fusion emits no greenhouse gases”

Fission emits greenhouse gases?

~~~
the8472
They're probably taking the whole fuel lifecycle into account.

[https://www.nirs.org/wp-
content/uploads/climate/background/s...](https://www.nirs.org/wp-
content/uploads/climate/background/sovacool_nuclear_ghg.pdf)

~~~
ccffph
Wouldnt then our “green renewables” also not be green due to their production
lifecycle as well? Plastics, batteries, fiberglass, rare earth metals, cobalt,
etc

~~~
the8472
To a small extent, yes. It's a matter of degree. Nuclear and renewables still
have a much lower footprint than coal. It's just not zero.

We don't know the full lifecycle costs of fusion plants, but at least the fuel
part won't involve open pit mining, unlike uranium ore, so it hopefully will
be better than fission.

~~~
ThomPete
Nuclear have a much lower fooprint than renewables, requires much less space,
last longer, is more robust, doesn't require rare earth materials or support
from ex coal (like wind and solar often end up doing) as a base component.

Solar and wind is not even close to being in competition with nuclear when it
comes to what is cleanest.

~~~
bjelkeman-again
This LCA study shows wind, large hydro and 4Gen nuclear to be in the same
range. With solar pv being higher.

[https://www.mdpi.com/1996-1073/11/12/3452/htm](https://www.mdpi.com/1996-1073/11/12/3452/htm)

~~~
nightski
Still that is only greenhouse gasses and not full environmental impact.
Renewables take up a lot of space.

~~~
adrianN
It's not like the world is running out of space anytime soon.

~~~
tomp
But maybe we don’t want to pave the Earth with PV panels...

~~~
pfdietz
The world is bathed in 100,000 TW of sunlight.

Current world primary energy consumption is 20 TW, 1/5000th of that amount.

In contrast, 11% of the Earth's land area is under cultivation for crops. Add
pastureland and that increases to 37%.

Why the outrage over PV land use, when it will be just a pimple on
agriculture's land use butt?

~~~
fisherjeff
Well, taking PV array efficiency and land vs. sea area into account, that’s
probably closer to 0.5% of Earth’s land area that would have to be covered
with panels. Obviously not a huge amount relative to agricultural land but
we’re still probably talking about a butt pimple around the size of
California.

~~~
pfdietz
Primary energy use, though, is energy content of sources before they go
through thermal cycles to get work. So one should also take into account the
heat rejected in the latter. Nearly 80% of the energy content of gasoline, for
example, goes out the tailpipe and radiator as heat.

PV would deliver energy in high quality form, electrical power, not as heat.
So less than 20 TW, probably much less, would be needed to be equivalent to
today's energy usage (although precisely how much would depend on details.)

Energy use will be increasing though, as the world gets wealthier. Still, this
will also put pressure on agriculture to increase production, as demand for
meat increases. Land constraints in the future will come from that, not from
PV.

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iforgotpassword
I like how they converted the number to Fahrenheit for the American readers -
like that helps grasping this in any way. :) the comparison to the sun's core
is much more helpful in this regard, but I still just cannot process how we're
able to do this in a controlled fashion. If this technology really ever
reaches production quality I'll be truly amazed.

~~~
bcatanzaro
But they did it wrong. The correct number is 180M degrees Fahrenheit. Sigh.

~~~
furgooswft13
If 100C == 212F then 100 million C == 212 million F. DUH. Just like 0 C == 0
F. Simple math, man. High quality article all around here.

~~~
mojomark
100M C to F => 100M*(9/5)+35 = 180,000,000 + 35 = 180,000,035.

...whoa

~~~
seiferteric
you mean 32?

~~~
mojomark
Lol, yup. I just realized furgoo was being sarcastical (I hope)

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jorblumesea
> But sustaining the high temperatures and other unstable conditions necessary
> is both extremely difficult and prohibitively expensive—the total cost of
> ITER is estimated at 20 billion euros ($22.5 billion)

Sadly, this maybe 3-5% of the annual US defense budget? Shows where our
priorities are that it's considered "prohibitively expensive".

~~~
vixen99
[https://en.wikipedia.org/wiki/Timeline_of_nuclear_fusion](https://en.wikipedia.org/wiki/Timeline_of_nuclear_fusion)

Tax payers have paid billions for this over decades and while no doubt physics
has benefited there's nothing to show for it in terms of a practical large
scale application to generate energy from fusion. Why do you think merely
throwing money at this project will do the trick after all this time?
Politicians can of course use your argument to score over opponents in the
realm where details don't count.

~~~
Tepix
There has been a lot of progress. Lots of hurdles were overcome. If you put
the chance of success st 5% if we invest another 50 billion, we should do it.
In the long run, it will ensure our future.

~~~
rgbrenner
If da Vinci had 50 billion, he still wouldn’t have achieved flight. There were
things he just didn’t know, and until those things were learned, all of his
efforts were in vain.

We’re still learning too.. and there’s no telling if we know enough to achieve
fusion. It may require physics that we won’t learn for another 100 years.
Until it’s invented, we don’t know what’s required.

