Yes, what I mean is that theoretically you could do something like have a very very wide base to passively dump heat into the ground (since we're still only looking at kW scale reactors in space), or actively cycle large amounts of regolith through the cooling loop (say, via a heat exchanger from a closed water loop) and dump it out. Depending on how much heat the system can handle, you could maybe even extract stuff boiling off from the regolith.

The nuclear plant nearest to me uses sea water, which is put back into the ocean.

Mostly cooling towers are not likely to work in a place with no atmosphere.

Radiators though, are constantly used in spacecraft, and seem to work well. Low gravity, no motion might let the thing be mostly the radiator, with not much support structure. Except it might need to be in shade, in the shadow of a building? hill? solar panels?

> How does that work in a place with no spare water?

I wonder if recycling human liquid waste through evaporation could be of some use for that purpose.

Yeah, that's what I meant, sorry about the incorrect naming.