[perihelions]

- "There is no risk of fallout without an atmosphere"

I'd speculate that it would spontaneously propagate along the lunar surface through electrostatic forces. The fallout particles would be highly charged (self-ionizing), very small, and in a perfect vacuum -- a recipe for some seriously weird dust physics.

[idontwantthis]

How much more dangerous would that be compared to space normally?

[marcosdumay]

Space usually stops being dangerous once you get into some atmosphere. Nuclear waste doesn't.

[itworkslikethat]

Space is very irradiated, and direct sunlight is radiation itself. Anything you add there will be a drop in the ocean. Atmosphere is not sufficient to resolve space radiation, you need a magnetosphere.

[marcosdumay]

You don't take sunlight inside with you when you enter some place.

You take neutron radiation (well, its consequences), but that is pretty much non-existent when compared to nuclear waste.