Nuclear weapons tests are experiments carried out to determine the effectiveness, yield, and explosive capability of nuclear weapons. Throughout the 20th century, most nations that have developed nuclear weapons have tested 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.
The first nuclear weapon was detonated as a test by the United States at the Trinity site on July 16, 1945, with a yield approximately equivalent to 20 kilotons. The first hydrogen bomb, codenamed "Mike", was tested at the Enewetak atoll in the Marshall Islands on November 1 (local date) in 1952, also by the United States. The largest nuclear weapon ever tested was the "Tsar Bomba" of the Soviet Union at Novaya Zemlya on October 30, 1961, with an estimated yield of around 50 megatons.
In 1963, three (UK, US, Soviet Union) of the then four (+France) 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 nuclear testing. France continued atmospheric testing until 1974, China continued up until 1980. Neither has ever signed the treaty.
France is known to have an arsenal of weapons of mass destruction. France is one of the five "Nuclear Weapons States" under the Nuclear Non-Proliferation Treaty; but is not known to possess or develop any chemical or biological weapons. France was the fourth country to test an independently developed nuclear weapon in 1960, under the government of Charles de Gaulle. The French military is currently thought to retain a weapons stockpile of around 300 operational nuclear warheads, making it the third-largest in the world. The weapons are part of the national Force de frappe, developed in the late 1950s and 1960s to give France the ability to distance itself from NATO while having a means of nuclear deterrence under sovereign control.
France did not sign the Partial Test Ban Treaty, which gave it the option to conduct further nuclear tests until it signed and ratified the Comprehensive Test Ban Treaty in 1996 and 1998 respectively. France denies currently having chemical weapons, ratified the Chemical Weapons Convention (CWC) in 1995, and acceded to the Biological and Toxin Weapons Convention (BWC) in 1984. France had also ratified the Geneva Protocol in 1926.
A nuclear explosion is a man-made explosion that occurs as a result of the rapid release of energy from an intentionally generated high-speed 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. Nuclear explosions produce radiation and radioactive debris.
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. Supersonic explosions created by high explosives are known as detonations and travel via supersonic shock waves. Subsonic explosions are created by low explosives through a slower burning process known as deflagration.