My worldbuilding involves a reasonably near-future, high-realism space station research outpost, and I'd like it to be powered by a nuclear reactor. However, I need as much detail on the actual reactor design as possible. (Also, if its totally impractical, should I move to fuel cells?)
Are any of today's reactor designs generally suitable for operation in zero-g? Or are there experimental/theoretical reactors out there which may be suitable? Where do current designs assume the presence of gravity, and what other factors complicate the use of existing designs when deployed in space? What aspects of the designs can be totally discarded in space (containment, biological shields, etc)?
So far, I've only found detailed info on commercial, land-based power reactors but those are probably overkill for a space station. I only need a few MWe. Can I simply scale down these reactors (I am using these as a starting point because the info on the commercial power plant systems is plentiful, compared to ship- and submarine-based reactors).
How can I provide adequate radiation shielding for my crew, that doesn't involve huge amounts of dead weight? Can the crews water or LOX tanks be arranged as shielding, and the turbines and other heavy reactor components? Do tokamaks and stellarators require elaborate shielding? Do they create torques on the supporting structures?
Let's assume that a resupply mission can provide fuels to the reactor if necessary, and if in-flight refueling is possible; that limited mining of resources is available on-site, and that we're not particularly concerned about dumping waste products overboard.
A good answer will provide deep reference material on a candidate reactor design, with discussion on the modifications necessary to adapt it to zero-g usage. Or, if nuclear power isn't going to work, provide similar resources for fuel-cell or other technology.