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nytecam
Postmaster

Reged: 08/20/05

Loc: London UK

Fusion - back to the Stoneage!
#5166325 - 04/11/12 05:06 AM

I was disappointed to read in current New Scientist #2859 page 22 that the much vaulted fusion reactor will use 'highly energetic neutrons' bombarding the reactor walls to create, in the surrounding enclosure, 'steam to drive turbines'

Is this really the best the 21st century can offer? I only want electrons to flow down a wire to power my house without steam in the equation.

I'd expect current fossil fuels like gas, oil and coal and even last century's atomic fission to be in the steam age for energy generation but not high tech physics of fusion power

Post Extras:

d00d
sage

Reged: 02/24/12

Loc: So Cal

Re: Fusion - back to the Stoneage! new

[Re: nytecam]
#5166630 - 04/11/12 10:16 AM

This will be the only way to generate anything other than research grant requests from a fusion reactor. If they can get the unit to sustain a plasma for longer than mere seconds that is...

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sirchz
super member

Reged: 09/21/09

Re: Fusion - back to the Stoneage! new

[Re: nytecam]
#5166985 - 04/11/12 01:59 PM

Quote:

I was disappointed to read in current New Scientist #2859 page 22 that the much vaulted fusion reactor will use 'highly energetic neutrons' bombarding the reactor walls to create, in the surrounding enclosure, 'steam to drive turbines'

It does seem so last century, but the inefficiency of using steam is low on the list of challenges faced by magnetically confined fusion energy. Confining the a dense, hot plasma long enough to produce energy is a major problem. Even if that is solved, those energetic neutrons will make a mess of any materials (ie the reactor first wall) in a short period of time. Fusion reactions that don't produce high energy neutrons require higher temperatures, making confinement even more difficult.

Just remember the fusion constant is 20 years. It is the answe to the question "How long until we overcome the problems with fusion energy?".

Chris

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FlorinAndrei
scholastic sledgehammer

Reged: 09/28/10

Loc: California

Re: Fusion - back to the Stoneage! new

[Re: nytecam]
#5167907 - 04/12/12 02:25 AM

The output of the reactor is heat.

Now your task is to convert heat into electricity.

It is surprising, but one of the better ways to accomplish that is still the steam turbine. Now these are not your Mack Sennett movie locomotives, but rather more like jet fighter engines in reverse, in some ways.

So, yeah, it's not a new technology, but it ain't that bad. I agree it would be nice if the nuclear energy would somehow push electrons directly. Something like a magnetohydrodynamic generator coupled with a fusion core directly would be awesome; there is some research in this general area, but it's pretty incipient.

http://adsabs.harvard.edu/abs/1977TepVT..15..879B

Now let us solve the fusion problem first, and then worry about the rest. We need a breakthrough in this area really badly.

Edited by FlorinAndrei (04/13/12 03:08 AM)

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deSitter
Still in Old School

Reged: 12/09/04

Re: Fusion - back to the Stoneage! new

[Re: FlorinAndrei]
#5168068 - 04/12/12 08:27 AM

I've never thought we had a ghost of a chance to make viable hot fusion reactors. You cannot rely on something whose main failure mode is to completely self-destruct and be down for weeks to months, if not permanently. Fusion "research" was, I think, the first bad example of how universities could milk the government for science cash, knowing that the military would fail to understand the difficulties and that Congress would be too timid to say no.

The equations of magnetohydrodynamics are so complicated that any technology based on them must be regarded as unstable and unreliable.

As for the laser pulse method, again, the main failure mode means destruction of equipment on a scale that is not quickly remedied, and so not practical for actual power generation.

Fission power, of course, is completely reliable and relatively cheap.

-drl

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jbattleson
Happily Retired

Reged: 03/02/09

Loc: Nebraska

Re: Fusion - back to the Stoneage! new

[Re: deSitter]
#5168367 - 04/12/12 11:50 AM

Quote:

Fission power, of course, is completely reliable and relatively cheap.

