
Lockheed's Skunk Works Building Bigger Fusion Reactor - SEJeff
https://www.thedrive.com/the-war-zone/29074/skunk-works-exotic-fusion-reactor-program-moves-forward-with-larger-more-powerful-design
======
amluto
> Containing the reaction, the same one that occurs in our sun and other
> stars...

Not really. Our sun is fueled mainly by the proton-proton chain reaction,
which produces no neutrons. This reaction is very very slow and happens at
comparatively low temperatures. The large power output of the sun is because
the sun is _huge_.

Useful fusion reactors need to use much faster reactions and require
temperatures several times higher than the sun’s core.

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

~~~
smallnamespace
To add to that, the sun's average power density barely rivals a compost heap.

~~~
techdragon
That’s awfully simplistic. Having spent most of today day wrestling with
permutations of the various radiometric flux and power formulas. It’s pretty
clear that depending on what you count as the “edge” you can get some very
disingenuous results when it comes to anything related to the sun’s density.
What’s the math behind the compost heap estimate there?

(Genuinely curious since I’ve spent the day doing math adjacent to this one)

~~~
analog31
That was my reaction too. Indeed, among the many possible ways to think about
it, the sun can warm the compost heap, but not vice versa.

On the other hand, the sun _is_ a cosmic compost heap. ;-)

~~~
maxander
Remember the square-cube law; for two things of different sizes, the
difference in surface area is proportional to the square and the difference in
volume is proportional to the _cube_ of the difference in sizes.

So, compared to any Earth-bound compost heap, each bit of the sun's surface
(wherever you draw the boundary) has more heat-generating interior backing it
up.

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pfdietz
Lockheed enlarged their original concept, reducing the power density (counting
the volume of the reactor, not just the plasma) by a factor of 100. It's now
about 0.5 MW/m^3, about the same as MIT's ARC concept.

In contrast, the power density of a PWR primary reactor vessel is 20 MW/m^3
(and of the core alone, 100 MW/m^3). How exactly is fusion supposed to be
cheaper than this, when the reactors are both so much larger and so much more
complex? Saving on fuel is irrelevant, as fuel is only a small part of the
cost of running a fission reactor.

~~~
hanniabu
You're not just saving on fuel, you're saving on waste

~~~
tlb
And safety. Fusion has the enormous advantage that you can just switch it off,
without the core continuing to generate heat and causing a meltdown if the
cooling system fails.

0.5 MW capacity costs around $1M with solar, so if 0.5 MW of fusion power
takes up a cubic meter that doesn't seem like a deal breaker.

~~~
pfdietz
The argument involves the comparison with fission. The low power density means
it's going to be more expensive than fission, and fission already fails
economically.

The difference between fission and solar is that solar lacks many systems
(like, turbines and generators) that fission and fusion would need.

More fundamentally, solar is distributed (even on a large solar farm), so
there's a lack of coupling between elements that makes everything easy to
assemble and very fault tolerant. In fission and fusion plants, the intricate
dependencies mean everything has to be highly reliable. Safety (for fission)
and the extreme difficulty of repair of activated structures (for fusion) also
drive this very expensive reliability.

~~~
bassman9000
_The argument involves the comparison with fission._

With the current LWR/HWR fission reactors, where core is solid.

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pletnes
The biggest hurdle for fusion power is, ultimately, how to deal with the
neutrons. These particles are electrically neutral and their trajectories are
unaffected by electromagnetic fields. The approach so far is to put a
«blanket» around the fusion core to slow them down, but this fails to mention
that the blanket will be slowly (or not so slowly) damaged by neutron induced
transmutation. Since a lot of the energy released in fusion power comes in the
form of kinetic energy of neutrons, it’s also essential to convert that energy
into eg steam, for power generation.

~~~
gmueckl
The blanket also has to have a high cross section for elastic collision with
neutrons to efficiently capture their energy as heat. ITER is planned to have
liquid lithium as this blanket because it has a high cross section and the odd
neutron capture will result in helium and much desired tritium that can be
extracted for use as the main fuel in the reactor. Unfortunatey, elementary
lithium is a very temperamental material.

~~~
darkpuma
I heard a story a while ago about a facility working with a lot of molten
sodium. The whole building had no running water at all, no bathrooms even,
because water and sodium mixing is a problem.

Lithium doesn't seem a whole lot safer.. but I don't think a fusion power
plant could be water free. As far as I'm aware there is no more efficient
method of using heat to spin a generator than a steam turbine. A lithium/water
heat exchanger seems pretty frightening. Do they have a better plan for that?

~~~
dojomouse
Haven't looked at the proposal, and not commenting either way on the risk of
using water in this context, but the water/reactive-metal issues have been
widely investigated in other liquid metal reactor designs and generally
intermediate cooling loops with some benign medium are used.

Edit to expand; having now looked it seems some of the intermediate loop
designs have the SAME material (e.g. sodium). This at least means the loop at
risk of mixing with water is isolated from the core (where an explosion is
difficult to manage). I thought I'd seen other designs, just can't find them
now.

------
Robotbeat
Fusion is hard. Neutrons are a concern, yes, but none of this matters without
ignition, without break-even (choose your definition). Until break-even is
achieved, it’s all premature optimization to me.

Compact or not, clever neutron handling or not, integrated tritium-breeding or
not, break-even is the minimum bar to cross, and no one has crossed it outside
of fission-triggered bombs. That must be the focus. Once that is achieved,
there will be plenty of resources to solve the myriad of other problems, but
until break-even is achieved (by ANY means other than fission trigger),
solving those other problems just doesn’t matter.

