Fragmentation nuclear rockets

[giveitawhirl2008]

On Oct 12, 10:52 am, Frogwatch <ohara...@mindspring.com> wrote:



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> Fission fragment rockets have been proposed where the thrust is
> provided by the very energetic fission fragments from fissioning
> uranium. The extremely high speed of these fragments could yield an
> ISP of up to 1,000,000 making it suitable for very deep space
> missions. In such a reactor, the fissionable material is arranged so
> that not only can criticality be achieved but so the fission fragments
> can escape from the core to be directed via magnetic fields. To
> achieve this, two types have been proposed, the disc reactor where
> discs of U are rotated so that criticality occurrs on a segment of a
> rotating U disc and it emits fragments and it rotates so the disc can
> cool. There is also a proposed "Dusty Fission Fragment" reactor where
> the fuel is composed of submicron particles of sufficient density to
> achieve criticality but small enough so the fragments can escape and
> the fuel particles can cool. Both designs suffer from the need to
> cool the fissioning fuel while maintaning criticality.
> I propose a Thorium fission fragment rocket that does not achieve
> criticality but does act as an "Energy Amplifier" as in Carlo Rubia's
> original idea. However, in this concept, we intend to use the fission
> fragments from the U233 (produced from the Thorium) to produce
> thrust. Fission is driven by means of spallation neutrons from a
> proton beam onto a heavy target material or by means of a good neutron
> emitter such as Cf. The "gain" from such a device would be on the
> order of 60x as originally proposed by Rubia. The Th would have to be
> arranged to absorb the starting neutrons and to capture the neutrons
> emitted by the U233 with very high efficiency but to also allow the
> emitted fission fragments to be used for thrust. Thus, fine particles
> would probably be best similar to the "Dusty Fission Fragment
> Rocket".
> The advantages of my Thorium Fission Fragment Rocket (TFFR) would be
> that the fuel particles would be cool because there is no criticality
> meaning that design is much easier and there is no possibility of a
> "runaway" reaction. Furthermore, the power output and hence the
> thrust can be varied by varying the neutron input whereas the "Dusty
> Fission Fraqment Rocket" has a minimum power level needed to maintain
> criticality.


You turn out to be talking about a serious proposal. (I had to check
it out on Google, first, and so, I certify you are not making stuff
up! [:-)])

NASA site on fission fragment rockets:
http://www.batse.msfc.nasa.gov/colloquia/abstracts_summer05/rsheldon2...


Also, though this site may not ref. fragrock (I love coining terms!),
the following society and its site are mentioned in an article I
referred to, aerlier:


http://www.tauzero.aero/site/html/getting_there.html


(Article ref: http://www.airspacemag.com/space-exploration/Mars-and-Step-on-It.html)


This foundation is intent upon interstellar but what's good for
interstellar is likely to be good for interplanetary!


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