Pellets of RTG Fuel
Pellets of RTG Fuel have the sole purpose of being placed inside the Radioisotope Thermoelectric Generator or the Radioisotope Heat Generator. Even though they are expensive to craft, the pellets will last forever inside the generators, and therefore that makes them the most efficient infinite energy generator(without addons).
Placing Pellets of RTG Fuel in a Radioisotope Thermoelectric Generator or Radioisotope Heat Generator will generate 1 EU or 2 hU/t in the respective machine. However, multiple Pellets can be inserted in each Generator, and each item inserted will double the EU or Heat Units generated, up to a maximum of 32 EU/t or 64 hU/t at six Pellets.
When held in the player's inventory without any protection from Radiation, Pellets of RTG Fuel will inflict the player with one minute of Radiation, which increases by one second per second per item held until removed from the inventory.
See: Crafting Guide