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Encyclopedia > Castle Bravo
A black-and-white photograph of the Castle Bravo mushroom cloud.
A black-and-white photograph of the Castle Bravo mushroom cloud.

Castle Bravo was the code name given to the first U.S. test of a so-called dry fuel thermonuclear device, detonated on March 1, 1954 at Bikini Atoll, Marshall Islands, by the United States, as the first test of Operation Castle (a longer series of tests of various devices). Unexpected fallout from the detonation—intended to be a secret test—poisoned the crew of Daigo Fukuryū Maru ("Lucky Dragon No. 5"), a Japanese fishing boat, and created international concern about atmospheric thermonuclear testing. Image File history File links Download high resolution version (1468x1174, 188 KB) Operation Castle, BRAVO Event - The BRAVO Event was an experimental thermonuclear device, 15-megaton weapons related surface event. ... Image File history File links Download high resolution version (1468x1174, 188 KB) Operation Castle, BRAVO Event - The BRAVO Event was an experimental thermonuclear device, 15-megaton weapons related surface event. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... is the 60th day of the year (61st in leap years) in the Gregorian calendar. ... Year 1954 (MCMLIV) was a common year (link will display full calendar) of the Gregorian calendar. ... The Flag of Bikini Atoll Bikini Atoll (also known as Pikinni Atoll) is an uninhabited 6. ... Operation Castle was the highest-yield nuclear test series ever conducted by the United States. ... Daigo FukuryÅ« Maru Lucky Dragon No. ...


The bomb used lithium deuteride fuel for the fusion stage, unlike the cryogenic liquid deuterium used as fuel for the fusion stage of the U.S. first-generation Ivy Mike device, which, being the size of a small office building, was an impracticable weapon for use at war. The bomb tested at Castle Bravo was the first practical deliverable fusion bomb in the U.S. arsenal. Ionic lattice structure of lithium hydride Lithium hydride (LiH) is the compound of lithium and hydrogen. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Cryogenics is the study of very low temperatures or the production of the same, and is often confused with cryobiology, the study of the effect of low temperatures on organisms, or the study of cryopreservation. ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ... The mushroom cloud from the Mike shot. ... 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 Soviet Union had previously used lithium deuteride in a nuclear bomb, their Sloika (also known as Alarm Clock) design, but since it relied on using the initial fission explosion to compress, inertially confine, and ignite the fusion fuel, its yield was limited (400 kt) in comparison to the Teller-Ulam-based Ivy Mike (10.4 Mt) and Castle Bravo (~15 Mt). Mike and Bravo both used the Teller-Ulam design, which featured separation of the fusion device from the fission device, and used radiation pressure (or probably radiation-induced ablation of the heavy tamper surrounding the fusion device) to produce staged-radiation implosion and fusion ignition of a much greater magnitude. After a few years, the Soviets, led by Andrei Sakharov, independently developed (Sakharov's Third Idea) and tested (RDS-37) their first Teller-Ulam device in 1956. 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 first (albeit not true) Soviet Hydrogen (Super) Test, dubbed Joe 4 Joe 4 (USSR version: RDS-4 (Reaktivnyi Dvigatel Stalina; Stalins Rocket Engine)) was an American nickname for the first Soviet test of a thermonuclear weapon and was on August 12, 1953. ... The basics of the Teller-Ulam configuration: a fission bomb suspended above fusion fuel. ... The basics of the Teller–Ulam configuration: a fission bomb uses radiation to compress and heat a separate section of fusion fuel. ... Andrei Sakharov, 1943 For the historian, see Andrey Nikolayevich Sakharov. ... The basics of the Teller–Ulam configuration: a fission bomb uses radiation to compress and heat a separate section of fusion fuel. ... RDS-37 was a Soviet name for their first nuclear test of a true hydrogen bomb. ... The basics of the Teller-Ulam configuration: a fission bomb suspended above fusion fuel. ...


Castle Bravo was the most powerful nuclear device ever detonated by the United States, with a yield of 15 megatons. That yield, far exceeding the expected yield of 4 to 8 megatons, combined with other factors to produce the worst radiological accident ever caused by the United States. The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 kilometers (11 mi) above the hypocenter A nuclear weapon derives its destructive force from nuclear reactions of fusion or fission. ... A megaton or megatonne is a unit of mass equal to 1,000,000 metric tons, i. ... The radiation warning symbol (trefoil). ...


Though some 1,000 times more powerful than the atomic bombs which were dropped on Hiroshima and Nagasaki during World War II, it was considerably smaller than the largest nuclear test conducted by the Soviet Union several years later, the ~50 Mt Tsar Bomba. The mushroom cloud over Hiroshima after the dropping of Little Boy. ... Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000... Site of the detonation. ...

Contents

Design and detonation

Castle Bravo mushroom cloud.
Castle Bravo mushroom cloud.

The device detonated for the test was named "Shrimp" and was the same basic configuration as the Ivy Mike device, except with a different kind of fusion fuel. This device also implemented a light case design, using aluminum instead of the heavy steel case used in Mike. Castle Bravos Mushroom Cloud. ... Castle Bravos Mushroom Cloud. ... Aluminum is a soft and lightweight metal with a dull silvery appearance, due to a thin layer of oxidation that forms quickly when it is exposed to air. ... For other uses, see Steel (disambiguation). ...


Inside a cylindrical case was a smaller cylinder of lithium deuteride fusion fuel, the secondary, with a regular fission atomic bomb (the primary) at one end; the latter was used to create the conditions needed to start the fusion reaction. Running down the center of the secondary was a cylindrical rod of plutonium (the sparkplug), which was used to ignite the fusion reaction. Surrounding this assembly was a natural uranium tamper; the space between the tamper and the case formed a radiation channel to conduct X-rays from the primary to the secondary. (The function of the X-rays was to compress the secondary (by various means; see Teller-Ulam design), increasing the density and temperature of the deuterium to the levels needed to sustain the thermonuclear reaction, and compressing the sparkplug to supercriticality ignition.) An induced nuclear fission event. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 km (11 mi) above the epicenter. ... General Name, Symbol, Number plutonium, Pu, 94 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery white Standard atomic weight (244) g·mol−1 Electron configuration [Rn] 5f6 7s2 Electrons per shell 2, 8, 18, 32, 24, 8, 2 Physical properties Phase solid Density (near r. ... General Name, symbol, number uranium, U, 92 Chemical series actinides Group, period, block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Standard atomic weight 238. ... Radiation as used in physics, is energy in the form of waves or moving subatomic particles. ... 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... The basics of the Teller–Ulam configuration: a fission bomb uses radiation to compress and heat a separate section of fusion fuel. ... A sphere of plutonium surrounded by neutron-reflecting blocks of tungsten carbide. ...


It was practically identical to the "Runt" device later detonated in Castle Romeo, but used partially enriched lithium in the fusion fuel. Natural lithium is a mixture of lithium-6 and lithium-7 isotopes (with 7.5% of the former); the enriched lithium used in Bravo was approximately 40% lithium-6. The primary was a standard RACER 4 fusion-boosted atomic bomb. Castle Romeo mushroom cloud. ... This article is about the chemical element named Lithium. ... Isotopes are atoms of a chemical element whose nuclei have the same atomic number, Z, but different atomic weights, A. The word isotope, meaning at the same place, comes from the fact that isotopes are located at the same place on the periodic table. ...


The device was a very large cylinder weighing 23,500 pounds (10.7 tonnes) and measuring 179.5 inches (4.56 m) in length and 53.9 inches (1.37 m) in width. It was mounted in a "shot cab" on an artificial island built on a reef off Namu Island, in the Bikini Atoll. A sizeable array of diagnostic instruments were trained on it, including a number of high-speed cameras which were trained through an arc of mirror towers around the shot cab. The pound or pound-mass (abbreviations: lb, lbm, or sometimes in the United States, #) is a unit of mass (sometimes called weight in everyday parlance) in a number of different systems, including English units, Imperial units, and United States customary units. ... A tonne (also called metric ton) is a non-SI unit of mass, accepted for use with SI, defined as: 1 tonne = 103 kg (= 106 g). ... Mid-19th century tool for converting between different standards of the inch An inch is an Imperial unit of length. ... The Flag of Bikini Atoll Bikini Atoll (also known as Pikinni Atoll) is an uninhabited 6. ...


