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Encyclopedia > Nuclear explosion
It has been suggested that Nuclear explosive be merged into this article or section. (Discuss)
 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.
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.
Nuclear weapons
One of the first nuclear bombs.
Nuclear weapons history
Nuclear warfare
Nuclear arms race
Nuclear weapon design
Nuclear explosion
Nuclear testing
Nuclear delivery
Nuclear proliferation
Nuclear countries

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. Image File history File links Please see the file description page for further information. ... A nuclear explosive is an explosive device that derives its energy from nuclear reactions. ... Image File history File links Download high resolution version (1151x953, 205 KB) Nuclear fireball from a US nuclear test. ... Image File history File links Download high resolution version (1151x953, 205 KB) Nuclear fireball from a US nuclear test. ... November 1951 nuclear test at Nevada Test Site. ... Operation Upshot-Knothole was a series of eleven nuclear test shots conducted in 1953 at the Nevada Test Site. ... A nuclear test explosion is an experiment involving the detonation of a nuclear weapon. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 km (11 mi) above the hypocenter. ... Image File history File links A picture of a mockup of the Fat Man nuclear device, from http://www. ... A nuclear fireball lights up the night in a United States nuclear test. ... Nuclear explosions have a distinctive mushroom shaped cloud. ... US (blue) and USSR/Russian (red) nuclear weapons stockpiles, 1945-2004. ... The first nuclear weapons, though large, cumbersome and inefficient, provided the basic design building blocks of all future weapons. ... A nuclear test explosion is an experiment involving the detonation of a nuclear weapon. ... Nuclear weapons delivery is the technology and systems used to place a nuclear weapon at the position of detonation, on or near its intended target. ... World map with nuclear weapons development status represented by color. ... There are currently seven states that have successfully exploded nuclear weapons. ... In nuclear physics, a nuclear reaction is a process in which two nuclei or nuclear particles collide, to produce products different to the initial products. ... An induced nuclear fission event. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ...


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 large amounts of radiation and radioactive debris. The atomic bombing of Nagasaki, Japan on August 9, 1945 A mushroom cloud is a distinctive mushroom-shaped cloud of smoke, flame, or debris resulting from a very large explosion. ... Radiation has a variety of different meanings. ... Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ...


The primary application to date has been military i.e. nuclear weapons however, potential other applications which have not yet applied, or the idea was considered but abandoned include: The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 km (11 mi) above the hypocenter. ...

Contents

An artists conception of a spacecraft powered by nuclear pulse propulsion Nuclear pulse propulsion (or External Pulsed Plasma Propulsion, as it is termed in one recent NASA document) is a proposed method of spacecraft propulsion that uses nuclear explosions for thrust. ... Artists impression of a major impact event. ... The Sun is a natural fusion reactor. ... Pacer could refer to: A type of British train, see Pacer (train). ... Chagan (nuclear test) in Soviet Union 1965 was used to create a dam on Semipalatinsk river Peaceful nuclear explosions (PNEs) are nuclear explosions conducted for non-military purposes, such as activities related to economic development including the creation of canals. ...


History

A nuclear explosion (nuclear detonation) has occurred on Earth:

The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 km (11 mi) above the hypocenter. ... The Fat Man mushroom cloud resulting from the nuclear explosion over Nagasaki rises 18 km (60,000 ft) into the air from the hypocenter. ... A nuclear test explosion is an experiment involving the detonation of a nuclear weapon. ... Chagan (nuclear test) in Soviet Union 1965 was used to create a dam on Semipalatinsk river Peaceful nuclear explosions (PNEs) are nuclear explosions conducted for non-military purposes, such as activities related to economic development including the creation of canals. ... The 1962 Sedan plowshares shot displaced 12 million tons of earth and created a crater 320 feet deep and 1,280 feet wide. ... Nuclear Explosions for the National Economy was a Soviet program to investigate peaceful uses of nuclear weapons (PNEs). ...

Milestone nuclear explosions

The following list is of milestone nuclear explosions. In addition to 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 (see megaton). The Fat Man mushroom cloud resulting from the nuclear explosion over Nagasaki rises 18 km (60,000 ft) into the air from the hypocenter. ... Trinitrotoluene (TNT, or Trotyl) is a pale yellow crystalline aromatic hydrocarbon compound that melts at 354 K (178 Â°F, 81 °C). ... A megaton or megatonne is a unit of mass equal to 1,000,000 metric tons, i. ...

