What is nuclear fission?

Nuclear fission: A heavy atomic nucleus divides into smaller nuclei when undergoing nuclear fission, releasing a lot of energy and neutrons in the process. The nucleus usually divides into smaller parts or splits when it is hit by a neutron, causing instability. For instance, in a nuclear power plant, uranium-235 can undergo nuclear fission and split into smaller parts, such as barium and krypton, while releasing neutrons and energy, which can be used to generate electricity.