To dream that you, someone that you are close to, or someone you would like to be close to, is radioactive suggests that there is a toxicity directly related to your interaction.
Your fear of getting closer may be causing a blockage in the natural flow of the relationship. Examine the emotions you feel in the dream as they may give you clues to a deeper understanding of your relationship.
To dream of an object that is radioactive implies that there is something you need to avoid in your waking life.
To dream of radiation is a sign to immediately leave a current toxic relationship or habit as you may be aligning yourself with negative fallout by continuing on a current path.
Dreaming that you have radiation under control may mean you have bought yourself some time, but there is still more work to be done to render yourself and your emotional world free from negative influence.