Turbine
A turbine is a large multiblock that turns steam into RF. Build a shell from Turbine Casing and Turbine Glass, put rods and blades inside for the rotor, fill the top with coil blocks (metal storage blocks), add ports, and place one Turbine Controller on a side wall.
Most players pipe steam from a Colossal Reactors fission reactor into the turbine and take RF out the power ports—a strong pairing for late-game power.
New here? Read Getting started first — Complete example, then Setup 1 (standalone steam) or Setup 2 (reactor coolant chain).