Castle Yankee was the code name given to one of the tests in the

Operation Castle Operation Castle was a United States series of high-yield (high-energy) nuclear tests by Joint Task Force 7 (JTF-7) at Bikini Atoll beginning in March 1954. It followed ''Operation Upshot–Knothole'' and preceded ''Operation Teapot''. Condu ...

series of American

tests Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film), ...

thermonuclear Thermonuclear fusion is the process of atomic nuclei combining or “fusing” using high temperatures to drive them close enough together for this to become possible. There are two forms of thermonuclear fusion: ''uncontrolled'', in which the re ...

bombs. It was originally intended as a test of a TX-16/EC-16 ''Jughead'' bomb, but the design became obsolete after the

Castle Bravo Castle Bravo was the first in a series of high-yield thermonuclear weapon design tests conducted by the United States at Bikini Atoll, Marshall Islands, as part of '' Operation Castle''. Detonated on March 1, 1954, the device was the most powerful ...

test was successful. The test device was replaced with a TX-24/EC-24 ''Runt II'' bomb which was detonated on May 5, 1954, at

Bikini Atoll Bikini Atoll ( or ; Marshallese: , , meaning "coconut place"), sometimes known as Eschscholtz Atoll between the 1800s and 1946 is a coral reef in the Marshall Islands consisting of 23 islands surrounding a central lagoon. After the Seco ...

. It released energy equivalent to 13.5 megatons of TNT, the second-largest yield ever in a U.S. fusion weapon test.

Jughead

Yankee was originally intended to be a test of a TX-16/EC-16, a weaponized version of the large and complex

Ivy Mike Ivy Mike was the codename given to the first full-scale test of a thermonuclear device, in which part of the explosive yield comes from nuclear fusion. Ivy Mike was detonated on November 1, 1952, by the United States on the island of Elugelab ...

device. A small number of emergency capability EC-16s were produced, without being tested, to provide a stop-gap

thermonuclear weapon A thermonuclear weapon, fusion weapon or hydrogen bomb (H bomb) is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a low ...

capability in response to the Russian nuclear weapons program. The test device, code-named ''Jughead'', had been prepared as a backup in case the non-cryogenic

''Shrimp'' device failed to work. The test of ''Jughead'' was cancelled when the Bravo test was successful, and the cryogenic EC-16s were withdrawn and dismantled.

Runt II

''Jughead'' was replaced by the ''Runt II'' device (a TX-24/EC-24), developed from the Castle Romeo ''Runt'' device ( a TX-17/EC-17). Externally identical, the principal difference between them was in the fuel for the fusion stage. While Runt used natural

lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid ...

(with 7.5% of the Lithium-6

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numb ...

), ''Runt II'' used the same partially enriched lithium (approximately 40% Lithium-6) as the ''Shrimp'' device of Castle Bravo. It was detonated on May 5, 1954, at

of the

Marshall Islands The Marshall Islands ( mh, Ṃajeḷ), officially the Republic of the Marshall Islands ( mh, Aolepān Aorōkin Ṃajeḷ),'' () is an independent island country and microstate near the Equator in the Pacific Ocean, slightly west of the Intern ...

, on a barge moored in the middle of the crater from the

Castle Union Castle Union was the code name given to one of the tests in the Operation Castle series of United States nuclear tests. It was the first test of the TX-14 thermonuclear weapon (initially the "emergency capability" EC-14), one of the first deploy ...

test. Although it had been predicted to produce a yield of 6 to 10

megatons TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a m ...

, it actually produced a yield of 13.5 megatons, the second-largest ever yield in a U.S. fusion weapon test. Like the Mike, Bravo and Romeo tests, a large percentage of the yield was produced by fast fission of the natural

uranium Uranium is a chemical element with the 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. Uranium is weak ...

tamper. Of the total yield, 7 megatons were from fission; the other 6.5 megatons were from fusion reactions. The high fusion yield was due to the enriched fuel and set a U.S. record that stood until

Hardtack Hardtack (or hard tack) is a simple type of dense biscuit or cracker made from flour, water, and sometimes salt. Hardtack is inexpensive and long-lasting. It is used for sustenance in the absence of perishable foods, commonly during long sea voy ...

Poplar in 1958.

External links

* * *
Operation Castle

References

* Chuck Hansen, ''U. S. Nuclear Weapons: The Secret History'' (Arlington: AeroFax, 1988) {{Nuclear weapons tests of the United States Explosions in 1954 Nuclear testing at Bikini Atoll 1954 in military history 1954 in the environment 1950s in the Marshall Islands 1954 in the Trust Territory of the Pacific Islands Articles containing video clips May 1954 events in Oceania