Industrial Craft Nuclear Reactor Design. However, they are very dangerous and require careful observation to control. They are a good source of EU.
This requires no external cooling and can run forever as. Mods like nuclear control if present in the pack have devices that can emit redstone signals at threshold temperatures IF the design uses hull heat - some These reactors have massive efficiency and output factors that mean that, even though they have an on/off cycle their averaged EU/t can exceed. Nuclear reactors are used at nuclear power plants for electricity.
A nuclear reactor, formerly known as an atomic pile, is a device used to initiate and control a self-sustained nuclear chain reaction.
What is a breeder reactor and how is it different from a nuclear reactor?
If this is all a bit over your head, you can try this tutorial. Any designs in particular worth noting? One bad setup can destroy the reactor and everything around it.