NUCLEAR FISSION &

FUSION

PRESENTATION CONTEXT History Definition of fission & fusion Process of These System Energy Comes From Fission &

Fusion Chain Reaction Usage Differences Quiz

History . . .Hahn & Strassman In 1939 They First Identified The Nuclear Fission

Their Statement Was :

Bombarded Uranium-235 samples with neutrons expecting the Uranium-235 to capture neutrons

Meitner & Frisch

Explained Hahn & Strassman results

Instead of heavier Uranium, it had split into smaller elements = Nuclear Fission

A LITTLE BIT ON THE ATOM

-

-

-

-

-

-

-

-

Negative electronsPositive protons

Neutral neutrons

Nucleus

NUCLEAR FISSION A reaction in which an atomic nucleus of a radioactive element splits by bombardment from an external source, with simultaneous release of large amounts of energy, used for electric power generation

CHAIN REACTION

A chain reaction occurs

• When a Critical Mass of Uranium Undergoes Fission.

• Releasing a Large

Amount of Heat and Energy That Produces an Atomic Explosion.

Nuclear Fission Diagram

1n + 235U “236 U” 91Kr + 142Ba + 3 1n + Energy0 92 92 36 56 0

U23592n 1

0

A neutron travels at high speed towards a uranium-235 nucleus

The Fission Process

U23592n 1

0

A neutron travels at high speed towards a uranium-235 nucleus

The Fission Process

U23592n 1

0

A neutron travels at high speed towards a uranium-235 nucleus

The Fission Process

U23592n 1

0

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

It transforms into an elongated shape for a short time

The Fission Process

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

It then splits into 2 fission fragments and releases neutrons

14156Ba

9236 Kr

n 1 0

n 1 0

n 1 0

The Fission Process

It then splits into 2 fission fragments and releases neutrons

14156Ba

9236 Kr

n 1 0

n 1 0

n 1 0

The Fission Process

It then splits into 2 fission fragments and releases neutrons

14156Ba

9236 Kr

n 1 0

n 1 0

n 1 0

The Fission Process

14156Ba

9236 Kr n 1

0

n 1 0

n 1 0

The Fission ProcessThe mass that was “lost” became energy

Conservation of Energy/Mass

• Energy cannot be created or destroyed – it can only change form

E = MC ²Einstein's Formula Above Tell Us How The Change Occurs In The Equation Above E = Energy M = Mass C = Speed Of Light ( Universal Constant)

MassEnergy LightSpeed

Energy from FissionEach uranium-235 atom has a mass of 3.9014 x 10-25 kg.

The total number of atoms in 1 kg of uranium-235 can be found as follows:

No. of atoms in 1 kg of uranium-235 = 1/3.9014 x 10-25

No. of atoms in 1 kg of uranium-235 = 2.56 x 1024 atoms

If one uranium-235 atom undergoes a fission reaction and releases 2.385 x 10-11 J of energy, then the amount of energy released by 1 kg of uranium-235 can be calculated as follows:

Total energy = energy per fission x number of atoms

Total energy = 2.385 x 10-11 x 2.56 x 1024

Total energy = 6.1056 x 1013 J

Energy from Fission

NUCLEAR POWER PLANT

In nuclear power plants: fission is used to produce energy control rods in the reactor absorb neutrons to slow and control the chain reactions of fission

FISSION CAN BE USED

• GOOD– A controlled chain reaction in a reactor used

in nuclear power plants to produce electricity.

• EVIL– An uncontrolled chain reaction is used to

create incredibly powerful weapons – the atomic bombs dropped on Japan.

NUCLEAR FUSION• Nuclear Fusion Is The Process By

Which Multiple Nuclei Join Together To Form a Heavier Nucleus.

• It Is Accompanied By The Release Or Absorption Of Energy Depending On The Masses Of The Nuclei Involved..

H 2

1+He

4

2+ n

1

0H

3

1+Energy

Fusion: Small Nuclei Form Larger Nuclide, Release Energy

This type of Fusion is beingExamined asAn alternativeEnergy sourceOn Earth.