When Bravo was detonated, it formed a fireball almost three miles (roughly 5 km) across within a second. This fireball was visible on the Kwajalein atoll over 250 miles (450 km) away. The explosion left a crater of 6,500 feet (2,000 m) in diameter and 250 feet (75 m) in depth. The mushroom cloud reached a height of 47,000 feet (14 km) and a diameter of 7 miles (11 km) in about a minute; it then reached a height of 130,000 feet (40 km) and 62 miles (100 km) in diameter in less than 10 minutes and was expanding at more than 6 kilometers (4 miles) per minute. Kwajalein Atoll - NASA NLT Landsat 7 (Visible Color) Satellite Image Kwajalein Atoll (Marshallese: Kuwajleen) is part of the Republic of the Marshall Islands (RMI). ... 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. ...


Coordinates for Bravo Crater are 11°41′50″N, 165°16′19″E. The coordinates for remains of Castle Bravo causeway are 11°42′6″N, 165°17′7″E.


Cause of high yield

The yield of 15 megatons was two and a half times what was expected. The cause of the high yield was a laboratory error made by designers of the device at Los Alamos National Laboratory. Los Alamos National Laboratory, aerial view from 1995. ...


It was expected that lithium-6 isotope would absorb a neutron from the fissioning plutonium, emit an alpha particle and tritium in the process, of which the latter would then fuse with deuterium (which was already present in the LiD) and increase the yield in a predicted manner. This article or section does not adequately cite its references or sources. ... An alpha particle is deflected by a magnetic field Alpha radiation consists of helium-4 nuclei and is readily stopped by a sheet of paper. ... Tritium (symbol T or 3H) is a radioactive isotope of hydrogen. ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ...


The designers missed the fact that when the lithium-7 isotope (which was considered basically inert) is bombarded with high-energy neutrons, it absorbs a neutron then decomposes to form an alpha particle, another neutron, and a tritium nucleus. This means that much more tritium was produced than expected, and the extra tritium in fusion with deuterium (as well as the extra neutron from lithium-7 decomposition) produced many more neutrons than expected and induced more fission of the uranium tamper, increasing yield. The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ...


This resultant extra fuel (both lithium-6 and lithium-7) contributed greatly to the fusion reactions and neutron production, and in this manner greatly increased the device's yield. The test used lithium with a high percentage of lithium-7 only because lithium-6 was (at the time) scarce and expensive; the later Castle Union test used almost pure lithium-6. Had more lithium-6 been available, the usability of the common lithium-7 might not have been discovered. The Castle Union test of the Mark 14 design. ...


Of the total 15-megaton yield, 10 megatons were from fission of the natural uranium tamper.


Fallout incident

The Bravo fallout plume spread dangerous levels of radiation over an area over 100 miles long, including inhabited islands.
The Bravo fallout plume spread dangerous levels of radiation over an area over 100 miles long, including inhabited islands.

The fission reactions of the natural uranium tamper were quite dirty, producing a large amount of fallout. That, combined with the much-larger-than-expected yield and a major wind shift, produced a number of very serious consequences. Although the leaders of the test knew that the change in weather would increase the probability that the test might affect areas of ocean that had not been cleared, they decided to proceed with the test[citation needed]. In the de-classified film "Operation Castle", task force commander General Clarkson points to a diagram indicating that the wind shift was still in the range of "acceptable fallout", although just barely. Image File history File links Download high resolution version (928x422, 23 KB) Image of nuclear fallout dispersal from the Castle Bravo nuclear test, 28 Feb 1954. ... Image File history File links Download high resolution version (928x422, 23 KB) Image of nuclear fallout dispersal from the Castle Bravo nuclear test, 28 Feb 1954. ... Fallout is the residual radiation hazard from a nuclear explosion, so named because it falls out of the atmosphere into which it is spread during the explosion. ...


