When satellites come back to earth, do they have levels of radiation from space?

You really need to learn what the words mean, remembering that even scientists don't always know what the words mean. Radiation does not come from space, it is either a light or a charged particle that is emitted from some object. Scientists talk about "radiation belts" when there is no source of radiation. They are in fact talking about a flow of charged particles, which is an electric current, but they deny electric currents in space. They speak only of weather analogies, and there is no weather without an atmosphere.

Bottom line: you can't always trust what a scientist tells you.

Here is a site where some scientists point out the mistakes of other scientists. It is a VERY unpopular site, as you would expect.
www.thunderbolts.info/wp/daily-tpod/