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Nuclear Fission and Nuclear Reactor for JEE

Introduction to the Concept of Nuclear

Last updated date: 23rd Mar 2023
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We all heard the word Nuclear right? It means relating to the nuclei of atoms, or to the energy released when these nuclei are split or combined. But here in this article let us learn some concepts that are related to nuclear energy. They are Nuclear Fusion and Nuclear Reactor but before getting into the concept let us understand a basic concept i.e., Nuclear Reaction.  


A nuclear reaction is a reaction that involves the change in the identity or characteristics of an atomic nucleus, induced by bombarding it with an energetic particle. The bombarding particle may either be an alpha particle, a gamma-ray photon, a neutron, a proton, or a heavy-ion. Now, we have the basic concept of nuclear reaction, so let's dive into the article to know the above-mentioned concepts.


What is Nuclear Fission?

A process in which the nucleus of an atom splits into two or more smaller nuclei is known as Nuclear Fission. This process releases a large amount of energy, which can be used to generate electricity or power weapons.


Nuclear fission occurs naturally in some radioactive materials, but it can also be induced by bombarding the nucleus with high-energy particles. When induced nuclear fission occurs, it usually produces a chain reaction in which other nuclei split and release energy, leading to a massive release of energy.


The most common fuel for nuclear fission reactors is uranium-235, which can be found in nature but is also enriched for use in reactors. Other materials that can undergo nuclear fission include plutonium-239 and thorium-232.


Examples of nuclear fission

The most common examples of nuclear fission are listed below: 

  • The splitting of uranium-235 nuclei when hit by a neutron, which results in the release of energy and two or three new nuclei.

  • The splitting of plutonium-239 nuclei when hit by a neutron, which also results in the release of energy and two or three new nuclei.


Nuclear Chain Reaction

A nuclear chain reaction is a process in which the nucleus of an atom splits apart, releasing energy that can be used to generate electricity. The process of nuclear fission, which is the basis for nuclear power plants, creates heat that is used to produce steam, which in turn drives turbines that generate electricity.


Nuclear fusion, which is the basis for thermonuclear weapons, also releases energy that can be harnessed to create massive amounts of destruction. In a nuclear fusion reaction, two atoms join together to form a single larger atom. This process releases energy in the form of heat and radiation.


What is a Nuclear Reactor?

A device in which nuclear fission reactions take place, such a device is known as Nuclear Reactor. The nuclear reactors are an important part of the nuclear power plants. The nuclear reactors contain and control nuclear chain reactions that are capable of generating heat energy through a physical reaction known as fission. The heat generated further utilised to make steam that helps to spin a turbine to produce the electricity. These reactions release energy that can be used to generate electricity or power an engine. Reactors are also used for research purposes and for producing radioactive isotopes.


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Nuclear Reactor


  • Fissionable material (Fuel): This material is used in the reactor and it is called the fuel of the reactor. The most commonly used fuels in the reactor are: Uranium isotope (U235), Thorium isotope (Th232), and Plutonium isotopes (Pu239, Pu240, and Pu241).

  • Moderator: Moderator is generally used to slow down the fast moving neutrons. Graphite and heavy water (D2O) are the most commonly used moderators.

  • Control Material: This material is used to control the chain reaction and to maintain a stable rate of reaction. It controls the number of neutrons available for the fission. For instance, cadmium rods are inserted into the core of the reactor because they can absorb the neutrons. Here the neutrons that are available for fission are controlled by moving the cadmium rods in or out of the core of the reactor.

  • Coolant: Coolant is a cooling material that removes the heat generated due to fission in the reactor. Water, CO2, and Nitrogen are the most commonly used Coolants in the reactors.

  • Protective shield: This shield in the form of a concrete thick wall surrounds the core of the reactor to save the persons working around the reactor from the hazardous radiations.


In India, currently, there are 22 nuclear reactors 6780 MW in operation. The nuclear power plants have a high capacity of producing electricity. 


Uses of Reactor

  • Used in electric power generation.

  • Used to produce radioactive isotopes for their use in medical science, agriculture, and industry.

  • Used in manufacturing of Pu239 which is used in the atom bomb.

  • They are used to produce neutron beams of high intensity which are used in the treatment of cancer and nuclear research.


Types of Reactors

There are different types of reactors and a few of them are mentioned below.

  1. Power Reactors: Power reactors use nuclear fission reactions to generate electricity. These reactions release heat, which is used to produce steam. The steam turns turbines, which generate electricity. There are two types of power reactors: boiling water reactors (BWRs) and pressurised water reactors (PWRs).

In India, Tarapur Atomic Power Station (TAPS), Maharashtra, is one of the BWR and Kudankulam Nuclear Power Station (KKNPS), Tamilnadu, is a pressurised water reactor with a highest capacity of 1000MWe in 2 units.

  1. Boiling Water Reactors: In a boiling water reactor (BWR), water boils inside the reactor vessel to create steam. The steam turns the turbine generators directly without the need for a separate steam generator. BWRs make up about one-third of all commercial nuclear power plants in the United States. General Electric's Fukushima Daiichi Nuclear Power Plant in Japan was a BWR plant.

  2. Pressurised Water Reactors: In a pressurised water reactor (PWR), water is heated by nuclear fission but does not boil. The hot water is kept under pressure, so it cannot turn into steam. This pressurised hot water then flows through pipes into a separate chamber, where it heats another body of water and creates steam. The steam turns the turbine generators, producing electricity. PWRs make up about two-thirds of all commercial nuclear power plants in the United States.


In India, all the pressurised water reactors are the pressurised heavy water reactors (PHWRs). And these PHWRs are fueled by Natural Uranium. 


Summary

At last, we conclude the article with a few key points. The reaction that involves the change in the identity or characteristics of an atomic nucleus, induced by bombarding it with an energetic particle, is known as a nuclear reaction. Nuclear fission is a process in which the nucleus of an atom splits into two or more smaller nuclei. This process releases a large amount of energy, which can be used to generate electricity or power weapons. A nuclear reactor is a device in which nuclear fission reactions take place. These reactions release energy that can be used to generate electricity or power an engine. There are different types of nuclear reactors and they have different types.

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FAQs on Nuclear Fission and Nuclear Reactor for JEE

1. What impact does fusion have on the environment?

One of the most eco-friendly forms of energy is fusion. Fusion doesn't produce any CO2 or other damaging atmospheric emissions, hence it doesn't cause any greenhouse gas emissions or global warming. Lithium and hydrogen, its two fuel sources, are abundantly accessible throughout much of the planet.

2. Does nuclear fusion generate radioactive nuclear waste in a similar manner to nuclear fission?

Because unstable nuclei are produced by nuclear fission power plants, some of them can remain radioactive for millions of years. On the other hand, fusion does not produce any nuclear waste that is long-lived radioactive. Helium is a gas that is produced by a fusion reactor and is inert. Tritium is also created and used in a closed circuit within the plant.


Although tritium is a beta emitter and radioactive, its half-life is brief. Because it is only utilised in small quantities, unlike long-lived radioactive nuclei, it cannot pose a severe threat to the environment. Another concern is the activation of the reactor's structural material by strong neutron fluxes. This heavily depends on the blanket and other structure solution chosen, and its lowering represents a significant hurdle for upcoming fusion trials.