was the code name given to one of the tests in the Operation Castle
series of American tests
Yankee was originally intended to be a test of a simplified and lightened bomb version (the TX-16, or "emergency capability" EC-16
) of the large and complex cryogenic
device (the first successful multi-stage fusion
device) tested in Ivy Mike
. A small number of EC-16s were produced on an emergency basis 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 "Shrimp" fusion device (first tested in Castle Bravo
) failed to work. The test of "Jughead" was cancelled when the Bravo device was successful, and the few EC-16s which were actually built were withdrawn and dismantled.
Jughead was replaced in the Yankee test by the so-called "Runt II" device (the TX-24 bomb, initially the "emergency capability" EC-24), a modified form of the "Runt" device (the TX-17/EC-17) tested in Castle Romeo
. 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 tested in Bravo.
It was detonated on May 5, 1954, at Bikini......