-drl

Fission is dirty in the long run. Also can turn into a Tiger by the tail scenario quite quickly.

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seryddwr
Innocent Bystander

Reged: 02/19/10

Loc: I don't know, you tell me.

Re: Fusion - back to the Stoneage! new

[Re: jbattleson]
#5168552 - 04/12/12 01:25 PM

Yep, fission's main mode of failure is Fukushima Dai Ichi, Chernobyl, Three Mile Island, "the China Syndrome", etc.

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groz
Carpal Tunnel

Reged: 03/14/07

Loc: Duncan, BC

Re: Fusion - back to the Stoneage! new

[Re: seryddwr]
#5168823 - 04/12/12 03:55 PM

Quote:

Yep, fission's main mode of failure is Fukushima Dai Ichi, Chernobyl, Three Mile Island, "the China Syndrome", etc.

That's only for reactors built with a 'fail catastrophic' design, one in which the moderators are required to keep the reaction under control. Remove moderators, and, reaction runs away. This is a 'fail catastrophic' design, as failure of controls results in a catastrophic runaway.

The candu style of reactors work on a totally different principle. Start with a 'cold' pile, and introduce heavy water which will start the reaction. As long as the heavy water moderator / coolant is in place, the reaction will run. Remove the moderator, and, the reaction stops, pile will stop producing energy. This is a 'fail safe' design, as a failure of the reaction control system results in a loss of reaction, rather than a runaway reaction.

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Shadowalker
Apocaloptimist

Reged: 11/23/04

Loc: Bay Saint Louis, Mississippi, ...

Re: Fusion - back to the Stoneage! new

[Re: groz]
#5168848 - 04/12/12 04:11 PM

Another plus for "heavy water" reactors is that require no uranium enrichment facilities.

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FlorinAndrei
scholastic sledgehammer

Reged: 09/28/10

Loc: California

Re: Fusion - back to the Stoneage! new

[Re: deSitter]
#5169662 - 04/13/12 03:22 AM

Quote:

I've never thought we had a ghost of a chance to make viable hot fusion reactors. You cannot rely on something whose main failure mode is to completely self-destruct and be down for weeks to months, if not permanently.

I thought the main problem was that the fusion core is inherently unstable with current designs, so any perturbation is amplified until the reaction fizzes out.

If that's the case, we need to find configurations that are inherently stable, neatly nested in local valleys of potential energy in the parameter space, protected against spurious deviations.

I mean, every star is like that - granted, that's because they are huge blobs of gas stabilized gravitationally, but that just shows it's not completely impossible.

Or some kind of pulsed configuration, stability be damned, designed for repeat firing. There are some proposals for interstellar fusion drives like that.

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deSitter
Still in Old School

Reged: 12/09/04

Re: Fusion - back to the Stoneage! new

[Re: FlorinAndrei]
#5169866 - 04/13/12 08:51 AM

In a typical design (tokomak) you have what is basically a powerful electric current contained only by a magnetic bottle of fiendish complexity. The behavior of both current and bottle are powerfully coupled, and instabilities are inevitable because exact solutions to the equations are not to be had, and the equations themselves depend on phenomenological parameters that are nearly impossible to explore in earthly conditions. Perhaps this work will be of use in the vacuum of space someday, but on Earth it is a hopeless dream, and this should have been obvious from the outset (and likely was, but the NSF cash train boiler needed to be stoked).

When the bottle breaks, a conducting gas at millions of degrees and at very high current destroys the apparatus needed to create the bottle. Imagine a car engine that regularly throws pistons through its block when there is the slightest anomaly in carburetion.

-drl

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Shadowalker
Apocaloptimist

Reged: 11/23/04

Loc: Bay Saint Louis, Mississippi, ...

Re: Fusion - back to the Stoneage! new

[Re: deSitter]
#5169919 - 04/13/12 09:30 AM

Quote:

Imagine a car engine that regularly throws pistons through its block when there is the slightest anomaly in carburetion.

Much like my old 1959 Volkswagen van!

