You can even dissolve the uranium in the water and use the same substance for both fuel and propellant and so capable of reaching far higher temperatures than t

You can even dissolve the uranium in the water and use the same substance for both fuel and propellant and so capable of reaching far higher temperatures than those that would cause any engine to melt. https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket