What is Nuclear Fusion?
Nuclear fusion is a reaction through which two or more light nuclei collide into each other to form a heavier nucleus. This reaction takes place with elements that have a low atomic number, such as hydrogen. It is the opposite of nuclear fission reaction in which heavy elements diffuse and form lighter elements. Both nuclear fusion and fission produce a massive amount of energy.
Nuclear Fusion in the Universe
Every star in the universe, including the sun, is alive due to nuclear fusion. It is through this process that they produce such a mind-boggling amount of heat and energy. The pressure at the core of any star is tremendously high and that is where the nuclear fusion reaction takes place.

Example of Nuclear Fusion
For example, the temperature at the core of the sun is around 15 million degrees Celsius. At this temperature. Coupled with very high pressure, two isotopes of Hydrogen, Deuterium, and Tritium, fuse to form Helium and releases the massive amount of energy in the form of heat. Around 600 million tons of hydrogen are converted into Helium every second in the sun.
Difference Between Nuclear Fission and Nuclear Fusion
These two are the major nuclear reactions that take place. The basic differences between Nuclear Fission and Nuclear Fusion are:
Nuclear Fission | Nuclear Fusion |
Breaks heavy atom into two or smaller ones. | Brings two or more small atoms together to form one large atom. |
Does not happen naturally. | The universe is full of instances of nuclear fusion reactions. Every star uses it to produce energy. |
Produces a great deal more energy than chemical reactions but still not as much as fusion. | Produces abundant energy than fission reaction. |
Does not require a lot of energy to split an atom into two. | Requires a lot of heat and pressure for the process to happen. |
Applications of Nuclear Fusion
We are still at an experimental stage as far as nuclear fusion reactions are concerned.
- Clean: No combustion occurs in nuclear power (fission or fusion), so there is no air pollution.
- Less nuclear waste:Â The fusion reactors will not produce high-level nuclear wastes like their fission counterparts, so disposal will be less of a problem. In addition, the wastes will not be of weapons-grade nuclear materials as is the case in fission reactors.
If utilised properly, nuclear fusion is the answer to the world’s power crisis problem. It is clean and produces a minimal amount of nuclear waste as compared to fission reactions. The fuel for fusion, Deuterium, and Tritium, are also readily available in nature. Scientists are hopeful that in the coming centuries, fusion will be a viable alternative power source.
Nuclear Fusion Example
Q1. Calculate the total energy released when tritium and deuterium fuse to give Helium 4.
Ans:Â The balanced nuclear reaction is given as:
\(H_{1}^{2}+H_{1}^{3}\rightarrow He_{2}^{4}+n_{0}^{1}\)ΔE = -17.6 Me.V.atom-1
ΔE = -1.697 × 109 kJ.mol-1.
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