There are two types of nuclear reactions
1. NUCLEAR FUSION
In nuclear physics,nuclear fusion is a nuclearreaction in which two or more atomic nuclei come very close and then collide at a very high speed and join to form a new type of atomic nucleus. During this process, matter is not conserved because some of the matter of the fusing nuclei is converted to photons (energy).
2. NUCLEAR FISSION
Nuclear fission isnuclear reaction process in which nucleus, when bombarded with a neutron, splits into smaller parts, often producing free neutrons, and releasing a very large amount of energy.