(first of all I DON'T suggest any nuclear weapons)
So, with the mod Clockwork being released, I've been thinking about electric ships. The only problem is that portable interfaces don't work currently (that is, between "world" and ships), and using single-block accumulators isn't an efficient way of transporting energy through items.
I am aware, that nuclear power may be too futuristic for create or Minecraft itself.
However, it would also require a few additional blocks to be added:

• Fluid turbine - a "reverse" pump, would provide rotational force from flowing fluid perpendicular to flow. High speed but low torque, enough to power a single alternator with 256 RPM
• Copper condenser - could turn vapour into liquid. There could be various variants of such, including air and liquid condensers; could only be placed vertically. Air condensers could work passively with small amounts of vapour, or if they are long enough or actively with an encased fan blowing in their way. Liquid condensers would require being fed with a cooling liquid, like water or ethanol. If lava was pumped into the condenser main pipe, it would turn into granite, clogging the condenser, and if it was pumped into a liquid condenser mantle, it would vapourize the flowing liquid, or even burn it (especially the seed oil, which would be turned into acrolein)
• Reactor controls - would work in a similar manner to fluid valve - would insert and take out control rods via rotational force; would need to be placed on a fluid tank. Wouldn't allow to insert control rods if there isn't any water in the tank. Could be multiblock

Note: For simplicity, let's assume, that uranium in minecraft is stable enough to only start fission with control rods present, and radiation is harmless.

Note 2: Fluid turbine only provides rotational force and requires a separate alternator to generate FE.

As every metal in create, uranium would have its own rock - canarite, as it would be yellow (canary yellow). No, it wouldn't glow in the dark.

Reactor controls would use four uranium rods as fuel and four iron rods as control rods. Uranium rods would get used over time, but at such a slow rate, that it would take 720 hours in game, to fully deplete one rod. One reactor controls block would contribute 1 unit to reactor power.

Here's an overexaggerated (in size) reactor idea

Note 3: I don't know how to model such things, so I resorted to existing things.

I think it would also be adorable to add a radiation sign as a decoration

(it's awful, but it's not my fault i can't draw)