4 ms·

How do you reflect neutrons? I thought they could only be absorbed?

• xxpor 6y ago
  Lots of ways :) A common material is Tungsten Carbide, which was what caused the accidents with https://en.wikipedia.org/wiki/Demon_core https://en.wikipedia.org/wiki/Demon_core But here's an overview: https://en.wikipedia.org/wiki/Neutron_reflector https://en.wikipedia.org/wiki/Neutron_reflector Reflectors are important because they allow you to have a quantity of radioactive material that's not supercritical on its own, but becomes supercritical when surrounded with the reflector. This allows controlling when things happen (unless you screw up like the accidents above)
  • jl2718 6y ago
    The original intent of the duoplasmatron breeder was to eliminate the dangers of going supercritical, actually to eliminate HE fissile material entirely from the bulk, as the plutonium would have to be neutron-bred by the fusion reactions triggered by the tritium beam. Also short pulse control. This was mainly to make it safe and cheap. You could also just use a subcritical mass of HE-fissile material surrounded by a neutron reflector with aperture in the direction of thrust. Recommended only if you are certain to be far enough away from humans to avoid recovery and conversion to a weapon. Aliens too; they might send one back. There is a design for a safer and simpler cylindrical slow-burn wave reactor that may also work for low levels of neutron propulsion.