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Compact nuclear fusion reactor is 'very likely to work,' studies suggest

nytimes.com

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Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#321

Post by woeirua »

ClumsyPilot wrote: post #190
woeirua wrote: post #90

After watching the video posted in the top comment, I have to wonder why we would keep dumping money and time into ITER. I know, don't put all your eggs in one basket, but if the ITER design is so out-of-date, why wouldn't we just scrap it in favor of something that we could build 10 years faster and for much less money? It seems that if we can't make fusion work for SPARC it won't likely work in ITER either since th…

Are you so sure ITER is obsolete? For instance, what prevents ITER to be upgraded with better magnets, like the ones used here, and to achieve higher power?

The video makes it pretty clear, magnetic field strength is directly related to the overall dimensions of the reactor. If you upgrade the magnets, then the physical dimensions would need to change as well, which at this point would be very difficult seeing as how they're already pouring concrete...

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#322

Post by woeirua »

jasonwatkinspdx wrote: post #206
woeirua wrote: post #90

After watching the video posted in the top comment, I have to wonder why we would keep dumping money and time into ITER. I know, don't put all your eggs in one basket, but if the ITER design is so out-of-date, why wouldn't we just scrap it in favor of something that we could build 10 years faster and for much less money? It seems that if we can't make fusion work for SPARC it won't likely work in ITER either since th…

This is a vast oversimplification, and not a particularly useful way of thinking about it. See my other brief comment: https://news.ycombinator.com/item?id=24634894

That's not a really good argument for continuing down this road. The US shuttered the large particle collider in Texas after it became apparent that it was going to be completely redundant with the LHC.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#324

Post by ta8964586 »

beervirus wrote: post #136
elil17 wrote: post #24

Earlier quoted context omitted.

You're correct, that's a good ballpark for the average heat generation rate in the sun. However, 99% of heat generation in the sun occurs in the core (approximately the center 25% by radius) and this area is much more energy dense. Further, fusion reactors could achieve an even higher volumetric heat generation rate then the sun's core does. To collect energy, heat would be transferred to a working fluid (e.g., molte…

There's something that feels so archaic about using a nuclear reactor to... boil water and spin a turbine. It's disappointing that we haven't figured out a better way to convert to electrical energy than what we were using in the 1800s.

We've had solid-state thermoelectric generators for a while that convert heat flux directly to electricity, they're just really inefficient (only 5-8% efficent). [0] I can't find anything suggesting a fundamental limit to the efficiency, but it would take a lot to catch up to steam-powered generators at 33%-48% efficiency [1].

[0]: https://en.wikipedia.org/wiki/Thermoelectric_generator#Effic...

[1]: https://en.wikipedia.org/wiki/Steam-electric_power_station#E...

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#325

Post by joncrane »

drran wrote: post #256
ClumsyPilot wrote: post #183

Earlier quoted context omitted.

I am really tired of this line - the taunami killed 18,500 people. The reactor incident killed no-one through radiation and 32 people through physical injuries. One failure of Banqiao Dam killed an estimated 240,000 people. That's more than all people who have ever died from anything to do with nuclear, reactors and bombs combined. Air pollution kills about 2,000 people every single day. Reactor incidents are like pl…

Tsunami and earthquakes are not man generated events, so we can dismiss them. Yes, they killed a lot of people, but cancer kills even more: about 10 millions per year. In part, cancer is caused by contamination of food by radionuclides from reactor leaks (Chornobyl) and nuclear bomb testing.

I believe that coal releases more radioactivity into the environment than nuclear energy.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#326

Post by sam »

nmca wrote: post #263
jagiammona wrote: post #195

Earlier quoted context omitted.

Here's a great article showing progress improving the triple product until now. https://www.fusionenergybase.com/article/measuring-progress-...

Well now I really want to see the projected SPARC reactor on that plot. Does anyone have the necessary familiarity to add it?

