Thin Man (nuclear bomb) Thin Man (nuclear bomb) "Thin Man" was the code name for a proposed plutonium gun-type nuclear bomb using plutonium-239 which the United States was developing during the Manhattan Project. They aborted its development when they discovered that the spontaneous fission rate of their nuclear reactor-bred plutonium was too high for use in a gun-type design, due to the high concentration of the isotope plutonium-240. In 1942, prior to the Army taking over wartime atomic research, Robert Oppenheimer held conferences in Chicago in June and Berkeley, California, in July at which various engineers and physicists discussed nuclear bomb design issues. A
B46 nuclear bomb was redesignated the B53 nuclear bomb and W53 warhead. 50 B53 bombs were in US inactive reserves from 1997 to 2011, though none were actively deployed during that period. B46 nuclear bomb The B46 nuclear bomb (or Mk-46) was an American high-yield thermonuclear bomb which was designed and tested in the late 1950s. It was never deployed. Though originally intended to be a production design, the B46 ended up being only an intermediate prototype which was test fired several times. These prototypes were known as TX-46 units (Test/Experimental). The B46 design roughly weighed 8,120 pounds and was about 37 inches