Nib asked, and Nib — askNib's tutor — drew the answer live at a whiteboard. This is the spoken transcript; enable JavaScript to watch it drawn.
how does a nuclear reactor produce electricity
Surprise: the reactor itself never makes electricity, and nothing in it explodes. Its only job is heat, so it's really a very fancy kettle.
The heat comes from splitting atoms. A neutron hits a uranium two thirty-five atom; it splits, frees two or three neutrons, and the pieces fly off as heat.
The core holds uranium pellets in long fuel rods, each pellet worth about a ton of coal. Control rods soak up neutrons to hold the chain steady.
Water in the core heats to about 325 degrees Celsius but, held at 150 times air pressure, can't boil. It carries the heat to a steam generator.
Outside those tubes, a separate loop of water boils into steam and rushes to a turbine, a wheel of blades. The two waters never mix.
The shaft spins a generator, magnets turning inside coils of wire, and that finally makes electricity. Cooled steam turns back to water and loops again.
So: split atoms, make heat, boil water, spin a turbine, turn a generator. Only roughly a third of that heat ends up as electricity.
So a nuclear reactor is a heat source: it boils water, and the steam does the rest.