The Manhattan Project was a research and development undertaking during
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
that produced the first
nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bom ...
s. It was led by the United States with the support of the United Kingdom and Canada. From 1942 to 1946, the project was under the direction of Major General
Leslie Groves
Lieutenant General Leslie Richard Groves Jr. (17 August 1896 – 13 July 1970) was a United States Army Corps of Engineers officer who oversaw the construction of the Pentagon and directed the Manhattan Project, a top secret research project ...
of the
U.S. Army Corps of Engineers
, colors =
, anniversaries = 16 June (Organization Day)
, battles =
, battles_label = Wars
, website =
, commander1 = ...
. Nuclear physicist
Robert Oppenheimer
J. Robert Oppenheimer (; April 22, 1904 – February 18, 1967) was an American theoretical physicist. A professor of physics at the University of California, Berkeley, Oppenheimer was the wartime head of the Los Alamos Laboratory and is often ...
was the director of the
Los Alamos Laboratory
The Los Alamos Laboratory, also known as Project Y, was a secret laboratory established by the Manhattan Project and operated by the University of California during World War II. Its mission was to design and build the first atomic bombs. Ro ...
that designed the actual bombs. The Army component of the project was designated the Manhattan District as its first headquarters were in
Manhattan
Manhattan (), known regionally as the City, is the most densely populated and geographically smallest of the five boroughs of New York City. The borough is also coextensive with New York County, one of the original counties of the U.S. state ...
; the placename gradually superseded the official codename, Development of Substitute Materials, for the entire project. Along the way, the project absorbed its earlier British counterpart,
Tube Alloys
Tube Alloys was the research and development programme authorised by the United Kingdom, with participation from Canada, to develop nuclear weapons during the Second World War. Starting before the Manhattan Project in the United States, the Bri ...
. The Manhattan Project began modestly in 1939, but grew to employ more than 130,000 people and cost nearly US$2 billion (equivalent to about $ billion in ). Over 90 percent of the cost was for building factories and to produce
fissile material
In nuclear engineering, fissile material is material capable of sustaining a nuclear fission chain reaction. By definition, fissile material can sustain a chain reaction with neutrons of thermal energy. The predominant neutron energy may be ty ...
, with less than 10 percent for development and production of the weapons. Research and production took place at more than thirty sites across the United States, the United Kingdom, and Canada.
The project led to the development of two types of atomic bombs, both developed concurrently, during the war: a relatively simple
gun-type fission weapon
Gun-type fission weapons are fission-based nuclear weapons whose design assembles their fissile material into a supercritical mass by the use of the "gun" method: shooting one piece of sub-critical material into another. Although this is sometim ...
and a more complex
implosion-type nuclear weapon
Nuclear weapon designs are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types:
* pure fission weapons, the simplest and least technically ...
. The
Thin Man gun-type design proved impractical to use with
plutonium
Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibi ...
, so a simpler gun-type called
Little Boy
"Little Boy" was the type of atomic bomb dropped on the Japanese city of Hiroshima on 6 August 1945 during World War II, making it the first nuclear weapon used in warfare. The bomb was dropped by the Boeing B-29 Superfortress ''Enola Gay'' p ...
was developed that used
uranium-235
Uranium-235 (235U or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exis ...
, an
isotope
Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...
that makes up only 0.7 percent of natural
uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...
. Because it is chemically identical to the most common isotope,
uranium-238
Uranium-238 (238U or U-238) is the most common isotope of uranium found in nature, with a relative abundance of 99%. Unlike uranium-235, it is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. However, it ...
, and has almost the same mass, separating the two proved difficult. Three methods were employed for
uranium enrichment
Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235U) has been increased through the process of isotope separation. Naturally occurring uranium is composed of three major isotopes: uranium-238 (238U ...
:
electromagnetic
In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions of a ...
,
gaseous
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).
A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
and
thermal
A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example ...