Small nuclei come together to form larger nuclide, releasing energy

Complete the Reaction

1H

4Be

1H

8O

4Be

2He

2He

1H

2He

2He

2He

6C

1H element atomic number (protons)

6C

THE FUSION PROCESS

H 2 1

H 3 1

H 2 1

H 3 1

THE FUSION PROCESS

H 2 1

H 3 1

THE FUSION PROCESS

H 2 1

H 3 1

THE FUSION PROCESS

THE FUSION PROCESS

THE FUSION PROCESS

THE FUSION PROCESS

THE FUSION PROCESS

He 4 2

n 1 0

ENERGY

THE FUSION PROCESS

He 4 2

n 1 0

ENERGY

THE FUSION PROCESS

He 4 2

n 1 0

ENERGY

THE FUSION PROCESS

He 4 2

n 1 0

ENERGY

THE FUSION PROCESS

ENERGY FROM FUSION

E = mc2m = 3.1 x 10-29 kg c = 3 x 108 ms-1

E = EE = 3.1 x 10-29 x (3 x 108)2

E = 2.79 x 10-12 J

H 2

1 +He 4

2+ n1

0H

3

1 +Energy

The energy released per fusion is 2.79 x 10-12 J.

THE SUNEvery second, the sun converts

500 million metric tons of hydrogen to helium. Due to the

process of fusion, 5 million metric tons of excess material is

converted into energy in each second. This means that every

year, 157,680,000,000,000 metric tons are converted into energy

A-BOMB vs. H-BOMB• ATOMIC BOMB (Hiroshima)

– Killed over 66,000 people instantly– 13 kilotons of TNT-equivalent– 2 exploded in warfare

• HYDROGEN BOMB– 10 megatons (million-tons) of TNT-

equivalent– NEVER exploded in warfare– Is it the bomb too big to ever be

used???

FUSION CAN BE USED• GOOD

– A controlled reaction in a reactor used to produce cleaner, inexpensive electricity

• EVIL– A fission bomb starts a fusion chain reaction

to create an incredibly powerful weapon – thermonuclear weapons (H-bombs), MUCH more destructive than atomic bombs.

FISSION VS FUSIONFission reaction does not normally occur in nature.

Fusion occurs in stars, such as the sun.

Fission produces many highly radioactive particles

Few radioactive particles are produced by fusion reaction, but if a fission "trigger" is used, radioactive particles will result from that

The energy released by fission is a million times greater than that released in chemical reactions; but lower than the energy released by nuclear fusion.

The energy released by fusion is three to four times greater than the energy released by fission.

One class of nuclear weapon is a fission bomb, also known as an atomic bomb or atom bomb

One class of nuclear weapon is the hydrogen bomb, which uses a fission reaction to "trigger" a fusion reaction

Fission is the splitting of a large atom into two or more smaller ones.

Fusion is the fusing of two or more lighter atoms into a larger one.

Critical mass of the substance and high-speed neutrons are required.

High density, high temperature environment is required.

Takes little energy to split two atoms in a fission reaction.

Extremely high energy is required to bring two or more protons close enough that nuclear forces overcome their electrostatic repulsion.

REVIEWNUCLEAR FISSION:A large nucleus splits into several small nuclei when impacted by a neutron, and energy is released in this process

NUCLEAR FUSION :Several small nuclei fuse together and release energy.

SOURCES • Fission and Fusion Animations:

http://reactor.engr.wisc.edu/fission.htm• Fission graphic:

http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/u235chn.html

• Data:http://www.w3.org/TR/xhtml1/DTD/html”http://en.wikipedia.org/wiki/Nuclear_force

Quiz• Which nuclear process produces large

amounts of energy?A. FissionB. FusionC. Both fission & fusionD. Neither fission nor fusion

• Contact: 01672-462007• Country : Bangladesh• Email: aliv_jauad@yahoo.com