Answer: Nuclear Fission
Explanation:
Nuclear fission reactions are one of the nuclear reactions in which heavier nuclei splits into two or more lighter nuclei. In these reactions, neutrons are released with a large amount of energy.
General equation for nuclear fission reactions is given by:

Nuclear fusion reactions are one of the nuclear reactions in which two or more lighter nuclei combines to form heavier nuclei. In these reactions, large amount of energy is released.