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Skunk Works Reveals Compact Fusion Reactor Details

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Re: Skunk Works Reveals Compact Fusion Reactor Details

#331

Post by peterfirefly »

scottlocklin wrote: post #302
nabla9 wrote: post #164

I'm not seeing any top physicists working in this program (McGuire is not one). I would be willing to bet 1000 EUR that their math and modeling does not add up, or they have skipped some details. Problem with fusion research like this is that the closer you get self sustainment or energy generation, the harder it gets and problems pile up. This project looks like many other similar projects that have gone bust. They…

"Top physicists?" Fusion is an engineering problem. The thing to check here is what plasma temperature/densities they have achieved with their new confinement scheme. They've basically said the results are preliminary, and some of the results are from simulation (which should not be trusted; aka look at how well the NIF simulations worked). This is not particularly interesting. Shielding was mentioned, though not eno…

> "Top physicists?" Fusion is an engineering problem."

So are refrigerators.

http://en.wikipedia.org/wiki/Einstein_refrigerator

Re: Skunk Works Reveals Compact Fusion Reactor Details

#332

Post by Someone »

hga wrote: post #23
ph0rque wrote: post #7

> Initial work demonstrated the feasibility of building a 100-megawatt reactor measuring seven feet by 10 feet, which could fit on the back of a large truck, and is about 10 times smaller than current reactors, McGuire said. So that would power 50k to 100k typical houses in the US... not bad!

Compact is good, because until you can fuse helium-3, the reactor is producing neutrons, which will transmute the reactor and its shielding into other, often radioactive elements. So the entire thing will have to be regularly replaced and disposed of (which we can do safely, but too many people believe otherwise).

I do not see how compact matters much here. As far as I understand, the basic reaction used is the same, so that compact design will produce the same number of neutrons per Watt produced as a large one.

Wouldn't the effect of its smaller mass be that the container will have to be replaced more often, more or less in the ratio of the masses of the machines?

Re: Skunk Works Reveals Compact Fusion Reactor Details

#333

Post by regularfry »

trhway wrote: post #256
regularfry wrote: post #109

Earlier quoted context omitted.

What's different this time (yeah, I know, I know) is that, if what they and EMC2 are separately claiming is true, it's gone from being a fundamental physics problem to relatively tractable engineering, with well-understood risks and timelines. Compare this with ITER, where they still don't know what material some fairly critical components can even be theoretically made of. It's just night and day.

>Compare this with ITER, where they still don't know what material some fairly critical components can even be theoretically made of. It's just night and day. the Skunk Works and EMC2 haven't even reached the stage where they would face the same issue of material - all of them would ultimately have to contain the same type of fast neutrons and there is no good known material to do it.

That's true as far as it goes, but it's not the problem I was actually thinking of.

The problem is related to how you get rid of the post-fusion products. ITER is designed with divertor plates in the floor to scoop off the fusion ash and shunt them outside the core. My understanding is that these plates have to be a) solid, and b) capable of withstanding contact with absurdly high temperature plasma. There are some candidate materials which are hypothesised to be able to stand up to temperatures somewhere near what's required, but to my knowledge (which admittedly might be out of date) nothing's actually known to be suitable.

The reason I don't think the neutron absorption issue is such a problem here or on Polywell is because with a smaller reactor, replacing the vessel when it stops working is a far less terrifying prospect, even if you have to do so every few months. And even this is far less insane than some of the proposals for how you might do commercial laser fusion. That's just bananas.

Beyond that, you actually want some fast neutrons from the reaction to give you a tritium source.

Re: Skunk Works Reveals Compact Fusion Reactor Details

#334

Post by Cthulhu_ »

trhway wrote: post #259
revelation wrote: post #254

Earlier quoted context omitted.

If you can make a coal plant twice as efficient, you can generate X amount of electricity for half the cost. Adding filters meanwhile just adds cost. I think both of these things happened, but only one of them is in the interest of a market actor.

>but only one of them is in the interest of a market actor. it is only until that market actor is allowed to externalize the costs of his pollution

Given how there's a huge trade going on in CO2 emission rights (at least in Europe), that's already a thing. Less CO2 emissions (catching them, filtering, etc) means they can sell off their CO2 emission rights to other companies. (see: https://en.wikipedia.org/wiki/Carbon_emission_trading )

Re: Skunk Works Reveals Compact Fusion Reactor Details

#335

Post by regularfry »

darkmighty wrote: post #314
trhway wrote: post #256

Earlier quoted context omitted.

