fission and fusion

1. TAU101 Applied physical sciences(2+1)

2. Nuclear Physics
BSF-10
001-A.Adhirai
002-Alex.K.George
003-Aravind.R.S
004-K.Bharathidasan
005-R.Deepak Kumar
TAU101 Applied physical sciences(2+1)

3. DEFINITION
Nuclear physics is the field of physics that studies the
building blocks and interactions of atomic nuclei.
It includes the study of,
1.The general properties of nucleus.
2.The particles contained in the nucleus.
3.The interaction between these particles.
4.Radio activity and nuclear reactions.
5.Practical applications of nuclear phenomena.
TAU101 Applied physical sciences(2+1)

4. NUCLEUS
Every atom contains a
centre, an extremely
dense, positively charged
nucleus.
The nucleus is made of
protons and neutrons.
Protons have positive
electric charge.
Neutrons have no
electrical charge.
TAU101 Applied physical sciences(2+1)

5. TAU101 Applied physical sciences(2+1)
NUCLEUS
 MASS NUMBER(A): total number of
nucleon.A=Z(protons)+N(neutrons).
 ATOMIC NUMBER(Z): number of
protons.
 NEUTRON NUMBER N: number of
neutrons.
RADIUS: r=r0A1/3 ,
r0=1.25x10-15
m.
MASS M=AU,u=1.66×10⁻27kg

6. α-RAY SCATTERING EXPERIMENT
Done by E.Rutherford.
From angular distribution of rescattered α -particles
Rutherford concluded existence of positively charged core
of atom,then called nucleus
The size of the nucleus was much smaller(10-14
m) than
size of the atom (10-10
m)
TAU101 Applied physical sciences(2+1)

7. TAU101 Applied physical sciences(2+1)
THE NUCLEAR FORCE
The force that binds together protons and neutrons
inside the nucleus is called the Nuclear Force.
Some characteristics of the nuclear force are:
1.It does not depend on charge.
2.It is very short range.
3.It is much stronger than the electric force.
4.It is saturated force .
5.It favours formation of pairs of nucleons with opposite
spins.

8. TAU101 Applied physical sciences(2+1)
NUCLEAR BINDING ENERGY
The total rest energy(mass) of the separated nucleons
is greater than the rest energy(mass) of the nucleus.
Eg:- Deuteron 2
H (1 proton + 1 neutron+1 electron)
mp=1.007276u +
mn=1.008665u But m2H=2.014102 u
mp+n=2.016490 u
mp+n-m2H=0.002338u
The deuteron is 0.002338 u lighter than the sum of
the separate proton and the neutron.
 This is the binding energy and is the energy needed
to break that nucleus apart in its separate constituents

9. BINDING ENERGY PER NUCLEON
Nuclei with the
largest binding
energy per
nucleon are the
most stable.
The largest
binding energy
per nucleon is 8.7
MeV, for mass
number A = 56.
Beyond bismuth,
A = 209, nuclei
are unstable.
Most stable
Iron 56

10. TAU101 Applied physical sciences(2+1)
RADIOACTIVITY
The Spontaneous emission of radiation by unstable
nuclei to become stable.
 Atain stability by the emission of ,
1. α particles(4
He)[atomic number decrease by2 & mass
number decrease by 4]
2. β particles (electrons or positrons)[atomic number
change by 1 & mass number remains same]
3. γ rays (energetic photons)

11. TAU101 Applied physical sciences(2+1)
HALF LIFE TIME
The half life means
time required for the
disintegration of half of
the sample.
Different for different
elements.
Applied for the
estimation of age of
fossils(14
C-dating).

12. NUCLEAR REACTIONS
A nuclear reaction is a rearrangement of nuclear
components induced by particle bombardment.
1.Fission
2.Fusion
Nuclear reactions are subject to the following
conservation laws:
1.Charge.
2.Momentum and angular momentum.
3.Energy.
4.Total number of nucleons.
TAU101 Applied physical sciences(2+1)

13. FISSION
 Splitting of large nucleus to
smaller ones results in the
liberation of energy.
 n + 235U →141Ba + 92Kr + 3n
 In this reaction more than
200MeV energy liberated.
 Emitted neutrons can induce
addtional fusion-chain reaction.
 Chain reaction is controlled and
is applied in fission reactors.
 Chain reaction left uncontrolled
and is applied in atom bomb.
TAU101 Applied physical sciences(2+1)
Ba
Kr

14. FISSION CHAIN REACTION
At each step energy is released !
TAU101 Applied physical sciences(2+1)

15. NUCLEAR FISSION REACTOR
Place where controlled fission chain reaction occurs.
Liberated energy is used for the production of
electricity.
PARTS OF THE REACTOR;
1.Fuel-Uranium,Plutonium,Thorium
2.Moderator-Water,Graphite-slow down neutron.
3.Control rods-Cadmium-absorb neutrons.
4.Concrete wall-block radiations.
TAU101 Applied physical sciences(2+1)

16. NUCLEAR FISSION REACTOR
TAU101 Applied physical sciences(2+1)

17. FUSION
TAU101 Applied physical sciences(2+1)
Two light nuclei fuse together to
form a heavier nucleus results in the
liberation of energy.
2H + 3H →4He + n + 17.6 MeV
It is the primary source of the
sun’s energy.
Fusion reaction is applied in
hydrogen bomb.

18. FISSION & FUSION
FUSIONFISSION
TAU101 Applied physical sciences(2+1)

19. FISSION & FUSION
FISSION
 Splitting a large mass
nucleus into two
medium mass
nucleus.
 Energy released per
nucleon is less.
 Can be controlled.
 Heat is not needed.
 Lot radioactive
byproducts.
FUSION
 Joining two low mass
nuclei into a larger
mass nucleus.
 Energy produced per
nucleon is large.
 Can not be
controlled.
 Extreme heat is
needed.
 No radioactive
byproducts.
TAU101 Applied physical sciences(2+1)

20. TAU101 Applied physical sciences(2+1)
NUCLEAR REACTORS
FISSION REACTOR:
use fission of heavy elements
like Uranium, Plutonium for power.
FUSION REACTOR:
work in progress: ITER
International Thermonuclear Experimental Reactor
(500MW power in 1000second through fusion reaction)

21. TAU101 Applied physical sciences(2+1)
APPLICATIONS ARE
Medical radio-isotopes (imaging & therapy).
Magnetic Resonance Imaging (MRI).
Identification of materials.
Dating of materials.
Power generation (fusion and fission).
Weapons of mass destruction (WMD).

22. REFERENCE
 NCERT physics text book.
 www.elsevier.com.
 www.sciencedirect.com.
 www.wikipedia.org.
TAU101 Applied physical sciences(2+1)

23. TAU101 Applied physical sciences(2+1)