I'd assume that NASA would we be smart enough to have a reactor type that would not require a precious resource on Mars. Although, NASA . . .
Generally speaking, you wouldn't need to overly worry about running out of power with a nuke reactor, as even small-scale reactors that are extremely simple and self-contained (and therefore somewhat less efficient) should go for atleast 5 years before needing fuel, and even then, that's generally only to maintain maximum output.
The majority of fuel rods that are no longer in use are still quite viable for lower output levels.
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Getting fuel rods is less a problem than the power output itself. I'm more concerned with figuring out how big a reactor needs to be to generate a given amount of power, and I know the design of that is a critical consideration. As Fallout 3 so wonderfully reminds us, back in the 60's they could build radial-nuclear reactors of roughly the same size and power output as a car motor.
(I think the proper term is radiothermal - basically, it's a "reactor" that just boils water with the heat of a naturally decomposing isotope. They're bulky and produce little power for their size, but they can be small, and are no more dangerous than just a loose fuel rod. They're mostly used today to power satellites when solar panels aren't feasible.)
EDIT: It just occurred to me that I can dig out my old GURPS Vehicles book and come up with a reasonable estimate of a reactor weight. Any learn'ed objections to that plan?
For image editing, my big problem is blending objects into the photo, which MSPaint can't do. I suppose I could just download GIMP or something, but trying to learn how to do this myself would just slow the process down. I only really need vista-type pictures for a few turns until enough people are in contact to make an actual map. I'll handle this one myself, and if anyone thinks they can improve what I post, go right ahead and I'll send you next turns pics to spruce up.
Also, yes, I'm back to updating right now because I unfortunately have the night off. Shouldn't be too much longer.