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Due to political and environmental concerns alone no modern terrestrial reactor design would be allowed to fly. That's usually not what nuclear propulsion propo

Due to political and environmental concerns alone no modern terrestrial reactor design would be allowed to fly. That's usually not what nuclear propulsion proponents argue for. There are several other reactor designs that have been researched over the last half century that can operate in a closed loop with much smaller amounts of nuclear fuel and more manageable radiation emissions. Designs like the nuclear lightbulb, which was researched by United Aircraft Corporation and NASA for almost a decade before the plug on the Mars mission was pulled in the 70s, are much better suited and are what proponents of active nuclear propulsion most often have in mind. Once there is some political will, we have decades old research to start from to build a flight capable nuclear reactor.

CydeWeys 10y ago
The nuclear lightbulb doesn't generate power though -- it's a rocket engine, and "generates" reaction mass leaving at high velocities. So it's not suitable for use powering an emdrive, the whole point of which being indefinite flight without needing to use up any reaction mass, which a nuclear lightbulb can't do.
- akiselev 10y ago
  No, the nuclear lightbulb generates energy in the form of heat and electromagnetic radiation. How you use that energy output depends on the design of the reactor and propulsion system. You can seed expanding liquid hydrogen in the outer cavity with tungsten nanoparticles which absorb the UV radiation to heat the hydrogen for use as a propellant. You can pump the outer cavity with a UV transparent coolant and line the walls with parabolic photovoltaics (that convert UV instead of visible spectrum) for direct conversion of the black body radiation to electricity. You can theoretically even create a magnetohydrodynamic "turbine" in the outer cavity that is coupled to the spinning nuclear fuel (which can be charged plasma). You may be thinking of an earlier that was mistakenly called nuclear lightbulb or another design that was lumped into the concept. The variation I have in mind is just as general purpose as any other nuclear reactor, it just uses a lot less fuel and has to actively maintain temperature and pressure to keep the neutron cross section energy high enough to sustain power positive fision.
  - CydeWeys 10y ago
    Do you have a link with more information to the specific concept that you're talking about? It looks like I was led astray by the Wikipedia article. I'm super interested.

CydeWeys 10y ago

The nuclear lightbulb doesn't generate power though -- it's a rocket engine, and "generates" reaction mass leaving at high velocities. So it's not suitable for use powering an emdrive, the whole point of which being indefinite flight without needing to use up any reaction mass, which a nuclear lightbulb can't do.

akiselev 10y ago
No, the nuclear lightbulb generates energy in the form of heat and electromagnetic radiation. How you use that energy output depends on the design of the reactor and propulsion system. You can seed expanding liquid hydrogen in the outer cavity with tungsten nanoparticles which absorb the UV radiation to heat the hydrogen for use as a propellant. You can pump the outer cavity with a UV transparent coolant and line the walls with parabolic photovoltaics (that convert UV instead of visible spectrum) for direct conversion of the black body radiation to electricity. You can theoretically even create a magnetohydrodynamic "turbine" in the outer cavity that is coupled to the spinning nuclear fuel (which can be charged plasma). You may be thinking of an earlier that was mistakenly called nuclear lightbulb or another design that was lumped into the concept. The variation I have in mind is just as general purpose as any other nuclear reactor, it just uses a lot less fuel and has to actively maintain temperature and pressure to keep the neutron cross section energy high enough to sustain power positive fision.
- CydeWeys 10y ago
  Do you have a link with more information to the specific concept that you're talking about? It looks like I was led astray by the Wikipedia article. I'm super interested.