A passing thought before I go away for a few days, Are there any physicists on the board?

It seems most of the older nuclear reactors like the problematic Japanese ones, store spent radio-active fuel rods on top of the reactor in water to keep it cool. Cleeeever. No one has any safe way yet of disposing of these rods or of storing them, so they just pile 'em up.

I just wondered what would happen if they were dumped into an active volcano? Would the immense heat liquify them and make them inert or would it mean radioactive smoke, etc etc.?

And apart from the risk of them falling back to earth in a Challenger type explosion, couldn't they be stored or 'lost' in space? Or sent into the sun?