Atomic Energy

Atomic Energy

Atomic energy is the energy that holds the subparticles of an atom together. An atom is made up of three subparticles: neutrons, protons and electrons. Neutrons and protons form the nucleus and are held together by very strong energy bonds.

The union or destruction of these links generates an enormous amount of energy that can be used in various ways: electricity, nuclear weapons, vehicle propulsion...

Often, when we refer to atomic or nuclear energy we are referring to the energy obtained from this source.

The name nuclear energy is used because most of the energy of an atom resides in its nucleus.

There are two types of nuclear reactions that release energy:

  • In fission reactions, a very large atom (with many protons and neutrons) breaks apart. Uranium atoms are ideal because they are very large and unstable.

  • In fusion reactions the objective is to join two very small atoms (for example, hydrogen). These reactions also release a large amount of energy. They are more difficult to obtain but offer many advantages.

Operation of a nuclear power plant

Atomic power plants (or nuclear power plants) are responsible for obtaining atomic energy from the nuclei of atoms to generate electricity.

All atomic power plants have a nuclear reactor. The nuclear reactor is responsible for generating the fission reactions of atoms.

What are fission reactions? They are reactions that split the nucleus of an atom.

These atomic reactions generate a large amount of thermal energy. Thanks to this large amount of energy, it is used to generate steam - or increase the pressure of water, depending on the type of reactor - to drive a turbine.

The turbine is connected to an alternator which is responsible for generating electricity.

During the process the energy undergoes the following transformations:

  1. We start from an atom with a large amount of nuclear energy contained in it.

  2. Obtaining heat energy (through nuclear fission).

  3. Obtaining kinetic energy (by driving the turbines).

  4. Obtaining electrical energy (through the alternator).

There are many types of nuclear power plants for the use of atomic energy but conceptually they all work through a similar process: nuclear reaction to obtain heat, drive a turbine and transform mechanical energy into electricity.

The most common nuclear reactors are:

  • Pressurized water reactors (PWR)

  • Boiling water reactors (BWR).

To date, all nuclear power plants in the world are fission-based.

Atomic research reactors

A research reactor is a nuclear reactor used for scientific purposes. These reactors are the key to the development and evolution of nuclear technology.

Research reactors have less power than nuclear reactors used for other purposes. A typical nuclear plant reactor has a thermal capacity of 3,000 MW (megawatts), while research reactors have a capacity between 10 kilowatts and 10 megawatts.

Compared to conventional reactors, research reactors are:

  • Simpler.

  • They operate at lower temperatures.

  • They require less fuel and therefore generate less spent fuel.

The fuel used in this type of reactor is usually more enriched uranium, usually up to 20% uranium-235. Some reactors use 93% uranium-235.

The large ratio of volume and power in the core requires special techniques in its design. As with other reactors, the core needs cooling. They are generally cooled by natural or forced convection with water.

A neutron moderator is also used to slow down the neutrons and control the atomic chain reactions that occur.

Nuclear fuel

To trigger atomic reactions, not all atoms are technically suitable.

Fuel for fission reactors: uranium and plutonium

In the case of nuclear fission reactions, very large atoms (with many protons and neutrons) are needed because they are very unstable. Uranium and plutonium atoms meet these conditions.

Uranium and plutonium atoms can have different configurations. These configurations depend on the number of neutrons they have in the nucleus. Each of these configurations is a different isotope of the same atom.

Uranium can be obtained naturally. Natural uranium is found with a composition of uranium isotopes, some of which (a few) are very unstable. To improve performance, natural uranium is subjected to an enrichment process to obtain a higher proportion of neutrons, making it less stable.

Fuel for fusion reactors: deuterium and tritium.

On the other hand, in nuclear fusion very small atoms are needed so that it is easier to form the force bonds that will join them.

The ideal atom is the smallest of all: hydrogen, which only has one proton.

Like uranium, hydrogen has several isotopes. Those that are most suitable for atomic fusion reactions are deuterium and tritium.

Currently, there are no nuclear power plants that use nuclear fusion for technical reasons. However, in France a nuclear research reactor is being built to achieve this: it is the ITER project.

Advantages and disadvantages of atomic energy

The use of atomic energy implies advantages and disadvantages.


  • Atomic energy makes it possible to obtain a large amount of energy with little fuel.

  • It does not depend on fossil fuels. This means that it does not emit greenhouse gases and does not contribute to global warming. Therefore, it does not negatively affect climate change.


  • Spent fuel remains radioactive and is very difficult to manage.

  • The radioactivity of nuclear waste lasts for dozens of years.

  • There is a possibility of nuclear accidents. Although the safety systems of atomic power plants are very advanced, there is always the possibility of suffering a nuclear accident. Nuclear disasters are rare but very damaging as were the Chernobyl and Fukushima nuclear accidents.

Publication Date: August 22, 2018
Last Revision: October 16, 2020