Chemistry - Nuclear Energy


  • Nuclear reactions release tremendous amount of energy (known as nuclear energy), which are being used to produce electricity in a nuclear power plant.

Nuclear Reaction
  • The nuclear energy normally produced by nuclear fission, nuclear fusion, and nuclear decay.

  • In 1938, German chemists Otto Hahn, Fritz Strassmann, and the Austrian physicist Lise Meitner conducted the experiments in which the products of neutron-bombarded uranium. As result of this experiment, the relatively tiny neutron split the nucleus of the massive uranium atoms into two roughly equal pieces and released massive energy.

  • The nuclear experiments of Otto Hahn and his colleagues are popular as nuclear fission.

Nuclear Fission

  • The process of nuclear fission produces free neutrons and gamma photons, while doing this also releases a very large amount of energy.

  • Nuclear fission is an exothermic reaction, which can release large amounts of energy in the forms of electromagnetic radiation as well as kinetic energy.

  • Nuclear fission, sometimes, can occur naturally (i.e. without neutron bombardment) as a type of radioactive decay.

Types of Nuclear Fission

  • Following are the major types of Nuclear Fission −

    • Chain Reaction and

    • Fission Reaction

Let’s discuss them in brief −

Chain Reaction

  • When one single nuclear reaction causes one or more subsequent nuclear reactions, it is known as chain reaction.

  • Such chain reaction increases the possibility of a self-propagating series of nuclear reactions.

  • The nuclear chain reactions release million times more energy per reaction than any other chemical reaction; therefore, it is also known as explosive or uncontrolled chain reaction.

  • When a heavy atom experiences nuclear fission, it normally breaks into two or more fission fragments. During the process, several free neutrons, gamma rays, and neutrinos are emitted, and ultimately a large amount of energy is released.

  • Following are the two examples of chain reaction −

    • 235U + → neutron Fission fragments + 2.4 neutrons + 192.9 MeV

    • 235Pu + → neutron Fission fragments + 2.9 neutrons + 198.9 MeV

  • In atom bomb, chain reaction technology is used, as it required consistent source of energy.

Fission Reactions

  • The fission reaction in which neutrons (produced by fission of fuel atoms) are used to induce yet more fission for the release of sustainable energy, is known as fission reactions.

  • Such reactions are slow and controllable; therefore, also known as controlled chain reaction.

  • The power (electricity) producing nuclear reactor is an ideal example of controlled chain reaction.

  • Based on the properties and type of usages, fission/controlled chain reaction is classified as −

    • Power reactors

    • Research reactors

    • Breeder reactors

  • These power reactors generally convert the kinetic energy of fission products into heat; further, the heat is used to heat a working fluid that drives a heat engine, which ultimately generates mechanical or electrical power.

Basic components of Nuclear Reactor

  • Following are the essential components of a nuclear reactor −

    • Nuclear fuels − Such as Uranium (233U, 235U), thorium (Th232), plutonium (Pu239).

    • Moderators − Used to control the emitted neutrons. E.g. heavy water, beryllium, graphite, etc.

    • Coolant − It is used to cool the reactor. E.g. water, steam, helium, CO2, air, molten metals, etc.

    • Control rods − It is used to run and stop the fission reaction. E.g. cadmium or boron rods are used for such purpose.

Nuclear Fusion

  • The process by which two light nuclei are fused to form a heavy nucleus is known as nuclear fusion; during this process, a tremendous amount of energy is being released known as nuclear energy.

  • The best example of nuclear fusion is – hydrogen bomb.

  • A hydrogen bomb is about 1,000 times more powerful than an atom bomb.