Here is an idea with additional science:
Plutonium is a decaying isotope which is used in unmanned probes and satellites to create energy from the heat it releases. The isotope Plutonium lasts 24,000 years before decaying completely. So as an alternative to using plutonium as a weapon or as science we could also have a recipe to build a small 2x1 building that would cost circuits, steel, copper and plutonium to make small generators which produce energy for free but not much to keep it balanced and realistic.

That would be a good idea, Maybe make it a little bit bigger and make it a squere so you can easy rotate the building.
It should be able to maybe power not much like a few lights or a mine so your can use them to power a generator setup or to create a roboport outpost surrounded by these sterling generators.
(A sterling generator converts heat to energy really efficient)

Yeah that is the idea of it. I wanted the idea because i have a lot of mods that need power and currently the power i'm looking at drawing would need a quadruple reactor to run which will be tough to get right so having the sterling generators help would massively.

The plutonium isotope involved in RTGs like the MSL is rather different than the plutonium isotope produced by a FBR. The isotope is Pu-238, and has a half life on the order of 90 years. Regular nuclear reactors produce Pu-239 (and Pu-240, and Pu-241, both of which make it useless for making nuclear bombs unless you have a low burnup ratio), but that aside, you are dealing with two rather different isotopes. Pu-238, if I am not mistaken, is made via the irradiation of Np-237, a material produced in really small quantities, detectable, but less than 3 kilograms per 800 MWy in nuclear fission reactors (it is made via the bombardment of U-235, and then the resultant isotopes). Thus you would reprocess spent fuel, get it as a byproduct, and then irradiate it some more to get a paltry amount of Pu-238. A more practical option would be to separate out the Sr-90 from spent fuel and use that as a heat source, which while shorter lived, composes on the order of 11% of all fission products, and thus could provide a small amount of power.

But either way, we are talking a small amount of power, on the order of powering a couple of steam boilers after 800 MWy of fuel, in the end you would get something like 1 MW at most from all of this. Now, mind, it could make an awe inspiring backup source, but otherwise it would be terrible for an actual power supply.

Though it would be excellent if we could conduct full on isotope production and manufacture things like H-3 illuminators and Co-60 radiation sources for things like radiation fences.

Right well it is a game so maybe some science could be broken so we could have another way of generating power without making 5 reactors to power one base so science man please step aside we need these things.

Those nuclear stations are basically like solar panels, except they work 24/7. If solar power output was closer to something realistic (5 kw) then such units could make a good competition to them.