Nuclear fission the Manhattan Project during World War II (September 1, 1939 – September 2, 1945) carried out most of the early scientific work on fission chain reactions, culminating in the three events involving fission bombs that occurred during the war. The first fission bomb, codenamed "The Gadget", was detonated during the Trinity Test in the desert of New Mexico on July 16, 1945. Two other fission bombs, codenamed "Little Boy" and "Fat Man", were used in combat against the Japanese cities of Hiroshima and Nagasaki in on August 6 and 9, 1945 respectively. Even the first fission bombs were thousands of
B46 nuclear bomb 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 in diameter. It was intended to have a 9 megaton yield. The design history of the B46 apparently derives most immediately from the older, larger Mark 21 nuclear bomb