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
Mark 10 nuclear bomb Mark 10 nuclear bomb The Mark 10 nuclear bomb was a proposed American nuclear bomb based on the earlier Mark 8 nuclear bomb design. The Mark 10, like the Mark 8, is a Gun-type nuclear weapon, which rapidly assembles several critical masses of fissile nuclear material by firing a fissile projectile or "bullet" into a hollow opening in a larger fissile "target", using a system which closely resembles a medium-sized cannon barrel and propellant. The Mark 10 was intended to be a general purpose airburst nuclear weapon, unlike the Mark 8 which was intended to penetrate into the ground as