Author of that article and plot here. SPARC is projected to have energy gain Q >=2 and potentially up to 11[1]. ITER is projected to achieve Q of >=10[2] so I would guess that SPARC's expected triple product would be in the same ballpark as the projected ITER datapoint, perhaps slightly lower, though potentially the same. We'll see!

[1] http://doi.org/10.1017/S0022377820001075

[2] https://www.iter.org/newsline/-/2845

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#327

Post by joncrane »

Tade0 wrote: post #84
zachrose wrote: post #78

Earlier quoted context omitted.

I’m also a layperson and also a fan of the 7-X, almost on purely aesthetic grounds. The plasma shape is a beautiful twisted loop, the magnets resemble a French crueler, and with the shielding and instrumentation it has all the charm of a steampunk time machine

To me it looks like alien technology. Such an organic shape. So many valves an openings. What is their purpose? How deliberate is their placement? Awe-inspiring.

To add to the others' responses on the purposes of ports, many of them are essentially vacuum pumps to maintain the near-perfect vacuum required for fusion to work.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#328

Post by Robotbeat »

MertsA wrote: post #318
dbetteridge wrote: post #274

Earlier quoted context omitted.

https://nationalmaglab.org/magnet-development/magnet-science... Looks like they 'only' need to be at 4.2Kelvin as well to operate, which is a definite improvement

They don't need to be that cold to start superconducting, 4.2K is just the temperature you could expect with liquid helium cooling. It would actually be superconducting with liquid nitrogen but the reason why you would still want to go colder is because superconductors have a maximum magnetic flux that they can sustain while still being superconducting. The current travelling through a superconductor itself also cont…

Right. To expand: Maybe someday we can use liquid hydrogen or nitrogen (or even water, depending on progress with hydride superconductors) for these reactors, but a big reason they’re able to make this more compact reactor work is the much higher critical currents/fields that these high temperature superconductors can handle when cooled far below their critical temperature. See: https://fs.magnet.fsu.edu/~lee/plot/plot.htm

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#329

Post by webmaven »

ArnoVW wrote: post #297
a1369209993 wrote: post #188

Earlier quoted context omitted.

To be fair, we have known how to build a working nuclear fusion power generator (probably with less than 30 years of construction) since the 1950s (see Project Orion); it's just a ridiculously huge construction/engineering project (basically a internal combustion engine powered by thermonuclear bombs).

Orion was essentially an "external combustion engine". I.e. you have a huge piston that is driven by repeated explosion of nuclear bombs. With a spring mecanism to even out the whallops. And no "engine block" around it. It did not generate electricity, and given the discrete/pulsed nature of the mecanism, I have a hard time seeing how you would "even out" the output, should you decide (somehow) to attach it to a gene…

Strange. I've read about Orion-type vehicles off-and-on for several decades, and the impression I always had was that the shield would be a hemisphere, or parabolic, rather than shaped like a nosecone.

Am I missing something? How do the lower parallel sides help capture the energy of an explosion below the shield?

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#330

Post by outworlder »

tuatoru wrote: post #277
Retric wrote: post #56

Earlier quoted context omitted.

There is ~zero expectation in the scientific community that fusion is going to be cheap at scale. It might eventually be cheaper than fission due to several factors. But, even that’s looking a long way off.

> It might eventually be cheaper than fission due to several factors. This surprises me, for a number of reasons. A fission reactor can be operated safely by a bunch of people with baccalaureates, whereas a fusion reactor will need PhDs, as I understand things. Also, its capacity factor will not be as good as that of fission reactors. The waste from fission reactors can be made pretty small by reprocessing and in-rea…

> whereas a fusion reactor will need PhDs

If you need a bunch of people with PhDs to operate a reactor, then you won't have a reactor. Not only does it mean that staffing is expensive and difficult, but also that it won't be reliable or predictable. If it is predictable, then steady state operation should be offloaded to computers.

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