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Moontanman
Post  Post subject: Is aneutronic Fission possible?  |  Posted: Tue Apr 16, 2013 2:08 am
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Are there any reactions that allow aneutronic fission? I remember vaguely reading about the possibility in Omni magazine many years ago but I forget the details.


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Moontanman
Post  Post subject: Re: Is aneutronic Fission possible?  |  Posted: Sun Apr 21, 2013 12:14 am
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As it turns out yes aneutronic fission is possible but it is called fusion. a p b11 reaction results in three alpha particles.


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

Quote:
Candidate aneutronic reactions

There are a few fusion reactions that have no neutrons as products on any of their branches. Those with the largest cross sections are these:
D + 3He → 4He (3.6 MeV) + p (14.7 MeV)
D + 6Li → 2 4He + 22.4 MeV
p + 6Li → 4He (1.7 MeV) + 3He (2.3 MeV)
3He + 6Li → 2 4He + p + 16.9 MeV
3He + 3He → 4He + 2 p + 12.86 MeV
p + 7Li → 2 4He + 17.2 MeV
p + 11B → 3 4He + 8.7 MeV
p + 15N → 12C +4He + 5.0 MeV[2]
The two of these which use deuterium as a fuel produce some neutrons with D–D side reactions.[citation needed] Although these can be minimized by running hot and deuterium-lean, the fraction of energy released as neutrons will probably be several percent, so that these fuel cycles, although neutron-poor, do not qualify as aneutronic according to the 1% threshold.
The next two reactions' rates (involving p, 3He, and 6Li) are not particularly high in a thermal plasma. When treated as a chain, however, they offer the possibility of enhanced reactivity due to a non-thermal distribution. The product 3He from the first reaction could participate in the second reaction before thermalizing, and the product p from the second reaction could participate in the first reaction before thermalizing. Unfortunately, detailed analyses do not show sufficient reactivity enhancement to overcome the inherently low cross section.
The pure 3He reaction suffers from a fuel-availability problem. 3He occurs in only minuscule amounts naturally on Earth, so it would either have to be bred from neutron reactions (counteracting the potential advantage of aneutronic fusion), or mined from extraterrestrial sources. The top several meters of the surface of the Moon is relatively rich in 3He, on the order of 0.01 parts per million by weight,[3] but mining this resource and returning it to Earth would be relatively difficult and expensive. 3He could in principle be recovered from the atmospheres of the gas giant planets, Jupiter, Saturn, Neptune and Uranus, but this would be even more challenging.
The p –7Li reaction has no advantage over p –11B, given its somewhat lower cross section.[citation needed]
For the above reasons, most studies of aneutronic fusion concentrate on the reaction, p –11B.[4] [5]


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iNow
Post  Post subject: Re: Is aneutronic Fission possible?  |  Posted: Sun Apr 21, 2013 12:41 am
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I must concede, I'm not terribly sure what this is or how it might be used. Perhaps this is something you're exploring as you think through ways to enable interstellar travel?

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Moontanman
Post  Post subject: Re: Is aneutronic Fission possible?  |  Posted: Sun Apr 21, 2013 2:19 am
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well the premise is that it could be used as a power source like any other nuclear reaction. the good thing is that it doesn't result in any neutron radiation so it wouldn't make other things radioactive and it has no radioactive waste...

It does compare favorably with uranium or thorium fission in energy output but the details of how it works and why it isn't being used are scarce...


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Moontanman
Post  Post subject: Re: Is aneutronic Fission possible?  |  Posted: Sun Apr 21, 2013 2:45 am
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I'm going to try and elaborate on this a bit but please remember this is based on 30 or so year old memories.

The idea was to split boron 11 into three alpha particles via a beam of accelerated protons. The alpha particles could be used to generate electricity directly with no heat engine go between. Supposedly this reaction could be contained in a reactor of about a cubic meter and generate enough power for a house or a small group of houses with no radioactive waste, discharging only helium as a by product of the reaction...

IOW your own personal nuclear power plant...


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iNow
Post  Post subject: Re: Is aneutronic Fission possible?  |  Posted: Sun Apr 21, 2013 3:39 am
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Interesting. A cure for our energy needs. I suspect there are some serious technical challenges or we'd have done it by now. I could even be something simple like it takes more energy to make the reaction happen than you can ultimately extract from the process... More energy into the lasers than is made by the fission? I'm just throwing stuff out there.

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Moontanman
Post  Post subject: Re: Is aneutronic Fission possible?  |  Posted: Mon May 06, 2013 4:25 pm
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An interesting story on this...

http://www.smartplanet.com/blog/bulleti ... &ttag=e660


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iNow
Post  Post subject: Re: Is aneutronic Fission possible?  |  Posted: Mon May 06, 2013 10:07 pm
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Isn't the primary problem right now with fusion that it takes more energy to get it to happen than we can reasonably hope to extract from the system?

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Moontanman
Post  Post subject: Re: Is aneutronic Fission possible?  |  Posted: Tue May 07, 2013 1:08 am
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Um let me guess, you didn't read the article?


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iNow
Post  Post subject: Re: Is aneutronic Fission possible?  |  Posted: Tue May 07, 2013 4:14 am
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I did, actually. I scanned it. But I was on a conference call and preparing for another meeting at the same time. :oops:

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jimmydasaint
Post  Post subject: Re: Is aneutronic Fission possible?  |  Posted: Mon Jun 24, 2013 6:45 pm
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Correct me if I am wrong here, but would you not need huge amounts of heat to make plasma of the elements/ions involved and then contain the charged plasma within a powerful magnetic field? If so, I cannot see the immediate possibilities for a fusion generator in the garage to power up houses yet...

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therealkaivik
Post  Post subject: Re: Is aneutronic Fission possible?  |  Posted: Sun Nov 20, 2016 11:16 pm

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