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Nuclear Reactions

Fission and Fusion

Presented by KIRAN KUMAR. V.A

Code 13973011

State that in fission a nucleus of large mass splits into 2

nuclei of smaller mass numbers, usually with the release

of neutrons.

State that fission may be spontaneous or induced by

neutron bombardment.

Nuclear Fission

There are 2 types of fission that exist:

1. Spontaneous Fission

2. Induced Fission

Spontaneous Fission

Some radioisotopes contain nuclei which are highly

unstable and decay spontaneously by splitting into 2

smaller nuclei.

Such spontaneous decays are accompanied by the

release of neutrons.

Induced Fission

Nuclear fission can be induced by bombarding atoms

with neutrons.

Induced fission decays are also accompanied by the

release of neutrons.

The nuclei of the atoms then split into 2 equal parts.

U23592n

10

The Fission Process

A neutron travels at high speed towards a uranium-235

nucleus.

U23592n

10

The Fission Process

A neutron travels at high speed towards a uranium-235

nucleus.

U23592n

10

The Fission Process

A neutron travels at high speed towards a uranium-235

nucleus.

U23592n

10

The neutron strikes the nucleus which then captures the

neutron.

The Fission Process

U23692

The nucleus changes from being uranium-235 to

uranium-236 as it has captured a neutron.

The Fission Process

The uranium-236 nucleus formed is very unstable.

The Fission Process

It transforms into an elongated shape for a short time.

The uranium-236 nucleus formed is very unstable.

The Fission Process

It transforms into an elongated shape for a short time.

The uranium-236 nucleus formed is very unstable.

The Fission Process

It transforms into an elongated shape for a short time.

It then splits into 2 fission fragments and releases

neutrons.

The Fission Process

14156Ba

9236Kr

n10

n10

n10

It then splits into 2 fission fragments and releases

neutrons.

The Fission Process

14156Ba

9236Kr

n10

n10

n10

It then splits into 2 fission fragments and releases

neutrons.

The Fission Process

14156Ba

9236Kr

n10

n10

n10

It then splits into 2 fission fragments and releases

neutrons.

The Fission Process

14156Ba

9236Kr

n10

n10

n10

Nuclear Fission Examples

U235

92+Ba

141

56+ n

1

03n

1

0+Kr

92

36

U235

92+Cs

138

55+ n

1

02n

1

0+Rb

96

37

Energy from Fission

Both the fission fragments and neutrons travel at high

speed.

The kinetic energy of the products of fission are far

greater than that of the bombarding neutron and target

atom.

EK before fission << EK after fission

Energy is being released as a result of the fission reaction.

Energy from Fission

U235

92+Cs

138

55+ n

1

02n

1

0+Rb

96

37

Element Atomic Mass (kg)

23592U 3.9014 x 10-25

13855Cs 2.2895 x 10-25

9637Rb 1.5925 x 10-25

10n 1.6750 x 10-27

Nuclear Fusion

In nuclear fusion, two nuclei with low mass numbers

combine to produce a single nucleus with a higher mass

number.

H2

1+He

4

2+ n

1

0H

3

1 +Energy

The Fusion Process

H21

H31

The Fusion Process

H21

H31

The Fusion Process

H21

H31

The Fusion Process

H21

H31

The Fusion Process

The Fusion Process

The Fusion Process

The Fusion Process

The Fusion Process

He42

n10

The Fusion Process

He42

n10

The Fusion Process

He42

n10

The Fusion Process

He42

n10

Energy from Fusion

Element Atomic Mass (kg)

21H 3.345 x 10-27

31H 5.008 x 10-27

42He 6.647 x 10-27

10n 1.6750 x 10-27

H2

1+He

4

2+ n

1

0H

3

1 +Energy

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