Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

nytimes.com

Post reply on HN
Print view View original

191–200 of 373 posts

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

#191

Post by pfdietz »

bilegeek wrote: post #106
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.

> massive, national-scale investments A reminder of what could have been: https://upload.wikimedia.org/wikipedia/commons/a/ab/U.S._his...

Yes, we could have wasted much more money back then (those crash budgets would not have worked, since they assumed tokamaks work better than it turned out they did.)

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

#192

Post by ClumsyPilot »

bpodgursky wrote: post #147
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 I know, don't put all your eggs in one basket, but if the ITER design is so out-of-date, why wouldn't we just scrap it in favor of something that we could build 10 years faster and for much less money?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…

Well, "we" is very precise -- it's an EU program, and this reactor is not. As far as "why", you can take your pick of: - ITER's design is older, and maybe could be considered "lower risk" (that it will work at all) - Sunk cost - Academic jobs program - Money has already been allocated to member states, and none are happy to give that up - Big changes take time I'm not optimistic on stuff like this, so IMO it's anothe…

Japan and US are members of the project. You should at least read basic info before speculating. https://www.iter.org/proj/Countries

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

#193

Post by wwweston »

samatman wrote: post #167
Tossrock wrote: post #150

I wish these people the best, and I really hope they get a working fusion plant soon. That said, I can't resist sharing Admiral Rickover on academic reactors vs practical reactors: Important decisions about the future development of atomic power must frequently be made by people who do not necessarily have an intimate knowledge of the technical aspects of reactors. These people are, nonetheless, interested in what a…

It's a good contribution to the conversation, keeping in mind that Adm. Rickover wrote these words in 1953. Anyone could have said similar things about computers in 1953, and been just as correct. Are nuclear reactors computers? Of course not, and neither have practical reactors kept pace in development with practical computers. But neither is it inevitable that steady progress cannot grind down the latter set of cha…

> Anyone could have said similar things about computers in 1953, and been just as correct.

Many people could say similar things about software in 2020 and be just as correct. :) The good Admiral may be describing some timeless aspects of engineering, possibly related to the recently discussed observation that reality has a surprising amount of detail: https://news.ycombinator.com/item?id=16184255 .

Though, as you say, over time engineering can grind out some of the practical into practice.

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

#194

Post by pfdietz »

RealityVoid wrote: post #97
m0zg wrote: post #88

Earlier quoted context omitted.

How so? Unlimited, non-radioactive fuel and inherent safety of the system alone could tip this scale pretty severely in favor of fusion once it becomes energy-positive. And remember, once that happens, investment is going to be through the roof, which will accelerate progress. Either the "scientific community" (whatever that means) is either too pessimistic about this, or you've just made this up.

My best guess is the latest "nuclear energy is failing because it's expensive" trend on HN is to blame for this outlook. My take is that it's all poppycock. The ability to make our own little sun is, IMO, transformational for humanity.

Fusion's primary accomplishment will be to make fission look economical in comparison. The fundamental reasons for this have been known for decades.

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

#195

Post by jagiammona »

sien wrote: post #148
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…

The Fusion Triple Product, which is the key determinant of whether there is a self-sustaining reaction, increased faster than Moore's law up until about 2005. Then all the money went into ITER. https://physicsworld.com/wp-content/uploads/2004/01/pwhoa4_0... From the article at : https://physicsworld.com/a/controlled-fusion-the-next-step/ more information about the triple product and the Lawson Criterion. https://en.w…

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

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

#196

Post by pfdietz »

skykooler wrote: post #176
DennisP wrote: post #162

Earlier quoted context omitted.

Looks like they're still working, and on their fifth test reactor, the largest so far: https://www.thedrive.com/the-war-zone/29074/skunk-works-exot...

What happened to General Fusion's steam piston design? It seemed like such an elegant concept.

The supersonic implosion approach was shown to be unworkable for at least two reasons (the shock wave hitting the pusher/gas boundary broke into a forest of jets due to the Richtmeyer-Meshkov instability, and the currents in the surface of that pusher [ignoring the instability] would have been so high the push surface would have been vaporized, contaminating the plasma.)

