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New design could finally help to bring fusion power closer to reality

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Re: New design could finally help to bring fusion power closer to reality

#41

Post by bane »

idlewords wrote: post #34
bane wrote: post #32

Earlier quoted context omitted.

Not a nuclear physicist, so this is my armchair layman's "why don't they just..." analysis. But doesn't nuclear fission work off of neutron bombardment? Why not build a hybrid reactor where the "shield" undergoes fission while the core is generating fusion and perhaps they can produce a useful amount of power, perhaps with the fission "shielding" powering the magnets or some such?

What would be the advantage of a hybrid like that over a straight-up fission reactor?

checks the box for fusion?

more seriously, it could split the energy production to some ratio of fusion/fission and produce less hard to handle waste. Since the fusion reaction provides the neutron source, it may not be as necessary to provide as fissionable material which may not be able to meltdown?

I dunno, I have no knowledge or experience at all, this is my "if I was a sci-fi writer this is a thing I would put into a story"

Re: New design could finally help to bring fusion power closer to reality

#42

Post by venomsnake »

idlewords wrote: post #34
bane wrote: post #32

Earlier quoted context omitted.

Not a nuclear physicist, so this is my armchair layman's "why don't they just..." analysis. But doesn't nuclear fission work off of neutron bombardment? Why not build a hybrid reactor where the "shield" undergoes fission while the core is generating fusion and perhaps they can produce a useful amount of power, perhaps with the fission "shielding" powering the magnets or some such?

What would be the advantage of a hybrid like that over a straight-up fission reactor?

If done correctly you fusion fission everything to pure iron?

Re: New design could finally help to bring fusion power closer to reality

#44

Post by empiricus »

bane wrote: post #32
iaw wrote: post #12

The big problem with controlled fusion, as I understand it, isn't creating a net energy positive fusion reactor like this article implies. The physics is already there, we just need the engineering to catch-up. The challenge is the materials that compose the reactor become brittle and highly radioactive far faster than usable. Controlled fusion as an energy source isn't just challenging because fusion is difficult, i…

Not a nuclear physicist, so this is my armchair layman's "why don't they just..." analysis. But doesn't nuclear fission work off of neutron bombardment? Why not build a hybrid reactor where the "shield" undergoes fission while the core is generating fusion and perhaps they can produce a useful amount of power, perhaps with the fission "shielding" powering the magnets or some such?

The light elements that you prefer for fusion, have a lower absortion rate for neutrons than the heavier elements, which you don't prefer to absorb neutrons. In other words, to get usable fusion, you need so much neutrons that a lot of material in/out of the reactor will get too radioactive.

Re: New design could finally help to bring fusion power closer to reality

#45

Post by DennisP »

bane wrote: post #32
iaw wrote: post #12

The big problem with controlled fusion, as I understand it, isn't creating a net energy positive fusion reactor like this article implies. The physics is already there, we just need the engineering to catch-up. The challenge is the materials that compose the reactor become brittle and highly radioactive far faster than usable. Controlled fusion as an energy source isn't just challenging because fusion is difficult, i…

Not a nuclear physicist, so this is my armchair layman's "why don't they just..." analysis. But doesn't nuclear fission work off of neutron bombardment? Why not build a hybrid reactor where the "shield" undergoes fission while the core is generating fusion and perhaps they can produce a useful amount of power, perhaps with the fission "shielding" powering the magnets or some such?

China's actually working on a reactor like that: http://www.scmp.com/tech/science-research/article/1840219/ch...

Advantages: the fusion side doesn't have to quite hit breakeven, and on the fission side you can handily break apart any transuranic atom, even more effectively than fast reactors. It'll destroy any transuranic waste (which is most of our nuclear waste, and almost all the long-term waste), or directly fission thorium or unenriched uranium.

On the other hand, fission people don't like the complexity and fusion people don't like introducing all that hassle with fission products and decay heat. But it may well find a niche for nuclear waste elimination at least, and produce a lot of energy along the way.

Re: New design could finally help to bring fusion power closer to reality

#46

Post by ZenoArrow »

iaw wrote: post #26
azernik wrote: post #20

Earlier quoted context omitted.

One thing mentioned in the article was another advance in this design, where some of the materials that deal with the most intense neutron bombardment are replaced by a liquid that can be pumped out and circulated. Presumably there's still a containment vessel for this liquid that is a maintenance pain, but they do seem to be working on the problem.