Date Name Yield (kt) Country Significance
Jul 16 1945 Trinity 19 United States USA First fission weapon test
Aug 6 1945 Little Boy 15 United States USA Bombing of Hiroshima, Japan
Aug 9 1945 Fat Man 21 United States USA Bombing of Nagasaki, Japan
Aug 29 1949 Joe 1 22 Soviet Union USSR First fission weapon test by the USSR
Oct 3 1952 Hurricane 25 United Kingdom UK First fission weapon test by the UK
Nov 1 1952 Ivy Mike 10,200 United States USA First "staged" thermonuclear weapon test (not deployable)
Aug 12 1953 Joe 4 400 Soviet Union USSR First fusion weapon test by the USSR (not "staged", but deployable)
Mar 1 1954 Castle Bravo 15,000 United States USA First deployable "staged" thermonuclear weapon; fallout accident
Nov 22 1955 RDS-37 1,600 Soviet Union USSR First "staged" thermonuclear weapon test by the USSR (deployable)
Nov 8 1957 Grapple X 1,800 United Kingdom UK First (successful) "staged" thermonuclear weapon test by the UK
Feb 13 1960 Gerboise Blue 60 France France First fission weapon test by France
Oct 31 1961 Tsar Bomba 50,000 Soviet Union USSR Largest thermonuclear weapon ever tested
Oct 16 1964 596 22 China First fission weapon test by China
Jun 17 1967 Test No. 6 3,300 China First "staged" thermonuclear weapon test by China
Aug 24 1968 Canopus 2,600 France France First "staged" thermonuclear test by France
May 18 1974 Smiling Buddha 12 India India First fission "peaceful nuclear explosive" test by India
May 11 1998 Shakti I 43 India India First potential fusion/boosted weapon test by India
(exact yields disputed, between 25kt to 45kt)
May 13 1998 Shakti II 12 India India First fission "weapon" test by India
May 28 1998 Chagai-I 9 Pakistan Pakistan First fission weapon test by Pakistan

"Deployable" refers to whether the device tested could be hypothetically used in actual combat (in contrast with a proof-of-concept device). "Staging" refers to whether it was a "true" hydrogen bomb of the so-called Teller-Ulam configuration or simply a form of a boosted fission weapon. For a more complete list of nuclear test series, see List of nuclear tests. Some exact yield estimates, such as that of the Tsar Bomba and the tests by India and Pakistan in 1998, are somewhat contested among specialists. // The explosive yield of a nuclear weapon is the amount of energy discharged when the weapon is detonated, expressed usually in the equivalent mass of trinitrotoluene (TNT), either in kilotons (thousands of tons of TNT) or megatons (million of tons of TNT), but sometimes also in terajoules (1 kiloton of... July 16 is the 197th day (198th in leap years) of the year in the Gregorian Calendar, with 168 days remaining. ... 1945 (MCMXLV) was a common year starting on Monday (link will take you to calendar). ... An early stage in the Trinity fireball. ... Image File history File links Flag_of_the_United_States. ... August 6 is the 218th day of the year in the Gregorian Calendar (219th in leap years), with 147 days remaining. ... 1945 (MCMXLV) was a common year starting on Monday (link will take you to calendar). ... This article is the current French Translation of the Month. ... Image File history File links Flag_of_the_United_States. ... The Fat Man mushroom cloud resulting from the nuclear explosion over Nagasaki rises 18 km (60,000 ft) into the air from the hypocenter. ... Main keep of Hiroshima Castle The city of Hiroshima (広島市; -shi) is the capital of Hiroshima Prefecture, and the largest city in the Chugoku region of western Honshu, the largest of Japans islands. ... August 9 is the 221st day of the year in the Gregorian Calendar (222nd in leap years), with 144 days remaining. ... 1945 (MCMXLV) was a common year starting on Monday (link will take you to calendar). ... A post-war Fat Man model. ... Image File history File links Flag_of_the_United_States. ... The Fat Man mushroom cloud resulting from the nuclear explosion over Nagasaki rises 18 km (60,000 ft) into the air from the hypocenter. ... Megane-bashi, the Eyeglasses Bridge Nagasaki (長崎市; -shi) is the capital and the largest city of Nagasaki Prefecture located at the south-western coast of Kyushu, Japan. ... August 29 is the 241st day of the year in the Gregorian Calendar (242nd in leap years), with 124 days remaining. ... 1949 (MCMXLIX) is a common year starting on Saturday. ... External links http://gawain. ... Image File history File links Flag_of_the_Soviet_Union. ... October 3 is the 276th day of the year (277th in leap years) in the Gregorian Calendar. ... 1952 (MCMLII) was a Leap year starting on Tuesday (link will take you to calendar). ... Operation Hurricane was the test of the first British atomic bomb. ... Image File history File links Flag_of_the_United_Kingdom. ... November 1 is the 305th day of the year (306th in leap years) in the Gregorian Calendar, with 60 days remaining. ... 1952 (MCMLII) was a Leap year starting on Tuesday (link will take you to calendar). ... The mushroom cloud from the Mike shot. ... Image File history File links Flag_of_the_United_States. ... August 12 is the 224th day of the year (225th in leap years) in the Gregorian Calendar. ... 1953 (MCMLIII) is a common year starting on Thursday. ... The first (not true) Soviet Hydrogen (Super) Test, dubbed Joe 4 Joe 4 was an American nickname for the first Soviet test of a hydrogen bomb and was on August 12, 1953. ... Image File history File links Flag_of_the_Soviet_Union. ... March 1 is the 60th day of the year in the Gregorian calendar (61st in leap years). ... 1954 (MCMLIV) was a common year starting on Friday of the Gregorian calendar. ... A black and white photograph of the Castle Bravo mushroom cloud. ... Image File history File links Flag_of_the_United_States. ... Fallout is the residual radiation hazard from a nuclear explosion and is named from the fact that it falls out of the atmosphere in to which it is spread during the explosion. ... November 22 is the 326th day (327th on leap years) of the year in the Gregorian calendar. ... 1955 (MCMLV in Roman) was a common year starting on Saturday of the Gregorian calendar. ... RDS-37 was a Soviet name for their first nuclear test of a true hydrogen bomb. ... Image File history File links Flag_of_the_Soviet_Union. ... November 8 is the 312th day of the year (313th in leap years) in the Gregorian Calendar, with 53 days remaining. ... 1957 (MCMLVII) was a common year starting on Tuesday of the Gregorian calendar. ... Operation Grapple: Grapple X Valiant XD824 being bombed-up behind canvas screens Operation Grapple was a United Kingdom tri-service exercise leading to the detonation of the first British hydrogen bomb on May 15, 1957. ... Image File history File links Flag_of_the_United_Kingdom. ... February 13 is the 44th day of the year in the Gregorian calendar. ... 1960 (MCMLX) was a leap year starting on Friday (link will take you to calendar). ... France is said to have an arsenal of 350 nuclear weapons stockpiled as of 2002 [1]. The weapons are part of the national Force de frappe. ... Image File history File links Flag_of_France. ... October 31 is the 304th day of the year (305th in leap years) in the Gregorian Calendar, with 61 days remaining, as the final day of October. ... 1961 (MCMLXI) was a common year starting on Sunday (link will take you to calendar). ... Tsar Bomba casing on display at Arzamas-16 // Tsar Bomba (Russian: , literally Emperor of bombs) is the Western name for the largest nuclear explosive ever detonated. ... Image File history File links Flag_of_the_Soviet_Union. ... October 16 is the 289th day of the year (290th in Leap years). ... For the Nintendo 64 emulator, see 1964 (Emulator). ... The Peoples Republic of China is said to have an arsenal of about 400 nuclear weapons stockpiled as of 1999, although this number is questionable because the Chinese government releases little information regarding nuclear weapons. ... Image File history File links Flag_of_the_Peoples_Republic_of_China. ... June 17 is the 168th day of the year in the Gregorian calendar (169th in leap years), with 197 days remaining. ... 1967 (MCMLXVII) was a common year starting on Sunday of the Gregorian calendar. ... The Peoples Republic of China is said to have an arsenal of about 400 nuclear weapons stockpiled as of 1999, although this number is questionable because the Chinese government releases little information regarding nuclear weapons. ... Image File history File links Flag_of_the_Peoples_Republic_of_China. ... August 24 is the 236th day of the year in the Gregorian Calendar (237th in leap years), with 129 days remaining. ... 1968 (MCMLXVIII) was a leap year starting on Monday (the link is to a full 1968 calendar). ... France is said to have an arsenal of 350 nuclear weapons stockpiled as of 2002 [1]. The weapons are part of the national Force de frappe. ... Image File history File links Flag_of_France. ... May 18 is the 138th day of the year in the Gregorian Calendar (139th in leap years). ... 1974 (MCMLXXIV in Roman) is a common year starting on Tuesday (click on link for calendar). ... The Smiling Buddha was the first test fission explosion by India on May 18, 1974. ... Image File history File links Flag_of_India. ... May 11 is the 131st day of the year in the Gregorian Calendar (132nd in leap years). ... 1998 (MCMXCVIII in Roman) is a common year starting on Thursday of the Gregorian calendar, and was designated the International Year of the Ocean. ... Operation Shakti refers to the second round of nuclear tests conducted by India on May 11 and May 13, 1998. ... Image File history File links Flag_of_India. ... May 13 is the 133rd day of the year in the Gregorian Calendar (134th in leap years). ... 1998 (MCMXCVIII in Roman) is a common year starting on Thursday of the Gregorian calendar, and was designated the International Year of the Ocean. ... Operation Shakti refers to the second round of nuclear tests conducted by India on May 11 and May 13, 1998. ... Image File history File links Flag_of_India. ... May 28 is the 148th day of the year in the Gregorian calendar (149th in leap years). ... 1998 (MCMXCVIII in Roman) is a common year starting on Thursday of the Gregorian calendar, and was designated the International Year of the Ocean. ... Television screenshot of the first known nuclear test conducted by Pakistan, 28 May 1998. ... Image File history File links Flag_of_Pakistan. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, in 1945 lifted nuclear fallout some 18 km (60,000 feet) above the epicenter. ... The basics of the Teller-Ulam configuration: a fission bomb suspended above fusion fuel. ... Boosted fission weapons are a type of nuclear bomb that uses a small amount of fusion fuel to increase the rate, and thus yield, of a fission reaction. ... The following is a list of nuclear test series designations, organized first by country and then by date. ... Tsar Bomba casing on display at Arzamas-16 // Tsar Bomba (Russian: , literally Emperor of bombs) is the Western name for the largest nuclear explosive ever detonated. ...


Effects of a nuclear explosion

The energy released from a nuclear weapon comes in four primary categories:

  • Blast—40-60% of total energy
  • Thermal radiation—30-50% of total energy
  • Ionizing radiation—5% of total energy
  • Residual radiation (fallout)—5-10% of total energy
An American nuclear test.
An American nuclear test.

However, the above values vary depending on the design of the weapon, and the environment in which it is detonated. The interaction of the X-rays and debris with the surroundings determines how much energy is produced as blast and how much as light. In general, the denser the medium around the bomb, the more it will absorb, and the more powerful the shockwave will be. Thermal radiation drops off the slowest with distance, so the larger the weapon the more important this effect becomes. Ionizing radiation is strongly absorbed by air, so it is only dangerous by itself for smaller weapons. Blast damage falls off more quickly than thermal radiation but more slowly than ionizing radiation. ImageMetadata File history File links Download high resolution version (559x700, 396 KB) 155kiloton atomic explosion, from a 1951 US nuclear test at the Nevada Test Site. ... ImageMetadata File history File links Download high resolution version (559x700, 396 KB) 155kiloton atomic explosion, from a 1951 US nuclear test at the Nevada Test Site. ... A nuclear test explosion is an experiment involving the detonation of a nuclear weapon. ...


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. This article is concerned solely with chemical explosives. ...


The energy of a nuclear explosive is initially released in the form of gamma rays and neutrons. When there is a surrounding material such as air, rock, or water, this radiation interacts with the material, rapidly heating it to an equilibrium temperature in about a microsecond. The hot material emits thermal radiation, mostly soft X-rays, which accounts for 75% of the energy of the explosion. In addition, the heating and vaporization of the surrounding material causes it to rapidly expand and the kinetic energy of this expansion accounts for almost all of the remaining energy. This article is about electromagnetic radiation. ... Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939. ... A microsecond is an SI unit of time equal to one millionth (10-6) of a second. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Kinetic energy is energy that a body has as a result of its speed or energy of motion. ...


When a nuclear detonation occurs in air near sea level, most of the soft X-rays in the primary thermal radiation are absorbed within a few feet. Some energy is reradiated in the ultraviolet, visible light and infrared, but most of the energy heats a spherical volume of air. This forms a fireball and its associated effects. Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of microwave radiation. ... The term fireball is often used in reference to any large explosion or burst of fire. ... Nuclear explosion photographed less than 1/1000 of a second after detonation. ...


In a burst at high altitudes, where the air density is low, the soft X-rays travel long distances before they are absorbed. The energy is so diluted that the blast wave may be half as strong or less. The rest of the energy is dissipated as a more powerful thermal pulse.


In 1945 there was some initial speculation among the scientists developing the first nuclear weapons that there might be a possibility of igniting the Earth's atmosphere with a large enough nuclear explosion. This would concern a nuclear reaction of two nitrogen atoms forming a carbon and an oxygen atom, with release of energy. This energy would heat up the remaining nitrogen enough to keep the reaction going until all nitrogen were finished. This was, however, quickly shown to be unlikely enough to be considered impossible [1]. Nevertheless, the notion has persisted as a rumour for many years. Layers of Atmosphere (NOAA) Earths atmosphere is a layer of gases surrounding the planet Earth and retained by the Earths gravity. ...


Direct effects

Blast damage

Overpressure ranges from 1 to 50 psi of a 1 kiloton of TNT air burst as a function of burst height. The thin black curve indicates the optimum burst height for a given ground range.
Overpressure ranges from 1 to 50 psi of a 1 kiloton of TNT air burst as a function of burst height. The thin black curve indicates the optimum burst height for a given ground range.

The high temperatures and pressures cause gas to move outward radially in a thin, dense shell called "the hydrodynamic front." The front acts like a piston that pushes against and compresses the surrounding medium to make a spherically expanding shock wave. At first, this shock wave is inside the surface of the developing fireball, which is created in a volume of air by the X-rays. However, within a fraction of a second the dense shock front obscures the fireball, making the characteristic double pulse of light seen from a nuclear detonation. Download high resolution version (1902x1300, 103 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (1902x1300, 103 KB) Wikipedia does not have an article with this exact name. ... In fluid dynamics, a shock wave is a nonlinear or discontinuous pressure wave. ...


Much of the destruction caused by a nuclear explosion is due to blast effects. Most buildings, except reinforced or blast-resistant structures, will suffer moderate to severe damage when subjected to overpressures of only 35.5 kilopascals (kPa) (5.15 pounds-force per square inch or 0.35 atm). The pascal (symbol Pa) is the SI unit of pressure. ... Pounds-force per square inch (lbf/in²) is a non-SI unit of pressure. ...


The blast wind may exceed several hundred km/h. The range for blast effects increases with the explosive yield of the weapon and also depends on the burst altitude. Contrary to what one might expect from geometry the blast range is not maximal for surface or low altitude blasts but increases with altitude up to an "optimum burst altitude" and then decreases rapidly for higher altitudes. This is due to the nonlinear behaviour of shock waves. If the blast wave reaches the ground it is reflected. Below a certain reflection angle the reflected wave and the direct wave merge and form a reinforced horizontal wave, the so-called Mach stem (named after Ernst Mach). For each goal overpressure there is a certain optimum burst height at which the blast range is maximized. In a typical air burst, where the blast range is maximized for 5 to 20 psi (35 to 140 kPa) , these values of overpressure and wind velocity noted above will prevail at a range of 0.7 km for 1 kiloton (kt) of TNT yield; 3.2 km for 100 kt; and 15.0 km for 10 megatons (Mt) of TNT. Ernst Mach Ernst Mach (February 18, 1838 – February 19, 1916) was an Austrian-Czech physicist and philosopher and is the namesake for the Mach number and the optical illusion known as Mach bands. ... A megaton or megatonne is a unit of mass equal to 1,000,000 metric tons, i. ... A megaton or megatonne is a unit of mass equal to 1,000,000 metric tons, i. ...


Two distinct, simultaneous phenomena are associated with the blast wave in air:

  • Static overpressure, i.e., the sharp increase in pressure exerted by the shock wave. The overpressure at any given point is directly proportional to the density of the air in the wave.
  • Dynamic pressures, i.e., drag exerted by the blast winds required to form the blast wave. These winds push, tumble and tear objects.

Most of the material damage caused by a nuclear air burst is caused by a combination of the high static overpressures and the blast winds. The long compression of the blast wave weakens structures, which are then torn apart by the blast winds. The compression, vacuum and drag phases together may last several seconds or longer, and exert forces many times greater than the strongest hurricane.


Acting on the human body, the shock waves cause pressure waves through the tissues. These waves mostly damage junctions between tissues of different densities (bone and muscle) or the interface between tissue and air. Lungs and the gut, which contain air, are particularly injured. The damage causes severe hemorrhaging or air embolisms, either of which can be rapidly fatal. The overpressure estimated to damage lungs is about 70 kPa. Some eardrums would probably rupture around 22 kPa (0.2 atm) and half would rupture between 90 and 130 kPa (0.9 to 1.2 atm). Grays illustration of a human femur, a typically recognized bone. ... A top-down view of skeletal muscle Muscle is the contractile tissue of the body and is derived from the mesodermal layer of embryonic germ cells. ... The lungs flank the heart and great vessels in the chest cavity. ... The tympanic membrane, colloquially known as the eardrum, is a thin membrane that separates the external ear from the middle ear. ...


Blast Winds: The drag energies of the blast winds are proportional to the cubes of their velocities multiplied by the durations. These winds may reach several hundred kilometers per hour.


Thermal radiation

Nuclear weapons emit large amounts of electromagnetic radiation as visible, infrared, and ultraviolet light. The chief hazards are burns and eye injuries. On clear days, these injuries can occur well beyond blast ranges. The light is so powerful that it can start fires that spread rapidly in the debris left by a blast. The range of thermal effects increases markedly with weapon yield. Electromagnetic radiation can be conceptualized as a self propagating transverse oscillating wave of electric and magnetic fields. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...


There are two types of eye injuries from the thermal radiation of a weapon:


Flash blindness is caused by the initial brilliant flash of light produced by the nuclear detonation. More light energy is received on the retina than can be tolerated, but less than is required for irreversible injury. The retina is particularity susceptible to visible and short wavelength infrared light, since this part of the electromagnetic spectrum is focused by the lens on the retina. The result is bleaching of the visual pigments and temporary blindness for up to 40 minutes. Legend: γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves: EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultrahigh frequency VHF = Very high frequency HF = High frequency... Blindness can be defined physiologically as the condition of lacking visual perception. ...


A retinal burn resulting in permanent damage from scarring is also caused by the concentration of direct thermal energy on the retina by the lens. It will occur only when the fireball is actually in the individual's field of vision and would be a relatively uncommon injury. Retinal burns, however, may be sustained at considerable distances from the explosion. The apparent size of the fireball, a function of yield and range will determine the degree and extent of retinal scarring. A scar in the central visual field would be more debilitating. Generally, a limited visual field defect, which will be barely noticeable, is all that is likely to occur.


Since thermal radiation travels in straight lines from the fireball (unless scattered) any opaque object will produce a protective shadow. If fog or haze scatters the light, it will heat things from all directions and shielding will be less effective. Massive spread of radiation would also occur, which would be at the mercy of the wind.


When thermal radiation strikes an object, part will be reflected, part transmitted, and the rest absorbed. The fraction that is absorbed depends on the nature and color of the material. A thin material may transmit a lot. A light colored object may reflect much of the incident radiation and thus escape damage. The absorbed thermal radiation raises the temperature of the surface and results in scorching, charring, and burning of wood, paper, fabrics, etc. If the material is a poor thermal conductor, the heat is confined to the surface of the material.


Actual ignition of materials depends on the how long the thermal pulse lasts and the thickness and moisture content of the target. Near ground zero where the light exceeds 125 J/cm2, what can burn, will. Farther away, only the most easily ignited materials will flame. Incendiary effects are compounded by secondary fires started by the blast wave effects such as from upset stoves and furnaces. The joule (symbol: J) is the SI unit of energy, or work. ... cm redirects here, alternate uses: cm (disambiguation) A centimetre (symbol cm; American spelling: centimeter) is an SI unit of length. ...


In Hiroshima, a tremendous fire storm developed within 20 minutes after detonation. A fire storm has gale force winds blowing in towards the center of the fire from all points of the compass. It is not, however, a phenomenon peculiar to nuclear explosions, having been observed frequently in large forest fires and following incendiary raids during World War II. For the movie about the decision process behind the dropping of the nuclear bomb on Hiroshima, see Hiroshima (film). ... For the comic book superhero, see Firestorm (comics). ... Combatants Allied Powers Axis Powers Commanders {{{commander1}}} {{{commander2}}} Strength {{{strength1}}} {{{strength2}}} Casualties 17 million military deaths 8 million military deaths {{{notes}}} World War II, also known as the Second World War, was a military conflict that took place between 1939 and 1945. ...


Indirect effects

The mushroom cloud from the first "true" Soviet hydrogen bomb test in 1955.
The mushroom cloud from the first "true" Soviet hydrogen bomb test in 1955.

soviet atomic bomb test First Soviet test of a thermonuclear device. ... soviet atomic bomb test First Soviet test of a thermonuclear device. ... 1955 (MCMLV in Roman) was a common year starting on Saturday of the Gregorian calendar. ...

Electromagnetic pulse

Gamma rays from a nuclear explosion produce high energy electrons through Compton scattering. These electrons are captured in the earth's magnetic field, at altitudes between twenty and forty kilometers, where they resonate. The oscillating electric current produces a coherent electromagnetic pulse (EMP) which lasts about 1 millisecond. Secondary effects may last for more than a second. Properties The electron is a fundamental subatomic particle that carries a negative electric charge. ... In quantum mechanics, the Compton scattering or Compton effect, observed by Arthur Holly Compton in 1923 that won him the 1927 Nobel Prize in Physics, is the increase in wavelength (decrease in energy) which occurs when X-ray (or gamma ray) photons with energies of around 0. ... In telecommunications and warfare, the term electromagnetic pulse (EMP) has the following meanings: The electromagnetic radiation from an explosion (especially nuclear explosions) or an intensely fluctuating magnetic field caused by Compton-recoil electrons and photoelectrons from photons scattered in the materials of the electronic or explosive device or in a...


The pulse is powerful enough to cause long metal objects (such as cables) to act as antennae and generate high voltages when the pulse passes. These voltages, and the associated high currents, can destroy unshielded electronics and even many wires. There are no known biological effects of EMP. The ionized air also disrupts radio traffic that would normally bounce off the ionosphere. This article may be too technical for most readers to understand. ... In electricity, current refers to electric current, which is the flow of electric charge. ... The ionosphere is the part of the atmosphere that is ionized by solar radiation. ...


One can shield electronics by wrapping them completely in conductive mesh, or any other form of Faraday cage. Of course radios cannot operate when shielded, because broadcast radio waves can't reach them. In science and engineering, conductors are materials that contain movable charges of electricity. ... Entrance to a Faraday room In electromagnetism, the Faraday cage is an application of Gausss law, one of Maxwells equations. ...


The largest-yield nuclear devices are designed for this use. An air burst at the right altitude could produce continent-wide effects.


Ionizing radiation

About 50% of the energy released in a nuclear air burst is in the form of ionizing radiation: neutrons, gamma rays, alpha particles, and electrons moving at incredible speeds, but with different speeds that can be still far away from the speed of light (alpha particles). The neutrons result almost exclusively from the fission and fusion reactions, while the initial gamma radiation includes that arising from these reactions as well as that resulting from the decay of short-lived fission products. Ionizing radiation is a type of particle radiation in which an individual particle (for example, a photon, electron, or helium nucleus) carries enough energy to ionize an atom or molecule (that is, to completely remove an electron from its orbit). ... Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939. ... This article is about electromagnetic radiation. ... An alpha particle is deflected by a magnetic field Alpha particles or alpha rays are a form of particle radiation which are highly ionizing and have low penetration. ... Properties The electron is a fundamental subatomic particle that carries a negative electric charge. ... In general fission is a splitting or breaking up into parts. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ...


The intensity of initial nuclear radiation decreases rapidly with distance from the point of burst because the radiation spreads over a larger area as it travels away from the explosion. It is also reduced by atmospheric absorption and scattering.


The character of the radiation received at a given location also varies with distance from the explosion. Near the point of the explosion, the neutron intensity is greater than the gamma intensity, but with increasing distance the neutron-gamma ratio decreases. Ultimately, the neutron component of initial radiation becomes negligible in comparison with the gamma component. The range for significant levels of initial radiation does not increase markedly with weapon yield and, as a result, the initial radiation becomes less of a hazard with increasing yield. With larger weapons, above 50 kt (200 TJ), blast and thermal effects are so much greater in importance that prompt radiation effects can be ignored.


The neutron radiation serves to transmute the surrounding matter, often rendering it radioactive. When added to the dust of radioactive material released by the bomb itself, a large amount of radioactive material is released into the environment. This form of radioactive contamination is known as nuclear fallout and poses the primary risk of exposure to ionizing radiation for a large nuclear weapon. The radiation warning symbol (trefoil). ... Fallout is the residual radiation hazard from a nuclear explosion and is named from the fact that it falls out of the atmosphere in to which it is spread during the explosion. ...


Summary of the effects

The following table summarizes the most important effects of nuclear explosions under certain conditions:

  • relatively flat terrain,
  • clear weather, visibility 20 kilometres,
  • height of burst optimized for 15 PSI (103 kPa),
  • "average" bombs, i.e. no neutron bombs or other devices with extremely enhanced or reduced radiation.

Due to the applied cubic root scaling the peak overpressure in ground zero is approximately 42 PSI (290 kPa) in all cases. // A neutron bomb is a type of nuclear weapon invented by Samuel Cohen specifically designed to release a relatively large portion of its energy as energetic neutron radiation. ...

