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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

#351

Post by giblfiz »

wwweston wrote: post #193
samatman wrote: post #167

Earlier quoted context omitted.

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…

I, for one, never have corrosion problems on my software projects.

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

#352

Post by taneq »

el_oni wrote: post #314
taneq wrote: post #219

Earlier quoted context omitted.

Ah, back in 1953, when they were only 20 years away from practical nuclear fusion.

As opposed to 2020 where we're now only about 20 years away from practical nuclear fusion

Or 2050 when we will hopefully only be about 20 years away from practical nuclear fusion... ;)

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

#353

Post by elil17 »

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.

The reason that steam still drives turbines (as opposed to having the salt drive them directly) is that it’s hard to engineer blade materials that will withstand temperatures much higher than superheated steam.

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

#354

Post by solstice »

giblfiz wrote: post #351
wwweston wrote: post #193

Earlier quoted context omitted.

> 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…

I, for one, never have corrosion problems on my software projects.

I take it you're not programming in Rust? /s

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

#355

Post by Retric »

pfdietz wrote: post #346
Retric wrote: post #341

Earlier quoted context omitted.

Gaseous tritium being significantly lighter than air tends to end up in the upper atmosphere not contaminate the local environment. As it’s beta decay you could have a glass glass jar of the stuff on your desk for years without issue. Unlike fission power plants there isn’t going to be years worth of the stuff on site. For one thing 5% of the stuff decays sitting around so you want a tight loop of production to consu…

> Gaseous tritium being significantly lighter than air tends to end up in the upper atmosphere That's not how it works. A low molecular weight gas anywhere below the homopause remains well-mixed, and does not separate by molecular weight. On Earth, that's anywhere below 100 km altitude. https://en.wikipedia.org/wiki/Homosphere

Yes, but not what I am referring to. 100 miles is a long way up. A large release of Tritium would first quickly gain altitude while in a high concentration before mixing with other atmospheric gasses. For the same reason as hot air from a fire initially rises as a column. After that it’s going to keep mixing with other atmospheric gasses and spreading through literally billions of cubic miles of atmosphere around the globe because unlike fallout it can stay in the atmosphere.

As a beta emitter it’s blocked by just a few feet of atmosphere thus rendering the bulk of it harmless. Eventually, some will combine with oxygen and end up as water, but again most of that just ends up in the ocean.

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

#356

Post by ArnoVW »

webmaven wrote: post #329
ArnoVW wrote: post #297

Earlier quoted context omitted.

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?

I've always understood it to be a plate. That way the vector of the forces is in the direction of travel. A parabolic shape would have to resist sideways forces.

A bit like this:

  https://www.centauri-dreams.org/2016/09/16/project-orion-a-nuclear-bomb-and-rocket-all-in-one/

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

#357

Post by cromwellian »

Retric wrote: post #169
xyzzyz wrote: post #128

Earlier quoted context omitted.

You don't need as much containment as you do for fission, because you don't deal similarly large amounts of highly radioactive isotopes. Consequently, the safety standards required are closer to fossil plants than to nuclear plants, and these safety standards are really what drives the cost of nuclear fission. The steam/electricity conversion/transmission/cooling" are also present in fossil plants, and these are sign…

It’s not that simple. Fission’s primary form of shielding is generally large pools of water or other coolant which don’t directly become radioactive. Fusion on the other hand needs to maintain a near vacuum so your pressure vessel is under heavy neutron bombardment. However, small amounts of radioactive materials get dissolved in the fission’s water which the goes on to contaminate the primary coolant loop which incr…

In ARC the containment is not under vacuum, the reactor chamber is surrounded by molten salt of fluoride and lithium, and so the neutrons produced travel into molten salt where they collide and produce tritium.

It would help to actually watch the presentations. They’ve solved a lot engineering problems from Routine maintenance to blanket Renewal.

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

#358

Post by cromwellian »

Maursault wrote: post #220
ClumsyPilot wrote: post #173

Earlier quoted context omitted.

Thats not accurate at all, Uranium itself is much cheaper than coal / any fuel per unit energy. Some contries have permanent, final storage for nuclear waste, it does not cost any more once created. Furthermore, not only was solar power borderline non existent when those reactors were built, it is also still intermittent. You are just glossing over the biggest challenge of energy - balancing the powe grid. No-one nee…

I'll respond to your straw man. It isn't about the energy within the thing, the exorbitant cost of Uranium is in mining and refining. No one said anything about coal, but it doesn't need refined, and is cheaply mined... but you've also made a false equivalency, because coal isn't the only competition to nuclear. The sun just shines, wind just blows, water just flows, and the geothermals just produce heat, without any…

4 words: Thorium Molten Salt Reactor (LIFTR)

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

#360

Post by FriskyAlter »

drran wrote: post #338
FriskyAlter wrote: post #294

Earlier quoted context omitted.

Yes, cancer did not exist before nuclear. We can blame cancer on nuclear plants and bombs. That's quality commentary.

Radionuclides are major contribution to growth of cancer rate. Quote: Radioactive fallout from nuclear weapons tests probably caused 17,000 cancer deaths in the United States in the latter half of the 20th century http://news.bbc.co.uk/2/hi/americas/1849471.stm

"probably" 17000 in 70 years against 700 000 000 total cancer death. Pack it up, boys.

And if anything, that shows how bad nuclear weapons are, not the power plants.

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