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Nuclear Fission

Nuclear fission is the process of splitting an atom's nucleus into multiple smaller nuclei. This article includes the study material notes on nuclear fission.

Atoms are split apart in nuclear fission, releasing energy. Nuclear fission is used in all nuclear power reactors, where uranium atoms are used. A neutron collides with a uranium atom and divides it during nuclear fission, releasing a tremendous quantity of energy in the form of heat and radiation. There are two types of fission reactions: spontaneous and induced fission. When a fissionable nucleus, like uranium, captures a neutron, it enters an unstable system and finally breaks into two heavy components, known as induced fission. It also emits neutrons during this process. 

History

Physicists Lise Meitner and Otto Frisch used the term fission in 1939 to describe the breakup of a heavy nucleus into two lighter nuclei of roughly equal size. The origin of nuclear fission started with James Chadwick’s discovery of the neutron in England in 1932. Then, Enrico Fermi and his team in Italy began a comprehensive study of the nuclear reactions caused by bombarding various materials with an uncharged particle.

Nuclear Fission: Process

Nuclear fission is a reaction in which a heavy nucleus is attacked by neutrons and becomes unstable, causing it to decompose into two nuclei of equal size and magnitude, releasing a large amount of energy and two or three neutrons.

These neutrons can trigger other fissions by interacting with new nuclear fission nuclei, emitting more neutrons. Chain reaction is the term for this multiplying phenomenon. The amount of fissioned nuclei releases a million times more energy in a fraction of a second than burning a block of carbon or bursting a block of dynamite of the same mass. Energy is released significantly faster in a nuclear reaction than in a chemical reaction due to the speed of the reaction process.

The number of fissions every second will be limited if just one of the released neutrons may be used to cause subsequent fission. Nuclear reactors, which are regulated sources of nuclear fission energy, work on this concept.

Nuclear Fission Reactors

Nuclear fission is a powerful source of energy. A chain reaction is required to produce output energy or power flow. In a fission reactor, a nuclear chain reaction takes the following form: n + X —> Y + Z + fast neutrons.

A fissionable nucleus indicated by X captures a slow neutron (n). Fast neutrons are emitted when X fissions into two lighter but more firmly linked nuclei, Y and Z. For chain reactions to proceed, a reactor must have plenty of supply of fissionable material. Subcritical material is defined as having insufficient fissionable material to maintain a chain reaction.

A moderator, usually water, is utilised in the reactor to slow down the rapid neutrons and make them easier to absorb so that the chain reaction can be controlled. 

The kinetic energy of the neutrons produced by the chain reaction is used to heat water, create steam, and drive a generator that generates electricity in a standard nuclear fission reactor. 

Nuclear Fission: Harmful Effects

There are a few cons to nuclear fission, they are:

  • Fission generates hazardous waste that must be stored.
  • Fissionable material is in short supply, but breeder reactors that produce fissionable material may be a viable alternative.
  • The spread of fissionable material raises the risk of nuclear weapons being out of control.

Nuclear Fission: Useful Effects

  • Nuclear fission helps in generating electricity. Electricity holds much importance in our daily lives. Almost everything we use requires electricity. 
  • Electricity generation results in emission that is harmful to the environment; however, with the help of nuclear fission, it is possible to create electricity without affecting the environment by using the steam produced during nuclear fission to rotate the turbine for generating electricity.

This means it is sustainable and better for the environment.

Conclusion

To conclude what we have learned till now, we know that nuclear fission is the splitting of an atom’s nucleus into multiple smaller nuclei referred to as fission products. When the heavy atoms go through nuclear fission, this is known as an exothermic reaction that releases enormous amounts of energy. Nuclear fission occurs when the electromagnetic force pushing the nucleus apart overcomes the strong nuclear force holding it together with heavier atoms. As a result, nuclear power helps protect the environment by generating large amounts of carbon-free electricity.