Nuclear Energy: How It Works
Nuclear power is essentially a very complicated way to boil water.
Nuclear fuel consists of an element – generally uranium – in which an atom has an unusually large nucleus. The nucleus is made up of particles called protons and neutrons. The power produced by a nuclear plant is unleashed when the nucleus of one of these atoms is hit by a neutron traveling at the right speed.
The most common reaction is that the nucleus splits — an event known as nuclear fission — and sets loose more neutrons. Those neutrons hit other nuclei and split them, too. At equilibrium — each nuclear fission producing one additional nuclear fission — the reactor undergoes a chain reaction that can last for months or even years.
When the split atom flings off neutrons, it also sends out fragments. Their energy is transferred to water that surrounds the nuclear core as heat. The fragments also give off sub-atomic particles or gamma rays that generate heat.
Depending on the plant’s design, the water is either boiled in the reactor vessel, or transfers its heat to a separate circuit of water that boils. The steam spins a turbine that turns a generator and makes electricity.
Sometimes instead of splitting, the nucleus absorbs the neutron fired at it, a reaction that turns the uranium into a different element, plutonium 239 (Pu-239). This reaction happens some of the time in all reactors. But in what are known as breeder reactors, neutrons fired at a higher force are absorbed far more often. In this process, spent uranium fuel can be recycled into Pu-239, which can be used as new fuel. But problems with safety and waste disposal have limited their use – a fuel recycling plant that operated near Buffalo for six years created waste that cost taxpayers $1 billion to clean up.