The decision to fire the Bravo bomb under the prevailing winds was made by Dr Alvin C. Graves (1912-66), the Scientific Director of Operation Castle. Dr Graves had total authority over firing the weapon, above that of the military Commander of Operation Castle. Dr Graves had himself received an exposure of 200 Roentgens in the 1946 Los Alamos accident in which his personal friend, Dr Louis Slotin, died from radiation exposure. Dr Graves appears in the widely available film of the earlier 1952 test Mike, which examines the last minute fallout decisions. The narrator (Western actor Reed Hadley) is filmed aboard the control ship in that film which shows the final conference. Hadley points out that 20,000 people live in the potential area of the fallout. He asks the control panel scientist if the test can be aborted and is told yes but it would ruin all their preparations in setting up timed measuring instruments in the race against the Russians. In Mike the fallout correctly landed north of the inhabited area, but in the 1954 Bravo test, there was a lot of wind shear, and the wind which was blowing north the day before the test, steadily veered towards the east. The röntgen or roentgen (symbol R) is a unit of exposure to ionising radiation (X or gamma rays), and is named after the physicist Wilhelm Röntgen. ... A sketch used by doctors to determine the amount of radiation to which each person in the room had been exposed during the excursion. ... Reed Hadley (June 25, 1911 – December 11, 1974) was an American movie, television and radio actor. ... For the Marvel Comics character, see Windshear (comics). ...


Radioactive fallout was spread eastward onto the inhabited Rongelap and Rongerik atolls, which were soon evacuated. Many of the Marshall Islands natives have since suffered from birth defects and have received some compensation from the U.S. Federal government. See Project 4.1 for controversy surrounding this exposure.[1] Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ... Rongelap Atoll is an island-atoll located in Micronesia. ... Rongerik Atoll - NASA NLT Landsat 7 (Visible Color) Satellite Image Map of Rongerik Atoll, taken from the 1893 map Schutzgebiet der Marshall Inseln, published in 1897. ... A congenital disorder is a medical condition or defect that is present at or before birth (for example, congenital heart disease). ... The neutrality of this article is disputed. ...


A Japanese fishing boat, Lucky Dragon No. 5, also came into contact with the fallout which caused many of the crew to grow ill; one eventually died. This resulted in an international uproar and reignited Japanese concerns about radiation, especially in regard to the possibility of contaminated fish. The official U.S. line had been that the growth in the strength of atomic bombs was not accompanied by an equivalent growth in radiation released. Japanese scientists who had collected data from the fishing vessel disagreed with this. Sir Joseph Rotblat, working at St Bartholomew's Hospital, London, demonstrated that the contamination caused by the fall-out from the test was far greater than that stated officially. Rotblat was able to deduce that the bomb had three stages and showed that the fission phase at the end of the explosion increased the amount of radioactivity a thousandfold. Rotblat's paper was taken up by the media, and the outcry in Japan reached such a level that diplomatic relations became strained and the incident was even dubbed by some as "a second Hiroshima"[citation needed]. Nevertheless, the Japanese and U.S. governments quickly reached a political settlement which gave the fishery a compensation of 2 million dollars with the surviving victims receiving between 1.91 million yen and 2.29 million yen each. It was also agreed that the victims would not be given Hibakusha status. Daigo Fukuryu Maru (第五福龍丸, Daigo Fukuryū Maru) was a Japanese tuna fishing boat, which was exposed to and contaminated by radiation caused by the United States hydrogen bomb experiment in Bikini Atoll on March 1, 1954. ... Sir Józef Rotblat or Joseph Rotblat, (born November 4, 1908) is a Polish-Jewish (though with British citizenship) physicist who received the Nobel Peace Prize in 1995 in conjuction with the Pugwash Conferences on Science and World Affairs, an organization of scientists which he headed at the time, for... The King Henry VIII Gate at Barts, which was constructed in 1702. ... Fallout is the residual radiation hazard from a nuclear explosion, so named because it falls out of the atmosphere into which it is spread during the explosion. ... A victim of the atomic bombing of Hiroshima, she suffered severe burns; the pattern on her skin is from the kimono she was wearing at the time of the bombing. ...


