How deeply could molten uranium the Earth?

Specifically if there were a total meltdown at a nuclear reactor (god forbid). I presume the energy would be dissipated gradually thru the melting of various materials on its way down. It would also encounter pressurized rock with a high melting point would it not? The earth's core is some 1800 miles below the surface and it would seem absurd to me it could this far. Please elaborate and/or correct me thanks!