Not if it is shielded. (A common misconception is that nukes can be detected from long distance, such as from space. If they could, we would have no problem protecting ourselves.)
The radioactivity in this ship was picked up a couple of days ago by inspectors after they had boarded the ship. It was then ordered back to sea for further investigation.
Can you go into more detail? How much shielding? Sheilding with what? How heavy? How difficult is it to do? Etc.