Question

Which is the process used to harness nuclear energy these days? Explain it briefly.

Answer 1

Nuclear fission:

1. When heavy nuclei of elements get destabilized when they absorb a neutron. The destabilized nuclei split into two fragments. This process is known as nuclear fission.
2. For example, when an atom of uranium-235 is hit by a neutron, the nucleus of an element splits into two smaller nuclei. These extra neutrons will hit other surrounding uranium-235 atoms, and start a chain reaction hence generating additional neutrons. This is a multiplying effect, thus generating a chain reaction in a fraction of a second.
3. Every reaction release energy in the form of heat and radiation. This heat generated is converted into electricity in a nuclear power plant.
4. At present, the nuclear fission process is used to harness nuclear energy these days. Electricity is produced by the fission of uranium nuclei which are further converted to heat in a nuclear reactor. Heavy nuclei of uranium absorb a neutron, get destabilized, and split into two fragments. This is known as nuclear fission. A huge amount of energy produced during nuclear fission reaction is utilized to produce steam and therefore, helps in generating electricity.

An illustrative diagram of a nuclear reactor is shown below.

1. A nuclear reactor consists of a series of machines to control nuclear fission. The containment structure consists of the reactor and a steam generator. The coolant absorbs heat from the reaction and flows to the steam generator.
2. Steam generated is directed to run a turbine to generate electricity.
3. Pellets of uranium are used as a source of fuel for nuclear reactors.
4. In the reactor, atoms of elements are forced to break apart into tiny particles called fission products. Fission products start a chain reaction by causing the splitting of uranium atoms. The energy released from this chain reaction creates heat.
5. A cooling agent, that may be water or molten salt or molten metal, warms by the heat generated by the chain reactions.
6. The cooling agent, heated by nuclear fission, produces steam that rotates the turbines. The turbines drive engines to generate electricity.
7. The electricity production can be controlled on demand by adjusting the rods. Rods are also known as nuclear poisons usually made up of elements like xenon that absorb some of the fission products created by nuclear fission.
8. The increase in the number of rods during the chain reaction decreases the rate of reaction. More electricity can be generated by removing the rods to allow stronger chain reactions.

Hence, nuclear fission is used to harness nuclear energy.