That's not what volatile means in science. I'm getting half a dozen different definitions when I search for "volatile" so it's understandable that people are confused, the one I was thinking of when I wrote was:
Volatile definition, evaporating rapidly; passing off readily in the form of vapor: Acetone is a volatile solvent.I think a liquid can be volatile without being flammable, eg (though fairly extreme) liquid helium.Long-term issues with radioactivity are not a matter of volatility at all - there the correct comparison is to long-term issues with carbon dioxide and other chemical emissions caused by burning coal. Depleted uranium is horribly toxic, but not particularly volatile.