Nuclear Fission:�Nuclear fission is defined as a type of nuclear disintegration in which a heavy nucleus splits up into two nuclei of comparable size accompanied by a release of a large amount of energy.���
0n1 + 92U235 → (92U236) → 56Ba141 + 36Kr92 +30n1 + γ (200 MeV)
:Chain Reaction
n = 1
N = 1
n = 2
N = 9
n = 3
N = 27
Neutron (thermal) 0n1
Uranium
92U235
Barium
Krypton
56Ba141
36Kr92
n = No. of fission stages N = No. of Neutrons
N = 3n
Chain Reaction:
n = 1 n = 2
N = 1 N = 9
n = 3
N = 27
Critical Size:
For chain reaction to occur, the size of the fissionable material must be above the size called ‘critical size’.
A released neutron must travel minimum through 10 cm so that it is properly slowed down (thermal neutron) to cause further fission.
If the size of the material is less than the critical size, then all the neutrons are lost.
If the size is equal to the critical size, then the no. of neutrons produced is equal to the no. of neutrons lost.
If the size is greater than the critical size, then the reproduction ratio of neutrons is greater than 1 and chain reaction can occur.
Key components of a Nuclear reactor
Nuclear Fusion:
Nuclear fusion is defined as a type of nuclear reaction in which two lighter nuclei merge into one another to form a heavier nucleus accompanied by a release of a large amount of energy.
Energy Source of Sun:
Proton – Proton Cycle:
1e0
1H1 + 1H1 → 1H2 +
1H1 + 1H2 → 2He3
2He3 + 2He3 → 2He4
+ 2 1H1
+ 0.4 MeV
+ 5.5 MeV
+ 12.9 MeV
+
1H1
+
1e0
Energy Source of Star:
Carbon - Nitrogen Cycle:
+
+
1H1
1H1
+
1e0
+ γ (energy) (positron)
+ γ (energy)
+ γ (energy) (positron)
6C12
7N13
6C13
7N14
8O15
7N15
+
1H1
→
→
→
→
→
→
7N13
6C13
7N14
8O15
7N15
6C12
+ 2He4 + γ (energy)
End of Atomic Nucleus