Nuclear energy is a form of non-fossil energy, where energy is created through the fission of the nucleus of an atom (nuclear fission) or by a fusion of two atom nuclei (nuclear fusion).
All matter consists of millions of small particles called atoms. An atom has a nucleus of protons and neutrons (small red and blue balls). These particles are linked by the force of nuclear cohesion. It takes a lot of energy to separate them. Other smaller particles revolve around the nucleus, called electrons.
All atoms of a chemical element (for example iron, oxygen, uranium, plutonium) have the same chemical properties. Atoms can nevertheless have a different mass. Atoms from the same element but with a different mass are called isotopes.
These isotopes have different physical properties. This is how the uranium isotope with mass 235 can be fissioned by a slow neutron, whereas the isotope with mass 238 cannot be fissioned in this way.
In a nuclear fission, the uranium atom breaks apart after absorbing a neutron. During this fission, a large amount of heat (energy) is released. This is because the nuclear particles (protons and neutrons) are more bonded in the newly-formed lighter atoms than in the uranium atoms. The largest amount of bonding energy is released as heat and radiation. This is what we call nuclear energy.
The decomposition of the nucleus causes the formation of two new nuclei and the release of two or three neutrons. These neutrons fly in all directions and can themselves cause the fission of uranium atoms. This is what’s called a chain reaction.
Applications of nuclear fission
The best-known application of nuclear fission is the capture of heat generated by nuclear fission. Nuclear fission occurs in a nuclear reactor.
The heat produced in nuclear reactors from the nuclear fission can be used for:
- Electricity generation;
- Desalination of seawater;
- Nuclear submarine propulsion;
- Icebreaker propulsion;
- Spaceship propulsion;
- Urban heating
Besides heat, the products of the fission, the matter created by the nuclear fission can be used in various applications. In some nuclear research reactors equipped for this purpose, the products of the fission are created by nuclear fission and subsequently industrialised as medical or industrial radioisotopes in a laboratory. Medical radioisotopes are injected into the patient’s body for diagnosis or treatment. They can also be used in industry and agriculture. For example, for detecting leaks, sterilising tools or agricultural products.
Radioisotopes were previously used in fire detectors, lightning rods and luminescent watches.
Nuclear fusion is the recombination of two atoms into a new one. This is not simple, because both nuclei have the same charge. This is why they repel each other, which prevents fusion.
This fusion is, however, possible from the moment enough energy is provided in the nuclei to overcome the repulsion. If the energy released by the fusion is greater than that provided to obtain it, the fusion is productive.
Nuclear fusion is a phenomenon that occurs in the sun. We cannot, however, mimic the solar energy production system on earth due to pressure and extremely high temperatures (around 15 million degrees).
One of the raw materials for fusion is deuterium (an isotope of hydrogen). It can be extracted from seawater.