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| jumpboy11j |
 Posted: Mon Apr 21, 2008 11:44 am Post subject: NILFiR |
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Forum Freshman
Joined: 21 Apr 2008
Posts: 3
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As you can see in my sig, Nilfir stands for Neutron Induced Lithium Fission Reaction. It is an alternate way to create energy using Nuclear Fission.
This is the reaction:
Li-7 + N => Li-8
Li-8 => Be-8 + 16 MeV
Be-8 => 2 He-4 + 90 KeV.
The total energy gain is ~16.1 MeV. The energy density is about 2 MeV/AMU (193 trillion joules/ Kg) more than twice Uranium.
Now all of this so far is great, but you would need an expensive and power hungry external neutron source because this reaction doesn't produce any neutrons.
This is how I would alleviate this:
Beryllium-9 contains 4 protons and 5 neutrons. To split it, and create 2 Helium-4's and a neutron, you need 1.6 MeV (actually 2.45, but close enough). The fission products (2 alpha particles) have 8 MeV each, so a collision with Beryllium will be enough to split it. This design works best with a Gas Core Reactor, with both Li and Be as a gas. With a ratio of Li:Be of 1:2, 4 4/9 neutrons will be produces per fission.
The cross section for the reaction is small, .05 Barns, but the high neutron yield per mass, and the fact that the lithium atom is small to begin with, should keep the critical mass small. It will also help that Be is the best possible neutron moderator. Another positive is that the most radioactive thing this reaction can POSSIBLY create is tritium, which isn't that bad.
Sources:
Li-8 decay: http://nucleardata.nuclear.lu.se/Nucleardata/toi/nuclide.asp?iZA=30008
Be-8 decay: http://nucleardata.nuclear.lu.se/NuclearData/toi/nuclide.asp?iZA=40008
Reaction Cross-Section: http://www.ncnr.nist.gov/resources/n-lengths/elements/li.html
That was a long first post. What does everyone think?
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NILFiR is the Future 
--N--eutron --I--nduced --L--ithium --F--I--ssion --R--eaction
Last edited by jumpboy11j on Sun Aug 17, 2008 6:17 pm; edited 1 time in total |
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| Harold14370 |
| Posted: Mon Apr 21, 2008 4:41 pm Post subject: |
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Forum Professor
Joined: 13 Apr 2007
Posts: 1675
Location: Pennsylvania
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| I don't know much about core design and don't know if your reaction will work or not, but I did have a thought. A conventional uranium core has plenty of neutrons to spare. They try to design them with low leakage to minimize the embrittlement of the reactor vessel. Neutron shielding outside the vessel is also required to cut down personnel exposure when people have to go inside the Containment. Maybe some of your proposed fuel could be put in rods around the perimeter of a conventional core. |
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| thyristor |
| Posted: Tue Apr 22, 2008 5:55 am Post subject: |
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Joined: 11 Feb 2008
Posts: 190
Location: Sweden
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There are many reasons why you use uranium, for the first there is plenty of it.
For the second you have to look at the neutron absorbtion coefficient for lithium as well, I think that it is quite high.
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| jumpboy11j |
| Posted: Tue Apr 22, 2008 12:58 pm Post subject: |
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Joined: 21 Apr 2008
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| thyristor wrote: |
There are many reasons why you use uranium, for the first there is plenty of it.
For the second you have to look at the neutron absorbtion coefficient for lithium as well, I think that it is quite high. |
do you mean lithium 6? Yes, that one is pretty high, but it is fairly easy to remove li-6 from li-7.
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NILFiR is the Future
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| jumpboy11j |
| Posted: Thu Jul 10, 2008 4:43 pm Post subject: |
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Joined: 21 Apr 2008
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just bringing it up again...
Any other comments?
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NILFiR is the Future
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