Nuclear Fission

Whats the difference between nuclear fission and fusion

Nuclear Fission :-

Nuclear Fission is a reaction wherein a heavy nucleus is bombarded by neutrons and thus become unstable, which causes decompose or split into two nuclei with equivalent size and magnitude, with a great detachment of energy and the emission of two or three neutrons.

Example :- Isotope ₉₂U²³⁵ bombarded with a neutron breaks into two intermediate mass nuclear fragments.

₉₂U²³⁵ + ₀n¹ → ₉₂U²³⁶ → ₅₆Ba¹⁴⁴ + ₃₆Kr⁸⁹ + 3 ₀n¹

Nuclear fission reaction.svg
Fig :- Nuclear fission.

Another example :-

₀n¹ + ₉₂U²³⁵ →₉₂U²³⁶ → ₅₁Sb¹³³ + ₄₁Nb⁹⁹ + 4 ₀n¹


₀n¹ + ₉₂U²³⁵ → ₅₄Xe¹⁴⁰ + ₃₈Sr⁹⁴ + 2 ₀n¹

  • The fragment products are radioactive nuclei. They emit particles in succession to achieve stable end product.
  • The energy released in the fission reaction of nuclei like Uranium is of the order of 200 MeV per fissioning nucleus.

Let us

a nucleus with A = 240 breaking into two fragments each of A = 120


Energy for A = 240 nucleus is about 7·6 MeV

Energy for two A = 120 fragments nuclei is about 8·5 MeV

Gaining in binding energy per nucleon is about 0.9 MeV

Here the total gaining binding energy = 240 × 0.9 = 216 MeV

  • The source of energy in nuclear reactors, which produce electricity, is nuclear fission.
  • The enormous energy released in an atom bomb comes from uncontrolled nuclear fission.

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