The Manhattan Project -- Its Story

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Courtesy Argonne National Laboratory

The Manhattan Project -- Its Background

This year is the 70th anniversary of the establishment of the Manhattan Project, a predecessor of the U.S. Department of Energy.  To honor its impacts on science and history, various aspects of its background, establishment, operations, and immediate and long-term influences will be revisited.

It started during the fall of 1939, when President F. D. Roosevelt was made aware of the possibility that German scientists were racing to build an atomic bomb and was warned that Hitler would be more than willing to resort to such a weapon.  As a result, Roosevelt set up the Advisory Committee on Uranium, consisting of both civilian and military representatives, to study the current state of research on uranium and to recommend an appropriate role for the federal government.  The result was limited military funding for isotope separation and the work on chain reactions by Enrico Fermi and Leo Szilard at Columbia University.

On a separate front, in late 1939 Vannevar Bush, president of the Carnegie Foundation, became convinced of the need for the government to marshal the forces of science for a war that would inevitably involve the United States.  In June 1940, Roosevelt established a voice for the scientific community by establishing the National Defense Research Committee (NDRC), a reorganization of the Advisory Committee on Uranium into a scientific body that eliminated military membership.  The NDRC would have more influence and more direct access to money for nuclear research.  The NDRC's early priorities were studies on radar, proximity fuzes, and anti-submarine warfare with continued isotope separation and chain reaction work.

During 1939 and 1940, most of the research on isotope separation and chain reaction work was performed in university laboratories by academic scientists.  Ernest O. Lawrence, director of the Radiation Laboratory at the University of California at Berkeley, wanted the government to mobilize its scientific forces as rapidly as possible.  Specifically on his mind were experiments taking place in his Laboratory.  These included studies on uranium fission fragments by Edwin M. McMillan and Philip H. Abelson and research by Glenn T. Seaborg.

In 1941, Vannevar Bush became director of the Office of Scientific Research and Development (OSRD), which was established by Executive Order on June 28, 1941 and strengthened the scientific presence in federal government.  At this time, the NDRC became an advisory body to OSRD and the Uranium Committee became the OSRD Section On Uranium with the code name S-1.  Under the auspices of OSRD, S-1 was strengthened by the addition of Fermi as head of theoretical studies and Harold C. Urey as head of isotope separation and heavy water research.

In March 1942, with approval by Roosevelt, the Army Corps of Engineers began to participate in S-1 meetings.  This reflected the need for security within the S-1 program coupled with the Corps' expertise in construction, which would be needed to build the production facilities required for making the atomic bomb.  An Army officer would be in overall command of the entire project.  With this reorganization in place, the nature of the American atomic bomb effort changed from one dominated by research scientists to one in which scientists played a supporting role in the construction enterprise run by the U.S. Army Corps of Engineers.

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The Manhattan Project -- Its Establishment

President Roosevelt instructs the Army to take responsibility for construction of atomic weapons complex. The Army delegates the task to the Corps of Engineers, which establishes the Manhattan Engineer District.
Courtesy of National Nuclear
Security Administration

On August 13, 1942, the Manhattan Engineer District, which got its name from the geographical location of its headquarters, was established.  In September, the Army appointed Colonel Leslie R. Groves to head the effort.  Groves held that the exigencies of war required scientists to move from laboratory research to development and production in record time.  Though traditional scientific caution might be short-circuited in the process, there was no alternative if a bomb was to be built in time to be used in the current conflict.

Various isotope separation methods (uranium enrichment) to produce uranium-235 were being researched at this time.  One was gaseous diffusion being done at Columbia and another was the electromagnetic method being done at Berkeley under Ernest O. Lawrence.  Based upon the success of the electromagnetic method, the S-1 (The Office of Scientific Research and Development Section On Uranium) Executive Committee recommended building plants in Tennessee at Site X.

During this time, construction was taking place on the Stagg Field pile -- CP-1 (Chicago Pile Number one) at the Metallurgical Laboratory in Chicago where Enrico Fermi was conducting his research on chain reactions .  Also occurring was Glenn Seaborg's inventive work with plutonium, particularly his investigations on plutonium's oxidation states that seemed to provide a way to separate plutonium from the irradiated uranium to be produced in the pile.   In August, his team produced a microscopic sample of pure plutonium, a major chemical achievement and one fully justifying future work on the pile.

