Name: Law of Radioactive Decay
Uploaded: 2019-07-19
Duration: 8 min 24 s
Description: The radioactive decay follows the first-order kinetics. Watch this video to understand this process in detail. This topic is important for JEE main.

Question

Discuss chain reaction in fission. Explain uncontrolled and controlled chain reaction.

Accepted Answer

Chain Reactions are basically fission reactions which through the products produce more chain reactions. One of the most well-known and useful examples of a chain reaction is of $U^{235}$ which is used to harness nuclear energy. For $U^{235}$ on average $2.5$ neutrons are emitted, starting on average two more fission reactions.

(1) Controlled chain reaction: In the controlled chain reaction the number of neutrons released is maintained to be one. This is achieved by absorbing the extra neutrons with a neutron absorber leaving only one neutron to produce further fission. Thus, the reaction is sustained in a controlled manner. The energy released due to a controlled chain reaction can be utilised for constructive purposes. Controlled chain reaction is used in a nuclear reactor to produce energy in a sustained and controlled manner.

(2) Uncontrolled chain reaction: In the uncontrolled chain reaction the number of neutrons multiplies indefinitely and causes fission in a large amount of the fissile material. This results in the release of a huge amount of energy within a fraction of a second. This kind of chain reaction is used in the atom bomb to produce an explosion.

Discuss chain reaction in fission. Explain uncontrolled and controlled chain reaction.

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