Effective range GR / km

Explosive yield / Height of Burst

1 kT / 200 m

20 kT / 540 m

1 MT / 2.0 km

20 MT / 5.4 km

Blast effects

Urban areas almost completely levelled (20 PSI)

0.2

0.6

2.4

6.4

Destruction of most civil buildings (5 PSI)

0.6

1.7

6.2

17

Moderate damage to civil buildings (1 PSI)

1.7

4.7

17

47

Thermal radiation effects

Conflagration

0.5

2.0

10

30

Third degree burns

0.6

2.5

12

38

Second degree burns

0.8

3.2

15

44

First degree burns

1.1

4.2

19

53

Effects of instant nuclear radiation (at slant range1 SR / km)

Lethal2 total dose (neutrons and gamma rays)

0.8

1.4

2.3

4.7

Total dose for acute radiation syndrome2

1.2

1.8

2.9

5.4

1) For the direct radiation effects the slant range instead of the ground range is shown here, because some effects are not given even at ground zero for some burst heights. If the effect occurs at ground zero the ground range can simply be derived from slant range and burst altitude. The Pythagorean theorem: The sum of the areas of the two squares on the legs (blue and red) equals the area of the square on the hypotenuse (purple). ...


2) "Acute radiation syndrome" corresponds here to a total dose of one grays, "lethal" to ten grays. Note that this is only a rough estimate since biological conditions are neglected here. The gray (symbol: Gy) is the SI unit of absorbed dose. ...


Other phenomena

As the fireball rises through still air, it takes on the flow pattern of a vortex ring with incandescent material in the vortex core as seen in certain [photographs]. A vortex ring is a mass of moving fluid moving through the same or different fluid where the flow pattern takes on a donut shape. ...


At the explosion of nuclear bombs sometimes lightning discharges occur.


Not related to the explosion itself, often there are smoke trails seen in photographs of nuclear explosions. These are formed from rockets emitting smoke launched before detonation. The smoke trails are used to determine the position of the shockwave, which is invisible, in the milliseconds after detonation through the refraction of light, which causes an optical break in the smoke trails as the shockwave passes. // Headline text This article refers to refraction in waves. ...


A fizzle occurs if the nuclear chain reaction is not sustained long enough to cause an explosion. This can happen if, for example, the yield of the fissile material used is too low, the compression explosives around fissile material misfire or the neutron initiator fails. Albert Einsteins letter to President Roosevelt in 1939 about his concern, about (Nuclear chain reactions) Click for closeup of letter A nuclear chain reaction occurs when on average more than one nuclear reaction is caused by another nuclear reaction, thus leading to an exponential increase in the number of... This article or section should include material from Fissile material In nuclear engineering, a fissile material is one that is capable of sustaining a chain reaction of nuclear fission. ... The first nuclear weapons, though large, cumbersome and inefficient, provided the basic design building blocks of all future weapons. ...


See also

For the generic term for high-tension and / or indirect struggle between states, falling short of actual open hostilities, see cold war (war). ... A nuclear test explosion is an experiment involving the detonation of a nuclear weapon. ... Duck and cover was a method of personal protection against the effects of a nuclear detonation which the United States government taught to the generations of United States school children from the late 1940s into the 1980s. ... Film refers to the celluloid media on which movies are printed. ... 1951 (MCMLI) was a common year starting on Monday; see its calendar. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 km (11 mi) above the hypocenter. ... A nuclear fireball lights up the night in a United States nuclear test. ... The first nuclear weapons, though large, cumbersome and inefficient, provided the basic design building blocks of all future weapons. ... Nuclear explosions have a distinctive mushroom shaped cloud. ... Nuclear explosion photographed less than 1/1000 of a second after detonation. ...

References

The Smyth Report was the common name given to an administrative history written by physicist Henry DeWolf Smyth about the Allied World War II effort to develop the atomic bomb, the Manhattan Project. ...

External links


  Results from FactBites:
 
Nuclear explosion - Wikipedia, the free encyclopedia (2961 words)
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.
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.
The energy of a nuclear explosive is initially released in the form of gamma rays and neutrons.
Nuclear weapon - Wikipedia, the free encyclopedia (2843 words)
Although a nuclear weapon is capable of causing the same destruction as conventional explosives through the effects of blast and thermal radiation, it does so by releasing much larger amounts of energy in a much shorter period of time.
Nuclear weapons were symbols of military and national power, and nuclear testing was often used both to test new designs as well as to send political messages.
Nuclear weapons have been at the heart of many national and international political disputes, and have played a major part in popular culture since their dramatic public debut in the 1940s, and have usually symbolized the ultimate ability of mankind to utilize the strength of nature for destruction.
  More results at FactBites »

 
 

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