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Fusion reactors: Not what they’re cracked up to be

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Re: Fusion reactors: Not what they’re cracked up to be

#61

Post by Synaesthesia »

justinpombrio wrote: post #20
leephillips wrote: post #18

Earlier quoted context omitted.

Where does the author note that? "Tritium has a half life of 12.3 years which means it will be dangerous for at least 120 years, since the hazardous life for a radionuclide is ten to twenty times longer than its half-life"¹ If you come in contact with it during that time you will get cancer. [1] https://www.nirs.org/wp-content/uploads/factsheets/tritiumba...

Can confirm: I have a keychain thing that glows from Tritium, and has for years.

It's a very small amount. Don't eat it! Then it would be highly toxic.

Re: Fusion reactors: Not what they’re cracked up to be

#62

Post by marcgcombi »

Robotbeat wrote: post #26

There's nothing quite like trying to get fusion to work for a while to make you appreciate how awesome fission technology is. If we applied even half the cleverness needed for fusion to making better fission technology, we'd probably be way better off. ...and then there's solar. Why even bother with producing the energy, just capture it with a very thin solid state device! Just need to automate the planting of solar…

Bump to Robotbeat. Fission reactor designs, with many clever advances in safety, have never been tested because of the lack of support from U.S. DoE. Pilot-scale reactors are expensive, but would really help to advance our working knowledge of these new technologies. Overall, nuclear fission has gotten a bad wrap.

As for the cost of storage, that was worked out 20-30 years ago via the Yuca Mountain facility. If one of the local managers hadn't shifted to a "organic-based storage medium', that was not pre-approved for that application, the fire wouldn't have happened and everything would be fine.

Re: Fusion reactors: Not what they’re cracked up to be

#63

Post by short_sells_poo »

labcomputer wrote: post #58
short_sells_poo wrote: post #40

Earlier quoted context omitted.

How exactly do you propose to get that electricity from the desert to say Finland? Furthermore, you need to plaster a vast area in the desert with solar plants, which brings along all sorts of concentrated security risks. The alternative is to have many smaller plants dispersed, which results in a big loss of efficiency. I'm all for clean energy, but you seem to be handwaving away pretty huge issues as "thought exerc…

> Furthermore, you need to plaster a vast area in the desert with solar plants, which brings along all sorts of concentrated security risks This sentence seems to be at odds with itself. How does needing a large area concentrate security risks? If anything it seems to disperse them. Unlike a coal or nuclear plant, you can't just walk up to a critical part of a solar farm and blow it up. Any part that you damage is re…

Sorry I worded that sentence poorly. Let's assume two scenarios:

a) We create a 200 square mile solar field in the Sahara, from which cables run to Europe to supply electricity. To take this plant out, one just cuts the cables. There, you just plunged Europe into darkness.

b) We create a 20x 10 square mile solar fields in the Sahara, all dispersed over a very large area. Well, this is an engineering and construction project on the scale that dwarfs even the previous project. It is truly vast. Nevermind all the political issues again.

Re: Fusion reactors: Not what they’re cracked up to be

#64

Post by zamalek »

Recurecur wrote: post #12

I'm interested in the approach being investigated at LPPFusion, on a shoestring budget no less. http://lppfusion.com/ LPPFusion is attempting to harness hydrogen-boron fusion, which doesn't produce neutrons, only gamma radiation and helium nuclei (alpha particles). Both the gamma radiation and the alpha particles can be directly converted into electricity. There are many potential benefits of this approach, but a pri…

It's amazing how the human race is 'leaping ahead' the nowadays. Historically we've taken evolutionary steps, e.g. the steam engine to the combustion engine. A well-established paradigm is mastered before the next. Now, while we have people exploring 'easier' forms of fusion, we have people exploring the harder forms of fusion.

Although we don't live in the most exciting times (space-faring and everything after being the most), we are at the crux of all future human endeavors. Exciting times.

Re: Fusion reactors: Not what they’re cracked up to be

#65

Post by Robotbeat »

scriptkiddy wrote: post #60
Robotbeat wrote: post #26

There's nothing quite like trying to get fusion to work for a while to make you appreciate how awesome fission technology is. If we applied even half the cleverness needed for fusion to making better fission technology, we'd probably be way better off. ...and then there's solar. Why even bother with producing the energy, just capture it with a very thin solid state device! Just need to automate the planting of solar…

Spoken like someone who has never visited a desert. As a Southern California native, I am intimately familiar with the Mojave, Anza Borrego, and Sonora deserts. I will tell you that these deserts are far from "crappy land that nothing can grow on" as you put it. The North American deserts are areas of huge ecological and geological diversity. They are also some of the most beautiful and awe-inspiring landscapes that…

I said a fifth or a tenth of the land in the US used for ethanol production. NOT a fifth or a tenth of our deserts. More like 1%.