~~~
pfdietz
The focus on ignition is strange. If the engineering and economics look
hopeless, then why focus on ignition? The only reason I can think of is that
the people working on it want to keep their jobs and defer the likely
practical showstoppers until after the ultimately irrelevant plasma physics
problems are solved.

~~~
tim333
Well it's a step in the direction. If you can get that to work then maybe you
can then figure out the other stuff afterwards.

~~~
pfdietz
In the same sense that climbing a tree is a step in the direction of getting
to the moon.

~~~
gmueckl
Climbing a tree is useful for going to the moon. Having access to heights from
which to drop things is a prerequisite step for the first experiments that
lead to an understanding of gravity and acceleration ;).

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moreati
[http://julien.hillairet.free.fr/wiki/doku.php?id=list_of_fus...](http://julien.hillairet.free.fr/wiki/doku.php?id=list_of_fusion_startups)
is the most complete list I've seen, of private fusion efforts

------
hn23
Maybe also interesting in this context:

[https://en.wikipedia.org/wiki/Wendelstein_7-X](https://en.wikipedia.org/wiki/Wendelstein_7-X)

~~~
awkwardaardvark
If you understand German I can only recommend you give this interview a
listen: [https://alternativlos.org/36/](https://alternativlos.org/36/)

Edit: I should mention that it is about Wendelstein 7-X.

~~~
rland
For those who don't understand German, this is an interview in English, also
from someone at Max Planck about Wendelstein 7-X:

[https://omegataupodcast.net/312-the-
wendelstein-7-x-fusion-e...](https://omegataupodcast.net/312-the-
wendelstein-7-x-fusion-experiment/)

------
benj111
"Despite slower than expected progress"

I mean on the one hand this is the story of fusion. On the other they should
have preempted that by being extra pessimistic, so was extra pessimism built
in? Did they guess they were going to be perennially 5 years away when in fact
they're 10 years away. Or did they think the project would be done in 18
months, and is still 10 years away? Any bets on what the predicted timeframe
will be in 10 years time?

~~~
creeble
Five years:

[https://news.ycombinator.com/item?id=5323504](https://news.ycombinator.com/item?id=5323504)

The original article is gone, but the click-bait title of that HN post was
"Lockheed's Skunk Works: fusion power in four years?"

It _did_ end in a question mark, I guess.

------
inflatableDodo
>"How do you scale it up to generate power for a city or an entire town?
That’s all ahead of us,"

If they think they can get a working fusion reactor capable of powering 80,000
homes into a shipping container, I'd suggest not building them any bigger.
Being able to scale in container sized units over time via the existing
transport links sounds just peachy. Is quite a big 'if' there.

~~~
2muchcoffeeman
Why was this downvoted? I had the same idea. If you can power 80000 homes with
a container sized reactor, why not start deployment? Easy to transport, you
could power small neighbourhoods. No more wide spread black outs.

Not sure how much maintenance will factor in, but a reactor that size sounds
already practical.

~~~
tabs_masterrace
It's still a nuclear reactor... You don't just put them into containers and
ship them around, or turn them on or off by pressing a switch. They require
specialized staff to operate, maintenance, handling of materials, safety and
protection precautions and so on. Either you built them big or they are not
worth it to operate.

~~~
jpindar
OK but why can't we have just one of them running somewhere as a
demonstration?

------
adrianN
There is not much substance in this article. The most interesting part seems
to be the slide with the milestones. They seem to be three or four prototypes
away from ignition. How many years is that? How many years from the ignition
prototype to something that actually produces more energy than it consumes?

~~~
taneq
Well, based on the last 50 years of fusion research, the time from 'now' to
'net positive energy production' is quite consistently between 20 and 50
years.

~~~
cosmodisk
Even if it takes another 50 or 70 years to get there,people should still be
pushing for it.I wonder how this would change the political situation across
the world when oil,gas and coal wouldn't be required so much anymore...

~~~
imtringued
Yes, it will mark the end of world war 3 because humanity will be able to
survive by traveling to a new planet in a different solar system. Deep space
exploration becomes viable because we are no longer dependent on solar panels,
instead we carry our own mini sun within our spacecraft and simply sail forth!

------
Animats
The amazing thing is that Lockheed is doing this with their own money. Not for
PR; they seldom say much about the project.

------
nabla9
People running this project (Tom McGuire) are aerospace engineers who are
familiar with plasma in hypersonic speeds and computational fluid simulation.
It seems that they don't have experienced particle or plasma physicists in the
project.

Can anyone correct me on this?

------
Zardoz84
So, it's a design using magnetic mirrors? I was asking what happend with this
way of building a fusion reactor. The last that I know is that was used on the
60's.

~~~
gmueckl
Tokamaks are the direct evolutionary step up from magnetic mirrors because
these had problems with with electron containment at the mirrors. A circular
design removes the mirrors and therefore this problem. Unless these guys have
completely novel mirror configuration, they must run intonth same issue
because electron and proton trajectories are quite different at these
energies.

------
kalium-xyz
"we have a fusion reactor, she is real. You just never met her because she
goes to a different school"

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vertline3
I tip my hat to them. We need some boldness to move forward.

