Transplutonic adds a complex chain of nuclear fuel reprocessing and other interesting production challenges
Mods introducing new content into the game.
Things related to oil and other fluids.
Furnaces, assembling machines, production chains.
Changes to power production and distribution.
cool addition could be adding a lithium breeding inventory for the breeder reactor, letting you breed tritium at higher rates than normal breeding. perhaps a pure lithium inventory might not make sense, so maybe a 50/50 split of lithium and 238?