So they changed to a subsonic approach, and also moved to a spherical tokamak arrangement. This means the target now has a solid conductor running down the central axis, and this conductor would be exposed to utterly hellish levels of neutrons (orders of magnitude worse than conventional fusion reactors) as well as forces from 100T magnetic fields. I have no confidence this could be made to work, even for a single shot. Also, in subsonic implosion, there is pressure equilibrium in the pusher, so the outside of the chamber feels the same extreme pressure as the inside. 100T gives a pressure several times that of the bottom of the Marianas Trench.

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

#197

Post by GuB-42 »

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…

I didn't see the details but it looks like both ITER and Sparc are both Tokamaks performing D-T fusion.

And in fact, it looks like Sparc is more of an exercise in making fusion reactors cheaper, most notably by using different magnets. ITER is more about validating the concepts, with no regard for the price. Besides the fusion itself, ITER will study how to inject fuel and evacuate the waste products as it is running. They will also tackle the problem of producing the large quantities of tritium a fusion plant requires.

So, my understanding is that Sparc is not intended to make ITER obsolete, but instead tackle a different problem. If commercial fusion reactors happen one day, I expect they will have a bit of both.

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

#198

Post by maccam94 »

natch wrote: post #154

What are the decommissioning costs? Who will pay for the cost overruns? Just one of the big problems with nuclear is that it is very centralized and takes individual control away from the consumers, who foot the bill through increased taxes and fees, and who could otherwise be using their money to finance options that give them individual control over their energy costs.

This reactor prototype has gotten private investment, because it is both comparatively affordable (hundreds of millions instead of tens of billions of dollars) and it will likely be profitable to license the technology to commercial plant operators. It is unlikely that commercial reactors would require public funding.

Decommissioning costs should be negligible because the reactors won't generate radioactive fission byproducts. The reactor chamber is designed for a 10 year lifespan and easy replacement. The old chamber is slightly radioactive (due to neutron bombardment) for a few decades, which is much less of a problem than the highly radioactive waste from fission plants that has to be stored for thousands of years.

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

#199

Post by maccam94 »

JustAPerson wrote: post #75

https://www.youtube.com/watch?v=KkpqA8yG9T4 Here's a video lecture from the MIT Professor (Dennis Whyte) who was leading the research group that provided some of the key designs for the SPARC reactor. As the NYT article explains, that research has been spun out into a startup that raised $200M. The key breakthrough is the advancement of REBCO tape superconductors which allow you to (1) generate record breaking magnet…

Timeline (in case you want to skip over some parts):

00:01:00 - introducing Dennis Whyte, MIT department head for nuclear science

00:04:24 - presentation starts

00:06:00 - identifies breakthrough with REBCO magnets

00:07:25 - explains deuterium-tritium fusion

00:12:30 - basic metrics for reactor performance

00:17:15 - energy output of other previous fusion experiments

00:19:00 - examines ITER and the problems of its approach

00:22:00 - problems solved by high energy magnetic fields

00:28:15 - full scale reactor concept, teardown of REBCO magnets

00:37:00 - design limits and margins

00:39:00 - fixes plasma instabilities found in weaker magnetic chambers

00:40:00 - maintainability, lifespan, component replacement

00:45:00 - solution to neutron damage and energy capture

00:50:30 - cost and profitability

00:54:00 - full graph of field strength vs reactor scale (and thus funding requirements)

01:01:50 - Q&A

01:30:00 - question about the biggest risks

Also a more recent video, with more numbers and even more confidence than the first: https://www.youtube.com/watch?v=rY6U4wB-oYM

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

#200

Post by mbroncano »

ClumsyPilot wrote: post #192
bpodgursky wrote: post #147

Earlier quoted context omitted.

Well, "we" is very precise -- it's an EU program, and this reactor is not. As far as "why", you can take your pick of: - ITER's design is older, and maybe could be considered "lower risk" (that it will work at all) - Sunk cost - Academic jobs program - Money has already been allocated to member states, and none are happy to give that up - Big changes take time I'm not optimistic on stuff like this, so IMO it's anothe…

Japan and US are members of the project. You should at least read basic info before speculating. https://www.iter.org/proj/Countries

The EU is by far the biggest contributor though:

> Europe is responsible for the largest portion of construction costs (45.6 percent); the remainder is shared equally by China, India, Japan, Korea, Russia and the US (9.1 percent each)

Post reply on HN