Your first attempt at harnessing nuclear power is going to be the Fission Reactor, that generates energy by splitting atoms, unless you did something as weird as crafting 99 Radioisotope generators and fill them to the brim with Uranium pellets (not a bad idea in theory).

Fission reactor must be surrounded by water blocks in 5x5x2 area centered around the reactor. The walls can be made out of electromagnetic glass, but it is recommended to seal the reactor basin completely with ceramic lead insulation blocks. Atop of the water blocks shall be the turbines – by default they capture steam generated under them in 5×5 area centered around the reactor. The turbines shall be connected with wires to a downgrade transformer (if you’re using advanced lithium battery box, you can skip the transformer, as the lithium BB has voltage of 240V but not the regular battery box).

Simple Fission Reactor Setup. Note the downgrade transformer between the turbines and battery boxes.

There are 3 types of fuel you can use to power the Fission Reactor: Low Enriched UO2 Fuel, Highly Enriched UO2 Fuel, or Plutonium Fuel Rods. The more fuel you provide, the higher radiation is emitted, so be aware of the condition of your Hazmat Suit.

Low Enriched Uranium
Highly Enriched Uranium
Plutonium Rod

Plutonium is ideal for powering Fission Reactor, as it lasts the longest. Be careful with the temperature produced by the reactor; if it goes above 1400F, your reactor will literally explode and turn all the dirt around into radioactive dirt. The reactor will become a melted reactor and will start turning local stone blocks into lava