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deSitter
Still in Old School

Reged: 12/09/04

Re: Fusion - back to the Stoneage! new

[Re: Shadowalker]
#5169926 - 04/13/12 09:34 AM

ROFL. Well my Bug's engine far outlasted the body and chassis

-drl

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sg6
sage

Reged: 02/14/10

Loc: Norfolk, UK.

Re: Fusion - back to the Stoneage! new

[Re: deSitter]
#5170118 - 04/13/12 11:04 AM

A fusion reactor makes heat, the next step is to turn that heat into electricity, presently we use steam as it is cheap - heat water and you get steam, send steam through a turbine, get electricity and condense the steam back to water to use again.

Concening pistons and engine's you have heard of Lotus cars. In the early days it was said that LOTUS stood for: Lots Of Trouble, Usually Serious.

Post Extras:

Pess
(Title)

Reged: 09/12/07

Loc: Toledo, Ohio

Re: Fusion - back to the Stoneage! new

[Re: deSitter]
#5170133 - 04/13/12 11:10 AM

Perhaps we will discover a way to manufacture muons in bulk and accelerate them to near the speed of light so time dilation allows them to hang around a bit before decaying.

This could catalyze cold fusion without all the problems inherent in hot fusion.

Ferni has some initial designs for a muon producing accelerator.

There is also something that is low-threshold intriguing about what's going on in deuterium packed palladium. Something more than chemistry but less than nuclear? Maybe there is a clue there to fusion that may yet emerge.

Without some radical method to catalyze hydrogen into helium we are not going to see a Mr. Fusion machine in homes (or Delorean time machines) anytime soon.

Pesse (Fusion was discovered when 2 protons got bored just hanging out and decided to make something of themselves) Mist

Post Extras:

deSitter
Still in Old School

Reged: 12/09/04

Re: Fusion - back to the Stoneage! new

[Re: FlorinAndrei]
#5170410 - 04/13/12 01:27 PM

Quote:

Quote:

I've never thought we had a ghost of a chance to make viable hot fusion reactors. You cannot rely on something whose main failure mode is to completely self-destruct and be down for weeks to months, if not permanently.

I thought the main problem was that the fusion core is inherently unstable with current designs, so any perturbation is amplified until the reaction fizzes out.

If that's the case, we need to find configurations that are inherently stable, neatly nested in local valleys of potential energy in the parameter space, protected against spurious deviations.

I mean, every star is like that - granted, that's because they are huge blobs of gas stabilized gravitationally, but that just shows it's not completely impossible.

Or some kind of pulsed configuration, stability be damned, designed for repeat firing. There are some proposals for interstellar fusion drives like that.

I had forgot about Teller's "concave fields prohibition", that is, any confinement with a bottleneck, however slight, will eventually collapse. So it's either all convex or nothing in terms of final stability.

-drl

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Ira
Carpal Tunnel

Reged: 08/22/10

Loc: Mitzpe Ramon, Israel

Re: Fusion - back to the Stoneage! new

[Re: deSitter]
#5172821 - 04/14/12 10:17 PM

Solar energy is our way of turning nuclear fusion into electricity - directly.
Next question...

/Ira

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lightfever
Carpal Tunnel

Reged: 09/27/04

Loc: Macomb Michigan

Re: Fusion - back to the Stoneage! new

[Re: nytecam]
#5173474 - 04/15/12 10:49 AM

Quote:

I was disappointed to read in current New Scientist #2859 page 22 that the much vaulted fusion reactor will use 'highly energetic neutrons' bombarding the reactor walls to create, in the surrounding enclosure, 'steam to drive turbines'

More than likely that will not be the first use of a fusion reactor. It is more likely that neutrons produced from fusion will be used to run a non critical fission reactor. This would be a safe reactor that would be able to use the spent fuel from our current reactors and reduce nuclear waste by a factor of ten. When you flip the switch and turn off the fusion core the reactor shuts down.

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ColoHank
Carpal Tunnel

Reged: 06/07/07

Loc: western Colorado

Re: Fusion - back to the Stoneage! new