Castle Yankee

Castle Yankee
Information
Country	United States
Test series	Operation Castle
Test site	Bikini Atoll
Date	May 5, 1954
Test type	Atmospheric
Yield	13.5 Mt

Castle Yankee was the code name given to one of the tests in the Operation Castle series of American tests of thermonuclear bombs. It was originally intended as a test of a TX-16/EC-16 bomb, but the design became obsolete after the Castle Bravo test was successful. The test device was replaced with a TX-24/EC-24 bomb which was detonated on May 5, 1954, at Bikini Atoll. It released energy equivalent to 13.5 megatons of TNT, the second-largest yield ever in a U.S. fusion weapon test.

Yankee was originally intended to be a test of a TX-16/EC-16, a weaponized version of the large and complex Ivy Mike device. A small number of emergency capability EC-16s were produced, without being tested, to provide a stop-gap thermonuclear weapon 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 Castle Bravo "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 The test of Jughead was cancelled when the Bravo test was successful, and the cryogenic EC-16s were withdrawn and dismantled.

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 (with 7.5% of the Lithium-6 isotope), Runt II used the same partially enriched lithium (approximately 40% Lithium-6) as the Shrimp device.

It was detonated on May 5, 1954, at Bikini Atoll of the Marshall Islands, on a barge moored in the middle of the crater from the Castle Union test.

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