After the rejection of the demand for unconditional surrender by the Japanse government in July of 1945, the United States President, Harry S. Truman, decided to drop an atomic bomb on the Japanese city of Hiroshima. During World War II, Hiroshima on the Japanse island of Honshu was home to several military bases and industrial facilities that supplied the Japanese war effort.
After the Japanese rejected the U.S. demand for unconditional surrender in the spring on 1945, Harry Truman, the U.S. President authorized the use of atomic weapons in Japan. The Manhattan project had produced two nuclear weapons by that time, one based on uranium known as Little Boy and the other based on plutonium named Fat Man.
The Manhattan Project to create nuclear bomb during the early 1940s was successful. Two bombs were created, one based on the fission of uranium-235 called “Little Boy” and a second based on the fission of plutonium-239 called “Fat Man”. Upon completion of the bombs in the summer of 1945, the U.S.
On July 26, the United States, Britain and China produced the Potsdam Declaration which contained the terms that they demanded for the surrender of Japan. The Declaration required that Japan surrender immediately and without conditions. The surrender terms included:
After the successful test of a plutonium implosion device in July of 1945 at the Trinity site near Alamogordo, New Mexico, the Manhattan Project proceeded with the design and construction of a plutonium bomb to be used as a weapon. The code name for the device was “Fat Man”, homage to one of the characters in the movie “The Maltese Falcon.” The name came to be used for the whole class of nuclear bombs based on the same design.
While the Manhattan Project was developing plutonium production facilities and producing plutonium at Hanford, Washington in the early 1940s, the Project was also working on the design of a bomb that would utilize the plutonium. It turned out that gun-type design being worked on for a uranium bomb would not work for a plutonium bomb. Plutonium-239 was being produced in reactors but the reactors were also creating plutonium-240 as well.
In the summer of 1945, the United States Manhattan Project to create an atomic bomb delivered one hundred and ten pounds of uranium enriched to 89% U-235 too the Los Alamos testing grounds in New Mexico.
While the U.S. Manhattan project refined and enriched uranium for an atomic bomb in the early 1940, a parallel project was carried out to create plutonium. Plutonium is very rare in nature so it was necessary to create nuclear reactor in which plutonium could be generated by injecting neutrons into a mass of uranium. Most naturally occurring uranium is the U-238 isotope. When U-238 is bombarded with neutrons, some of it is converted to U-239 by absorption of a neutron.
After the Japanese attacked Pearl Harbor in December of 1942, the Manhattan project ramped up with millions of dollar and thousands of staff. Four major deposits of uranium ore had already been identified and efforts were being made to obtain ore from the three that were in Allied hands. In November of 1942 it had been determined that there should be sufficient ore available to produce an atomic weapon.
The Manhattan Project was started in 1939 by the US Government to explore the military potential of uranium. The knowledge that the Germans were working on nuclear weapons research at the same time spurred the creation of the program. It started with a modest budget and a small group of researchers. In the meantime, Brittan was also pursuing nuclear research and verified in 1939 that fifty pounds of uranium could be made into a bomb that could be carried in a conventional bomber.