Theoretical studies in fission research and instrument and measurement studies, led by Robert Oppenheimer and including Felix Bloch, Hans Bethe, and Edward Teller, were also influencing the decisions being made in the effort to build the bomb.   Additionally, a significant event occurred at CP-1 on December 2, 1942, when the massive lattice pile of 400 tons of graphite, six tons of uranium metal, and fifty tons of uranium oxide achieved the first self-sustaining chain reaction. [For more information, see the Neutronic Reactor patent and related article]

On December 28, 1942, President F. D. Roosevelt approved the authorization for the Manhattan Project to build full-scale gaseous diffusion, plutonium, and electromagnetic plants.  With this, all the pieces were being put into place to begin the operations of the Manhattan Project.

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The Manhattan Project -- Its Operations

President Roosevelt instructs the Army to take responsibility for construction of atomic weapons complex. The Army delegates the task to the Corps of Engineers, which establishes the Manhattan Engineer District.

Major operations for the Manhattan Engineer District (Manhattan Project) took place in remote site locations in the states of Tennessee, New Mexico, and Washington, with additional research being conducted in university laboratories at Chicago and Berkeley.

At the Metallurgical Laboratory in Chicago, Enrico Fermi's experiments at the CP-1 pile took place to determine the exact amount of neutron reduction needed for a safe and controlled sustained nuclear reaction.  A second pile (CP-2), with external cooling, was built at Argonne in order to move the continuing experiments away from populated areas.

Under the umbrella of Clinton Engineer Works near Oak Ridge, Tennessee, the X-10 experimental plutonium pile and separation facilities, the Y-12 Electromagnetic Plant, and the K-25 Gaseous Diffusion Plant were constructed. 

In February 1943, ground was broken at X-10 for an air-cooled experimental pile, a pilot chemical separation plant, and support facilities.   On November 4, the pile went critical and it produced plutonium by the end of the month.  The chemical separation plant completed the steps needed for producing pure plutonium by extracting the plutonium from the irradiated uranium.  Chemical separation techniques were so successful that Los Alamos received plutonium samples in the spring of 1944.

Because of security requirements, fear of radioactive accidents, need for a long construction season and abundant water for hydroelectric power, an isolated area near Hanford, Washington (Site W) was chosen for the production plants.  Three water-cooled piles and three chemical separation plants were constructed.

At Y-12, using a design that was based upon research at Berkeley Lab, the first electromagnetic plant began to take shape in 1943.   By the end of February 1944, 200 grams of twelve-percent enriched uranium was produced.  Part of this was sent to Los Alamos and part was used to feed continuing production at Y-12.   Site preparation for the gaseous diffusion plant at K-25 was begun in June 1943.  This plant ultimately provided feed material for Y-12 at around fifty percent enriched uranium.  A thermal diffusion plant (S-50) to produce enriched uranium was added in early 1945.

In New Mexico, the Los Alamos Scientific Laboratory, under the direction of J. Robert Oppenheimer, was set up to design and fabricate the first atomic bombs.  To do this, it was necessary to start a chain reaction in a mass that would release the greatest possible amount of energy before it was destroyed in the explosion.  Two types of bombs became the focus of the work:  The uranium gun design (the Little Boy) and the plutonium implosion design (the Fat Man).

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The Manhattan Project -- Its Immediate Influences

With the Manhattan Project on the brink of success in spring 1945, the atomic bomb became an increasingly important element in American strategy to bring an end to World War II.

Because of the generally accepted view that the Japanese would fight to the bitter end, a costly invasion of the home islands seemed likely, even though some American policy makers held that successful combat delivery of one or more atomic bombs might convince the Japanese that further resistance was futile.  They contended that the bomb could possibly lead to Japanese surrender without an invasion and should be used as soon as possible, without warning.
Strategies for forcing Japanese capitulation occupied center stage in June 1945.  Wording of an early surrender offer received considerable attention, the sticking point being the term “unconditional.” It was clear that the Japanese would fight on rather than accept terms that would eliminate the Imperial House or demean the warrior tradition, but American policy makers feared that anything less than a more democratic political system and total demilitarization might lead to Japanese aggression in the future.  The definition of unconditional surrender was clarified.  Japan need not fear total annihilation.  Once demilitarized, Japan would be free to choose its political system and would be allowed to develop a vibrant economy.  It was hoped that this public statement to Japan would lead to surrender before a costly invasion would have to be launched.  However, the Japanese continued to search for an alternative to unconditional surrender.

On July 26, 1945, a formal warning was given to Japan.  The message called for the Japanese to surrender unconditionally or face “prompt and utter destruction.”  The Potsdam Proclamation left the emperor’s status unclear by making no reference to the royal house in the section that promised the Japanese that they could design their new government as long as it was peaceful and more democratic.

