Nuclear energy is the energy released from the nucleus (core) of atoms, which consist of protons and neutrons. This energy can be produced mainly through two processes: nuclear fission, where atomic nuclei split into smaller parts, and nuclear fusion, where nuclei combine together. Currently, most nuclear power plants use fission, particularly of uranium-235 or plutonium atoms, to generate heat and electricity

. In a nuclear reactor, the fission process generates heat by splitting uranium atoms, releasing energy and neutrons that sustain a chain reaction. This heat is used to boil water, creating steam that drives turbines connected to electric generators, producing electricity

. Nuclear power plants provide a reliable and consistent source of electricity, often referred to as baseload power, capable of running continuously without interruption

. Globally, nuclear energy supplies about 9% of the world's electricity and is the second largest source of low-carbon power after hydroelectricity. In the United States, nuclear power accounts for about 20% of electricity generation and is the largest producer of nuclear energy worldwide

. Nuclear power plants do not emit greenhouse gases during operation, making nuclear energy a clean energy source that helps reduce carbon dioxide and other harmful air pollutants, contributing positively to air quality

. Nuclear fuel primarily comes from uranium, a naturally occurring element mined and processed for use in reactors. Uranium-235 is favored because its atoms split easily to sustain fission reactions. Although uranium is abundant in the Earth's crust, the specific isotope used in reactors is relatively rare

. While nuclear fusion-the process powering the sun-holds promise for future energy generation, it is not yet commercially viable due to technical challenges in controlling the reaction

. In summary, nuclear energy is a powerful, reliable, and low-carbon energy source generated mainly through nuclear fission in reactors, playing a significant role in global electricity production and efforts to combat climate change