The general principles of the " classical Super " design were public knowledge even before thermonuclear weapons were first tested . After President Truman ordered the crash program to develop the H-bomb in January 1950 the '' Boston Daily Globe '' published a cutaway description of a hypothetical H-bomb with the caption '' Artist 's conception of how H-bomb might work using atomic bomb as a mere " trigger " to generate enough heat to set up the H-bomb 's " thermonuclear fusion " process . '' The fact that a large proportion of the yield of a thermonuclear device stems from the fission of a uranium 238 tamper ( fission-fusion-fission principle ) was revealed when the Castle Bravo test " ran away , " producing a much higher yield than originally estimated and creating large amounts of nuclear fallout
Castle Bravo
Castle Bravo
History of the Teller–Ulam design