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
Nagasaki Atomic Bomb Museum glass, burnt clothing, a lunchbox with its contents still charred inside of it, and a helmet with the remains of a victim’s skull on the inner surface. Section B shows damage caused by the radiation, damages caused by the blast, appeals of the atomic bomb survivors, and the rescue and relief activities which were carried out. After viewing the city scene, museum visitors are invited to think about issues related to war and nuclear non-proliferation. This section of the museum contains the political sections entitled "The Road to the Atomic Bombing" and "The War between China and Japan and the