Millénaire (or an EXTREMELY large and productive wheat farm)
Optional: (for an easy power source in the meantime)
So, I was fiddleing around with my world and I found I can get infinite uranium. First, you NEED a ThuamCraft Crucible and a Duplicator, at the minimum. Next, find your village in Millenaire. It should have a big wheat farm so ideally, the Japanese would be best for this from what little of the other villiges i've seen. Next, help your villiage as normal but DON'T BUY ANYTHING UNLESS YOU NEED IT. From here, make lots of cobblestone and some electric furnaces. Possibly a geothermal generator to keep the power flowing. If you can sink a pump into a RedPower volcano to get lava, that makes things really easy for power generation.
At some point, your villiage will start to not buy anything from you. Usually this happens when they ask for 900 stone or so. all their chests are full and you have to empty some things from them. This is where the Thuamcraft comes in. Buy as much wheat as you can (three stacks should do it though more is never a bad thing) and sell the stone you have remaining. Now that you have all this wheat, you can turn it into bread and head back home. Ideally, you should have a stupid amount of it like 64 bread or more.
Toss the bread into your crucible (CAREFULLY because bread give you a lot of Vis and you don't want the crucible to overflow). Now that you have all this vis, put some raw uranium into it and voila! Effectivly, you now have infinite uranium ore and for the price of a bunch of smooth stone that you smelted. The best part of this is that it's infinity renewable because the village will keep producing wheat and you can just make the vanilla minecraft cobblestone generator. Charcoal can be used for the smelts unless you want to use something else. Take the stone to them, buy wheat, and there you go. A zero cost, fully renewable uranium generator.... and the same for iron, lapis, glowstone, and all the other stuff you'll need to make a reactor! With the exception of sticky resin to make rubber. I don't think Thuamcraft accepts those but since resin is fully renewable as is, that's not a problem.
Addemdum: I haven't tried it with refined uranium so it might not work if you put that in. I've only tried it with the raw stuff.
I do have a lot of other mods installed on my computer, but Thuamcraft and Millénaire are the ones you need to make this work.