1. 1
Sri.M.Ragu
ASSISTANT PROFESSOR
DEPARTMENT OF CHEMISTRY
NUCLEAR CHEMISTRY

2. References
2

3. Plan of Presentation
 Introduction
 Nuclear Reactions
 Nuclear fission – Atom Bomb
 Nuclear fusion – Hydrogen bomb
 Applications of radioactive isotopes
 Summary
3

4. Atomic Structure
 Atoms are composed of protons, neutrons and electrons
Protons – positively charged particles
Neutrons – neutral particles
Electrons – negatively charged particles
Protons and neutrons are located in the nucleus
Electrons are found in orbitals surrounding the nucleus
4

5. Nucleus
 The central part of an atom
 Composed of protons and neutrons
 A strong attractive force between nucleons in the
atomic nucleus that holds the nucleus together
5

6. Nuclear Reaction
 Fission: the splitting of nuclei
 Fusion: the joining of nuclei
6

7. 7
Nuclear Fission

8. 8
Nuclear Fission
 Heavy nucleus splits into lighter nuclei and energy is released
 Nucleus can be induced to undergo fission by bombardment with
neutrons
 It is much easier to crash a neutral neutron than a positive proton
into a nucleus to release energy
U
n 235
92
1
0  n
3
Kr
Ba 1
0
94
36
139
546 

.

9. • Uncontrolled chain reactions take place during the
explosion of an atomic bomb.
9
Nuclear Fission

10. • On earth, nuclear fission reactions take place in
nuclear reactors, which use controlled chain
reactions to generate electricity.
10
Nuclear Fission

11. 11
Atom bomb

12. Germany started experimenting
with Nuclear Fission in 1938.
German scientist Otto Hahn and
Fritz Strassman bombarded
Uranium with neutrons and
discovered Barium atoms.
Conclusion: Nuclear fission
releases a massive amount of
energy
12
Atom bomb

13.  Dropped on Hiroshima, on August 6, 1945
 The "Little Boy" - 3 m in length, 71 cm
wide and weighed 4000 kg
13
-7 feet 8 inches (2.34 m) long, five feet
(1.52 m) in diameter, and weighed
10,200 pounds (4,630 kg) - detonated
over Nagasaki at an altitude of about
1,800 feet - Uses plutonium
Little Boy Fat Man

14. 14

15. 15
Hiroshima
Before Atomic bomb blast
http://www.jfeenstra.com/pacific/S
P205.jpg
After Atomic bomb blast

16. Before After 16
Nagasaki

17. Chain Reaction
• A chain reaction is an
ongoing series of fission
reactions. Billions of
reactions occur each
second in a chain
reaction.
17

18. Nuclear Fusion
• The opposite of fission, fusion is when 2 nuclei combine to
form a larger nucleus.
• A large amount of energy is generated during nuclear fusion.
• Small nuclei combine to form heavier, more stable nuclei.
• No radioactive products are produced.
• Fusion reactions are easier to control, so the risk of
explosions & accidents are decreased.
18

19. Nuclear Fusion
When two light
atoms join to form
heavy atoms.
Energy is also
released.
Sun, stars and
the hydrogen
bomb
19

20. Animations of Nuclear Fusion
D = deuterium
T = tritium
He = helium
n = neutron
20

21. THERMONUCLEAR (HYDROGEN) BOMB
A fission bomb is exploded around the fusion fuel to
produce the high temperatures and density required
for a fusion chain reaction in a thermonuclear bomb.
21

22. Nuclear Fusion
• Atoms lighter than Fe. Deuterium used
• Requires extremely high temperatures ~ 1 billion K
• Currently not technically possible for use as a power source – issues with
confinement
• Used as “Hydrogen bomb”
• Sun’s energy captured for our use
22

23. NUCLEAR POWER PLANT (NPP)
Fuel
Rods

24. ADVANTAGES
Nuclear power generation does emit relatively low amounts of
carbon dioxide (CO2). The emissions of green house gases and
therefore the contribution of nuclear power plants to global
warming is therefore relatively little.
This technology is readily available, it does not have to be
developed first.
It is possible to generate a high amount of electrical energy in one
single plant

25. DISADVANTAGES
Nuclear power plants as well as nuclear waste could be preferred
targets for terrorist attacks..
During the operation of nuclear power plants, radioactive waste is
produced, which in turn can be used for the production of nuclear
weapons.

26. Operating Nuclear Power Plants in India
TARAPUR-1&2 RAJASTHAN-1to 6 MADRAS-1&2
NARORA-1&2 KAKRAPARA-1&2 KAIGA-1 to 4
Total Capacity 4780 MWe
TARAPUR 3&4
26

28. Applications
• Medicine
– Chemotherapy
– Power pacemakers
– Diagnostic tracers
• Agriculture
– Irradiate food
– Pesticide
• Energy
– Fission
– Fusion
28

29. Food Irradiation
•Food can be irradiated with g rays from 60Co
or 137Cs.
•Irradiated milk has a shelf life of 3 month
without refrigeration.
•USDA has approved irradiation of meats
and eggs.
29

30. Nuclear Medicine: Imaging
Thyroid imaging using Tc-99m
30

32. Meson Theory

33. 33

34. Nuclear Forces
• What holds an atom together?
• Why doesn’t the nucleus of an atom fly apart
if it’s made of positively charged protons?
34

35. Nuclear Forces
35

36. Nuclear Reactions
• Two types:
–Fission = the splitting of nuclei
–Fusion = the joining of nuclei (they fuse
together)
• Both reactions involve extremely large
amounts of energy
Albert Einstein’s
equation E = mc2
illustrates the energy
found in even small
amounts of matter
36

37. Presentation of Lecture Outlines, 21–37
Nuclear Fission
• Nuclear fission is a nuclear reaction in which a
heavy nucleus splits into lighter nuclei and
energy is released.
– In some cases a nucleus can be induced to undergo fission by
bombardment with neutrons.
n
4
Sr
Xe 1
0
90
38
142
54 

U
n 235
92
1
0  n
3
Kr
Ba 1
0
94
36
139
546 

n
2
Rb
Cs 1
0
90
37
144
55 


38. Nuclear Fission
U-235
Ba-141
Kr-92
N
N
N
+
Neutrons are used to make nuclei unstable
It is much easier to crash a neutral neutron than a
positive proton into a nucleus to release energy.
38

39. Fissionable Isotopes
• U-235 is fissionable, but U-238 is not.
• Pu-239 is fissionable
• Th-232 is fissionable only with a fast moving
neutron.
• Slow-moving neutrons are used for controlled
fission reactions in power plants.
39

40. Nuclear Fission
When a heavy atomic
nucleus is bombarded
with a neutron…
Two middle weight
atoms result
Neutrons and Energy
also result
= Chain Reaction!
Nuclear power
stations and bombs
40

41. Animation of a Nuclear Fission Chain
Reaction
41

42. 42

43. 43

44. Disposal of Radio active wastes
44

45. Intermediate Level Waste
ILW
• Intermediate level waste requires shielding
when being handled.
• 7% volume of waste
• Not recognized in the United States.

46. 46