Class 12 Physics Nuclei Nuclear Fission

Nuclear Fission

 

  • Scientist named Fermi was the one who performedfirst nuclear fission reaction.
  • He considered the sample of 92235U and bombarded it with a neutron 10n i.e.
    • 10n + 92235U(Target nuclei)à92236U(unstable so broke down into) -->56144Ba + 8936kr +310n
      • Where (56144Ba) = Barium,(8936kr)=Krypton and (10n) =neutron.
    • This reaction is known as nuclear fission reaction as heavier nuclei is broken down into lighter nuclei,thereby releasing large amounts of energy.

 

Types of Nuclear Fission reactions:

  1. Uncontrolled chain reaction:-
    1. In uncontrolled chain reaction, the reaction is uncontrolled and rapid.The reaction keeps increasing and becomes huge.
    2. Energy of the order of mega electron volts is produced.
    3. This reaction is known as chain reaction as the product formed in first reaction initiates the second reaction and so on.
    4. One of the important applications of this reaction is in making atom bombs,hydrogen bombs and nuclear bombs.
    5. (Number of neutrons hitting next target)/ (number of neutrons emitted)>=1.
    6. Reaction that takes place :-
      1. 10n + 92235U -->92236U(unstable so broke down into) -->56144Ba + 8936kr +3 10n

 

  1. Controlled chain reaction:-
    1. In controlled chain reaction, the reaction is controlled and steady.
    2. Reaction that takes place :-
      1. 10n + 92235U --> 92236U(unstable so broke down into) -->56144Ba + 8936kr +3 10n
      2. Using some methods 2 neutrons are removed and only 1 neutron is allowed to hit the next target.
    3. Energy released is less as compared to the energy released in the nuclear fission reaction.
    4. One of the most important applications is in Nuclear Reactor where electricity can be produced.
    5. (Number of neutrons hitting next target)/ (number of neutrons emitted)<1.

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