I don't understand why they don't dump sand on the fuel rods. The heat from the rods would melt the sand, vitrifying it into glass. This is how spent fuel is treated already; this would be in effect "abandoning it in place". Maybe the little water that is there would pressurize and now you'd have radioactive glass going sky high? I dunno.

the problem with nuke plants is that sooner or later the small probability but severe risk profile will catch up with you.