Nuclear fission and nuclear fusion are two fundamental nuclear processes through which a large amount of energy can be produced by changes occurring within the nucleus of an atom. Both processes are important in the field of renewable and advanced energy systems because they release energy based on Einstein’s mass–energy relation, where a small amount of mass is converted into a large amount of energy. However, the mechanisms, conditions, fuel requirements, safety aspects, and technological development of the two processes are quite different. Nuclear fission is the process in which a heavy atomic nucleus splits into two or more smaller nuclei along with the release of a large amount of energy. This process generally occurs when the nucleus of a heavy element such as uranium-235 or plutonium-239 absorbs a neutron. After absorbing the neutron, the nucleus becomes unstable and breaks into smaller fragments called fission products. During this splitting process, additional neutrons and a large amount of heat energy are released. These emitted neutrons can further strike other nuclei and continue the reaction, leading to a chain reaction. In nuclear power plants, this chain reaction is carefully controlled using control rods and moderators to ensure a steady release of energy. The energy released in nuclear fission is mainly in the form of heat. In a nuclear power plant, this heat is used to convert water