If you whack enough neutrons into it, you'll eventually get Rhenium and Osmium. Both are actually pretty useful and while not actually dangerous you might not want to get any on you, especially if it's still hot from the reactor.

Osmium in powder form will oxidise to osmium tetroxide, and you want to avoid that because it stains just about any kind of plant or animal tissue including the surface of your eyes, and is spectacularly poisonous.