New records on Wendelstein 7-X

Looking at the picture, I wonder if complexity of these devices will significantly be reduced once it finally works. I assume a lot of the bells and whistles are needed to find the way, but once it's found..

Your question reminds me of the image showing how SpaceX raptor motors evolved https://imgur.com/a/4w3q3lS

I'm not keen on the idea of applying a 'keep subtracting things until it blows up' mentality to fusion reactors.

The nice thing about fusion reactors is that they don’t blow up but just don’t work anymore.

I wouldn't be concerned about this, personally, for the precise reason that it is a fusion device - not fission!

Fusion is incredibly difficult just to start, let alone keep burning - unlike fission, which is only too happy to enter runaway conditions if not very carefully regulated. Fusion is like a little ember in your fireplace you have to carefully blow on to keep alight; fission is like keeping a fireplace lit by pouring gasoline into it.

I mean, it's expensive but there's nothing that can happen, they just stop working the nanosecond the environment isn't just right.

That's not what they're doing though. Reducing manifolds actually improves the durability.

I'd say (older-generation) fission is more like having an indoor swimming pool filled with burning gasoline, but keeping the windows shut so there's only enough air for it to burn at the rate you want to heat the house.

You could probably summarize the history of bridge-building as "keep subtracting things until they don't stand up anymore."

Building bridges (and large structures in general) has always been about the tension between over-engineering (for safety) and under-engineering (for cost/aesthetics).

The Brooklyn Bridge is massive; they'd never built a bridge like that so they over-engineered it. But once they saw that it was more than strong enough to stand up, the next bridge was lighter. And the next one after that was even lighter. And so on, until a bridge collapses because some new factor came into play (e.g., harmonic resonance).

Source: To Engineer Is Human by Henry Petroski--one of my favorite engineering books.

In my experience doing plumbing/hydraulics/pneumatics for industrial equipment, the first generation of a new product always looks way more complex than later versions. But I'm not sure they're actually more complex, they're often using a smaller variety of more flexible "industrial Lego" rather than custom, unique parts that are harder to extend or modify.

Yeah, a single welded tube of the right diameter that necks down just so in that one spot to prevent cavitation, which has that sweeping multi-planar bend to just barely sneak through that obstruction, will look neat and tidy to a casual observer. Conversely, a stack of triclamp flanges, a straight length of pipe that shoots way out away from the guts of the equipment before it jogs sideways and down and back in with 90 degree couplings and gaskets and a manual shut-off valve and a pressure transmitter/flow meter and a "T" with a cap (just in case) and a sight glass looks like an awful mess.

But I can build the latter in half an hour with parts we have on hand. And I'm not even a fitter, I'm an engineer! And when you do want to add something to it, I can do that in 5 minutes. After observing it function through the full regime of pressure and flow and viscosity parameters the equipment might have to deal with, I can maybe generate a print for the real plumbers to build the former dedicated-purpose component that sets all the constraints in stone (or rather, in welded stainless). That part will be unique and inflexible, embedding all the restrictions and history and test results and design decisions into a component that looks deceptively smooth to a layman's eyes.

Is that simpler? I suppose it depends on your perspective.

The real problem with fusion power is that even if they figure it out, it still won't be cost competitive with solar and wind.

Economically all the cost of building a "boil some water and turn some turbines" plant is _already_ in the "boiling some water and turning some turbines" part of the generation, and even if the heat part of it was _free_, the rest of it would be too expensive to bother building a plant for it, compared to just building solar and wind generation and some better batteries.

they have fission reactors that have done that since the 60s (CANDU Reactor). They just don't help you produce nuclear bombs...

Not read the book but I thought the Brooklyn Bridge was over specified on the wire strength because they knew the corrupt supplier would circumvent quality control to supply them with substandard material.

When I was an engineering summer intern at HP, they had all the interns do a side project of building a bridge (model sized). The designs would be judged by stacking bricks on the bridges and then dividing the max count of bricks before failure by the weight of the bridge. Most interns, myself included, over engineered our designs. One intern “got it” and submitted a bridge that was built out of just a few pieces of balsa wood. It only held one or two bricks before snapping, but it was ultra-light and won the competition. That exercise always stayed with me. Engineers always need to focus on the correct priorities and understand when “enough is enough.”

It's a bit like interpreted code vs optimized machine code.

Or a swimming pool full of those spicy rocket propellents discussed in the book Ignition! which have combustion products like hydrogen fluoride.

