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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

#131

Post by rurp »

simonh wrote: post #112
Florin_Andrei wrote: post #40

Earlier quoted context omitted.

> this is still exciting given how anemic advancement in the fusion space has been for 50+ years At the top of my list for when I'll be king for a day is - massive, national-scale investments (think: reaching towards one percent of GDP) in fusion research. This is a major roadblock, but things look awesome on the other side. We just need to get our stuff together to hop over this fence somehow.

I think it’s generally very hard to force technological progress along by just throwing money at it. Let’s suppose this proposal works out, ITER will become a very expensive boondoggle. A technological dead end. But if you’d taken the ‘Manhattan Project’ approach and thrown 10x as much money at fusion research 20 years ago we’d most likely have spent most of it on a super-ITER. It might be operational by now and migh…

Do you think that a better approach, given a lot of resources, would be to push more general/fundamental research without a clear end goal in mind? That approach makes sense to me intuitively given how many surprising breakthroughs there have been throughout history, but I admittedly know very little about actual research.

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

#132

Post by pfdietz »

Baeocystin wrote: post #123
pfdietz wrote: post #110

Earlier quoted context omitted.

80% of the energy from DT fusion comes out as neutrons, which enter a blanket and deposit energy there by collisions and nuclear interactions.

Thank you! Do you know how far along are we in understanding how to build an effective blanket that can withstand the neutron flux while maintaining its physical integrity?

It's not a solved problem (since really testing a wall design requires a working high power source of fusion neutrons), and it's not clear it can be solved in a sufficiently practical way. Indeed, the ability of the first wall to withstand the energy flowing through it will likely cause DT fusion reactors to have low volumetric power density, with sad effects on their economics.

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

#133

Post by beervirus »

simonh wrote: post #112
Florin_Andrei wrote: post #40

Earlier quoted context omitted.

> this is still exciting given how anemic advancement in the fusion space has been for 50+ years At the top of my list for when I'll be king for a day is - massive, national-scale investments (think: reaching towards one percent of GDP) in fusion research. This is a major roadblock, but things look awesome on the other side. We just need to get our stuff together to hop over this fence somehow.

I think it’s generally very hard to force technological progress along by just throwing money at it. Let’s suppose this proposal works out, ITER will become a very expensive boondoggle. A technological dead end. But if you’d taken the ‘Manhattan Project’ approach and thrown 10x as much money at fusion research 20 years ago we’d most likely have spent most of it on a super-ITER. It might be operational by now and migh…

> But if you’d taken the ‘Manhattan Project’ approach and thrown 10x as much money at fusion research 20 years ago we’d most likely have spent most of it on a super-ITER.

Or maybe someone would have had enough sense to think "you know, what we really need is better superconducting magnets. Let's throw 1% of the budget at that problem."

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

#134

Post by yholio »

About time to consider alternative paths to fusion.

ITER and similar projects are abject failures from non-scientific perspectives, they fail to improve on the economic weaknesses of fusion (radiological waste, massive capital costs, scarcity of fuel, proliferation risk), and only deliver on issues that have become irelevant for modern fision, like the risk of a meltdown.

There is zero economic potential for any ITER direct descendant.

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

#135

Post by xyzzyz »

dnautics wrote: post #127
xyzzyz wrote: post #124

Earlier quoted context omitted.

Sure, but on the other hand, such a lucky break of this new approach might have had never happened. At the same time, if super-ITER approach was shown to work, by producing it en masse, it would likely be cheaper per installed MW than nuclear power, which would remove the need for solar panels and wind altogether. We'd have cheap power with no danger of nuclear pollution, no real nuclear waste problem, and no destroy…

You don't know that. What if you had spent 1000x the budget of the manhattan project on building an atom bomb in the year 1789? You would have gotten squat.

I know that, because we already got ITER, which is widely expected to be energy positive. Moreover, the ITER approach is known to scale upwards: in fact, the ITER is so large, because it's the smallest size that is expected to work.

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

#136

Post by beervirus »

elil17 wrote: post #24
isoprophlex wrote: post #8

I never quite understood the math behind power densities in a fusion reactor. In the sun, isn't energy production occurring at something like 100-1000 W/m3? So, if you want to build a multiple MW fusion plant, shouldn't these plants be ridiculously huge compared to, say, a wind turbine rated at a couple of MW? Is the density of the plasma so much higher in a fusion reactor? Also, something else I never grokked, how d…

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.

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

#137

Post by ElFitz »

mdorazio wrote: post #16

Here's the actual summary: "Although many significant challenges remain, the company said construction would be followed by testing and, if successful, building of a power plant that could use fusion energy to generate electricity, beginning in the next decade." In other words, "very likely" in this case means "if several roadblocks are overcome, it might be a net-positive power generator in a decade". Even so, this…

> this is still exciting given how anemic advancement in the fusion space has been for 50+ years.

"Nuclear fusion. 30 years away since 1950"

Joking aside. I too am glad to see some progress of any kind, and new (seemingly credible) initiatives being funded and pursued

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

#138

Post by Baeocystin »

pfdietz wrote: post #132
Baeocystin wrote: post #123

Earlier quoted context omitted.

Thank you! Do you know how far along are we in understanding how to build an effective blanket that can withstand the neutron flux while maintaining its physical integrity?

It's not a solved problem (since really testing a wall design requires a working high power source of fusion neutrons), and it's not clear it can be solved in a sufficiently practical way. Indeed, the ability of the first wall to withstand the energy flowing through it will likely cause DT fusion reactors to have low volumetric power density, with sad effects on their economics.

Thanks again for the reply.

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

#139

Post by beervirus »

pfdietz wrote: post #113
pdonis wrote: post #13

Earlier quoted context omitted.

The arxiv paper describing the design concept is here: https://arxiv.org/abs/1409.3540 Some additional features (besides the magnets) that jump out at me: The reactor vessel has joints to allow it to open up for maintenance access (previous tokamak designs have a reactor vessel that cannot be opened up once constructed, so maintenance inside has to be done through small access ports using remote manipulators). The ex…

Also note from this paper: The power density of the reactor is 0.5 MW/m^3, which is 1/40th the power density of a commercial PWR primary reactor vessel. The reactor (a single one!) uses something like 40% of the world's current annual production of beryllium. If all the world's estimated resource of Be is used to make these reactors, it would be enough for reactors producing just 1% of world primary energy demand.

> The reactor (a single one!) uses something like 40% of the world's current annual production of beryllium. If all the world's estimated resource of Be is used to make these reactors, it would be enough for reactors producing just 1% of world primary energy demand.

That's crazy. I guess if the design works out we can start casting about for a beryllium replacement.

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

#140

Post by dnadler »

yholio wrote: post #134

About time to consider alternative paths to fusion. ITER and similar projects are abject failures from non-scientific perspectives, they fail to improve on the economic weaknesses of fusion (radiological waste, massive capital costs, scarcity of fuel, proliferation risk), and only deliver on issues that have become irelevant for modern fision, like the risk of a meltdown. There is zero economic potential for any ITER…

I wasn't aware of any radioactive waste from these fusion processes. I was also under the impression that fusion fuel is quite abundant (Deuterium and Lithium as an example discussed in one of the videos linked in the comments).
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