More fuel types for the nuclear engine

I would like to see more fuel types for the nuclear engine in game for variety
Plus more fuels for the nuclear engine, because water and LH2 are not the best
Hydrogen has an annoyingly low density, water gives bad isp.
So more fuels should be added, like liquid methane, ammonia, liquid nitrogen, liquid carbon monoxide and carbon dioxide
With all of these fuel types we could make smaller ships using this engine, because we can use much more fuels, giving the nuclear engine more uses