Fission vs. Fusion – What’s the Difference?

Difference between fission and fusion

Nuclear Fission vs. Nuclear Fusion


  • The first Nuclear reactor, the Chicago Pile-1, was built by Enrico Fermi, in the year 1940.
  • About 10% of electricity around the world is produced from 440 power reactors.
  • As of 2018, Nuclear power is the second-largest source of low-carbon power, with 29% in total.
  • From 2018 to 2019, produced electricity went up from 2563TWh to 2657 TWh.

What is Nuclear energy?

The energy in the nuclear or at the core of an atom is known as Nuclear energy. The energy released from the atom is used to generate electricity. This is Nuclear Fission.

The reaction on the Sun, on the other hand, is called Nuclear Fusion.

What is nuclear fission?

Nuclear Fission in a simple sense is the splitting of a large atom into two or smaller atoms.

Fission is a process when a neutron slams into a larger atom, and as a result, the large atom splits into smaller atoms. These smaller atoms are called fission products.

When the smaller atoms are created, it releases immense energy.

What is nuclear fusion?

Nuclear fusion in simple words is two lighter atoms joining together, and forming a large atom.

Similar to nuclear fission, fusion also produces a tremendous amount of energy. However, this energy is far greater than fission.

fission vs fusion

The difference between Nuclear Fission and Nuclear Fusion


The difference between the two nuclear reactions is in the process of the reaction.

In Nuclear Fission, high-speed particles, neutrons, are bombarded into a somewhat unstable isotope. As a result, the isotope breaks down into smaller isotopes, three high-speed neutrons, and enormous energy.

  • The majority of Nuclear power plant nowadays uses Uranium-235.

The high-speed neutrons which are produced as the fission product, initiate other fission reactions. This results in a chain reaction.

Nuclear fusion is best describes as what occurs in a Sun.

In a Fusion, isotopes of hydrogen, hydrogen-3, and hydrogen-2, respectively, merge under pressure and temperature. As a result, it produces a neutron and a helium isotope, along with tremendous energy, several times greater than fission.


  • Fission can be controlled. It is used by the nuclear power plant to produce electricity.
  • Fusion cannot be easily controlled. Moreover, it is expensive and requires specific conditions.


  • Nuclear fusion produces more energy than nuclear fission, but requires more initial energy.

Scientists are still studying Fusion Nuclear Reaction. However, it is difficult, for the fact that it cannot be sustained for a longer time period due to the gigantic energy it produces under extreme pressure and temperature.

Advantages of Nuclear Fission

  • One of the most cost-effective forms of energy source. More than 30 countries use nuclear power to generate electricity in order to meet the increasing demand.
  • Nuclear fission has a low-carbon emission rate. This does not produce any harmful gasses, thus does not contribute to air pollution.
  • Nuclear power plants are created with the use of extensive concrete and metals. Hence, it keeps people safe.
  • Nuclear fission can be sustained for a longer time period. In a well-controlled environment, it can produce energy for up to 36 months. It is 8,000 times more effective.

Disadvantage of Nuclear Fission

  • An uncontrolled reaction in a nuclear reactor could result in contamination of air and water.
  • A nuclear fission produces radioactive waste. Some of these wastes can stay radioactive for almost 10,000 years. Proper disposal and storage is required when it comes to nuclear fission.
  • Nuclear fission reactors involve the risk of radiation as seen in the result of the attack in Fukushima and Chernobyl. The radiation can have negative impact on air and water for a long time, harming the life around it.

Advantages of Nuclear Fusion

  • Nuclear Fusion, under a controlled environment, produces around 4 million times more energy than any other reaction.
  • Fusion as well does not emit any harmful gasses. The helium it generates is a non-toxic gas.
  • Fusion fuels are inexhaustible and largely available. Deuterium can be found in any form of water.
  • Nuclear fusion cannot be exploited to create any form of a nuclear weapon. It does not employ any fissionable material.

Disadvantage of Nuclear Fusion

  • A nuclear fusion is highly uncontrollable. It can cause hazard beyond repair.
  • A nuclear fusion is only possible at the temperature of 10 to 15 million Kelvin. It would be very expensive to prepare for such conditions.
  • Additionally, there are no materials that can withstand such enormous amount of energy.

Data about Nuclear plant in the USA

  • The USA generated 20% electricity for its country with the help of nuclear power in the year 2019.
  • As of 2020, in the USA there are 56 operating nuclear plants with 94 operable nuclear reactors.
  • Out of all, 32 nuclear plants have two nuclear reactors and 3 plants have three nuclear reactors.
  • In Arizona, the Palo Verde nuclear plant is the largest with three nuclear reactors. It produces net summer electricity of 3,937 MW.
  • In New York, the Ginna Nuclear Power Plant is the smallest with one reactor and a net capacity of 581 MW.