Size is not equal to quality or fun. You need a good concept and hard work. :)
Exactly this! It is all on how well made the gameplay is. There are plenty of mods that throw in things just to throw them in, like the multitude of mods that just add more tiers of assemblers or so, Bob's Mods is dangerously close to being like that but it still adds enough 'new gameplay' that is decently balanced that it works well. Angel's Mods are a mod set that on initial glance just throws in everything, but it is so well balanced and does so much for gameplay and puzzles and near every bit of it is new that it just works very well. MadClown's Nuclear works well because it adds the proper centrifuging process to start, which is the 'throw in to throw it in part' it seems, however it works well with its overall design in that it splits output and products out amongst those various centrifuging steps, adding more to the puzzle that is the gameplay, in addition to the various forms of other fuels, how to mix them and balance them and all, and although it is very useful and works well especially with the higher tier fuel types, it is still dangerously close to that territory of throwing things in just to throw them in (especially with the fuel rod tiers and centrifuging, although with the fuel rod tiers it gives you a useful enhancement for essentially 'unlocking' more byproducts from the reactors themselves).
At the moment I don't really know what this mod does as the description doesn't really say, but as it does not seem like it would work with madclown's it hasn't been added to the server as of yet. If it works with madclown's, or it is better than madclown's (not in terms of 'stuff', but in terms of gameplay and efficiency, madclown has no UPS hit thankfully as it has no running scripts) then I'd easily replace madclown's on the server with this one as we haven't reached nuclear yet (death world, haven't even reached blue science yet, so much military focus...) or add it with madclown's if it extends and/or refines it at well. :-)
For note, if you do find a way to work with madclown's mods that would increase visibility as well, the 'C' of the ABC mod packs stands for 'clown' (angel/bob/clown) so it would be more drop-in with that and thus increase usage in existing ABC ecosystems. MadClown's mods are modular like Angels and Bobs so it is not a stretch for people to leave out just the nuclear portion if yours ends up better though incompatible. :-)
It is the gameplay that matters about mods, not the 'stuff' that they add after all. :-)