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New records on Wendelstein 7-X

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Re: New records on Wendelstein 7-X

#101

Post by XorNot »

Retric wrote: post #64
pama wrote: post #22

Earlier quoted context omitted.

I agree vague language in popular press is sometimes annoying. “Off by 17 orders of magnitude” would be off by 136 billion years, so not that much for sure. Assuming you want to be able to test the plant and or maintain it once per year, 43 seconds is less than 6 orders of magnitude off. The jump was more than a full order of magnitude compared to past records, so another handful such developments and we are there.

Even 1 hour of stability with a relatively short restart period (under 5 minutes) would be fine with a battery system assuming the rest of the power plant was cheap enough to build and operate. Nuclear already gets taken offline for several weeks for refueling, but redundancy covers such issues.

Or just two reactors staggered in operation. Power grids can already coordinate on that sort of timescale.

Re: New records on Wendelstein 7-X

#102

Post by mathw »

thinkcontext wrote: post #72
sheepscreek wrote: post #51

TL;DR - Looks dangerous, but is it? (open question) Can we quantify it or at least make it more tangible? God, this contraption appears to be the kind of thing I wouldn’t trust my life with. Every time I look at a fusion reactor, it seems far more dangerous than my hobby lab, failing to inspire any confidence. The numerous moving parts create an equal number of potential points of failure. In contrast, a nuclear reac…

That fusion reactions are so difficult to get started makes the reactors very safe because failure makes them stop. So, if you lose magnetic confinement the reaction stops. The reactor may be damaged but that's it. This is unlike fission reactors, where a failure causes reactivity to increase. That causes meltdown and the possibility of explosion and all the nasty radioactive contamination.

My understanding is that more recent fission reactor designs are done in such a way that they fail in ways which cause the reaction to diminish rather than build up further, which puts you in a better place than, say, Chernobyl.

You still have a very hot very radioactive lump of death in the middle of your busted reactor when it's all done though, and that's definitely not fun. Fusion failure modes - in current designs anyway - are far more appealing to anybody who happens to be in the area at the time.

Re: New records on Wendelstein 7-X

#103

Post by weregiraffe »

HarHarVeryFunny wrote: post #37
wedn3sday wrote: post #6

I've always been somewhat partial to the stellarator design, I mean a big plasma donut is cool and all, but what if we twisted it around a whole bunch first!?

I think gravitational confinement is the way to go - it's the only operationally proven design! Gotta think big!

No, it's not the only proven design. The other is a hydrogen bomb. Google project PACER.

Re: New records on Wendelstein 7-X

#104

Post by greesil »

WhereIsTheTruth wrote: post #92
greesil wrote: post #90

Earlier quoted context omitted.

The irony is delicious. Especially considering the total budget of it is $340 millions vs ITER's tens of billions.

Their findings complement and help each other, there is no irony in there

Of course they can complement each other but ITER can still be an inefficient use of science funds at the same time.

Re: New records on Wendelstein 7-X

#105

Post by greesil »

Ey7NFZ3P0nzAe wrote: post #93
greesil wrote: post #90

Earlier quoted context omitted.

The irony is delicious. Especially considering the total budget of it is $340 millions vs ITER's tens of billions.

To be fair, they might not be totally independent figures in the sense of, I would be surprised if the cheaper project did not benefit at all from the knowledge created by the larger project.

They're both riding on the back of the past 70 years of R&D on fabrication, scientific instruments and data acquisition, and plasma physics. My point is what's the marginal research value per euro spent on one vs the other? Tokamaks are sort of a known thing. It's almost pointless to discuss now because the money is spent, but ITER has always felt to me a a very inefficient use scientific funding.

Re: New records on Wendelstein 7-X

#106

Post by HarHarVeryFunny »

weregiraffe wrote: post #103
HarHarVeryFunny wrote: post #37

Earlier quoted context omitted.

I think gravitational confinement is the way to go - it's the only operationally proven design! Gotta think big!

No, it's not the only proven design. The other is a hydrogen bomb. Google project PACER.

True - inertial confinement - also used by NIF (laser based). I guess I should have said continuous operation, although I do like the simplicity of Helion's system.

Re: New records on Wendelstein 7-X

#107

Post by svantana »

TheOtherHobbes wrote: post #100
pama wrote: post #22

Earlier quoted context omitted.

I agree vague language in popular press is sometimes annoying. “Off by 17 orders of magnitude” would be off by 136 billion years, so not that much for sure. Assuming you want to be able to test the plant and or maintain it once per year, 43 seconds is less than 6 orders of magnitude off. The jump was more than a full order of magnitude compared to past records, so another handful such developments and we are there.

Any fusion reactor that produces masses of free neutrons is uneconomic, because the neutrons are ridiculously corrosive to everything they collide with. Neutron activation produces a mess of radioactive isotopes, some of which fission quickly. It doesn't take long - certainly much less than a year - before you're left with components that no longer do their jobs and are also radioactive. This is a much less sexy prob…

General Fusion claim to get around these issues by having the fusion take place inside a centrifuge of liquid lithium. I'm not knowledgable enough to determine how plausible their claims are, though.

Re: New records on Wendelstein 7-X

#108

Post by nabla9 »

greesil wrote: post #90
chris_va wrote: post #48

A better link: https://www.ipp.mpg.de/5532945/w7x?c=5481737 (there is some irony in using the iter.org link for a stellarator announcement) 1.8GJ over 360 seconds, beta of 0.03

The irony is delicious. Especially considering the total budget of it is $340 millions vs ITER's tens of billions.

Iter and 7-X are both publicly funded research in confinement fusion with different topologies.

90% of the basic research Iter does can be switched to 7-X if it turns out to be more successful topology. Among other things, Iter develpes technologies and processes needed for a fusion power station, something 7-X is not even touching.

Re: New records on Wendelstein 7-X

#109

Post by HarHarVeryFunny »

grumbelbart wrote: post #67
ars wrote: post #59

Earlier quoted context omitted.

It has density issues though. If you had a piece of the sun the size of a huge power plant - like enormous, the power output would be too low to be useful.

Mandatory: We should build it in space and beam the electricity back to earth using electromagnetic waves. We could collect those using solar cells. And then get rid of the plant and use the sun instead.

Yes - exactly. No need for a Dyson sphere, or a man-made sun - just use the real sun and solar panels!

Re: New records on Wendelstein 7-X

#110

Post by mortarion »

greesil wrote: post #90
chris_va wrote: post #48

A better link: https://www.ipp.mpg.de/5532945/w7x?c=5481737 (there is some irony in using the iter.org link for a stellarator announcement) 1.8GJ over 360 seconds, beta of 0.03

The irony is delicious. Especially considering the total budget of it is $340 millions vs ITER's tens of billions.

ITER is like a NASA project. Built to work from the start. Still an experiment, but if they weren't sure Q > 1 would be achieved with the design, they would shut it down.
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