Castle Bravo was the first in a series of high-yield thermonuclear-weapon design tests conducted by the United States at Bikini Atoll in the Marshall Islands, as part of Operation Castle. Detonated on March 1, 1954, the device was the most powerful nuclear device detonated by the United States and the first lithium deuteride–fueled thermonuclear weapon tested using the Teller–Ulam design. Castle Bravo's yield was 15 megatonnes of TNT (63 petajoules), 2.5 times the predicted 6 megatonnes of TNT (25 petajoules), due to unforeseen additional reactions involving lithium-7, which led to radioactive contamination in the surrounding area. This photograph shows the Castle Bravo nuclear device, known as SHRIMP, in its shot cab.Photograph credit: United States Atomic Energy Commission; restored by Bammesk