Nuclear explosion

A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage 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. It is possible to have an air-burst nuclear explosion without those clouds. Nuclear explosions produce radiation and radioactive debris.

Operation Upshot-Knothole - Badger 001
A 23 kiloton tower shot called BADGER, fired on April 18, 1953 at the Nevada Test Site, as part of the Operation Upshot–Knothole nuclear test series.
The Greenhouse George test early fireball.
Upshot–Knothole Grable test (film)


The first man made nuclear explosion occurred on July 16, 1945 at 5:50 am on the Trinity Test Site near Alamogordo, New Mexico in the United States, an area now known as the White Sands Missile Range.[1][2] The event involved the full-scale testing of an implosion-type fission atomic bomb. In a memorandum to the U.S. Secretary of War, General Leslie Groves describes the yield as equivalent to 15,000 to 20,000 tons of TNT.[3] Following this test, a uranium-gun type nuclear bomb (Little Boy) was dropped on the Japanese city of Hiroshima on August 6, 1945, with a blast yield of 15 kilotons; and a plutonium implosion-type bomb (Fat Man) on Nagasaki on August 9, 1945, with a blast yield of 21 kilotons. In the years following World War II, eight countries have conducted nuclear tests with 2475 devices fired in 2120 tests.[4]

In 1963, the United States, Soviet Union, and United Kingdom 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. Many other non-nuclear nations acceded to the Treaty following its entry into force; however, two nuclear weapons states have not acceded: France, China

The primary application to date has been military (i.e. nuclear weapons), and the remainder of explosions include the following:

Nuclear weapons

Only two nuclear weapons have been deployed in combat—both by the United States against Japan in World War II. The first event occurred on the morning of 6 August 1945, when the United States Army Air Forces dropped a uranium gun-type device, code-named "Little Boy", on the city of Hiroshima, killing 70,000 people, including 20,000 Japanese combatants and 20,000 Korean slave laborers. The second event occurred three days later when the United States Army Air Forces dropped a plutonium implosion-type device, code-named "Fat Man", on the city of Nagasaki. It killed 39,000 people, including 27,778 Japanese munitions employees, 2,000 Korean slave laborers, and 150 Japanese combatants. In total, around 109,000 people were killed in these bombings. (See Atomic bombings of Hiroshima and Nagasaki for a full discussion). Nuclear weapons are largely seen as a 'deterrent' by most governments; the sheer scale of the destruction caused by a nuclear weapon has prevented serious consideration of their use in warfare.

Nuclear testing

Since the Trinity test and excluding the combat use of nuclear weapons, mankind (those few nations with capability) has detonated roughly 1,700 nuclear explosions, all but 6 as tests. Of these, six were peaceful nuclear explosions. Nuclear 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 had a staged test 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 a nuclear explosion. 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 megakelvin. Nuclear weapons are quite different from conventional weapons because of the huge amount of explosive energy they can put out and the different kinds of effects they make, like high temperatures and nuclear radiation.

The devastating impact of the explosion does not stop after the initial blast, as with conventional explosives. A cloud of nuclear radiation travels from the epicenter of the explosion, causing an impact to life forms even after the heat waves have ceased.

Any nuclear explosion (or nuclear war) would have wide-ranging, long-term, catastrophic effects. Radioactive contamination would cause genetic mutations and cancer across many generations.[5]

See also


  1. ^ U.S. Department of Energy. "Trinity Site - World's First Nuclear Explosion". Office of Management. Retrieved 23 December 2016.
  2. ^ Taylor, Alan (July 16, 2015). "70 Years Since Trinity: The Day the Nuclear Age Began". The Atlantic. Retrieved 23 December 2016.
  3. ^ Groves, General Leslie (July 18, 1945). "The First Nuclear Test in New Mexico: Memorandum for the Secretary of War, Subject: The Test". United States War Department. Retrieved 23 December 2016.
  4. ^ Yang, Xiaoping; North, Robert; Romney, Carl; Richards, Paul G. (August 2000), Worldwide Nuclear Explosions (PDF), retrieved 2013-12-31
  5. ^ Malcolm Fraser and Tilman Ruff. 2015 is the year to ban nuclear weapons, The Age, February 19, 2015.

External links

1958 in spaceflight

Explorer 1 was the first American satellite to reach orbit on 31 January 1958.

Antibody (film)

Antibody is a 2002 science fiction thriller directed and edited by Christian McIntire that debuted as a Sci Fi Pictures TV-movie on the Sci Fi Channel on February 8, 2003.A scientist (Lance Henriksen) leads a team in an experimental miniaturized craft injected into the bloodstream of a dying terrorist (Julian Vergov) whose body conceals a computer chip that will trigger a nuclear explosion in the U.S. Capitol Building in less than 24 hours.

Effects of nuclear explosions

The effects of a nuclear explosion on its immediate vicinity are typically much more destructive and multifaceted than those caused by conventional explosives. In most cases, the energy released from a nuclear weapon detonated within the troposphere can be approximately divided into four basic categories:

the blast itself: 40–50% of total energy

thermal radiation: 30–50% of total energy

ionizing radiation: 5% of total energy (more in a neutron bomb)

residual radiation: 5–10% of total energy with the mass of the explosionDepending on the design of the weapon and the location in which it is detonated, the energy distributed to any one of these categories may be significantly higher or lower. The blast effect is created by the coupling of immense amounts of energy, spanning the electromagnetic spectrum, with the surroundings. The environment of the explosion (e.g. submarine, ground burst, air burst, or exo-atmospheric) determines how much energy is distributed to the blast and how much to radiation. In general, surrounding a bomb with denser media, such as water, absorbs more energy and creates more powerful shockwaves while at the same time limiting the area of its effect. When a nuclear weapon is surrounded only by air, lethal blast and thermal effects proportionally scale much more rapidly than lethal radiation effects as explosive yield increases. The physical-damage mechanisms of a nuclear weapon (blast and thermal radiation) are identical to those of conventional explosives, but the energy produced by a nuclear explosion is usually millions of times more powerful per unit mass and temperatures may briefly reach the tens of millions of degrees.

Energy from a nuclear explosion is initially released in several forms of penetrating radiation. When there is a surrounding material such as air, rock, or water, this radiation interacts with and rapidly heats the material to an equilibrium temperature (i.e. so that the matter is at the same temperature as the fuel powering the explosion). This causes vaporization of the surrounding material, resulting in its rapid expansion. Kinetic energy created by this expansion contributes to the formation of a shockwave. When a nuclear detonation occurs in air near sea level, much of the released energy interacts with the atmosphere and creates a shockwave which expands spherically from the center. Intense thermal radiation at the hypocenter forms a nuclear fireball which, if the burst is low enough, is often associated with a mushroom cloud. In a high-altitude burst, where the density of the atmosphere is low, more energy is released as ionizing gamma radiation and X-rays than as an atmosphere-displacing shockwave.

In 1942, there was some initial speculation among the scientists developing the first nuclear weapons that a large enough nuclear explosion might ignite the Earth's atmosphere. This notion concerned the nuclear reaction of two atmospheric nitrogen atoms forming a carbon and an oxygen atom, with an associated release of energy. The scientists hypothesized that this energy would heat up the remaining atmospheric nitrogen enough to keep the reaction going until all nitrogen atoms were consumed, thereby burning all of the Earth's atmosphere (which is composed of nearly 80% diatomic nitrogen) in one single massive combustion event. Hans Bethe was assigned the task of studying this hypothesis in the very early days, and eventually concluded that combustion of the entire atmosphere was not possible: the cooling of the fireball due to an inverse Compton effect all but guaranteed that such a scenario would not become a reality. Richard Hamming, a mathematician, was asked to make a similar calculation just before Trinity, with the same result. Nevertheless, the notion has persisted as a rumor for many years and was the source of gallows humor at the Trinity test.

Fallout shelter

A fallout shelter is an enclosed space specially designed to protect occupants from radioactive debris or fallout resulting from a nuclear explosion. Many such shelters were constructed as civil defense measures during the Cold War.

During a nuclear explosion, matter vaporized in the resulting fireball is exposed to neutrons from the explosion, absorbs them, and becomes radioactive. When this material condenses in the rain, it forms dust and light sandy materials that resemble ground pumice. The fallout emits alpha and beta particles, as well as gamma rays.

Much of this highly radioactive material falls to earth, subjecting anything within the line of sight to radiation, becoming a significant hazard. A fallout shelter is designed to allow its occupants to minimize exposure to harmful fallout until radioactivity has decayed to a safer level.


Fizzle may refer to:

Fizzle (nuclear explosion), a nuclear weapons term

Luke's Fireworks Fizzle, a 1916 short comedy film

Fizzle Promotions, a Music promoters

Battle of Fort Fizzle, an American Civil War

Fizzle Like A Flood, a moniker Doug Kabourek

Fizzles, a short stories by Samuel Beckett

Fizzle (Transformers), a fictional character, member of the Sparkabots

Fizzle (nuclear explosion)

A fizzle occurs when the detonation of a device for creating a nuclear explosion (such as a nuclear weapon) grossly fails to meet its expected yield. The cause(s) for the failure can be linked to improper design, poor construction, or lack of expertise. All countries that have had a nuclear weapons testing program have experienced some fizzles. A fizzle can spread radioactive material throughout the surrounding area, involve a partial fission reaction of the fissile material, or both. For practical purposes, a fizzle can still have considerable explosive yield when compared to conventional weapons.

In multistage fission-fusion weapons, full yield of the fission primary that fails to initiate fusion ignition in the fusion secondary is also considered a "fizzle", as the weapon failed to reach its design yield despite the fission primary working correctly. Such fizzles can have very high yields, as in the case of Castle Koon, where the secondary stage of a device with a 1 megaton design fizzled, but its primary still generated a yield of 110 kilotons.

Flash blindness

Flash blindness is an either temporary or permanent visual impairment during and following exposure of a varying length of time to a light flash of extremely high intensity, such as a nuclear explosion, flash photograph, or extremely bright light, i.e. a searchlight or laser pointer. The bright light overwhelms the retinas of the eyes and generally gradually fades, lasting anywhere from a few seconds to a few minutes. However, if the eyes are exposed to a high enough level of light, such as a nuclear explosion, the blindness can become permanent.

Flash blindness may also occur in everyday life. For example, the subject of a flash photograph can be temporarily flash blinded. This phenomenon is leveraged in non-lethal weapons such as flash grenades and laser dazzlers.

High-altitude nuclear explosion

High-altitude nuclear explosions are the result of nuclear weapons testing. Several such tests were performed at high altitudes by the United States and the Soviet Union between 1958 and 1962.


A hypocenter (or hypocentre) (from Ancient Greek: ὑπόκεντρον [hypόkentron] for 'below the center') is the point of origin of an earthquake or a subsurface nuclear explosion. In seismology, it is a synonym of the focus. The term hypocenter is also used as a synonym for ground zero, the surface point directly beneath a nuclear airburst.


Megadeath (or megacorpse) is one million human deaths, usually caused by a nuclear explosion. The term was used by scientists and thinkers who strategized likely outcomes of all-out nuclear warfare.

Narasimhiah Seshagiri

Narasimhiah Seshagiri (born 1941) was an Indian computer scientist, writer and a former director-general of the National Informatics Centre, an apex organization of the Government of India, handling its e-governance applications. He was a member of the Y2K Action Force of the Government, formed to combat the 9999 computer bug. He is credited with many publications which included The bomb! : fallout of India's nuclear explosion and Information systems for economies in transition. The Government of India awarded him the third highest civilian honour of the Padma Bhushan, in 2005, for his contributions to science and technology.

Nuclear weapons testing

Nuclear weapons tests are experiments carried out to determine the effectiveness, yield, and explosive capability of nuclear weapons. Testing nuclear weapons offers practical information about how the weapons function, as well as how detonations are affected by different conditions; and how personnel, structures, and equipment are affected when subjected to nuclear explosions. However, 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 device 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 of TNT. The first thermonuclear weapon technology test of an engineered device, codenamed "Ivy Mike", was tested at the Enewetak Atoll in the Marshall Islands on November 1, 1952 (local date), 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 the largest yield ever seen, an estimated 50–58 megatons.

In 1963, three (UK, US, Soviet Union) of the four nuclear states 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, and China continued until 1980. Neither has signed the treaty.Underground tests in the United States continued until 1992 (its last nuclear test), the Soviet Union until 1990, the United Kingdom until 1991, and both China and France until 1996. In signing the Comprehensive Nuclear-Test-Ban Treaty in 1996, these states have pledged to discontinue all nuclear testing; the treaty has not yet entered into force because of failure to be ratified by eight countries. Non-signatories India and Pakistan last tested nuclear weapons in 1998. North Korea conducted nuclear tests in 2006, 2009, 2013, 2016, and 2017. The most recent confirmed nuclear test occurred in September 2017 in North Korea.

Object 279

Object 279 Kotin (Объект 279 Котин) was a Soviet experimental heavy tank developed at the end of 1959.

This special purpose tank was intended to fight on cross country terrain, inaccessible to conventional tanks, acting as a heavy breakthrough tank, and if necessary withstanding even the shockwave of a nuclear explosion. It was planned as a tank of the Supreme Command Reserve.

Peaceful nuclear explosion

Peaceful nuclear explosions (PNEs) are nuclear explosions conducted for non-military purposes. Proposed uses include excavation for the building of canals and harbours, electrical generation, the use of nuclear explosions to drive spacecraft, and as a form of wide-area fracking. PNEs were an area of some research from the late 1950s into the 1980s, primarily in the United States and Soviet Union.

In the U.S., a series of tests were carried out under Project Plowshare. Some of the ideas considered included blasting a new Panama Canal, the use of underground explosions to create electricity, and a variety of geological studies. The largest of the excavation tests was carried out in the Sedan nuclear test in 1962, which released large amounts of radioactive gas into the air. By the late 1960s, public opposition to Plowshare was increasing, and a 1970s study of the economics of the concepts suggested they had no practical use. Plowshare saw decreasing interest from the 1960s, and was officially cancelled in 1977.

The Soviet program started a few years after the U.S. efforts and explored many of the same concepts under their Nuclear Explosions for the National Economy program. The program was more extensive, eventually conducting 239 nuclear explosions. Some of these tests also released radioactivity, including a significant release of plutonium into the groundwater and the polluting of an area near the Volga River. A major part of the program in the 1970s and 80s was the use of very small bombs to produce shock waves as a seismic measuring tool, and as part of these experiments, two bombs were successfully used to seal blown-out oil wells. The program officially ended in 1988.

As part of ongoing arms control efforts, both programs came to be controlled by a variety of agreements. Most notable among these is the 1976 Treaty on Underground Nuclear Explosions for Peaceful Purposes (PNE Treaty). The Comprehensive Nuclear-Test-Ban Treaty of 1996 prohibits all nuclear explosions, regardless of whether they are for peaceful purposes or not. Since that time the topic has been raised several times, often as a method of asteroid impact avoidance.

Smiling Buddha

Smiling Buddha (MEA designation: Pokhran-I) was the assigned code name of India's first successful nuclear bomb test on 18 May 1974. The bomb was detonated on the army base Pokhran Test Range (PTR), in Rajasthan, by the Indian Army under the supervision of several key Indian generals.Pokhran-I was also the first confirmed nuclear weapons test by a nation outside the five permanent members of the United Nations Security Council. Officially, the Indian Ministry of External Affairs (MEA) characterised this test as a "peaceful nuclear explosion".

Trinity (nuclear test)

Trinity was the code name of the first detonation of a nuclear device. It was conducted by the United States Army at 5:29 a.m. on July 16, 1945, as part of the Manhattan Project. The test was conducted in the Jornada del Muerto desert about 35 miles (56 km) southeast of Socorro, New Mexico, on what was then the USAAF Alamogordo Bombing and Gunnery Range, now part of White Sands Missile Range. The only structures originally in the vicinity were the McDonald Ranch House and its ancillary buildings, which scientists used as a laboratory for testing bomb components. A base camp was constructed, and there were 425 people present on the weekend of the test.

The code name "Trinity" was assigned by J. Robert Oppenheimer, the director of the Los Alamos Laboratory, inspired by the poetry of John Donne. The test was of an implosion-design plutonium device, informally nicknamed "The Gadget", of the same design as the Fat Man bomb later detonated over Nagasaki, Japan, on August 9, 1945. The complexity of the design required a major effort from the Los Alamos Laboratory, and concerns about whether it would work led to a decision to conduct the first nuclear test. The test was planned and directed by Kenneth Bainbridge.

Fears of a fizzle led to the construction of a steel containment vessel called Jumbo that could contain the plutonium, allowing it to be recovered, but Jumbo was not used. A rehearsal was held on May 7, 1945, in which 108 short tons (96 long tons; 98 t) of high explosive spiked with radioactive isotopes were detonated. The Gadget's detonation released the explosive energy of about 22 kilotons of TNT (92 TJ). Observers included Vannevar Bush, James Chadwick, James Conant, Thomas Farrell, Enrico Fermi, Richard Feynman, Leslie Groves, Robert Oppenheimer, Geoffrey Taylor, Richard Tolman and John von Neumann.

The test site was declared a National Historic Landmark district in 1965, and listed on the National Register of Historic Places the following year.

Underground nuclear weapons testing

Underground nuclear testing is the test detonation of nuclear weapons that is performed underground. When the device being tested is buried at sufficient depth, the explosion may be contained, with no release of radioactive materials to the atmosphere.

The extreme heat and pressure of an underground nuclear explosion causes changes in the surrounding rock. The rock closest to the location of the test is vaporised, forming a cavity. Farther away, there are zones of crushed, cracked, and irreversibly strained rock. Following the explosion, the rock above the cavity may collapse, forming a rubble chimney. If this chimney reaches the surface, a bowl-shaped subsidence crater may form.

The first underground test took place in 1951; further tests provided information that eventually led to the signing of the Limited Test Ban Treaty in 1963, which banned all nuclear tests except for those performed underground. From then until the signing of the Comprehensive Test Ban Treaty in 1996, most nuclear tests were performed underground, in order to prevent nuclear fallout from entering into the atmosphere.

Underwater explosion

An underwater explosion (also known as an UNDEX) is a chemical or nuclear explosion that occurs under the surface of a body of water.

Vela incident

The Vela incident, also known as the South Atlantic Flash, was an unidentified double flash of light detected by an American Vela Hotel satellite on 22 September 1979 near the Prince Edward Islands in the Indian Ocean.

The cause of the flash remains officially unknown, and some information about the event remains classified. While it has been suggested that the signal could have been caused by a meteoroid hitting the satellite, the previous 41 double flashes detected by the Vela satellites were caused by nuclear weapons tests. Today, most independent researchers believe that the 1979 flash was caused by a nuclear explosion — perhaps an undeclared nuclear test carried out by South Africa and Israel.


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