Atombombentest Bravo (Sprengkraft 15 Mt). Nuclear weapon test Bravo (yield 15 Mt) on Bikini Atoll. The test was part of the Operation Castle. The Bravo event was an experimental thermonuclear device surface event... March 1954. United States Department of Energy. ... Public domain. This image is a work of a United States Department of Energy (or predecessor organization) employee, taken or made as part of that person's official duties. As a work of the U.S. federal government, the image is in the public domain.