~~~
NullPrefix
>It may require physics that we won’t learn for another 100 years

It may require physics that we won’t learn without another 50 billion

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ksec
Apart from the initial cost construction and maintenance. Are there cost of
Fusion in terms of cost/W? Or do we get Free, limitless Energy?

Wouldn't the first country achieve this be in huge / leap forward advantage?
Especially for a country like China with lots of Production and Exports.

~~~
amluto
I assume you mean cost/J or cost/MWh. Construction and maintenance will be
most of that. Most credible fusion reactor designs product a lot of neutrons,
and neutrons get absorbed by most materials and degrade them. (And turn some
materials radioactive — avoiding long term radioactivity is an important
design considerations.)

There will also be staffing costs, fuel costs (small, but still — deuterium
and tritium aren’t free), and even costs associated with obtaining cooling
water.

The big benefits of fusion over fission, as I see it, are that the fuels are
safe and plentiful, the byproducts are harmless (if neutron activation is well
managed), and the reactor itself isn’t full of extremely dangerous materials.
If you turn a fusion reactor off, it’s off, and there’s no risk that it
accidentally keeps reacting.

~~~
jmpman
Does it also reduce proliferation concerns?

~~~
mandelken
You can not make a bomb with fusion materials alone. Hydronuclear bombs use
fission materials (uranium, plutonium) to start the fusion reaction.

However, maybe a fusion reactor may be used for fission bomb research, but I'm
not sure how.

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m3kw9
Would a run away reaction turn earth into a sun?

~~~
chadcmulligan
Seems unlikely - once the magnetic bottle collapses the reaction stops, its
very hard to keep it going. Its not like fission where the reaction cascades
and causes a melt down. Some localised melting is perhaps possible if things
go astray.

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Traminer
2050 :'(

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wemdyjreichert
That's 180M degrees Fahrenheit, for those of us who are American, Liberian, or
Burmese.

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tromp
"EAST's main reactor stands within a concrete structure, with pipes and cables
spread outward like spokes that connect to a jumble of censors and other
equipment encircling the core."

Even reactors are not exempt from censorship!

~~~
pjc50
Entertaining typo/correction for "censer", I suppose?

~~~
dmoy
sensor probably?

I would assume no incense burning (censer) in there.

Yay English!

A censer censor sensor is something that detects someone who covers up the
existence of incense burning things.

~~~
jbay808
Not to be confused with a censer sensor censor, who censors the censer
sensor's central censer detections.

~~~
AnimalMuppet
Two comments ago, I knew what all those words mean. Now I'm not sure...

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rayiner
This may be how China wins. While the West has capitulated to the hippies in
moving to renewables and conservation, China is investing in increasing energy
production capacity through nuclear. (Not just research into fusion, they’ve
got 20 fission reactors under construction right now.) More energy means more
economic capabilities and more war making capabilities.

~~~
jeandejean
If you read the article you'd realize they're still late compared to western
nuclear technology. It's great that they invest a lot in the technology but
that's both wrong and premature to award them any achievement.

~~~
rayiner
Sure we’re ahead. But we’ve stopped trying, and diverted our resources to dead
end technology.

~~~
eloff
Nuclear is dead end tech. Renewables are cheaper than nuclear without the PR
problems or risks, and getting cheaper all the time. The future is solar,
wind, and hydro with a lot of energy storage and long distance transmission.

~~~
rayiner
Renewables will, at best, allow us to maintain our current energy expenditures
in a more sustainable manner. (If that.) But they are incredibly space
inefficient. Nuclear is the only avenue for increasing our energy production
by an order of magnitude or more. (Not to mention, there is no such thing is a
solar powered attack submarine or aircraft carrier.)

~~~
jfk13
Why should we want to increase our energy production by an order of magnitude?

Maybe a new generation needs to read E. F. Schumacher.

~~~
rayiner
Building a fully electric transportation network, supporting a greater
population, advanced weapons like rail guns, etc. You know, progress. The
future. Maintaining our technological supremacy.

China, Russia, etc., aren’t going to be reading E.F. Schumacher. Energy
production equals economic, military, and political power. Whoever figures out
how to break past the fossil fuel bottleneck is going to own the future.

~~~
chimpburger
And for space exploration. Nuclear propulsion would enable humans to reach
Alpha Centauri within a lifetime.

~~~
pfdietz
No, fusion could not allow humans to reach Alpha Centauri in a lifetime,
unless you mean they flew through the Alpha Centauri system without stopping.

If you want human interstellar travel, that probably means beamed power
propulsion. That's a better solution anyway, since it allows higher power
density at the vehicle. There is no need for fusion for that.

~~~
chimpburger
Let's restrict it to travel within the solar system. We'll need fusion to
power all of those beams.

~~~
pfdietz
Why is fusion needed to power the beams? Sunlight would work just fine.

~~~
chimpburger
There is a cap on potential solar power generation. Compare the amount of
power generated per square meter for a solar panel versus a nuclear power
station. Nuclear reactors can be stacked vertically or located underground.
Also it is ugly to have vast areas of the natural landscape covered in panels.
Ugly waste of space.

~~~
pfdietz
We're talking here about solar collectors IN SPACE, where the beam sources
would be placed. The cap there is the entire output of the Sun.