. Scientists conducted most of this work at the
Clinton Engineer Works
The Clinton Engineer Works (CEW) was the production installation of the Manhattan Project that during World War II produced the enriched uranium used in the 1945 bombing of Hiroshima, as well as the first examples of reactor-produced plutoni ...
at
Oak Ridge, Tennessee
Oak Ridge is a city in Anderson and Roane counties in the eastern part of the U.S. state of Tennessee, about west of downtown Knoxville. Oak Ridge's population was 31,402 at the 2020 census. It is part of the Knoxville Metropolitan Area. Oak ...
.
In parallel with the work on uranium was an effort to produce plutonium, which researchers at the
University of California, Berkeley
The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant u ...
, discovered in 1940. After the feasibility of the world's first artificial nuclear reactor, the
Chicago Pile-1
Chicago Pile-1 (CP-1) was the world's first artificial nuclear reactor. On 2 December 1942, the first human-made self-sustaining nuclear chain reaction was initiated in CP-1, during an experiment led by Enrico Fermi. The secret development of t ...
, was demonstrated in 1942 at the
Metallurgical Laboratory
The Metallurgical Laboratory (or Met Lab) was a scientific laboratory at the University of Chicago that was established in February 1942 to study and use the newly discovered chemical element plutonium. It researched plutonium's chemistry and m ...
in the
University of Chicago
The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park neighborhood. The University of Chicago is consistently ranked among the b ...
, the project designed the
X-10 Graphite Reactor at Oak Ridge and the production reactors at the
Hanford Site in
Washington state
Washington (), officially the State of Washington, is a state in the Pacific Northwest region of the Western United States. Named for George Washington—the first U.S. president—the state was formed from the western part of the Washington ...
, in which uranium was irradiated and
transmuted into plutonium. The plutonium was then chemically separated from the uranium, using the
bismuth phosphate process
The bismuth-phosphate process was used to extract plutonium from irradiated uranium taken from nuclear reactors. It was developed during World War II by Stanley G. Thompson, a chemist working for the Manhattan Project at the University of Califor ...
. The
Fat Man
"Fat Man" (also known as Mark III) is the codename for the type of nuclear bomb the United States detonated over the Japanese city of Nagasaki on 9 August 1945. It was the second of the only two nuclear weapons ever used in warfare, the fir ...
plutonium implosion-type weapon was developed in a concerted design and development effort by the Los Alamos Laboratory.
The project was also charged with gathering intelligence on the
German nuclear weapon project
The Uranverein ( en, "Uranium Club") or Uranprojekt ( en, "Uranium Project") was the name given to the project in Nazi Germany, Germany to research nuclear technology, including nuclear weapons and nuclear reactors, during World War II. It wen ...
. Through
Operation Alsos, Manhattan Project personnel served in Europe, sometimes behind enemy lines, where they gathered nuclear materials and documents, and rounded up German scientists. Despite the Manhattan Project's tight security, Soviet
atomic spies successfully penetrated the program.
The first nuclear device ever detonated was an implosion-type bomb during the
Trinity test, conducted at New Mexico's
Alamogordo Bombing and Gunnery Range
Alamogordo () is the seat of Otero County, New Mexico, United States. A city in the Tularosa Basin of the Chihuahuan Desert, it is bordered on the east by the Sacramento Mountains and to the west by Holloman Air Force Base. The population was ...
on 16 July 1945. Little Boy and Fat Man bombs were used a month later in the
atomic bombings of Hiroshima and Nagasaki
The United States detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki on 6 and 9 August 1945, respectively. The two bombings killed between 129,000 and 226,000 people, most of whom were civilians, and remain the onl ...
, respectively, with Manhattan Project personnel serving as bomb assembly technicians and weaponeers on the attack aircraft. In the immediate postwar years, the Manhattan Project conducted weapons testing at
Bikini Atoll as part of
Operation Crossroads, developed new weapons, promoted the development of the network of
national laboratories, supported medical research into
radiology
Radiology ( ) is the medical discipline that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography (which is why its name has a root referring to radiat ...
and laid the foundations for the
nuclear navy. It maintained control over American atomic weapons research and production until the formation of the
United States Atomic Energy Commission
The United States Atomic Energy Commission (AEC) was an agency of the United States government established after World War II by U.S. Congress to foster and control the peacetime development of atomic science and technology. President H ...
in January 1947.
