Question

Explain the process of controlled and uncontrolled chain reactions.

Answer 1

• Controlled chain reaction

1. 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.
2. Thus, the reaction is sustained in a controlled manner. The energy released due to a controlled chain reaction can be utilized for constructive purposes.
3. The controlled chain reaction is used in a nuclear reactor to produce energy in a sustained and controlled manner.

• Uncontrolled chain reaction:

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