And my point is we can install solar on land that has no other use. Like land contaminated by industrial waste, etc.

Re: Fusion reactors: Not what they’re cracked up to be

#66

Post by Recurecur »

Robotbeat wrote: post #42
Recurecur wrote: post #36

Earlier quoted context omitted.

The ocean environment isn't easy on equipment, plus storms are a major issue. Then there's cabling...

That all looks trivial compared to the challenges of fusion power, though.

Truthfully in the medium term next generation modular fission reactors seem like the way to go, as a complement to intermittent and variable solar/wind power.

If the LPPFusion approach eventually works out, it will be a giant win compared to the Tokomak or implosion fusion reactors.

Re: Fusion reactors: Not what they’re cracked up to be

#67

Post by spdionis »

Robotbeat wrote: post #42
Recurecur wrote: post #36

Earlier quoted context omitted.

The ocean environment isn't easy on equipment, plus storms are a major issue. Then there's cabling...

That all looks trivial compared to the challenges of fusion power, though.

Are you sure? This is a recurring theme in your arguments but I don't necessarily agree with you.

What are the reasons for you to think that?

Re: Fusion reactors: Not what they’re cracked up to be

#68

Post by FiatLuxDave »

VLM wrote: post #55
erikgrinaker wrote: post #23

Much of the (valid) criticism in this article relates to the deuterium-tritium fuel cycle. This is the easiest reaction to accomplish on Earth, so most experimental reactors are designed with this fuel in mind, and we're certainly having a hard enough time making even this work. However, I've always considered D-T fusion an intermediate step on the path to aneutronic fusion, such as Helium-3 or proton-Boron reactions…

The nice thing about fusion neutrons is you get to control the isotopes, you have no control over fission waste isotopes. Some fission isotopes are really icky to deal with, as everyone has heard... On the other hand if you don't like dealing with cobalt-60 waste at your fusion plant, simply stop using cobalt alloys in your reactor vessel. It turns out to be "not that big of a deal" to design a fusion plant where neu…

This is true. Back at Fiat Lux when we designed our D-D reactor, we intended it to sit inside a pool of water and borax. Since we didn't need to regenerate tritium, just absorbing the neutrons with boron was the cheapest solution. As far as I know, Borax is the cheapest effective neutron shielding known. We would have liked to have built our vacuum chamber out of purely Al (since Al-28 has a two-minute half-life), but we went with steel for cost reasons.

Unfortunately, we never made enough neutrons to activate anything worthwhile. Nevertheless, it is certainly possible to work around neutrons through design decisions.

Re: Fusion reactors: Not what they’re cracked up to be

#69

Post by dkirtley »

DennisP wrote: post #44
Robotbeat wrote: post #35

(Thinking about the far future, here.) Inertial fusion using Deuterum and Helium 3 would solve a lot of these problems. Of course, He3 is rare here on Earth. I don't think mining the Moon for He3 makes much sense. It's just too rare in the lunar soil. Instead, my favorite concept is mining it from Uranus (whose gravity at Earth-like pressures is actually slightly less than 1g...). There's vast amounts available at us…

Another option is to simply breed He3 with pure deuterium fusion; the output of the D-D reaction is He3 half the time, and otherwise tritium, which decays into He3 with a 12-year half-life. D-D produces neutrons but at normal fission energies, not the really high energy of D-T neutrons. Fusion startup Helion, which is funded by YCombinator, is attempting a hybrid D-D/D-He3 reactor, saying the combined reaction would…

6% is about the best we can do with a closed cycle. Extra-terrestrial sources could push those numbers even lower by running up to a pure D-He3 reaction.

Re: Fusion reactors: Not what they’re cracked up to be

#70

Post by erikgrinaker »

VLM wrote: post #55
erikgrinaker wrote: post #23

Much of the (valid) criticism in this article relates to the deuterium-tritium fuel cycle. This is the easiest reaction to accomplish on Earth, so most experimental reactors are designed with this fuel in mind, and we're certainly having a hard enough time making even this work. However, I've always considered D-T fusion an intermediate step on the path to aneutronic fusion, such as Helium-3 or proton-Boron reactions…

The nice thing about fusion neutrons is you get to control the isotopes, you have no control over fission waste isotopes. Some fission isotopes are really icky to deal with, as everyone has heard... On the other hand if you don't like dealing with cobalt-60 waste at your fusion plant, simply stop using cobalt alloys in your reactor vessel. It turns out to be "not that big of a deal" to design a fusion plant where neu…

Sure, activation in itself isn't necessarily a big problem, but I believe that embrittlement of the blanket and other plasma-facing surfaces due to the high neutron fluxes is one of the major engineering challenges for ITER and similar tokamak designs.
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