At the moment, the nuclear science pack is a terrific idea, but the current recipe for nuclear science is a bit uninspired. I don't blame you. Nuclear science is a fairly niche subject, and there aren't a lot of things in vanilla Factorio to work with. That's why I think the science pack name should be changed to "Energy Science Pack," and make the pack incorporate other ingredients exclusive to Nauvis.
Nauvis has four resources that other planets don't have in similar quantities:
Uranium
Water
Wood
Fish
With this in mind, my proposal for a new science pack is the following:
1x Uranium-235
10x wood
500x steam (150 MJ at 165 C)(Equivalent to 37.5 coal)
= 1 Energy Science pack
Making the pack require these three items will require setting up Uranium processing, automated wood harvesting, and a massive source of steam, an amount that can't be easily pumped in, forcing the steam to be made nearby. Once the player has a nuclear power plant, sourcing the steam will become a lot easier. This will make sourcing Energy Science more interesting than it is currently. You would need to move the agricultural tower and wood harvesting earlier in the tech tree to make this work, but I think it's an acceptable change.
Expanding the subject to energy in general will make it easier to justify more technologies requiring this science pack.
