I need to go to sleep, but I'll give you the tl;dr version of how you sanitize waste from most of the reactors currently in operation. First, let it cool off f

I need to go to sleep, but I'll give you the tl;dr version of how you sanitize waste from most of the reactors currently in operation. First, let it cool off for a while. We're doing this. Since the volume of the waste is so small, and it's so well contained, there's really no rush to process it right away. Second, chemically separate it into its parts. Deal with them in different ways: Uranium and plutonium can be recycled and used as fuel again. Hooray for recycling! France does this; other countries are just storing the waste for later, since non-recycled uranium is cheap these days. Short-lived isotopes can be left to decay. They are short-lived, after all. This is happening as we speak. Medium-lived isotopes are the really troublesome ones. Hit them with some spare neutrons to transmute them into something shorter-lived. Put the remaining, much-diminished waste in storage. It should become harmless after a few hundred years, rather than a few hundred thousand. Fun fact: it's a lot easier with something like a liquid fluoride thorium reactor, which makes the chemistry really easy and prevents a lot of the nasty isotopes from forming in the first place. You can skip most of the rigmarole. (Huh. I guess that was longer than I thought. Oh well; who needs sleep, anyway?)