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NUCLEAR FISSION Dr. ANANT KUMAR SINHA ASSOCIATE PROFESSOR DEPTT. OF PHYSICS A.M. COLLEGE, GAYA

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Page 1: NUCLEAR FISSION - magadhuniversity.ac.in FIS… · Nuclear fission is either a nuclear reactionor a radioactive decay process in which the nucleus of an atom splits into smaller parts

NUCLEAR FISSION

Dr. ANANT KUMAR SINHA ASSOCIATE PROFESSOR DEPTT. OF PHYSICSA.M. COLLEGE, GAYA

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CONTENTS

History

Introduction

Fission Chain Reaction

Nuclear Reactor

Applications

Page 3: NUCLEAR FISSION - magadhuniversity.ac.in FIS… · Nuclear fission is either a nuclear reactionor a radioactive decay process in which the nucleus of an atom splits into smaller parts

HISTORY OF NUCLEAR

FISSION

Page 4: NUCLEAR FISSION - magadhuniversity.ac.in FIS… · Nuclear fission is either a nuclear reactionor a radioactive decay process in which the nucleus of an atom splits into smaller parts

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.

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Otto Hahn Fritz Strassmann

NUCLEAR FISSION OF HEAVY ELEMENTS WAS

DISCOVERED ON DECEMBER 17, 1938 BY

GERMAN OTTO HAHN AND HIS

ASSISTANT FRITZ STRASSMANN.

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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 amountsof energy both as electromagnetic radiation and

as kinetic energy of the fragments.

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INTRODUCTION TO

FISSION REACTION

Page 8: NUCLEAR FISSION - magadhuniversity.ac.in FIS… · Nuclear fission is either a nuclear reactionor a radioactive decay process in which the nucleus of an atom splits into smaller parts

INTRODUCTION:

Nuclear fission is either a nuclear reaction or

a radioactive decay process in which the nucleus ofan 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.

Page 9: NUCLEAR FISSION - magadhuniversity.ac.in FIS… · Nuclear fission is either a nuclear reactionor a radioactive decay process in which the nucleus of an atom splits into smaller parts

WHEN NEUTRON STRIKES 92U235 CONVERTED

TO 92U236 ;

Page 10: NUCLEAR FISSION - magadhuniversity.ac.in FIS… · Nuclear fission is either a nuclear reactionor a radioactive decay process in which the nucleus of an atom splits into smaller parts

CONT……

This process may be represented by the following nuclear equation:

56Ba14192U235 + O1n —› + 36Kr92 + 3 01n + Q

Where Q is the energy released in this reaction.

When this is done, the amount of energy typicallyreleased in the case of U-235 is around 200MeV(0.00,000,000,003,204 joules).

Page 11: NUCLEAR FISSION - magadhuniversity.ac.in FIS… · Nuclear fission is either a nuclear reactionor a radioactive decay process in which the nucleus of an atom splits into smaller parts

FISSION REACTION OF 92U235 ;

Page 12: NUCLEAR FISSION - magadhuniversity.ac.in FIS… · Nuclear fission is either a nuclear reactionor a radioactive decay process in which the nucleus of an atom splits into smaller parts

FISSION CHAIN

REACTION

Page 13: NUCLEAR FISSION - magadhuniversity.ac.in FIS… · Nuclear fission is either a nuclear reactionor a radioactive decay process in which the nucleus of an atom splits into smaller parts

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.

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CHAIN REACTION:

A chain reaction is a sequence of reactions wherea reactive product or by-product causes additionalreactions 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.

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CHAIN REACTION;

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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.

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NUCLEAR REACTOR

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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.

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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.

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POWER GENERATION THROUGH NUCLEAR

REACTOR;

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WORKING OF REACTOR;

Reactor Core; cylindrical tubes in which fuel is kept.

Uranium- 92U235 is used asfuel.

The quantity of 92U235 in the naturally occurringUranium 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.

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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.

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APPLICATIONS

Page 24: NUCLEAR FISSION - magadhuniversity.ac.in FIS… · Nuclear fission is either a nuclear reactionor a radioactive decay process in which the nucleus of an atom splits into smaller parts

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.

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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.

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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.

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Advantages Disadvantages

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 innuclear reactors.

High cost of installation of nuclear plants.

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