FACT SHEET CASTLE was a six-detonation nuclear weapon test series (see tabJe) held at the Atomic Energy Commission's (AEC) Pacific Proving Ground (PPG) in Spring 1954. The PPG consisted principally of Enewetak* and Bik#ni atolls in the northwestern Marshall Islands in the Central Pacific Ccean. Date Assigned Name Location 1 March BRAVO Bikini; sandspit off Nam Island 27 March ROMEO Bikini; barge in BRAVO crater KOON Bikini; surface of Eneman Island 190 KT 26 April UNION Bikini; barge in lagoon off [roij Island 649 MT 5 May YANKEE Bikini; barge in UNION crater 1355 MT 14 May NECTAR Enewetak; barge in MIKE> crater 14 MT 7 April Maghitude [5 MT? 1 MT Notes: “One kiloton equals the approximate energy release of the explosion one thousand tons of TNT; one megaton equals the approximate energ release of the explosion of one million tons of TNT. b Pf 10.4-MT IVY series detonation in 1952. HISTORICAL BACKGROUND The CASTLE series was held to test large-yield thermonuclear, or drogen, devices. y~ Work on this class of devices had progressed throug the GREENHOUSE, GEORGE experimental shot in 1951 and the IVY, MIKE shot o 1952. MIKE was the first device that generated a substantial explosife energy from the fusion, or joining, of hydrogen atoms. These explosive * The spelling of Marshall Island place names has changed in recent years in order to more accurately render the sounds of the Marshall Islan names using English spelling.