Origins
The
discovery of nuclear fission
Nuclear fission was discovered in December 1938 by chemists Otto Hahn and Fritz Strassmann and physicists Lise Meitner and Otto Robert Frisch. Fission is a nuclear reaction or radioactive decay process in which the nucleus of an atom splits in ...
by German chemists
Otto Hahn and
Fritz Strassmann in 1938, and its theoretical explanation by
Lise Meitner
Elise Meitner ( , ; 7 November 1878 – 27 October 1968) was an Austrian-Swedish physicist who was one of those responsible for the discovery of the element protactinium and nuclear fission. While working at the Kaiser Wilhelm Institute on rad ...
and
Otto Frisch
Otto Robert Frisch FRS (1 October 1904 – 22 September 1979) was an Austrian-born British physicist who worked on nuclear physics. With Lise Meitner he advanced the first theoretical explanation of nuclear fission (coining the term) and first ...
, made the development of an
atomic bomb
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions (thermonuclear bomb), producing a nuclear explosion. Both bomb ...
a theoretical possibility. There were fears that a
German atomic bomb project
The Uranverein ( en, "Uranium Club") or Uranprojekt ( en, "Uranium Project") was the name given to the project in Germany to research nuclear technology, including nuclear weapons and nuclear reactors, during World War II. It went through s ...
would develop one first, especially among scientists who were refugees from
Nazi Germany
Nazi Germany (lit. "National Socialist State"), ' (lit. "Nazi State") for short; also ' (lit. "National Socialist Germany") (officially known as the German Reich from 1933 until 1943, and the Greater German Reich from 1943 to 1945) was ...
and other
fascist
Fascism is a far-right, Authoritarianism, authoritarian, ultranationalism, ultra-nationalist political Political ideology, ideology and Political movement, movement,: "extreme militaristic nationalism, contempt for electoral democracy and pol ...
countries. In August 1939, Hungarian-born physicists
Leo Szilard and
Eugene Wigner drafted the
Einstein–Szilard letter
The Einstein–Szilard letter was a letter written by Leo Szilard and signed by Albert Einstein on August 2, 1939, that was sent to President of the United States Franklin D. Roosevelt. Written by Szilard in consultation with fellow Hungarian ...
, which warned of the potential development of "extremely powerful bombs of a new type". It urged the United States to take steps to acquire stockpiles of
uranium ore and accelerate the research of
Enrico Fermi
Enrico Fermi (; 29 September 1901 – 28 November 1954) was an Italian (later naturalized American) physicist and the creator of the world's first nuclear reactor, the Chicago Pile-1. He has been called the "architect of the nuclear age" and ...
and others into
nuclear chain reaction
In nuclear physics, a nuclear chain reaction occurs when one single nuclear reaction causes an average of one or more subsequent nuclear reactions, thus leading to the possibility of a self-propagating series of these reactions. The specific nu ...
s. They had it signed by
Albert Einstein
Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for developing the theory ...
and delivered to President
Franklin D. Roosevelt
Franklin Delano Roosevelt (; ; January 30, 1882April 12, 1945), often referred to by his initials FDR, was an American politician and attorney who served as the 32nd president of the United States from 1933 until his death in 1945. As the ...
. Roosevelt called on
Lyman Briggs
Lyman James Briggs (May 7, 1874 – March 25, 1963) was an American engineer, physicist and administrator. He was a director of the National Bureau of Standards during the Great Depression and chairman of the Uranium Committee before America e ...
of the
National Bureau of Standards to head the
Advisory Committee on Uranium
The S-1 Executive Committee laid the groundwork for the Manhattan Project by initiating and coordinating the early research efforts in the United States, and liaising with the Tube Alloys Project in Britain.
In the wake of the discovery of nucl ...
to investigate the issues raised by the letter. Briggs held a meeting on 21 October 1939, which was attended by Szilárd, Wigner and
Edward Teller. The committee reported back to Roosevelt in November that uranium "would provide a possible source of bombs with a destructiveness vastly greater than anything now known."
