Nuclear Weapons!! There are two basic types of nuclear weapon

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Nuclear Weapons!!

There are two basic types of nuclear weapon:

fission bombs

Atomic bombs, atom bombs, or A-bombs.

fusion bomb

hydrogen bombs, H-bombs, thermonuclear bombs, and fusion bombs.

Fission bombs (overview)

Fissile materials (Uranium-235, Plutonium-239, and Uranium-233)
Gun method and Implosion method
Little boy and fat man
Maximum yield is only 500 kt
Low efficiency at about maximum 25%

Fission Materials:

Fission Materials (cont.)

Weapon(s)-grade contains 85% or more of 235U
Though for a crude, inefficient weapon 20% is sufficient (called weapon(s)-usable);
U-235 is one of the very few atoms that can undergo induced fission.

Fission Material (cont.)

◊ Plutonium

The most important isotope of plutonium is 239Pu (half-life 24,110 years)
key fissile component in modern nuclear weapons.
It can be made from natural uranium.
Mainly used due to its ease of fissioning and availability.
The critical mass for an unreflected sphere of plutonium is 16 kg.
When use of a neutron reflecting tamper the pit of plutonium in a fission bomb is reduced to 10 kg, which is a sphere with a diameter of 10 cm.
Complete detonation of plutonium will produce an explosion of 20 kilotons of (TNT) per kilogram.

Fission Bomb Types:

Gun method:
Shooting one piece of fissile material as a projectile against a second part as a target

Dropped at altitude of 580 m

Dropped at altitude of 580 m
Yield estimate of "Little Boy" was about 15 kilotons of TNT
Approximately 70,000 people were killed as a direct result of the blast.
60 kg of 80% grade U-235 was used (hence 48 kg)

Implosion method:

Implosion method:
Uses conventional explosives surrounding the material to rapidly compress the
mass to a supercritical state.

Main problems with fission weapon:

Efficiency

The efficiency of a fission weapon is the fraction of the fissile material that actually fissions.
The maximum efficiency is calculated to be 25%.
For Little Boy only 1.4%.
For Fat Man it was 14%.

Maximum Power

“Little Boy” is about 15 kilotons of TNT
“Fat Man” is only 21 kilotons of TNT
Maximum at 500 kilotons of TNT

Fusion Bomb (Overview):

Produces a large amount of its energy through nuclear fusion
reactions.
More energy per reaction than fission
Thousand times more powerful than fission bombs.
Very efficient fuel by weight (because of light weight of element used as fusion fuel and large energy release)
Teller-Ulam design.
“Ivy Mike"

Fusion Bomb History:

The Teller-Ulam design is a nuclear weapon design that is more
colloquially referred to as "the secret of the hydrogen bomb".
It is named after two of its chief contributors, Hungarian physicist Edward Tellar and Polish mathematician Stanislow Ulam.
Design was developed in 1951.
Basic principle of the Teller-Ulam configuration is based upon the idea that different parts of a thermonuclear weapon can be chained together in
"stages" which allow for the full detonation of each (staged thermonuclear weapon).

The Way Fusion Reacts:

Combination of two light atoms, usually isotopes of hydrogen, to form a more stable heavy atom and release excess energy.

Fusion can also used for boosting:

By placing mixture of deuterium and tritium inside the hollow core of an
implosion style plutonium pit.
Imploding fission first gives sufficient pressure for fusion reaction
Then it releases a large number of energetic neutrons into the surrounding
fissile materials.
This increases the rate of burn of the fissile material, so more fissile
materials are consumed before the pit disintegrates.
Thus increase the pure fission bomb efficiency from 20% to 40 %.
Allow less fissile material for a given yield.
Avoid radiation interference (RI) by using less Plutonium.
(Plutonium pits would be particularly susceptible to partial pre-detonation
if exposed to the intense radiation of a nearby nuclear explosion. This
means one nuclear explosion can make all other nuclear weapon in close by range to explode).

Staged Thermonuclear Weapons (Teller-Ulam design):

Diagram explanation:

Steps explanation:

Fission weapon (primary) is placed at one end of the warhead casing
When detonated, it first releases X-rays.
X-rays are travel into a space surrounding the secondary part (column of lithium deuterium fusion fuel encased by a natural uranium “tamper”)
The plastic foam between the radiation casing and secondary part which is essentially just carbon and hydrogen becomes completely ionized and transparent as the x-rays penetrate.
Then the temper gets heated and ablates (causing an implosion).
Capsule is compressed to perhaps 1/30 of its original diameter, reaches or exceeds 1000 times its original density.
Fissionable rod experience an extremely violent shock wave that will heat it to high temperatures cause to compress and doing so increases its density by a factor of about 4 and cause the rod to become super-critical.
As the rod undergoes fission, it releases neutrons into the surrounding deuterium and causes some deuterium to become tritium.
Then the high temperature ignites the deuterium and tritium fuel and cause fusion reaction.
As fusion reaction explodes, it releases neutron and cause the temper to fission.

Flash of a Fusion Bomb:

All of these events happened in about 600 billionths of a second (550 billionths of a second for the fission bomb implosion, 50 billionths of a second for the fusion events).

Fusion test bombs

The first device based on this principle that was detonated by the United States is the “Ivy Mike" nuclear test on October, 1952. (0715 hours local time on November 1, 1952)
It uses cryogenic liquid deuterium.
It is measured 80 inches in diameter and 244 inches in height and weighed about 60 tons.

The blast created a crater 6,240 feet in diameter and 164 feet deep

The blast created a crater 6,240 feet in diameter and 164 feet deep
stripped the test islands clean of vegetation
the water around the blast site boiled for up to twelve hours afterwards

King of Bombs

most powerful nuclear explosive ever detonated
Developed by the Soviet Union
~50 megaton bomb
tested on October 30, 1961 in Novaya Zemlya
Detonate at a height of 4,000 m over the land surface.
The explosion could be seen and felt in Finland
Compare to the largest one tested by U.S. which was 15 megaton.

