Nuclear explosion debris. The first man made nuclear explosion occurred on July 16, 1945 at 5:50 am on the Trinity Test Site near Alamogordo, New Mexico in the United States, an area now known as the White Sands Missile Range. The event involved the full-scale testing of an implosion-type fission atomic bomb. In a memorandum to the U.S. Secretary of War, General Leslie Groves describes the yield as equivalent to 15,000 to 20,000 tons of TNT. Following this test, a uranium-gun type nuclear bomb (Little Boy) was dropped on the Japanese city of Hiroshima on August 6, 1945, with a blast yield
Pumpkin bomb the more usual cylindrical shape of other bombs, intended to enclose the Fat Man's spherical "physics package" (the plutonium implosion nuclear weapon core). Pumpkin bombs were a means of providing realistic training with non-nuclear bombs for the 509th Composite Group's Boeing B-29 Superfortress crews assigned to drop the atomic bomb. The pumpkin bomb had the same weight, size, and weight distribution as the Fat Man plutonium bomb, giving it the same ballistic and handling characteristics. Specifications for the bomb required that it be carried in the forward bomb bay of a Silverplate B-29 bomber and be fuzed to be effective