[Spaceships] getting into orbit without superscience?

[Anthony]

Originally Posted by Fred Brackin

Free neutrons don't constitute any sort of long-term radiation hazard. All of the major components of Earth's atmosphere are still harmless after absorbing a neutron.

Mean free path of a neutron in air near is something like half a mile at 1 atmosphere, so it's a bit of a direct radiation hazard and also can activate materials on the ground.