Recent content by sevenperforce

Contrary to potential appearance, this is not homework. I've been out of college for a long time now. Just working on a project with my kids and I'm trying to approach specific energy of these reduction reactions from the theoretical side, mostly so I know what sort of safety precautions to...

A low-energy-barrier exothermic fission reaction which releases D could potentially do so at high enough particle energy to result in 6Li + D fusion with decay of the resulting 8Be to 2 4He at 22 MeV. Such a fuel could be mixed into the 6Li saltwater and serve as the trigger for the more...

Probably sound like I'm clutching at straws here, but I'm honestly just curious about what the possibilities are... Are there any fission events or decay chains which produce deuterium? 2He and 6He both have a low probability of decaying to deuterium, but that's all I've found. Alpha decay...

Hmm. Are there any fissionable but non-radioactive isotopes with a net positive prompt or delayed neutron output? Lithium-7, of course, fissions endothermically and releases a thermal neutron when struck by a very fast neutron, but that's just break-even. Barring that, which fissile isotope...

Did a bit more digging. Quoting from this paper: The paper goes on to discuss the high probability of reaching fluxes in excess of 1017 neutron/cm2*sec. It seems likely that with the use of molten salt reactors, pebble-bed reactors, or other more specialized designs, further improvements to...

What about using some kind of neutron multiplier that would be consumed by the reaction? A sufficiently active layer or layer set of neutron multipliers might even make a D-T fusion deuterium ion accelerator design feasible.

Yuck. What about increasing the path length of the lithium? I know the High Flux Isotope reactor produces a flux of roughly 1e12 neutrons per second per square cm, but it is intentionally poisoned to keep the flux variance as low as possible. I wonder whether it would be possible to set up a...

It would be entirely possible to keep the lithium metal or lithium salt in a solid form and simply react it with water as needed, but then you end up pumping hot gas into the reactor core rather than liquid, and that's problematic. Not that it isn't going to flash to gas and then to plasma soon...

Engineering the propellant stream to pass around the reactor on its way out rather than through it could serve to partially shield the rest of the ship from neutron flux, as the lithium would suck up a lot of the neutrons. I wonder if adding sulfur or chlorine or fluorine or some other...

If you could design a fusion-based nuclear reactor with the potential to completely revolutionize energy access around the world, but the reactor could only function by releasing environmentally significant amounts of superheated tritium directly into the atmosphere, would there be any way to...

The ion thruster version using nothing but pure lithium-6 has a maximum theoretical specific impulse of 1.17 million seconds. The lithium hydride ion thruster has a maximum theoretical specific impulse of 1.09 million seconds. Cutting it down to the high-thrust versions, a saturated lithium-6...

I absolutely want the fission products to be thermalized. MeV energies are far, far too high to handle; distributing this energy to the oxygen and deuterium in the heavy saltwater reduces the velocities well out of the relativistic range while massively increasing the momentum and therefore the...

4.78 MeV / 7.023 amu = 6.567e13 J/kg. Definitely. I was initially pointing out that neutron flux on pure lithium hydride could produce a low-power ion thruster with a stupidly high exhaust velocity, but I also that that wasn't what I was primarily interested in. More interested in the...

I depicted a conventional de Laval nozzle for convenience, but you're completely right; I would almost definitely need a long cylindrical reaction chamber with a convex-section diverging nozzle. It won't have the near-perfect efficiency achievable by a properly choked converging-diverging...

Had been talking NSWRs on a spaceflight forum and a thought occurred to me. Lithium-6 fission can be triggered with relatively low-energy neutrons and releases 4.78 MeV, a helium-4 atom, and a tritium atom. Without a neutron flux, however, lithium-6 is completely stable. With a small...