Nuclear weapon

in 1953.]]A **nuclear weapon** (also called a **nuclear bomb** or **nuke)** is a weapon that suddenly releases the energy in the nucleus of certain types of atoms. When triggered, the device releases a huge amount of energy in the form of a nuclear explosion.  

Nuclear explosions can destroy a city and kill most of its people. They also make nuclear fallout.  This radioactive material can make people ill.  Nuclear weapons are the most damaging weapons mankind has created. 

There are two types of nuclear weapons. They make energy for the nuclear explosion in different ways. The first type, fission weapons, use a special isotope of uranium or plutonium. These weapons are also called atomic bombs or A-bombs. The second type, fusion weapons, use a special isotope of hydrogen and create bigger explosions. They are also called hydrogen bombs, H-bombs, or thermonuclear weapons. 

The United States built the first nuclear weapons during World War II and used them to attack two cities in Japan. This is the only time nuclear weapons have ever been used in a war. 

Only a few nations possess such weapons or are suspected of seeking them. The only countries which have admitted detonating nuclear weapons are the United States, the Soviet Union (succeeded as a nuclear power by Russia), the United Kingdom, France, China, India, Pakistan, and North Korea. Between them, these countries have detonated over 2,000 nuclear weapons for testing and demonstration. 

Israel is believed to have nuclear weapons, but in a policy of deliberate ambiguity, does not say so.  Germany, Italy, Turkey, Belgium, and the Netherlands share nuclear weapons with other countries.  South Africa is the only country that has independently developed nuclear weapons and later renounced and dismantled them. 

Following the dissolution of the Soviet Union in 1991, Ukraine, Belarus, and Kazakhstan all inherited nuclear weapons (approximately 3300). However, all three countries chose to denuclearize in exchange for diplomatic and economic support.  

The Treaty on the *Non-Proliferation of Nuclear Weapons* aims to reduce the spread of nuclear weapons. Its effectiveness has been questioned. 
## History 
In the years after 1895, physicists began to understand how atoms are made. In 1939, physicists began to understand the theory of nuclear fission weapons, but no country knew how to build one. 

When World War II started Germany, the United Kingdom, and the United States wanted to build nuclear weapons. The United Kingdom started this work in 1939 but found it so expensive that the program was shut down in 1942. Later that year, the United States started a very large program to build nuclear weapons. It built upon the work done in the United Kingdom and was called the "Manhattan Project".

By August 1945, the Manhattan Project had built three nuclear fission weapons. The United States used two of these bombs to attack the cities of Hiroshima and Nagasaki in Japan. After these attacks, Japan surrendered and World War II ended.

According to the Manhattan Project, around 105,000 people were killed by the bombs and another 94,000 were hurt. However, many more people died later from health problems caused by nuclear fallout. Counting these people, over 225,000 individuals died from the bombings, according to medical professionals.

After World War II, the Soviet Union began working to create nuclear weapons..]]

## How they work 
### Fission weapons 
Nuclear fission weapons release energy by breaking atoms apart. This is how atomic bombs work.  

Usually, nuclear fission weapons use isotopes of uranium or plutonium. Those elements can be made to undergo nuclear fission, causing a nuclear chain reaction.  

### Fusion weapons 
Nuclear fusion weapons release much more energy and cause bigger explosions. They release energy by fusing atoms together, using hydrogen isotopes (deuterium and tritium) in addition to uranium or plutonium. They are also called thermonuclear weapons or hydrogen bombs.

Despite its name, a typical hydrogen bomb has only enough hydrogen to produce additional neutrons to detonate a casing made of natural uranium. The fuel in hydrogen bombs is thus mostly unrefined uranium.

### Effects 
Nuclear weapons produce a very large amount of energy and radiation, mostly in the form of X-rays. These heat the air to produce a huge nuclear fireball. The rapid expansion of the fireball creates a dangerous shock wave that can destroy buildings and kill living things within several kilometers.  

Not everyone who dies from a nuclear bomb dies immediately. The bombs cause nuclear fallout (nuclear material and dust that has been irradiated and become radioactive). Fallout can be blown by the wind over large distances from the explosion and can remain dangerous for long periods of time. Survivors can also suffer from radiation poisoning, which can be fatal and can result in DNA mutations that cause cancer.  

## Building nuclear weapons 
Nuclear weapons are difficult to build because they need special isotopes of uranium or plutonium, as well as specialized technology.  This is why so few countries have them.  When countries without nuclear weapons create their own, that is commonly referred to as nuclear proliferation.

## Getting nuclear weapons to target 
Getting a nuclear weapon to its target can be as hard as making one. The explosive material can be placed in a bomb or artillery shell or into a missile. When a nuclear device is placed on a missile it is commonly called a nuclear missile and can be carried by airplanes, submarines, or trucks or placed into underground missile silos. Some kinds of airplanes like the B-29 Superfortress, B-36 Peacemaker, B-52 Stratofortress, and B-2 Spirit have carried nuclear weapons. 

They are also carried by missiles, such as intercontinental ballistic missiles (ICBMs) or submarine-launched ballistic missiles (SLBMs). Some missiles travel to the border of space and then launch a number of separate nuclear weapons back toward the ground, with each weapon travelling to a different target. That is called a MIRV Warhead, or Multiple Independent Re-entry Vehicles. Very large nuclear bombs have been produced, but in practice a weapon with multiple warheads can produce much more damage by attacking more targets.

Nuclear weapons take many resources to make because the materials they are made of are rare, and it takes many scientists to make them. However, several countries have managed to create nuclear weapons and many have them today. The countries that have nuclear weapons are listed here in the order that they were invented: United States (1945), Russia (1949), United Kingdom (1952), France (1960), China (1964), India (1974), and Pakistan (1998). Other countries are believed to secretly have nuclear weapons or develop them. Some countries used to have nuclear weapons but have since then said that they have gotten rid of them. 

Some countries have lost nuclear weapons while transporting them. There are 92 known instances of atom bombs being lost at sea by all of the countries known to posses them. Bombs have been lost in 15 different cases. However, there could be more lost bombs.

## Nuclear explosions to date 
This is a list is of the main nuclear explosions which have happened. As well as the atomic bombings of Hiroshima and Nagasaki, the first nuclear test of a given weapon type for a country is included, and tests which were otherwise notable (such as the largest test ever). All yields (explosive power) are given in their estimated energy equivalents in kilotons of TNT. 

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## Compensation for victims
Over 500 atmospheric nuclear weapons tests were done at various sites around the world from 1945 to 1980. As public awareness and concern grew over the possible health hazards associated with exposure to nuclear fallout, various studies were done. A Centers for Disease Control and Prevention study says that nuclear fallout might have led to 11,000 excess deaths, most caused by thyroid cancer linked to exposure to iodine-131.

## People associated with nuclear weapons
Notable individuals who have been associated with nuclear weapons and related issues include:

* Albert Einstein
* Hermann Joseph Muller
* J. Robert Oppenheimer
* Jonathan Schell
* Edward Teller

## Related pages 
* Atomic bomb
* Nuclear deterrent
* Nuclear war

## References 
## Other websites 
* WW2DB: Operation Trinity and the Manhattan Project
* WW2DB: Destruction of Hiroshima and Nagasaki
* The natural voice of A-bomb victims. VOSHN.com  (archived)
* Nuclear weapon  Citizendium