Carey Sublette. “‘Teller-Ulam’ Summary” Nuclear Weapon Archive. http://nuclearweaponarchive.org/Library/Teller.html

Carey Sublette. “‘Teller-Ulam’ Summary” Nuclear Weapon Archive. http://nuclearweaponarchive.org/Library/Teller.html
Craig C. Freudenrich, Ph.D. “How Nuclear Bombs Work” Howstuffworks .
Glasstone, Samuel and Dolan, Philip J. “The Effects of Nuclear Weapons (third edition)”. Washington, D.C.: U.S. Government Printing Office, 1977.
“Image:Teller-Ulam device firing sequence.png” Wikipedia The Free Encyclopedia. http://en.wikipedia.org/wiki/Image:Teller-Ulam_device_firing_sequence.png
“Ivy Mike” Wikipedia The Free Encyclopedia. http://en.wikipedia.org/wiki/Ivy_Mike
“Nuclear weapon” Wikipedia The Free Encyclopedia. http://en.wikipedia.org/wiki/Nuclear_Weapon
“The Tsar Bomba ("King of Bombs")” Nuclear Weapon Archive. http://nuclearweaponarchive.org/Russia/TsarBomba.html
“Tsar Bomba” Wikipedia The Free Encyclopedia. http://en.wikipedia.org/wiki/Tsar_Bomba

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Nuclear Weapons!! There are two basic types of nuclear weapon

Nuclear Weapons!!

There are two basic types of nuclear weapon:

fission bombs

fusion bomb

Fission bombs (overview)

Fissile materials (Uranium-235, Plutonium-239, and Uranium-233)

Gun method and Implosion method

Little boy and fat man

Maximum yield is only 500 kt

Low efficiency at about maximum 25%

Fission Materials:

Fission Materials (cont.)

Weapon(s)-grade contains 85% or more of 235U

Though for a crude, inefficient weapon 20% is sufficient (called weapon(s)-usable);

U-235 is one of the very few atoms that can undergo induced fission.

Fission Material (cont.)

◊ Plutonium

Fission Bomb Types:

Gun method:

Shooting one piece of fissile material as a projectile against a second part as a target

Dropped at altitude of 580 m

Dropped at altitude of 580 m

Yield estimate of "Little Boy" was about 15 kilotons of TNT

Approximately 70,000 people were killed as a direct result of the blast.

60 kg of 80% grade U-235 was used (hence 48 kg)

Implosion method:

Implosion method:

Uses conventional explosives surrounding the material to rapidly compress the

mass to a supercritical state.

Main problems with fission weapon:

Efficiency

Maximum Power

Fusion Bomb (Overview):

Produces a large amount of its energy through nuclear fusion

reactions.

More energy per reaction than fission

Thousand times more powerful than fission bombs.

Very efficient fuel by weight (because of light weight of element used as fusion fuel and large energy release)

Teller-Ulam design.

“Ivy Mike"

Fusion Bomb History:

The Teller-Ulam design is a nuclear weapon design that is more

colloquially referred to as "the secret of the hydrogen bomb".

It is named after two of its chief contributors, Hungarian physicist Edward Tellar and Polish mathematician Stanislow Ulam.

Design was developed in 1951.

Basic principle of the Teller-Ulam configuration is based upon the idea that different parts of a thermonuclear weapon can be chained together in

"stages" which allow for the full detonation of each (staged thermonuclear weapon).

The Way Fusion Reacts:

Combination of two light atoms, usually isotopes of hydrogen, to form a more stable heavy atom and release excess energy.

Fusion can also used for boosting:

By placing mixture of deuterium and tritium inside the hollow core of an

implosion style plutonium pit.

Imploding fission first gives sufficient pressure for fusion reaction

Then it releases a large number of energetic neutrons into the surrounding

fissile materials.

This increases the rate of burn of the fissile material, so more fissile

materials are consumed before the pit disintegrates.

Thus increase the pure fission bomb efficiency from 20% to 40 %.

Allow less fissile material for a given yield.

Avoid radiation interference (RI) by using less Plutonium.

(Plutonium pits would be particularly susceptible to partial pre-detonation

if exposed to the intense radiation of a nearby nuclear explosion. This

means one nuclear explosion can make all other nuclear weapon in close by range to explode).

Staged Thermonuclear Weapons (Teller-Ulam design):

Diagram explanation:

Steps explanation:

Fission weapon (primary) is placed at one end of the warhead casing

When detonated, it first releases X-rays.

X-rays are travel into a space surrounding the secondary part (column of lithium deuterium fusion fuel encased by a natural uranium “tamper”)

The plastic foam between the radiation casing and secondary part which is essentially just carbon and hydrogen becomes completely ionized and transparent as the x-rays penetrate.

Then the temper gets heated and ablates (causing an implosion).

Capsule is compressed to perhaps 1/30 of its original diameter, reaches or exceeds 1000 times its original density.

Fissionable rod experience an extremely violent shock wave that will heat it to high temperatures cause to compress and doing so increases its density by a factor of about 4 and cause the rod to become super-critical.

As the rod undergoes fission, it releases neutrons into the surrounding deuterium and causes some deuterium to become tritium.

Then the high temperature ignites the deuterium and tritium fuel and cause fusion reaction.

As fusion reaction explodes, it releases neutron and cause the temper to fission.

Flash of a Fusion Bomb:

All of these events happened in about 600 billionths of a second (550 billionths of a second for the fission bomb implosion, 50 billionths of a second for the fusion events).

Fusion test bombs