Can the enrichment of Uranium be done via manipulating the boiling/melting point difference between differing isotopes of the same element?
Of course isotopes may be separated by distillation, but it's useful, AFAIR, only for hydrogen isotopes.
For uranium, gas centrifuge is proven much cheaper, to some orders of magnitude: https://ru.wikipedia.org/wiki/Газовая_центрифуга
(translate this page, it contains more information than English Wikipedia article).
The essence of this technology is known for decades, and included in basic chemistry textbooks. Only engineering/technological know-hows are sort of classified.
But in the politics, mass media, and perhaps on stackexchange, the whole topic is still considered taboo and is surrounded by fear.