How would a lunar base handle heat rejection from a small fission reactor?

[Oliver.M]

I'm trying to get a handle on the practical challenges of building a permanent base on the Moon, specifically around power generation during the long lunar night. I keep reading that solar alone won't cut it for a two-week darkness, and the idea of using a small fission reactor seems to be the leading alternative. I'm just unsure how they plan to manage the heat rejection from one of those units in the vacuum, with all that loose regolith everywhere.

[HannahUD]

We did some vacuum chamber tests on a small power unit and the heat rejection problem was the showstopper. On the Moon there’s no convection, so everything has to radiate away. Any surface that gets dirty or sits in shadow loses efficiency fast. The loose surface material would drift and settle on the radiator fins, which makes you rethink big shielded radiators and some way to keep them clear.

[Thomas_T]

We tried a deployable radiator array on booms and pointed it toward deep space. It worked in daylight, but when the night cycle hit the load stayed high and the radiators had to shed heat while the habitat kept drawing power. Dust charging and deposition on the fins slowed heat rejection, even with seals and a cover, so we started talking about trenching the radiator and burying part of it under a shield.

[Zachary_S]

I keep wondering if we’re solving the wrong problem. Maybe the real win isn’t just more radiator area but smarter heat management: bigger thermal mass to ride through the night, or staged heat release so you don’t need full power on a two week cold swing. Feels like a lot of moving parts to manage.

[ElizabethFT]

Is the bottom line the heat rejection path, or is it about how you store or throttle the heat during the two week darkness?