Nuuuuukes Innnn Spaaaaaaace!

[Ender]

Would there be any difference as to how a reactor might operate in space?

Quite a bit. You'd be shocked how many components depend on gravity to do things ranging from scram, to simply improving turbine life.

[Ender]

............you really have no idea how a turbine works do you?

It's the PRESSURE of the steam.

True, but you can't have a closed loop system unless it has directionality. I mean, you want to have water or low temperature steam coming in from one pipe and the hot steam going out through another pipe that powers the turbine. The only problem is that, without gravity, I see no reason for the steam not to escape through the input valvue instead of the output valve. You can make the input one way, but that just means that no new water gets into the reactor until enough steam escapes for the pressures to equalize. But that becomes the equilibrium (with maybe some natural occilation around it), and the pressure on one side of the turbine is the same as the pressure on the other side, resulting in no energy gain. And I have no idea how a condensation chamber would work in 0-G either.

*rubs temples*
About the only thing you have right there is that some of the steam traps would not function.

Being appropriatly vague, I'm just going to make a few points:
We have methods today that allow for one way entry. Its insanely easy.
The rate of feed can be increased by pumps to overcome the pressure by the steam.
Flow can be caused by use of orfices and venturis like we currently do for some reactor types.

The big concerns in current designs will be things like automatic protection, steam traps, gravity drains, MAEGECs, keeping the tubes covered, etc. I think we will either need a new design that does straight heat-electricity conversion like a thermocouple, only much more efficient (which according to theAdmiral's speech to us, is what we were contacted to do, design a new reactor), or we'll just spin the fucker.