This mod adds a new Radioisotope thermoelectric generator that is supposed to bridge the gap between early game solar panels and late game fusion reactors for modular armor power. It only requires production science so you can get it before high tech and it requires 20 U-235 to craft, so it will require you to have a nuclear processing setup. If you are using the "Nuclear Fuel" mod by GotLag it will instead use more realistic Plutonium, which requires you to set up a reactor to breed it. It also slightly rebalances some other recipes from "Nuclear Fuel" to allow Plutonium to be used for trains. The texture is based on that of the RTG in KSP with some edits to make it fit in a bit better in the factorio artstyle.