In February 1940, the
U.S. Navy awarded
Columbia University
Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a private research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhatt ...
$6,000 in funding, most of which
Enrico Fermi
Enrico Fermi (; 29 September 1901 – 28 November 1954) was an Italian (later naturalized American) physicist and the creator of the world's first nuclear reactor, the Chicago Pile-1. He has been called the "architect of the nuclear age" and ...
and Szilard spent on purchasing
graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...
. A team of Columbia professors including Fermi, Szilard,
Eugene T. Booth
Eugene Theodore Booth, Jr. (28 September 1912 – 6 March 2004) was an American nuclear physicist. He was a member of the historic Columbia University team which made the first demonstration of nuclear fission in the United States. During the ...
and
John Dunning created the first nuclear fission reaction in the Americas, verifying the work of Hahn and Strassmann. The same team subsequently built a series of prototype
nuclear reactor
A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nu ...
s (or "piles" as Fermi called them) in
Pupin Hall
Pupin Physics Laboratories , also known as Pupin Hall, is home to the Columbia University Physics Department, physics and astronomy departments of Columbia University in New York City. The building is located on the south side of 120th Street (Man ...
at Columbia, but were not yet able to achieve a chain reaction. The Advisory Committee on Uranium became the
National Defense Research Committee (NDRC) on Uranium when that organization was formed on 27 June 1940. Briggs proposed spending $167,000 on research into uranium, particularly the
uranium-235
Uranium-235 (235U or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exis ...
isotope, and
plutonium
Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibi ...
, which was discovered in 1940 at the
University of California
The University of California (UC) is a public land-grant research university system in the U.S. state of California. The system is composed of the campuses at Berkeley, Davis, Irvine, Los Angeles, Merced, Riverside, San Diego, San Francisco, ...
.
On 28 June 1941, Roosevelt signed Executive Order 8807, which created the
Office of Scientific Research and Development (OSRD), with
Vannevar Bush
Vannevar Bush ( ; March 11, 1890 – June 28, 1974) was an American engineer, inventor and science administrator, who during World War II headed the U.S. Office of Scientific Research and Development (OSRD), through which almost all wartime ...
as its director. The office was empowered to engage in large engineering projects in addition to research.
[.] The NDRC Committee on Uranium became the S-1 Section of the OSRD; the word "uranium" was dropped for security reasons.
In Britain, Frisch and
Rudolf Peierls at the
University of Birmingham
, mottoeng = Through efforts to heights
, established = 1825 – Birmingham School of Medicine and Surgery1836 – Birmingham Royal School of Medicine and Surgery1843 – Queen's College1875 – Mason Science College1898 – Mason Univers ...
had made a breakthrough investigating the
critical mass
In nuclear engineering, a critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The critical mass of a fissionable material depends upon its nuclear properties (specifically, its nuclear fissi ...
of uranium-235 in June 1939. Their calculations indicated that it was within an
order of magnitude
An order of magnitude is an approximation of the logarithm of a value relative to some contextually understood reference value, usually 10, interpreted as the base of the logarithm and the representative of values of magnitude one. Logarithmic dis ...
of , which was small enough to be carried by a bomber of the day.
[.] Their March 1940
Frisch–Peierls memorandum
The Frisch–Peierls memorandum was the first technical exposition of a practical nuclear weapon. It was written by expatriate German-Jewish physicists Otto Frisch and Rudolf Peierls in March 1940 while they were both working for Mark Oliphant a ...
initiated the British atomic bomb project and its
MAUD Committee
The MAUD Committee was a British scientific working group formed during the Second World War. It was established to perform the research required to determine if an atomic bomb was feasible. The name MAUD came from a strange line in a telegram fro ...
, which unanimously recommended pursuing the development of an atomic bomb.
In July 1940, Britain had offered to give the United States access to its scientific research, and the
Tizard Mission's
John Cockcroft
Sir John Douglas Cockcroft, (27 May 1897 – 18 September 1967) was a British physicist who shared with Ernest Walton the Nobel Prize in Physics in 1951 for splitting the atomic nucleus, and was instrumental in the development of nuclea ...
briefed American scientists on British developments. He discovered that the American project was smaller than the British, and not as far advanced.
