Topic+17+(Manhattan+Project)

The Manhattan Project
The Manhattan Project was a secret endeavor by the United States to build the first nuclear bomb, culminating in the Trinity test, and the bombings of Hiroshima and Nagasaki. At its height, the Manhattan Project employed over 140,000 people, and cost $2 billion ($30 billion in current USD). ("Manhattan Project") By 1940, it looked increasingly likely that the US was going to be dragged into the war, and Germany had begun work on constructing a nuclear weapon, much to the alarm of the scientific community.

In July of 1939, a Leo Szilard, a refugee from the Nazis, met with Albert Einstein. Together, they discussed the possibility that Germany would acquire a nuclear weapon before the US. Alarmed, Einstein agreed to warn Pres. Roosevelt of the possibility. Roosevelt immediately replied, a result of Einstein’s great standing. Roosevelt commissioned a committee to begin work on an American nuclear weapon, but with the US seeking to avoid conflict, the project was mostly shelved. When the US entered the war, renewed interest was brought to the project, and work on the Manhattan Project began in earnest. ("Manhattan Project") Before the Manhattan Project had truly begun however, Enrico Fermi, working underneath the University of Chicago’s campus, had demonstrated, by way of his 500+ ton atomic pile, that it was feasible to sustain a fission reaction. It began looking more and more likely that a bomb could be built, and pressure mounted as the US raced both Germany and the USSR to build the first bomb. (Roleff 46)

Gen. Leslie Groves was assigned to the Manhattan Project. An engineer, he was furious to have been assigned to what he deemed “a waste of time”, immediately upon completion of the Pentagon. He first organized all the scientists and military workers onto a site at Los Alamos, picked for its remoteness, and there, work began on creating a bomb. (Sullivan 30)

Almost immediately, the scientists hit an enormous hurdle. The only uranium suitable for bomb-making was U-235, a rare isotope, chemically identical to the vastly more common and useless U-238. The scientists had devised two ways of separating them; a modified mass spectrometer, in which the small mass difference was exploited, and a gaseous diffusion chamber, in which the slight size difference was exploited. Unfortunately, to produce the 200 kg thought necessary would require the largest manufacturing sites ever constructed. ("Manhattan Project") Undaunted, Gen. Groves immediately ordered construction to begin on a site in Oak Ridge, Tennessee, of a massive spectrometer separation site. Due to the secrecy of the site, even the construction workers and later factory workers had no idea what they were doing. As soon as the site was constructed, problems were found in everything. In his typical fashion, after Groves decided that this plant could not run at full capacity, he built several more, at Oak Ridge and then at Hanford, Washington. Oak Ridge in particular was a center of uranium production. At its peak, Oak Ridge grew to be the fifth largest city in Tennessee, and consumed over 10% of the US’ total electrical power. ("Manhattan Project")

At the same time, it had been discovered that by bombarding U-238 with neutrons, a new element, plutonium P-239 could be created, which was fissile, like U-235. Furthermore, a simpler process was required to create P-239; the bombardment of U-238 in reactors with neutrons. When Groves and Oppenheimer heard of the discovery, the scientists were ordered to find ways to construct a reactor to create P-239, and as soon as that process was completed, Groves built several reactors to create the new element.

Eventually, there was found to be enough uranium for one bomb, which was to be used against Japan, and enough plutonium for two, one of which was to be a test. ("Manhattan Project") At the same time, work was being done on how to create a critical mass of fissile material. The scientists settled for the simple gun type bomb. In a gun type bomb, a subcritical mass of uranium was fired at another subcritical mass at high velocity. The resulting compression was hoped to be enough to create a critical mass. However, it was determined that the gun type assembly method could not work for plutonium. After much deliberation, an implosion device was settled on. In the implosion assembly, a subcritical mass was held in the center of several pounds of conventional explosives. These conventional explosives were then designed to detonate simultaneously, directing symmetrical pressure inward, and compressing the plutonium into a critical mass. However, the implosion device presented many challenges of its own. Never before had explosives been used to direct symmetrical shocks, and initially, Groves was not in favor of this plan. Fortunately, despite its complexity, it would prove to be sound. ("Manhattan Project")

On April 12, 1945, Pres. Roosevelt died. The secrecy surrounding the Manhattan project was so great that Truman was not aware of it until he had been sworn in. In mid-May, Groves announced that the test of the first plutonium device would be conducted on July 16. The location chosen was the aptly named Jornada del Muerto (Journey of Death). The scientists arrived on July 13, and immediately began working. It was testament to how difficult the build had been that scientists, right up until the last hours, had been working on the bomb. One scientist remarked the bomb was a huge debt to 3M, since most of it was held together with masking tape! ("Manhattan Project") At 5:00 am, on July 16, the world entered the atomic age, with a flash, an eruption of noise, and a tremendous shockwave. The yield from the Trinity test was determined to be 18 kilotons of TNT.

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Personnel

 * Gen. Leslie Groves
 * J. Robert Oppenheimer
 * Albert Einstein
 * Enrico Fermi

Locations

 * Los Alamos
 * Oak Ridge
 * Hanford
 * Trinity Test

Other

 * Nuclear Fission