For the most part, I believe that cosmic radiation should not be radioactive. Cosmic radiation can be either photons(light particles) or cosmic rays, which are atomic nuclei.
Most cosmic rays are protons (hydrogen nuclei) or alpha particles(helium nuclei) but there are also a small amount of heavier particle cosmic rays. A small fraction of the heavier particles could theoretically be unstable or radioactive but chances are that any radioactive particle would collide with something
or otherwise decay into other particles before
anyone would notice.
Since there is no air in space to carry heat away from objects, things can heat up very quickly if the sun is shining on them. Now it turns out that the sun shines mainly with visible radiation (which is why we can see it)and things that are at 300 K (27 degrees C) radiate in the infrared (not visible). The beauty of some white paints is that they radiate much better in the infrared then they absorb in visible light. So when the sun shines on something that is white, it absorbs a small fraction of the incoming radiation and then re-radiates it all away if the object is at a temperature around 300 K, which is the perfect temperature for someone who is used to being on Earth.
Can you think of why the visors on space suit helmets are coated with thin layers of gold or other metal rather than being clear?