The liquid blanket technology is nothing new or unusual and, from what I recall, seems to be generally agreed as the way to go. You are exactly correct about the containment vessel, and there is also the raw machinery needed to maintain the containment field and the reaction. I think the lifespan for these things is on an upper bound of 3 years, and I can't remember if that is at power plant or experimentation scale…

> "It's an interesting problem to me because fusion is largely solved and well understood from the physics perspective (which is what most people consider the challenging esoteric part), the remaining challenge is a much more 'mundane' task of developing economic methods to create the needed materials."

On one level, yes, it's a well understood problem. I mean when you get to the point when Make can teach you how to build your own fusion device I think it's safe to say we have a fairly decent handle on what's involved:

http://makezine.com/projects/make-36-boards/nuclear-fusor/

However, the challenge of producing a nuclear fusion device that generates more energy than it consumes is still a technical challenge. Perhaps it'll just be a question of better materials, but from a layman's perspective the plasma confinement/control aspect does not appear to be a completely solved problem.

Re: New design could finally help to bring fusion power closer to reality

#47

Post by ZenoArrow »

iaw wrote: post #24
ZenoArrow wrote: post #17

Earlier quoted context omitted.

> "The challenge is the materials that compose the reactor become brittle and highly radioactive far faster than usable. Controlled fusion as an energy source isn't just challenging because fusion is difficult, it's also challenging because materials don't handle neutron bombardment well." Isn't that problem solved with aneutronic fusion? https://en.wikipedia.org/wiki/Aneutronic_fusion Of course we should focus on ge…

I can honestly say I'd never heard of that before you posted your link. I don't know enough to form a valid opinion here.

Thank you for your honesty.

I'm not an expert in this field either, but I have been following the development of the Focus Fusion reactor being developed by Lawrenceville Plasma Physics, which is where I was introduced to the concept of aneutronic fusion. This video is a fairly decent introduction to their approach (note that the plan is to use the standard deuterium fuel first as it's cheaper and easier to work with, but the design can potentially support an aneutronic fuel such as pB11 in the future):

https://www.youtube.com/watch?v=O4w_dzSvVaM

Re: New design could finally help to bring fusion power closer to reality

#48

Post by alexggordon »

I think one of the biggest issues fusion power needs to deal with is whether or not it's worth the money. Renewable energy has gained serious momentum in the past years, and while it takes up significantly more land-mass-mass (things like solar panels and wind turbines), it requires less research and development than fusion, and is advancing at a significant pace. Contrast this with something like nuclear fusion, that has been under development for decades, and still has yet to produce a long term viable product.

The one area I still think I see fusion reactors succeeding in, is that they can theoretically use nuclear waste as a fuel[0][1]. However, outside of Transatomic Power, I really don't see many fusion companies interested in dealing with that issue. Given fusions history of failure, I think that fusion energy really needs a hell of a selling point beyond a simple "we make energy" to be able to succeed. I think that selling point doesn't get much better than using nuclear waste as fuel.

[0] http://www.transatomicpower.com/

[1] https://www.youtube.com/watch?v=4UXXwWOImm8

Re: New design could finally help to bring fusion power closer to reality

#50

Post by Someone »

mikeash wrote: post #5
Someone wrote: post #4

"The design could produce a reactor that would provide electricity to about 100,000 people, they say." It would be a huge step forward if this can be built, but there still would be a long way to go. To scale that to "electricity for everyone in the USA", you would need to build about 3,000 of these (or build much bigger ones). And that's for _current_ electricity use, not if everybody starts driving an electric car.…

A fusion reactor able to produce net electricity at all would be a massive breakthrough. I don't think the size matters much at all. Once anything is working, progress on scaling it up is likely to come quickly. The hard part is getting to the point where it works at all. The first nuclear power plant attached to a grid was only 6MW. The first "full-scale" plant, according to Wikipedia and the BBC, had four reactors…

Honest question: how does this design scale up?

Does scaling up mean making a bigger setup with magnets of the same strength? If so, I agree it is just a matter of making the effort, but this 150-ish MW thing is "half the size of ITER", which means it already is enormous (ITER will be gargantuan with its 1400 cubic meter vacuum vessel).

Even at 'to the fourth power', I fear this would get really huge before it significantly improves on our largest fission reactors.

Alternatively, can one inject more fusion material while keeping the same magnetic field strength to get more power out without building a larger device, or would that require stronger magnetic fields? If so, are we sure we can make those stronger fields? (Correction welcome, but I don't expect we can; if we could, we likely could scale this design down)

I still think that, if this works as advertised, it will be both a huge result and only one important step on a long road ahead to 'free' clean energy.

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