Ivy King was the largest pure- fission

nuclear bomb A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission or atomic bomb) or a combination of fission and fusion reactions (thermonuclear weapon), producing a nuclear exp ...

ever tested. The bomb was tested by the United States'

Truman administration Harry S. Truman's tenure as the List of presidents of the United States, 33rd president of the United States began on April 12, 1945, upon the death of President Franklin D. Roosevelt, and ended on January 20, 1953. He had been Vice President ...

as part of Operation Ivy. This series of tests involved the development of very powerful nuclear weapons in response to the nuclear weapons program of the

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. The production of Ivy King was hurried to be ready in case its sister project,

Ivy Mike Ivy Mike was the code name, codename given to the first full-scale test of a Thermonuclear weapon, thermonuclear device, in which a significant fraction of the explosive nuclear weapon yield, yield comes from nuclear fusion. Ivy Mike was detona ...

, failed in its attempt to achieve a thermonuclear reaction. The Ivy King test actually took place two weeks after the Mike test. Unlike the Mike bomb, the Ivy King device could theoretically have been added to United States' nuclear arsenal, because it was designed to be air-deliverable. On November 16, 1952 at 11:30 local time (23:30 GMT) a B-36H bomber dropped the bomb over a point north of

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in the Enewetak atoll, resulting in a 500

kiloton TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. A ton of TNT equivalent is a unit of energy defined by convention to be (). It is the approximate energy released in the det ...

explosion at . The

tropopause The tropopause is the atmospheric boundary that demarcates the lowest two layers of the atmosphere of Earth – the troposphere and stratosphere – which occurs approximately above the equatorial regions, and approximately above the polar regi ...

height at the time of the detonation was about . The top of the King cloud reached about with the mushroom base at about .Operation Ivy. Project 7.5. Dispersion of Gaseous Debris from Nuclear Explosions; Philip W. Allen, Department of the Air Force, Washington, DC. Defense Technical Information Center, 1985. The Ivy King bomb, designated as a Mark 18 nuclear bomb and named the "Super Oralloy Bomb", was a modified version of the Mk-6D bomb. Instead of using an implosion system similar to the Mk-6D, it used a 92-point implosion system initially developed for the Mk-13. Its

uranium Uranium is a chemical element; it has chemical symbol, symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Ura ...

plutonium Plutonium is a chemical element; it has symbol Pu and atomic number 94. It is a silvery-gray actinide metal that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four ...

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was replaced by 60 kg of highly enriched uranium (HEU) fashioned into a thin-walled sphere equivalent to approximately four

critical mass In nuclear engineering, critical mass is the minimum mass of the fissile material needed for a sustained nuclear chain reaction in a particular setup. The critical mass of a fissionable material depends upon its nuclear properties (specific ...

es. The thin-walled sphere was a commonly used design, which ensured that the fissile material remained sub-critical until imploded. The HEU sphere was then enclosed in a natural-uranium tamper. To physically prevent the HEU sphere collapsing into a critical condition if the surrounding explosives were detonated accidentally, or if the sphere was crushed following an aircraft accident, the hollow center was filled with a

chain A chain is a serial assembly of connected pieces, called links, typically made of metal, with an overall character similar to that of a rope in that it is flexible and curved in compression but linear, rigid, and load-bearing in tension. A ...

made from

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and

boron Boron is a chemical element; it has symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the boron group it has three ...

, which was pulled out to arm the bomb. The boron-coated chain also absorbed the

neutron The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The Discovery of the neutron, neutron was discovered by James Chadwick in 1932, leading to the discovery of nucle ...

s needed to drive the nuclear reaction. The primary designer of the Super Oralloy Bomb, physicist Ted Taylor, later became a vocal proponent of

nuclear disarmament Nuclear disarmament is the act of reducing or eliminating nuclear weapons. Its end state can also be a nuclear-weapons-free world, in which nuclear weapons are completely eliminated. The term ''denuclearization'' is also used to describe the pro ...

. With an explosive yield of 500 kilotons, Ivy King is the largest known fission-only device ever tested. The Orange Herald nuclear device, a 720-kiloton bomb tested by the United Kingdom on 31 May 1957, used

fusion boosting A boosted fission weapon usually refers to a type of nuclear bomb that uses a small amount of Nuclear fusion, fusion fuel to increase the rate, and thus yield, of a Nuclear fission, fission reaction. The Fusion neutron, fast fusion neutrons rele ...

, making it the largest non-

Teller-Ulam A thermonuclear weapon, fusion weapon or hydrogen bomb (H-bomb) is a second-generation nuclear weapon design Nuclear weapons design are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to det ...

device ever tested.

Gallery

File:IvyKingDetonation.gif, ''King'' test, from aerial view. File:Ivy King - distance.jpg, Distant shoreline view. File:Ivy King - mushroom cloud.jpg

References

* *Chuck Hansen (1995) ''Swords of Armageddon.'' Published on CD-Rom only by Chukelea, Sunnyvale, CA.

External links

Operation Ivy
*Video of th
Ivy King Nuclear Test
{{Nuclear weapons tests of the United States Explosions in 1952 Enewetak Atoll nuclear explosive tests 1952 in the United States Articles containing video clips November 1952 in the United States