>Compare this with ITER, where they still don't know what material some fairly critical components can even be theoretically made of. It's just night and day. the Skunk Works and EMC2 haven't even reached the stage where they would face the same issue of material - all of them would ultimately have to contain the same type of fast neutrons and there is no good known material to do it.

What part of the reactor degrades so quickly? Can't it be replaced continuously? Why isn't the shielding done with some non-degradable matter, like water or some oil?

As an example of the problem, anything made of metal will become brittle. For why this might be a problem, take a look at what's in the middle of the ITER toroid: you've got a stack of magnetic coils, which have to be physically braced against a colossal magnetic repulsion by a great big pre-stressed metal core.

I'm sure someone at ITER has done the maths and figured out how long that core can last under operation before it becomes too brittle to keep the coils together, but I wouldn't be at all surprised if that was one of the reasons why ITER isn't designed for long-term power generation.

Re: Skunk Works Reveals Compact Fusion Reactor Details

#336

Post by Cthulhu_ »

Confusion wrote: post #330
Turing_Machine wrote: post #315

Earlier quoted context omitted.

"Hacker News is full of people from the software field; folks whose professions are often unconstrained by physics" Lockheed Skunk Works, on the other hand, is not. They've been pushing the frontiers of engineering in areas that are very much constrained by physics since 1943, and succeeding. Many times.

What have they successfully designed that was not an airplane?

An experimental stealth ship, apparently: https://en.wikipedia.org/wiki/Sea_Shadow_(IX-529)

Re: Skunk Works Reveals Compact Fusion Reactor Details

#337

Post by lovemenot »

drjesusphd wrote: post #321
27182818284 wrote: post #42

> could be ready for use in a decade. That's the standard issue joke. "Nuclear fusion has been just ten years away for the last fifty years" It is so common as a joke I'm surprised the article didn't mention it.

It's not mentioned because it's tired, played out, and has no intellectual merit.

Aren't you being rather too hard on fusion there? I heard it could be just a decade or two away.

Re: Skunk Works Reveals Compact Fusion Reactor Details

#338

Post by geon »

peterfirefly wrote: post #331
scottlocklin wrote: post #302

Earlier quoted context omitted.

"Top physicists?" Fusion is an engineering problem. The thing to check here is what plasma temperature/densities they have achieved with their new confinement scheme. They've basically said the results are preliminary, and some of the results are from simulation (which should not be trusted; aka look at how well the NIF simulations worked). This is not particularly interesting. Shielding was mentioned, though not eno…

> "Top physicists?" Fusion is an engineering problem." So are refrigerators. http://en.wikipedia.org/wiki/Einstein_refrigerator

> It has been suggested that most of the actual inventing was performed by Szilárd, with Einstein merely acting as a consultant and helping with the patent-related paperwork.[1]

Plausible, since he had the experience.

Re: Skunk Works Reveals Compact Fusion Reactor Details

#339

Post by FranOntanaya »

nabla9 wrote: post #164

I'm not seeing any top physicists working in this program (McGuire is not one). I would be willing to bet 1000 EUR that their math and modeling does not add up, or they have skipped some details. Problem with fusion research like this is that the closer you get self sustainment or energy generation, the harder it gets and problems pile up. This project looks like many other similar projects that have gone bust. They…

Maybe the trick is that the reactor design is either cheap enough to be disposable, or just lasts enough to run a submarine for a few months (not necessarily in an economical fashion, but with other desirable advantages) and have it replaced like a car battery.

Re: Skunk Works Reveals Compact Fusion Reactor Details

#340

Post by privong »

privong wrote: post #188
tonyplee wrote: post #185

Earlier quoted context omitted.

How much dangerous are the neutrons from such device? Similar to radiation, worst? Time sell any oil company stocks, mutual fund holding?

> How much dangerous are the neutrons from such device? Similar to radiation, worst? Neutrons are interesting in that they dump all their energy into a very small region. Instead of losing energy continually and gradually, they travel a ways and then dump all their energy into one spot. This makes them potentially very useful for things like cancer treatment (you can select neutrons to ensure they deliver most of the…

I should note that my response here was incorrect. Thanks to loarake and tjradcliffe for the correction.
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