A fission design similar to focus fusion

[dennisp]

NASA is looking at a fission fragment rocket, which could also be used for an efficient power plant, running a beam of fission fragment ions through a direct conversion process.

http://www.rbsp.info/rbs/RbS/PDF/aiaa05.pdf
http://nextbigfuture.com/2012/03/proposal-for-concept-assessment-of.html

Not as cool as fusion but if this gets any serious development, maybe some beam conversion technology could cross over.

[Tulse]

I doubt this could be used in a terrestrial plant, as the beam of fragments is radioactive, and would have to be captured and stored in some fashion. However, it appears to be a very promising technology for space propulsion, with enormous specific impulse, and could get craft up to a reasonable fraction of c.

[dennisp]

For a power plant the idea is definitely not to vent the fission fragments to the atmosphere 🙂 …but rather to trap them electromagnetically and extract energy as you reduce their velocity to zero. That’s the part it might have in common with a focus fusion reactor.

After that you have to dispose of the waste, just like any fission reactor. But the problem is easier than for a light-water reactor, because the (relatively short-lived) fission products are separated from the heavy isotopes. I would guess you can also achieve high fuel burnup, which in a LWR is limited because fission products are trapped in the solid fuel. Some of them absorb a lot of neutrons, and some are gases that are bad for fuel integrity.

[Tulse]

dennisp wrote: For a power plant the idea is definitely not to vent the fission fragments to the atmosphere 🙂

I kinda figured that 🙂

On the other hand, unless I’m mistaken, it sounds like the waste ends up as a gas, or at least a very fine powder, and that would be seriously difficult to handle and dispose of.

[dennisp]

Some fission products are gases at room temperature, but that’s the same for any fission reactor. It does have to be handled carefully but there are well-developed ways to do it. I think one is to embed them in blocks of glass.

I don’t want to give the impression that I think it’s as good as fusion. But I think it’s worth keeping an eye on, just for technology sharing if nothing else.

[Author]

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