Raptor 3 really is quite an achievement. Good on them.

CANDU has low intrinsic nuclear proliferation resistance. It can run on natural uranium, so it's easier to fuel than light water reactors which need enriched uranium, and its online fuel-swapping design means that it's easy to switch to low-burnup operation for generating weapons grade plutonium. Current CANDU power reactors have extensive monitoring to confirm that they are used peacefully, but if e.g. South Korea had a security crisis and decided to pursue a crash nuclear weapons program, world opinion be damned, its CANDU based reactors at Wolseong could be quickly reconfigured for weapons purposes:

https://en.wikipedia.org/wiki/Wolseong_Nuclear_Power_Plant

True if you look at the cost to build the plant, but it’s hard to colocate enough solar with heavy users, land near there is expensive, and transmission capacity is pretty hard to get built, so something very power dense with a small footprint is helpful. I haven’t dug into the numbers, so I could very well be wrong that it pencils out when you consider those.

And there are efforts to make building out transmission and interconnecting with the grid more streamlined, so maybe some of those problems will be gone by the time fusion’s ready.

Someone said recently that it’s nicer to have bad laws and good tech than a bad tech and good laws, solar+storage seems like it’s in the former now, and if we can clear the bureaucratic hurdles, we’ll see it boom here like we’ve seen elsewhere.

These reactors are build for research, so presumably they need to be more modular, have more measuring components and be more accessible for changes.

That's how it goes most of the time. First you have to make it work somehow, often in a very complex way. Once you have something that works, either you can strip away a lot or the components get commoditized and you can buy them in a nice package. A lot of our devices are super complex but you can build a device without much knowledge because the complexity is hidden away in nicely packaged components.

You should be keen on that idea. Simpler designs are usually more reliable. And a fusion reactor doesn't really blow up. It's hard enough to make it do something.

Fusion is incredibly safe with none of the risks of runaway reactions like in fission.

"Things I will not work with" - "at this point hydrogen fluoride loses its gentle nature".

Wow - beautiful. So there is hope! As someone unfamiliar with the challenges of mechanical engineering, I’ve often wondered at the complexity of fusion reactors. This picture puts a lot into perspective. Thanks for sharing!

Would love to take a look at your library.

Neither of the hypergolics described in Command and Control seem chill either: the fuel reacts with atmospheric water and oxygen, the oxidizer is in the highest category of poison (https://www.penguinrandomhouse.co.za/extracts/command-and-co...).

Indeed there's no such thing as a free launch, and that is rocket science.

Current fusion reactors are also studded with a ton of sensors and adjustments and injection ports and such that might not be present in a production reactor. They are experimental platforms, more like scientific instruments for studying the problem domain than production systems.

It'll be expensive, but will it be more expensive than the costliest disaster ever, Chernobyl, which apparently cost (is costing) $700 billion to contain / clean up?

No,... so?

> real problem with fusion power is that even if they figure it out, it still won't be cost competitive with solar and wind

This is difficult to say when comparing an emerging technology with an established technology in an emerging economy.

Based on every historical prior, it would be surprising if there weren't diminishing returns to solar and wind. And I wouldn't underestimate the degree to which power is, in part, fashion. Today we value emissions. Tomorrow it may be preserving and expanding wild spaces.

On a practical level, fusion research doesn't compete with solar and wind deployment. Pursuing both is optimal.

It's topical that India's nuclear weapons program was started up with a Canadian-supplied heavy water reactor (though not CANDU; a not-power-generating type).

https://en.wikipedia.org/wiki/CIRUS_reactor

> "Canada stipulated, and the U.S. supply contract for the heavy water explicitly specified, that it only be used for peaceful purposes. Nonetheless, CIRUS produced some of India's initial weapons-grade plutonium stockpile,[6] as well as the plutonium for India's 1974 Pokhran-I (Codename Smiling Buddha) nuclear test, the country's first nuclear test.[7]"

Batteries are nowhere near that cheap.

Currently the cheapest non-intermittent energy source is gas; solar costs about half as much, and nuclear costs 50% more than gas [0]. Battery storage is currently competitive with gas for storing around 4 hours of electricity [1].

If we would want to replace the baseload with solar + batteries we would need to store 12 hours instead, during the dark half of the day, so it would cost 3x as much, 200% more than gas.

Maybe we can hope for battery prices to drop, but extrapolating from a Wright's law curve, for them to become cheaper by a factor of 3 we need to produce 32 times as many of them [1, again], it won't happen in the near future.