Japanese wanted to surrender but felt they could not accept the terms offered in the Potsdam Proclamation. American policy makers, however, anxious to end the war without committing American servicemen to an invasion of the Japanese homeland, were not inclined to undertake revisions of the unconditional surrender formula and cause further delay.  A blockade of Japan combined with conventional bombing was rejected as too time-consuming and an invasion of the islands as too costly. And few believed that a demonstration of the atomic bomb would convince the Japanese to give up. Primarily upon these grounds, American policy makers concluded that the atomic bomb must be used.  Information that Hiroshima might be the only prime target city without American prisoners in the vicinity placed it first on the list.

Japan, Hiroshima, NagasakiIn the end, in the early morning hours of August 6, 1945, the Enola Gay released the untested 9,700-pound uranium bomb, nicknamed Little Boy, above Hiroshima, an important military and communications center.  Little Boy detonated 1900 feet above the city and caused total devastation for five square miles.  Japan was then warned that if it still refused to surrender unconditionally as demanded by the Potsdam Proclamation of July 26, the United States would attack additional targets with equally devastating results.

In the absence of a surrender announcement, on August 9, a second atomic attack took place. The bomber, Bock's Car, approached Nagasaki, home to the Mitsubishi plant that had manufactured the torpedoes used at Pearl Harbor, and dropped her single payload, a plutonium bomb weighing 10,000 pounds and nicknamed Fat Man.  Three square miles of the city were destroyed.

Still the Japanese leadership struggled to come to a decision. Word finally reached Washington early on August 10 that the Japanese, in accordance with the emperor’s wishes, would accept the surrender terms, provided the emperor retain his position. A third atomic attack was held up while the United States considered a response, finally taking a middle course and acknowledging the emperor by stating that his authority after the surrender would be exercised under the authority of the Supreme Commander of the Allied Powers.

Japan surrendered on August 14, 1945 and the Instrument of Surrender was signed on September 2, 1945.  This ended the war that began for the United States with the surprise attack at Pearl Harbor on December 7, 1941.

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The Manhattan Project -- Its Long-term Influences

After the end of World War II, Congress established the United States Atomic Energy Commission (AEC) to foster and control the peacetime development of atomic science and technology, declaring that atomic energy should be employed not only in the Nation's defense, but also to promote world peace, improve the public welfare, and strengthen free competition in private enterprise.  President Harry S. Truman confirmed the civilian control of atomic energy by signing the Atomic Energy Act on August 1, 1946.

On January 1, 1947, the AEC took over from the Manhattan Engineer District (Manhattan Project) the research and production facilities built during World War II to develop the atomic bomb.  Because of the need for great security, all production facilities and nuclear reactors would be government-owned, while all technical information and research results would be under Commission control.  The Commission recognized the need to maintain the vitality of the national labs and to encourage the university research teams and industry groups whose research on the peaceful uses of atomic energy would provide the technology of the future.

Atoms for PeaceIn his Atoms-for-Peace proposal of December 8, 1953, President Dwight D. Eisenhower had proposed that the nuclear powers contribute portions of their stockpiles of normal uranium and fissionable materials to an international atomic energy agency, which would then allocate these materials toward peaceful uses.  As a result the International Atomic Energy Agency (IAEA) was formally inaugurated in Vienna, Austria on October 1, 1957.

On August 26, 1964, President Lyndon B. Johnson brought to an end an eighteen-year mandatory government monopoly of special nuclear materials by signing into law the "Private Ownership of Special Nuclear Materials Act', permitting private entities to assume title to special nuclear materials.  By the end of 1974 two hundred and thirty-three nuclear central-station generating units, with a capacity of 232,000 megawatts, were either in operation, under construction, or on order in the United States.

Advance in medical diagnostic techniques based on the use of radioisotopes and radiation machines added to the skills of the medical profession, while immunological research provided the knowledge needed for successful transplants.  Other medical breakthroughs included the treatment of Parkinson's Disease, the preservation of cells for transfusion, and the introduction of small accelerators to produce short-lived radioisotopes of immediate use in patients. 

During the 1960's the Commission produced a series of radioisotope-powered and reactor-powered electrical-generating units for space applications.  In addition, significant progress was made in developing cardiac pacemakers for human use and ultimately artificial hearts using radioisotopic-power sources.
The legacy of the Manhattan Project includes its impact on history, science, medicine, space exploration, electricity, and much more.  The facilities built during the war have grown into National Laboratories that continue to contribute to science research, with key breakthroughs in various science fields, including physics, chemistry, biology, medicine and medical imaging, renewable energy, and improved transportation.  

The Manhattan Project is the predecessor of the Atomic Energy Commission (AEC),  the Energy Research and Development Administration (ERDA), and the Department of Energy (DOE), whose research results permeate many aspects of our lives.  DOE continues to build and expand upon the research that was conducted under the auspices of the Manhattan Project.

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