The Manhattan Project

The Manhattan Project

In 1939, the Nazis were rumored to be developing an atomic bomb. The United States initiated its own program under the Army Corps of Engineers in June 1942. America needed to build an atomic weapon before Germany or Japan did. General Leslie R. Groves, Deputy Chief of Construction of the U.S. Army Corps of Engineers, was appointed to direct this top-secret project.

(1896-1970)

General Leslie R. Groves directed the Manhattan Project. Groves established three large engineering and production centers at remote U.S. sites: the Clinton Engineer Works at Oak Ridge, Tenn.; the Hanford Engineer Works in eastern Washington State; and Project Y, a code-named site 100 miles north of Albuquerque at Los Alamos, N.M.

Meanwhile, experiments in a small laboratory beneath the University of Chicago’s abandoned Stagg Field were expanding understanding of atomic theory. The first controlled nuclear reaction occurred under Stagg Field.

Italian physicist Enrico Fermi managed the University of Chicago reactor, called Chicago Pile 1 (CP-1). Nobel Prize-winner Fermi had fled Fascist Europe. On the afternoon of December 2, 1942, it happened. Under the abandoned west stands of Stagg Field, the first controlled nuclear reaction occurred. Humankind had controlled energy released from the nucleus of the atom.

Scientists now had to create the fuel for an atomic bomb. The Oak Ridge facility separated the nuclear fuel U-235 from U-238, natural uranium. Scientists needed to find fuel, for the reactors, which meant using uranium (U-235) or plutonium (Pu-238), the only suitable substances know by 1942. Project leaders did not know how quickly or how much of each they could produce, so they decided to produce both at the same time.

Three methods existed for extracting U-235: an electromagnetic process, gaseous diffusion and thermal diffusion. Oak Ridge crews built a plant for each method. The electromagnetic process at the facility, called Y-12, was the most promising.

The process of extracting U-235 from natural uranium started at the Clinton Engineer Works, 20 miles west of Knoxville, TN. Work began on the plant in 1942. In 1943, the facility name was changed to Oak Ridge. This Appalachian site spanned 59,000 acres of wilderness and farmland.

The Clinch River provided hydroelectric power through the Tennessee Valley Authority (TVA). To build on of the largest U.S. industrial complexes, more than 1,000 rural families were relocated from their farms.

The Hanford Engineer Works produced plutonium. The search for this location included sites along the Colorado and Columbia Rivers in California, Oregon, and Washington. The isolated 500,000-acre Hanford site offered security for sensitive operations. Large quantities of electricity and cooling water (at least 25,000 gallons per minute) were available and a mild climate allowed year-round work.

The facility encompassed three small towns—Hanford, White Bluffs, and Richland—and bordered the Columbia River. Sheep had grazed the flat, rocky countryside, which was dotted with orchards, vineyards, and farms. To build the facility, the townships of Richland, White Bluffs, and Hanford vanished. As at Oak Ridge, 1,500 people were relocated in the process. Close to a half-million acres were purchased for more than $5.1 million by the spring of 1943. The new facility was named Hanford Engineer Works after the riverside village.

(1904-1967)
Theoretical physicist Oppenheimer, who would direct Los Alamos research, identified top scientists and engineers from universities nationwide. In November 1942, General Leslie Groves and physicist Oppenheimer chose the site where the first atomic bombs were designed and built. The site at Los Alamos, N.M. had been a boys’ school and Oppenheimer had visited it in the 1920s.

At Los Alamos, an international team of scientists and engineers labored around the clock to create the first atomic weapons. The remote location and existing school buildings helped make Los Alamos the choice for a research and development site. The owners of the school were willing to sell it to the military for $440,000, since they were having problems obtaining and keeping qualified teachers during the war.

By March 1943, Los Alamos had become an intellectual boomtown. Known as “the hill,” Los Alamos produced two bombs. One, nicknamed Little Boy, was a gun-type weapon that used U-235. A slug of U-235 would be projected down a gun barrel into the center of another piece of U-235. When combined, a nuclear explosion would occur. The second bomb, Fat Man, used implosion to detonate plutonium. Here, explosives would surround the plutonium ball. When detonated, they would compress the plutonium, causing a nuclear explosion.

Uranium Fission
(1938)
Otto Hahn and Fritz Strassmann’s discovery of fission steered Germany toward developing an atomic weapon. This motivated the U.S. to launch the Manhattan Project.

The Race for the Atomic Bomb Begins
(1939-1941)
World War II started September 1, 1939, when Germany attacked Poland. By 1941, the Germans were leading the race for the atomic bomb. They had a heavy-water plant, high-grade uranium compounds, a nearly complete cyclotron, capable scientists and engineers, and the greatest chemical engineering industry in the world.

The Research Effort Struggles
(1941-1945)
Factors including internal struggles, a major scientific error, and the devastation of total war compromised any successful research toward a German atom bomb. Unlike the American program, the Germans never had a clear mission under continuously unified leadership.

The First Controlled Nuclear Reaction
(1942)
At the University of Chicago reactor, Enrico Fermi oversaw the first controlled energy release from the nucleus of the atom.

U-235 Output Begins
(1945)
After intense effort, the Y-12 plant in Oak Ridge, Tenn., began to produce bomb-grade U-235, which was shipped to Los Alamos, N.M. U-235 was used in the Little Boy bomb and plutonium was used in the Fat Man bomb produced at Los Alamos.