How Fusion Reactors Work ? 5 Facts You Should Know!

The main purpose of nuclear fusion reactors is to produce electricity by the heat energy released during the merging two light nuclei. Let us study the working of fusion reactors.

  • Nuclear fusion reactor generally uses the isotope of hydrogen-like deuterium or tritium as a fuel.
  • Initially, the fusion fuel is heated up to 100 million degree Celsius in a high vacuum chamber, which is turned into plasma.
  • The fusion reaction requires high temperature and pressure, provided by a very strong magnetic field or high vacuum pump.
  • Under the influence of such pressure and temperature, plasma is confined within the chamber and fused with the target proton to form a heavier nucleus.
  • The energy is released during the fusion process, then collected and converted into another useful form of energy.

Deuterium is present in water, so they are widely used as a fusion fuel. Tritium does not occur naturally; thus, lithium is used along with deuterium as fuel for nuclear fusion. In this post, let us discuss interesting facts regarding the working and generation of energy from nuclear fusion reactors.

How do fusion reactors generate electricity?

The generation of electricity from nuclear fusion reactor follows the energy conservation principle. Let us focus on the process of electricity generation by fusion reactors.

Fusion reactors generate electricity in two ways:

  • Through steam turbines –in this method, the heat released during the fusion is collected and converted into steam by using the water as a coolant. It is passed through a large turbine and makes them rotate, which drives electricity generation.
  • Direct conversion –the fast-moving nuclei of the fusion carry electrical charges. These charges can be converted into electricity using the heat engine.

The efficiency of fusion reactor

The efficiency accounts for the ratio of input to output energy that is converted into useful work. Let us check the efficiency of a nuclear fusion reactor.

The fusion reactor produces an enormous amount of heat; thus, its heat efficiency is 70% and the efficiency of a nuclear fusion reactor to generate electricity is 40%. A gram of fusion fuel can produce energy the same as 10kg of fossil fuel can produce, so it is more efficient in terms of energy generation.

Are nuclear fusion reactors safe?

Nuclear fusion involves an element whose atomic number is less than 56. Now, we shall look into whether a fusion reactor is safe.

The nuclear fusion reactor is safe to harness energy because it is a self-limiting process, i.e., if you cannot control reaction, the reactor turns off itself. The explosion of fusion reactor is very rare as it does not undergo chain reaction, The radioactive waste is minimal in a fusion reactor, so it is safe to use.

Nuclear fusion neither releases any heavy radioactive element nor toxic gases such as carbon dioxide, or any greenhouse gas, so it is safe for environment. Nuclear fusion reactors are not always safe because sometimes they undergo neutron induced radioactivity, generating high-energy neutrons that are not so safe.

Image: Schematic diagram of nuclear fusion reactor by Evan Mason, (CC BY-SA 3.0)

How many fusion reactors are there?

Building a fusion power plant is difficult because achieving the necessary conditions, such as high temperature and pressure, is hard. Let us know the number of fusion reactor that exists.

Only two nuclear fusion reactors can be used to generate energy. They are

  • Magnetic confinement reactors
  • Inertial confinement reactors

Magnetic confinement reactors

Magnetic confinement reactors use the magnetic field to confine the deuterium or tritium plasma. They utilize the electrical conductivity of plasma to interact with the magnetic field to offset high plasma pressure; thus, hot plasma keeps touching the walls of the confining chamber by means of the magnetic field.

Inertial confinement reactors

The inertial confinement reactors use the fusion fuel in the form of small pellets, which is compressed to extremely high energy density and heated at high temperature. The inertial confinement takes a very short span of time, and the high energy beam of proton, electrons or ions does compression.

How do fusion reactors not melt?

The advantage of a nuclear reactor is that even at extremely high temperatures, there is no risk of melting. Let us find the reason behind the no melting of a nuclear fusion reactor.

The nuclear fusion reactor does not melt even at million degrees of temperature because of the magnetic field applied to confine the plasma. The magnetic field encloses the plasma as a shield, thus providing perfect heat insulation to withstand extreme temperatures. Thus the outer core of the reactor does not melt.

In a nuclear fusion reactor, if anything goes wrong, like the magnetic field breakdown, the plasma cools down within a second so that it does not have the risk of melting. It is one of the great advantages of nuclear fusion reactors.

How are fusion reactors heated?

In order to achieve nuclear fusion, high temperature is an essential criterion. Let us know how the fusion reactor is heated to achieve the required temperature.

The nuclear reactor is initially heated through an external electric current that is passed to the fuel nucleus to accelerate them. As they begin to accelerate, the nuclei acquire kinetic energy and undergo collision with themselves. The collision between these nuclei causes the heating up of nuclear fusion reactor.

The heat generated due to each collision increases up to the required temperature, causing the removal of an electron from neutral hydrogen and then the target nucleus injected into the plasma fuel. This results in the merging two lighter nuclei to form a single heavy nucleus.


Let us end this post by stating that a nuclear fusion reactor is the safest energy generator yet hard to build. The production of energy from the fusion reactor follows Einstein’s mass-energy conversion E=mc2. There are only 20 nuclear fusion reactors built across the world.

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