Unanticipated fallout and radiation also affected many of the vessels and personnel involved in the test, in some cases trapping them in bunkers. One prominent scientist later recalled that he was on a ship 30 miles away, and received 10 Röntgen of radiation as a result. Sixteen crew members of the aircraft carrier USS Bairoko received beta burns and there was a greatly increased cancer rate[citation needed]. Radioactive contamination also affected many of the testing facilities built on other islands of the Bikini atoll system. The röntgen or roentgen (symbol R) is a unit of exposure to ionizing radiation (X or gamma rays), and is named after the German physicist Wilhelm Röntgen. ... USS Bairoko (CVE-115) was a United States Navy Commencement Bay-class escort aircraft carrier. ... A radiation burn is damage to the skin or other biological tissue caused by exposure to ionizing radiation. ...


The fallout spread traces of radioactive material as far as Australia, India and Japan, and even the US and parts of Europe. Though organized as a secret test, Castle Bravo quickly became an international incident, prompting calls for a ban on the atmospheric testing of thermonuclear devices.[2]


In addition to the radiological accident, the unexpectedly high yield of the device severely damaged many of the permanent buildings on the control site island on the far side of the atoll. Very little of the desired diagnostic data on the shot was collected; many instruments designed to transmit their data back before being destroyed by the blast were instead vaporized instantly, while most of the instruments that were expected to be recovered for data retrieval were destroyed by the blast.


Later devices

A formerly secret Rand Corporation simulation of the Castle Bravo fallout indicating that high levels on Rongelap may have been due to a hotspot. Hotspots downwind are typical of bursts on coral in humid atmospheres, and also occurred in the 1954 Yankee and Nectar water surface bursts, and the 1956 coral surface bursts Zuni and Tewa.
A formerly secret Rand Corporation simulation of the Castle Bravo fallout indicating that high levels on Rongelap may have been due to a hotspot. Hotspots downwind are typical of bursts on coral in humid atmospheres, and also occurred in the 1954 Yankee and Nectar water surface bursts, and the 1956 coral surface bursts Zuni and Tewa.

The Shrimp device design later evolved into the Mk-21 bomb, of which 275 units were produced, weighing 15,000 pounds (6,800 kg) and measuring 12.5 feet (3.8 m) long and 56 inches (1.4 m) in diameter. This 4 megaton bomb was produced until July 1956. In 1957, it was converted into the Mk-36 and entered into production again.
Image File history File links Download high resolution version (855x530, 61 KB) Summary Rand Corporation land gamma dose rate fallout pattern for 14. ... Image File history File links Download high resolution version (855x530, 61 KB) Summary Rand Corporation land gamma dose rate fallout pattern for 14. ...


See also

A nuclear fireball lights up the night in a United States nuclear test. ... This article is about the nuclear test. ...

References

  1. ^ Nuclear Issues. Retrieved on 2006-03-26.
  2. ^ DeGroot 2004, pp. 196-198
  • Gerard DeGroot, The Bomb: A Life (London: Jonathan Cape, 2004) ISBN 0-224-06232-8
  • Chuck Hansen, U. S. Nuclear Weapons: The Secret History (Arlington: AeroFax, 1988)
  • Richard Rhodes, Dark Sun: The Making of the Hydrogen Bomb (New York: Simon and Schuster, 1995)
  • Holly M. Barker, Bravo for the Marshallese: Regaining control in a Post-Nuclear, Post Colonial World (Belmont, CA: Wadsworth, 2004)
  • Republic of the Marshall Islands Embassy website
  • Cronkite E. P., Conard R. A., Bond V. P. (1997). "Historical events associated with fallout from Bravo Shot - Operation Castle and 25 Y of medical findings". Health Physics 73 (1): 176-186. 

Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Richard Rhodes (born July 4, 1937) is an American author of fiction and verity, including the Pulitzer Prize-winning The Making of the Atomic Bomb in 1986, and most recently, John James Audubon: the Making of an American in 2004. ...

External links

Coordinates: 11°41′50″N, 165°16′19″E BBC News is the department within the BBC responsible for the corporations news-gathering and production of news programmes on BBC television, radio and online. ... Map of Earth showing lines of latitude (horizontally) and longitude (vertically), Eckert VI projection; large version (pdf, 1. ...


 
 

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