Difference Between Nuclear Fission and Nuclear Fusion (With Table)

Nuclear reactions can be of two types. First nuclear fission and second nuclear fission. Both of these reactions are high energy-yielding reactions. They yr old energy in the form of heat but also emit radioactive waves of various wavelengths that are harmful to humans or even other animals. Nuclear energy is also a limited source of energy.

Nuclear Fission vs Nuclear Fusion

The difference between nuclear fission and nuclear fusion is that while one is destructive, the other is constructive. The terms destructive and constructive are only used in terms of breaking or formation of an atom and not in any other sense. Fission includes breaking, while fusion includes formation.

Nuclear fission is a type of nuclear reaction in which a heavy atom that is usually unstable in energy breaks into two or smaller atoms with comparatively stable energy due to either internal factors or external factors like bombarding with high energy beams or any such measures.

Nuclear fusion is a type of nuclear reaction in which two or more light atoms are usually unstable combines with one another to form a larger atom with comparatively stable energy. This can occur in natural or temporary conditions of high temperature and pressures, which forces the atoms to combine.

Comparison Table Between Nuclear Fission and Nuclear Fusion

Parameters of ComparisonNuclear FissionNuclear Fusion
MeaningWhen two unstable atoms are bombarded with high-speed particles, they split into two, causing nuclear fission.When two atoms combine under suitable conditions, it causes a nuclear fusion.
ReactantOne heavy mass radioactive isotope is the sole reactant of fusion.Two low mass isotopes are the starting reactant of nuclear fusion.
ProductTwo smaller isotopes are created as a result of the division of the nucleus.One large isotope is created as a result of combining the nucleus.
Energy ReleaseLess energy is released compared to nuclear fusion.More energy is released compared to nuclear fission.
HarnessingFission is a controlled phenomenon, and hence the energy can be harnessed.Nuclear fusion energy cannot be harnessed.

What is Nuclear Fission?

Nuclear fission, coined and discovered by Neither Hann and Fritz, is a reaction in which a large atom is energetically unstable, which means it has a large of protons in comparison to neutrons, and this atom is also an isotope meaning it has other atoms with the same number of protons, but a different number of neutrons splits into two smaller atoms due to the division of the nucleus.

The resultant atoms are more energetically balanced and also have a lower mass in comparison to the starting atom, which is a heavy isotope. Usually, initial energy is provided to kick start the reaction by bombarding the nucleus with high-speed particles, after which the reaction continues unhindered by itself until the atoms cannot split into further smaller atoms.

A large amount of energy is released during nuclear fission, which can be harnessed to be utilized to produce power in homes and electricity. Nuclear fission luckily is a more controlled form of nuclear reaction as it halts after a certain time, and this energy released is successfully harnessed in nuclear reactors.

However, radioactive waste is produced in large amounts, and the process also eliminates harmful radioactive rays unsuitable for animal or plant contact, and this must be done under very regulated conditions.

What is Nuclear Fusion?

Nuclear fusion is a type of chemical reaction studied by various scientists like Rutherford, Edington, Einstein and so on. It is a reaction in which two smaller energetically unbalanced atoms or isotopes combines to form one large atom or isotope of an atom.

The resultant atom is not only larger but also in mass from the low mass isotopes that began the reaction. The process occurs in conditions of extreme temperatures and pressures. The surface of the Sun is the best example of an all-time occurring nuclear fusion as the temperature and pressures on the surface of the Sun is suitable for nuclear fusion to occur.

Nuclear fusion emits a large amount of energy, a by-product of the reaction; however, the energy is too large to be harnessed or controlled, and hence there are no nuclear reactors on Earth that support a nuclear fusion reaction. However, if the efforts are successful, then nuclear fusion can prove to be an unlimited source of energy.

It is also more environmentally healthy as it produces less toxic waste that need not be disposed of. The combination of Deuterium and Tritium to form Helium is a good example of nuclear fusion.

Main Differences Between Nuclear Fission and Nuclear Fusion

  1. Nuclear fission was discovered in 1938, whereas the concept of fusion is said to be around since as early as the 1920s.
  2. Nuclear fission results in the formation of two products, whereas nuclear fusion results in the formation of one large product.
  3. Nuclear fission generates more radioactive waste in comparison to nuclear fusion, which may continue limitlessly this consume all the raw products.
  4. Nuclear fission takes place on large-sized heavy atoms, whereas nuclear fusion combines two small-sized light atoms to make a heavy one.
  5. Nuclear fission can be controlled, whereas nuclear fusion cannot be controlled, and hence there are no nuclear reactors for nuclear fusion in the world.


Since the Manhattan Project, which brought into existence the possibility of harnessing nuclear power as a resource of power for man, numerous scientists, projects and reactors have been set up to control and conduct experiments on nuclear reactions like fission and fusion.

Nuclear energy can be one of the main sources of energy shortly in the case of natural resource depletion; however, effective methods to dispose of nuclear wastes, as well as a safe method of controlling nuclear fission, must be implemented to make it possible. Fission and fusion, in short, are opposite to each other, but both releases energy.


  1. https://journals.aps.org/pr/abstract/10.1103/PhysRev.56.426
  2. https://www.sciencedirect.com/science/article/pii/S0920379610005119
2D vs 3D