[0] https://www.eia.gov/outlooks/aeo/electricity_generation/pdf/... [1] https://www.lesswrong.com/posts/mnaEgW9JgiochnES2/2024-was-t...

W7-X looks insane because its configuration was discovered by a computer pursuing a numerical optimization. We don't have any sound reasons to believe the next one will be simpler.

Is that an actual honest photo? The first two seem fully equipped including what seems to be shielded wiring harnesses. #3 looks totally devoid of any electronics.

disclaimer: I don't follow this stuff at all. It just looks like a b.s. photo deliberately exaggerating how simplified #3 is vs. the others to this grease monkey.

Ready to rock(et)

https://x.com/gwynne_shotwell/status/1821674726885924923?s=4...

Not the poster above, but as someone who also has a copy of Ignition! in their library, I think you might enjoy the pdf version:

https://library.sciencemadness.org/library/books/ignition.pd...

IIRC not only did they remove many parts completely, but others have been integrated into the interior, which makes repair harder but will improve reliability since they are no longer exposed.

This completely ignores the need for baseload generation. Wind and solar will probably always be cheaper, but the power grid will likely always need a diverse array of power supplies. If your photovalic cell factories get bombed, how will you make more? If Egypt were 100% solar powered, it would be trivial to defeat them in a war by shooting less than a million dollars of artillery shells into their solar plants, leaving everyone in the dark in perpetuity. Japan was almost wholly dependent on the US for oil and coal before the US pulled their delivery contracts which was partly why they bombed pearl harbor, they had little to no power diversity. Nuclear and hydro will always backstop grid energy, even if solar becomes free or net negative.

Additionally, the total amount of solar and wind is limited. Surely more than we need now, don't get me wrong, but how much more? Factor 2? 10? I could see a future that is extremely energy hungry, and not just because of AI.

PV Panel production acts more like typical mass production and has therefore much higher cost benefits compared to every other way of producing power.

For every other way of producing energy you need separate land for PV you don't. You can put them on rooftops, over parking lots or even vertical in a field. The last one increases the crop yield. Crops get less harsh sun, lose less water and the evaporation cools down the panels, which increases their production.

Today we value costs of energy production and tomorrow we will to. Especially if it results in energy independence. You don't need to buy fuel for PV and wind. As with nuclear fuel only a few countries are probably going to manufacturing the fuel needed for fusion reactors. Producing enough of it and in a sufficient purity needs specialized facilities and they will only be profitable if they produce a lot of it.

To be fair, the reason the right-most Raptor looks so clean is because they moved all the piping (all the complexity) to inside the casing. And the reason they made the effort is because the casing protects the tubing from the heat of re-entry. Otherwise they'd have to waste mass on heat shielding. [Take a look at videos of Superheavy Booster returning back to the launch tower--the bottom engine sections starts to glow from the heat.]

I don't think that applies to Stellarators, so there may not be an incentive to simplify it. [But what do I know; I'm just a simple programmer.]

> PV Panel production acts more like typical mass production and has therefore much higher cost benefits compared to every other way of producing power

Turbines are also mass manufactured. (Albeit less than PVs.)

> You can put them on rooftops, over parking lots or even vertical in a field

The first power plant burned coal in Manhattan [1]. You can put turbines on top of buildings. We don’t because we don’t want to.

I think wind turbines are pretty. But lots of people don’t, and many wouldn’t want their rooftops to be shaded by panels, or wide open fields and natural expanses turned into something that looks more industrial. (I personally think looking down on rooftop gardens is far prettier than panels.)

Maybe there is a perfect power source out there, one which justifies a monoculture. I haven't seen it. I don't believe it's solar or wind.

[1] https://en.m.wikipedia.org/wiki/Pearl_Street_Station

I dunno dude, if you fuse tritium and deuterium it does make neutrons.

> the total amount of solar and wind is limited

I'd be shocked if we max out on insolation before area we're willing to cover with solar panels and windmills.

> the bottom engine sections starts to glow from the heat

It's fuel burning, not glow. Speed is too low for glowing; glow would start at the edge, not from deep inside the skirt etc.

> We don't have any sound reasons to believe the next one will be simpler.

Yes and no. I think you are right that the plasma shape is going to remain very complex.

But that's not the only reason why W7-X looks complicated. It has a ton of diagnostics ports on the plasma vessel just for research. Most of those we can probably design out for a production version.

So I would expect a production version of a stelarator to be simpler than W7-X, but still remain very complex.