Video narration
Inside a household kettle, heat turns water into steam; in a nuclear plant, the same handoff begins somewhere far smaller. Start with a tiny uranium fuel pellet. Its atoms hold energy in their nuclei. Zoom out: the pellet sits inside a long fuel rod; many rods form a fuel assembly, and that assembly sits inside the reactor vessel. Now look inside. One neutron strikes a uranium atom. The nucleus splits—a process called fission—releasing heat and extra neutrons. Those neutrons strike nearby atoms, and the chain reaction spreads through the same assembly. Control rods slide down between the fuel rods, absorbing some neutrons. The reaction continues, but at a controlled rate. Here is the key: the reactor does not make electricity directly. It makes heat. Water surrounding the rods takes that heat, then a connected pipe carries the hot water to a steam generator. There, a separate water loop receives the heat and becomes steam, while the reactor water stays in its own loop. That steam rushes through a second connected pipe and strikes turbine blades, spinning the turbine. The turbine shaft turns magnets inside a generator, past stationary copper coils. Changing magnetic fields induce electricity in those coils. Electric wires carry it to a transformer, which changes its voltage for efficient transmission, then onward through the transmission tower and city grid to a house, where a bulb glows. Meanwhile, the steam cools in a condenser and returns as water through a pump to the steam generator. Separate cooling water removes heat from the condenser; it is not the reactor loop. Follow the whole machine now: uranium fission becomes heat, heat becomes steam, steam becomes motion, motion becomes electricity, and electricity becomes light. A pellet starts it; the plant transforms it.