In our previous blog, we have already discussed the site selection of nuclear power plants and the advantages and disadvantages of the nuclear power plant, but in our today’s blog, we are going to discuss some basics that are required to understand the working of the nuclear power plant such as What is nuclear fission and how does it work, What is nuclear chain reaction and nuclear fuels.
What is nuclear fission and how does it work
At first, we have to understand nuclear fission because it is the building block of the whole nuclear power plant. Only this process decides how much energy will be generated.
The splitting of a heavy nucleus into two or smaller nuclei is called nuclear fission.
Nuclear fission is when a heavy nucleus splits when bombards certain particles such as U-235, U-233, and Pu-239.
So what causes the fission reaction?
Fission can be caused by bombarding high-energy particles such as protons, neutrons, and x- rays. But in all of the above, neutrons are most suited for fission reaction.
Why neutrons are best suited for fission? The reason behind this is neutrons have no charge, and therefore they can make their way through shells of electrons and then through the nucleus at low energy.
The process of fission is accompanied by the ejection of two or more neutrons and liberating vast energy atom that breaks up into two nuclei.
What do you think is the byproduct of this reaction? Every action has an equal and opposite reaction. During the fission reaction, a large quantity of energy is released in the form of a radioactive product, and the neutrons are emitted.
The neutrons can cause fission of the material nucleus and release more neutrons, leading to a chain reaction.
Summary of what happens during fission reaction.
- Upon capturing a neutron, a heavy nucleus is converted into two or more nuclei.
- Two or more neutrons are produced by the fission of each nucleus.
- Vast quantities of energy (that is, 3 million times produces the equivalent of coal) are products of converting small mass into energy.
- All the fission products are radioactive, giving of ϒ and β radiations.
What is nuclear chain reaction
The chain reaction is the series of nuclear fission in which the neutrons produced in each fission cause additional fission.
U-235 nucleus, when hit by a neutron, undergoes the reaction. Each of the three neutrons produced in the reaction strikes another U-235 nucleus, thus causing nine subsequent reactions.
This process of propagation reaction by multiplication in three at each fission is referred to as a chain reaction.
Heavy unstable isotopes exhibit a chain reaction by releasing two or three neutrons at each fission.
It can also be explained as a fission reaction where the neutrons from the previous step continue to propagate and repeat the reaction.
The chain reaction continues till most of the original nuclei in a given sample are fission. All the neutrons released in the reaction are not used in propagating chain reactions. Some lost to surroundings.
A single fission reaction produces a large amount of energy. But, imagine how much energy can a chain reaction produce. A massive amount of energy is produced in a chain reaction, containing innumerable fissions.
Materials fission by a thermal or low-speed neutron is U-235, U-233 and Pu-239 (plutonium-239).
Nuclear energy
The energy released by nuclei fission is called nuclear energy and sometimes it is also called atomic energy.
The fission of one radioactive element causes the release of about 200 MeV of energy. ( MeV stands for mega electron volt).
You can imagine that how massive energy a one fission event can produce.
The fission of U-235 or Pu-239 generated incomprehensible quantities of energy in the form of heat and radiation. And if the chain reaction is not controlled, it can cause massive explosion violence; this is why radioactive materials are used to create missiles and bombs.
When controlled in a reactor with the help of moderators, the fission of U-235 is harnessed to generate electricity.
Nuclear fuels
Fuels used for nuclear power generations are as below
- Natural uranium (U-235)
- Enriched uranium
- Plutonium (secondary fuel)
- U-233(secondary fuel from breeder reactor)
What is secondary fuel?
Secondary fuel is derived from primary fuels through different processes such as chemical and physical.
And breeder reactor is a reactor that produces more fissionable material than it consumes to generate energy.
