Short Details about Nuclear Fission

1. NUCLEAR FISSION
M.Hammad (BChE-FA16-012)
Abrar Ahmed (BChE-FA16-014)
Hafiz Rizwan (BChE-FA16-015)
Vicky Vicky (BChE-FA16-006)
Esharib Zaheer (BChE-FA16-019)

2. CONTENTS
History
Introduction
Fission Chain Reaction
Nuclear Reactor
Applications
References

3. HISTORY OF NUCLEAR
FISSION

4. HISTORY:
 After James Chadwick discovered the neutron in 1932.
 Enrico Fermi and his colleagues in Rome studied the
results of bombarding uranium with neutrons in 1934.
 Fermi concluded that his experiments had created new
elements with 93 and 94 protons, which the group
dubbed Ausonium and Hesperium respectively.
However, not all were convinced by Fermi's analysis of
his results.

5. NUCLEAR FISSION OF HEAVY ELEMENTS WAS
DISCOVERED ON DECEMBER 17, 1938 BY
GERMAN OTTO HAHN AND HIS
ASSISTANT FRITZ STRASSMANN.
Otto Hahn Fritz Strassmann

6. CONT……
 Nuclear fission explained theoretically in January
1939 by Lise Meitner and her nephew Otto Robert
Frisch.
 Frisch named the process by analogy with biological
fission of living cells. It is an exothermic
reaction which can release large amounts
of energy both as electromagnetic radiation and
as kinetic energy of the fragments.

7. INTRODUCTION TO
FISSION REACTION

8. INTRODUCTION:
 Nuclear fission is either a nuclear reaction or
a radioactive decay process in which the nucleus of
an atom splits into smaller parts (lighter nuclei).
 The fission process often produces
free neutrons and gamma photons, and releases a
very large amount of energy even by the energetic
standards of radioactive decay.
 Fission is a form of nuclear transmutation because the
resulting fragments are not same element as the
original atom.

9. WHEN NEUTRON STRIKES 92U235 CONVERTED
TO 92U236 ;

10. CONT……
 This process may be represented by the following
nuclear equation:
92U235 + O
1n —› 56Ba141 + 36Kr92 + 3 0
1n + Q
Where Q is the energy released in this reaction.
 When this is done, the amount of energy typically
released in the case of U-235 is around 200MeV
(0.00,000,000,003,204 joules).

11. FISSION REACTION OF 92U235 ;

12. FISSION CHAIN
REACTION

13. INTRO:
 "Chain reactions" at that time were a known
phenomenon in chemistry, but the analogous
process in nuclear physics, using neutrons, had
been foreseen as early as 1933 by Szilárd,
although Szilárd at that time had no idea with what
materials the process might be initiated. Szilárd
considered that neutrons would be ideal for such a
situation, since they lacked an electrostatic charge.

14. CHAIN REACTION:
 A chain reaction is a sequence of reactions where
a reactive product or by-product causes additional
reactions to take place.
 An atom of uranium-235 to undergo fission by
bombarding it with neutrons.
 Along with barium and krypton, three neutrons are
released during the fission process. These neutrons
can hit further U-235 atoms and split them,
releasing yet more neutrons. This is called a chain
reaction.

15. CHAIN REACTION;

16. CONT……
 Although the half-life of U-235 is a very long time, if
we get enough of the atoms together in one place
the chances that any one of them will
undergo spontaneous fission is very, very high.
 Additional Neutrons create a chain reaction, which
is controlled by the control rods.
 Newly created fission neutrons move at about 7%
of the speed of light, and even moderated neutrons
move at about 8 times the speed of sound.

17. NUCLEAR REACTOR

18. NUCLEAR REACTOR:
 “The assembly which is used to convert heat
generated in nuclear reaction into electrical energy
is called Nuclear Reactor.”
 In a reactor fission reaction produces heat.
 When fission takes place in atom of uranium or any
heavy atom, then energy at the rate of 200MeV per
nucleus is produced in form of Kinetic energy of
fission fragments.
 These fast moving fragments besides colliding with
one another also collide to uranium atoms.

19. CONT……
 Due to collisions kinetic energy gets transformed
into heat energy.
 Heat produced is used to produce steam which in
turn rotates the turbine.
 As a result, turbine rotates the generator which
produces electricity.

20. POWER GENERATION THROUGH NUCLEAR
REACTOR;

21. WORKING OF REACTOR;
 Reactor Core; cylindrical tubes in which fuel is kept.
Uranium- 92U235 is used as fuel.
 The quantity of 92U235 in the naturally occurring
Uranium is 0.7%.
 Fuel rods are placed in substances of small atomic
weight, such as water, heavy water, carbon etc
called moderators.
 Moderator; is used to slow down the speed of
neutrons produced during the fission process to
direct them towards the fuel.

22. CONT……
 Control rods; number of neutrons produced are
controlled because only one neutron has to
produce further fission reaction.
 Control rods are made of cadmium or boron.
 Chain reaction takes place in the core and
produces heat. Temperature rise about 500°C.
 Steam is produced from this heat and is transported
with the help of water or heavy water.
 Temperature of steam coming out from turbine is
about 300°C which is further cooled to produce
water again.

23. APPLICATIONS

24. APPLICATIONS:
 December 20, 1951- Electricity was generated for
the first time by a nuclear reactor – A the EBR-I
experimental station near Arco, Idaho – initially
produced about 100 kW
 1956 - world's first commercial nuclear power
station in Sellafield, England – initial capacity of 50
MW (later 200 MW)
 In July 1945, the first atomic explosive device,
dubbed "Trinity", was detonated in the New Mexico
desert. It was fueled by plutonium created at
Hanford.

25. IN AUGUST 1945, TWO MORE ATOMIC DEVICES –
"LITTLE BOY", A URANIUM-235 BOMB, AND "FAT
MAN", A PLUTONIUM BOMB – WERE USED AGAINST
THE JAPANESE CITIES OF HIROSHIMA AND NAGASAKI.

26. CONT……
 In August 1945, two more atomic devices – "Little
Boy", a uranium-235 bomb, and "Fat Man", a
plutonium bomb – were used against the Japanese
cities of Hiroshima and Nagasaki.
 These fission reactions produce new nuclides or
elements which are used in medical diagnose and
treatments and biological experimentations.
 Nuclear fission reaction is used to produce energy
for nuclear power.
 It causes nuclear bomb to explode.

27. ADVANTAGES & DISADVANTAGES
 It produces
tremendous energy
from small amount of
nuclear fuel.
 Once a fuel added a
plant can work for
years.
 Does not produce
greenhouse gases like
CO2.
 Difficult to dispose the
radioactive waste from
nuclear fission
reaction.
 Risks of accidents in
nuclear reactors.
 High cost of installation
of nuclear plants.
Advantages Disadvantages

28. REFERENCES:
 http://www.science.uwaterloo.ca/~cchieh/cact/nucte
k/nrapplication.html
 https://en.wikipedia.org/wiki/Nuclear_fission#Fissio
n_reactors
 http://www.zamandayolculuk.com/nuclearfissionx.ht
ml