Nuclear Chain Reactions: How Reactors Work

Nuclear reactors generate electricity by splitting heavy atomic nuclei like uranium-235.
The heat from fission boils water, producing steam to drive turbines.
Moderators such as water or graphite slow neutrons to sustain the reaction.
Control rods absorb excess neutrons, keeping the chain reaction stable.
Reactors operate at “criticality,” where fission reactions are self-sustaining but controlled.
Pressurized water reactors and boiling water reactors are the most common designs.
Some reactors can breed new fuel, like plutonium, from uranium.
Nuclear power provides about 10% of the world’s electricity.
Safety systems and containment structures protect against radiation leaks.
Advances in reactor design aim for cleaner, safer, and more efficient energy.