It would be a good idea to add thorium and neptunium as part of the uranium and plutonium processing. It would add more realism and coherence, and offer more alternatives to the uranium for energy production.

I've considered making a Thorium Energy mod, even collected a bit of info to get an idea of how to make it unique. But didn't get to making it yet.

And I think this doesn't quite fit Plutonium Energy

Thorium isn't fissile, rather it is fertile. It needs a fissile helper material such as plutonium or uranium to uphold a nuclear chain reaction. So I would say adding thorium could really fit.

I've been playing with both enchanted nuclear and plutonium energy, for those looking for thorium and neptunium cycles as well as more reactors and a few other tidbits, i would recommend installing enchanted nuclear as well. It seems to play fairly nice with plutonium energy so far. Though i will say the vanilla thorium fuel recipe is quite silly. I ended up running a variant of it with an additional recipe for my own usage.