Nuclear Fusion and Nuclear Fission are the terms commonly used in the physics (or) Nuclear physics. Nuclear Fusion and Nuclear Fission may sound the same but have a lot of difference. Before knowing the difference lets find the meaning of each distinctively.
The process by which a substance is changed from solid state into Liquid state is called fusion. Fusion takes place at a fixed temperature called melting point(MP). Freezing the process by which a substance is changed from liquid state to solid state is called freezing. Freezing takes place at a fixed temperature called freezing point(FP).
MP of a substance changes with the change in the pressure. Melting point of a substance which contracts in the process of fusion decreases with the increase in pressure. Melting point of a substance which expands in the process of a fusion increases with the increase in pressure. With the addition of impurity melting point of a substance decreases.
When two or more light nuclei combine together to form a heavier nucleus, tremendous energy is released. This phenomena is called nuclear fusion. A typical example of nuclear fusion is :
1H²+ 1H³ = 2He⁴ + 0n¹ + 17.6 Mev.
The energy released by sun and other starts is called nuclear fusion. For the nuclear fusion a temperature of the order of 10 K is required.
The nuclear reaction in which a heavy nucleus splits into two nuclei of nearly equal mass is called Nuclear Fission. The energy released in the nuclear fission is called nuclear energy. The rays emitted by Radioactive were first recognised by RutherFord. The end product of all natural radioactive element after emission of radioactive rays is lead.
Nuclear Fission was first demonstrated by Strassmann and Hahn. They found that when U²³⁵ nucleus is excited by the capture of a Neutron it splits into two nuclei Ba¹⁴² & K⁹².
Nuclear reactor is an arrangement in which controlled Nuclear Fission reaction takes place. There are several components of nuclear reactor which are as follows:
Fissionable Fuel: U²³⁵ or U²³⁹ is used.
Moderator: Moderator decreases the energy of neutrons so that they can be further used for fission reaction heavy water and graphite are used as moderator.
Control Rod: rods of cadmium or Boron are used to observe the excess neutrons produced in fission of Uranium nucleus so that the chain reaction continues to be controlled.
Difference between Nuclear Fusion and Nuclear Fission:
|Nuclear Fusion||Nuclear Fission|
|Nuclear fusion occurs naturally||Nuclear Fission doesn't occur naturally|
|Hydrogen bomb works on the principle of nuclear fusion||Atomic bomb works on the principle of nuclear fission|
|Two or more lighter nuclei collide to form nuclear fusion.||Nucleus of an atom is split into lighter nuclei to form Nuclear Fission|
|It takes more energy to collide and Infuse the lighter nuclei of an atom.||Small amount of energy is enough to split the nucleus of an atom|
Nuclear fission requires high speed of neutrons and produces a higher amount of energy. Nuclear Fusion requires high temperature and high pressure conditions. While in the Nuclear Fusion the lighter nuclei produces very high amount of energy while heavy nuclei may not produce energy.
If you want to read more about Difference between Atoms and Molecules click here.