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| Ivy King | |
|---|---|
 Ivy King's fireball and subsequentmushroom cloud from sea-level view. | |
| Information | |
| Country | United States |
| Test series | Operation Ivy |
| Test site | Enewetak |
| Date | November 16, 1952 |
| Test type | Atmospheric |
| Yield | 500kt (2092 TJ) |
| Test chronology | |
IvyKing was the largestfissionnuclear weapon to not attemptfusion boosting, yielding 500kilotons of TNT.[1] It was tested on November 16, 1952, onEnewetak Atoll in the Pacific, by the United States'Truman administration as part ofOperation Ivy. Alongside the first multi-megatonthermonuclear test inIvyMike, the operation was in response to thenuclear weapons program of the Soviet Union.
The production of Ivy King was hurried to be ready in case its sister project, IvyMike, failed in its attempt to achieve athermonuclear reaction. IvyKing actually took place two weeks afterMike. Unlike the static experimental setup of theSausage device in IvyMike, the IvyKing device was air-deliverable, and as theMark 18 nuclear bomb, 90 weapons were produced by theAtomic Energy Commission. The weapons were extremely expensive due to the high mass ofhighly enriched uranium used in the core.
On November 16, 1952 at 11:30 local time (23:30 GMT) aB-36H bomber dropped the bomb over a point 2,000 feet (610 m) north ofRunit Island in theEnewetak atoll, resulting in a 500 kiloton[2] explosion at 1,480 feet (450 m). Thetropopause height at the time of the detonation was about 58,000 feet (18 km). The top of the King cloud reached about 75,000 feet (23 km) with the mushroom base at about 40,000 feet (12 km).[3]
The Ivy King bomb, designated as a and named the "SuperOralloy Bomb", was a modified version of theMk-6D bomb. Instead of using animplosion system similar to the Mk-6D, it used a 92-point implosion system initially developed for theMk-13. Itsuranium-plutoniumcore was replaced by 60 kg ofhighly enriched uranium (HEU), similar to the HEU mass in thegun-typeLittle Boy, but fashioned into a thin-walled sphere equivalent to approximately fourcritical masses. 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-uraniumtamper. 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 achain made fromaluminum andboron, which was pulled out to arm the bomb. The boron-coated chain also absorbed theneutrons needed to drive the nuclear reaction.[citation needed]
The primary designer of the Super Oralloy Bomb, physicistTed Taylor, later became a vocal proponent ofnuclear disarmament.[citation needed]
With an explosiveyield of 500 kilotons, Ivy King is the largest fission device ever tested that did not attempt fusion boosting. TheOrange Herald nuclear device, a 720-kiloton bomb tested by the United Kingdom on 31 May 1957, attempted to employ fusion boosting with alithium deuteride component in its core, but its disappointing yield made it unclear if any fusion boosting actually took place.[4] Regardless, Orange Herald was the largest non-Teller-Ulam device ever tested, while IvyKing was the largest nuclear device to lack thermonuclear materials. A related boosting concept, thelayer cake design, was tested by the Soviet Union, Britain, and China, achieving its largest yield of 400 kilotons in theRDS-6s test.
