Author Topic: Thin Film Isotope Nuclear Engine Rocket (TFINER)  (Read 2669 times)

Online litton4

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Thin Film Isotope Nuclear Engine Rocket (TFINER)
« on: 01/12/2024 08:54 am »
Not seen any discussion on this concept of using the momentum of decay products to provide thrust.

https://www.nasa.gov/general/thin-film-isotope-nuclear-engine-rocket/

To me, it seems far fetched and can't provide the stated thrust over time, but what do I know?
« Last Edit: 01/12/2024 08:57 am by litton4 »
Dave Condliffe

Offline edzieba

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Re: Thin Film Isotope Nuclear Engine Rocket (TFINER)
« Reply #1 on: 01/12/2024 11:53 am »
Sounds like a Fission Fragment Engine (or Robert Forward's Fission Sail) but using decay rather than neutron triggered fission. I can't recall the idea of using extra films to capture and reuse decay products being proposed before, though.

Offline InterestedEngineer

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Re: Thin Film Isotope Nuclear Engine Rocket (TFINER)
« Reply #2 on: 01/12/2024 03:26 pm »
"always be thrusting" would be the motto.
And a mission planning headache.

  Unless you make it refoldable, but then I don't see how such a mechanism can fit inside 30kg of payload.

The useful design metric at scale is ~8.5m2 per kg of payload.

So if one wants a more realistic 10t payload (e.g. with a decent deep space antenna), that's 85,000m2 of sail, or 300m on a side.  On the high end, but possibly deployable from a Starship.

Seems to me this should be combined with a solar wind sail, which gives it 400-1000km exit velocity and then 100km/sec of further deltaV.

Offline KelvinZero

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Re: Thin Film Isotope Nuclear Engine Rocket (TFINER)
« Reply #3 on: 05/25/2024 02:42 pm »
I was wondering... Could there be a version of this that starts with mostly just safe-to-launch fertile nuclear material?

Although I think their idea relies on alpha emitters, I guess any nuclear reactions tend to produce charge particles if only through ionisation of whatever they are embedded in.

I imagine something like long rolls of film stretched out by a slow rotation. They can be rolled in to soak up neutrons and then unrolled to produce some thrust and get rid of heat.

Offline sanman

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Re: Thin Film Isotope Nuclear Engine Rocket (TFINER)
« Reply #4 on: 05/27/2024 12:47 am »
Sounds like a Fission Fragment Engine (or Robert Forward's Fission Sail) but using decay rather than neutron triggered fission. I can't recall the idea of using extra films to capture and reuse decay products being proposed before, though.

How is the absorber ("extra film" shown in blue) allowing trapped decay-product nuclei to produce extra thrust that is directional rather than omni-directional? Once those decay product nuclei are embedded in the absorber film, then isn't the ability to control direction of their further decay emissions then gone?

Isn't directional thrust only happening from the original film shown in orange?
« Last Edit: 05/27/2024 01:24 am by sanman »

Offline sanman

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Re: Thin Film Isotope Nuclear Engine Rocket (TFINER)
« Reply #5 on: 05/27/2024 01:23 am »
I was wondering... Could there be a version of this that starts with mostly just safe-to-launch fertile nuclear material?

I thought the definition of fertile is that it can absorb a neutron to turn into fissile isotope. That's what Th-232 does.
When it comes to nuclear decay, there doesn't seem to be any way to control that. It's just a hard physical law.

I recall some experiment from ~2000 where a researcher trapped some heavy isotope inside a C60 buckyball, and then surrounded it with negatively-charged anions to see if it would somehow crowd the electronic orbital clouds into the interior of the buckyball, and possibly have an effect on the beta-decay of the trapped heavy atom. Apparently it didn't do anything.


Quote
Although I think their idea relies on alpha emitters, I guess any nuclear reactions tend to produce charge particles if only through ionisation of whatever they are embedded in.

I imagine something like long rolls of film stretched out by a slow rotation. They can be rolled in to soak up neutrons and then unrolled to produce some thrust and get rid of heat.

So would the film rolls be wrapped around some nuclear fuel rods acting as a neutron source?
« Last Edit: 05/27/2024 01:49 am by sanman »

Offline KelvinZero

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Re: Thin Film Isotope Nuclear Engine Rocket (TFINER)
« Reply #6 on: 05/27/2024 03:34 pm »
I was wondering... Could there be a version of this that starts with mostly just safe-to-launch fertile nuclear material?
I thought the definition of fertile is that it can absorb a neutron to turn into fissile isotope. That's what Th-232 does.
When it comes to nuclear decay, there doesn't seem to be any way to control that. It's just a hard physical law.
Fertile creates fissile, fissile could rapidly bathe the film in neutrons when rolled up to create the short lived isotopes.

It is not about triggering the short lived isotopes. We just rely on them usually happening to decay while the film is unrolled since it usually is.

I have heard some types of reactors are safe to launch because they don’t create all the dangerous isotopes until turned on.. but maybe by safe they just meant fissile with massively long half-lives. I may have confused myself there.

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