NUCLEAR EXPLOSION

A 'nuclear explosion' occurs as a result of the rapid release of energy from an uncontrolled nuclear reaction. The driving reaction may be nuclear fission, nuclear fusion or a multistage cascading combination of the two, though to date all fusion based weapons have used a fission device to initiate fusion, and a pure fusion weapon remains a hypothetical device.
Atmospheric nuclear explosions are associated with "mushroom clouds" although mushroom clouds can occur with large chemical explosions and it is possible to have an air burst nuclear explosion without these clouds. Atmospheric nuclear explosions produce large amounts of radiation and radioactive debris.

Contents

History

Peaceful nuclear explosions

Nuclear weapons

Nuclear testing

Effects of nuclear explosions

History

In 1963, all nuclear and many non-nuclear states signed the Limited Test Ban Treaty, pledging to refrain from testing nuclear weapons in the atmosphere, underwater, or in outer space. The treaty permitted underground tests.
The primary application to date has been military (i.e. nuclear weapons). However, there are other potential applications, which have not yet been explored, or have been considered all but abandoned. They include:

★ Nuclear pulse propulsion, including using a nuclear explosion as asteroid deflection strategy.

★ Power generation; see PACER

★ Peaceful nuclear explosions

Peaceful nuclear explosions

'Peaceful nuclear explosions' (PNEs) are nuclear explosions conducted for non-military purposes, such as activities related to economic development including the creation of canals. During the 1960s and 1970s, both the United States and the Soviet Union conducted a number of PNEs.
Six of the explosions by the Soviet Union are considered to have been of an applied nature, not just tests.
Subsequently the United States and the Soviet Union halted their programs. Definitions and limits are covered in the Peaceful Nuclear Explosions Treaty of 1976.

Nuclear weapons

In the history of warfare, two nuclear weapons have been detonated — both by the United States, during the closing days of World War II. The first event occurred on the morning of 6 August 1945, when the United States dropped a uranium gun-type device code-named "Little Boy" on the Japanese city of Hiroshima. The second event occurred three days later when, again, the United States dropped a plutonium implosion-type device code-named "Fat Man" on the city of Nagasaki. These bombings resulted in the immediate deaths of around 120,000 people and even more over time. The use of these weapons was and remains controversial. (See ''Atomic bombings of Hiroshima and Nagasaki'' for a full discussion).

Nuclear testing

'Nuclear tests' are experiments carried out to determine the effectiveness, yield and explosive capability of nuclear weapons. Throughout the twentieth century, most nations that have developed nuclear weapons have staged tests of them. Testing nuclear weapons can yield information about how the weapons work, as well as how the weapons behave under various conditions and how structures behave when subjected to nuclear explosions. Additionally, nuclear testing has often been used as an indicator of scientific and military strength, and many tests have been overtly political in their intention; most nuclear weapons states publicly declared their nuclear status by means of a nuclear test.

Effects of nuclear explosions

The dominant effects of a nuclear weapon (the blast and thermal radiation) are the same physical damage mechanisms as conventional explosives, but the energy produced by a nuclear explosive is millions of times more per gram and the temperatures reached are in the tens of millions of degrees.