What does radioactive waste actually look like?

[flashingnose]

Because I've no idea and yet it's a phrase that's been bandied about for years. Anyone know?

It's green and it glows in a sinister fashion....

I think I saw it in DS2's nappy today.....

A river where I used to live had radioactive mud for it's banks. It came from a reprocessing plant a little way upstream.

It just looked like mud!