As part of the scientific exchange, the MAUD Committee's findings were conveyed to the United States. One of its members, the Australian physicist
Mark Oliphant
Sir Marcus Laurence Elwin Oliphant, (8 October 1901 – 14 July 2000) was an Australian physicist and humanitarian who played an important role in the first experimental demonstration of nuclear fusion and in the development of nuclear weapon ...
, flew to the United States in late August 1941 and discovered that data provided by the MAUD Committee had not reached key American physicists. Oliphant then set out to find out why the committee's findings were apparently being ignored. He met with the Uranium Committee and visited
Berkeley, California
Berkeley ( ) is a city on the eastern shore of San Francisco Bay in northern Alameda County, California, United States. It is named after the 18th-century Irish bishop and philosopher George Berkeley. It borders the cities of Oakland and Emer ...
, where he spoke persuasively to
Ernest O. Lawrence
Ernest Orlando Lawrence (August 8, 1901 – August 27, 1958) was an American nuclear physicist and winner of the Nobel Prize in Physics in 1939 for his invention of the cyclotron. He is known for his work on uranium-isotope separation f ...
. Lawrence was sufficiently impressed to commence his own research into uranium. He in turn spoke to
James B. Conant
James Bryant Conant (March 26, 1893 – February 11, 1978) was an American chemist, a transformative President of Harvard University, and the first U.S. Ambassador to West Germany. Conant obtained a Ph.D. in Chemistry from Harvard in 1916. ...
,
Arthur H. Compton
Arthur Holly Compton (September 10, 1892 – March 15, 1962) was an American physicist who won the Nobel Prize in Physics in 1927 for his 1923 discovery of the Compton effect, which demonstrated the particle nature of electromagnetic radia ...
and
George B. Pegram
George Braxton Pegram (October 24, 1876 – August 12, 1958) was an American physicist who played a key role in the technical administration of the Manhattan Project. He graduated from Trinity College (now Duke University) in 1895, and taught high ...
. Oliphant's mission was therefore a success; key American physicists were now aware of the potential power of an atomic bomb.
On 9 October 1941, President Roosevelt approved the atomic program after he convened a meeting with Vannevar Bush and Vice President
Henry A. Wallace
Henry Agard Wallace (October 7, 1888 – November 18, 1965) was an American politician, journalist, farmer, and businessman who served as the 33rd vice president of the United States, the 11th U.S. Secretary of Agriculture, and the 10th U.S. S ...
. To control the program, he created a Top Policy Group consisting of himself—although he never attended a meeting—Wallace, Bush, Conant,
Secretary of War Henry L. Stimson
Henry Lewis Stimson (September 21, 1867 – October 20, 1950) was an American statesman, lawyer, and Republican Party politician. Over his long career, he emerged as a leading figure in U.S. foreign policy by serving in both Republican and D ...
, and the
Chief of Staff of the Army,
General
A general officer is an Officer (armed forces), officer of highest military ranks, high rank in the army, armies, and in some nations' air forces, space forces, and marines or naval infantry.
In some usages the term "general officer" refers t ...
George C. Marshall
George Catlett Marshall Jr. (December 31, 1880 – October 16, 1959) was an American army officer and statesman. He rose through the United States Army to become Chief of Staff of the United States Army, Chief of Staff of the US Army under Pre ...
. Roosevelt chose the Army to run the project rather than the Navy, because the Army had more experience with management of large-scale construction projects. He also agreed to coordinate the effort with that of the British, and on 11 October he sent a message to Prime Minister
Winston Churchill
Sir Winston Leonard Spencer Churchill (30 November 187424 January 1965) was a British statesman, soldier, and writer who served as Prime Minister of the United Kingdom twice, from 1940 to 1945 Winston Churchill in the Second World War, dur ...
, suggesting that they correspond on atomic matters.
[.]
Feasibility
Proposals
The S-1 Committee held its meeting on 18 December 1941 "pervaded by an atmosphere of enthusiasm and urgency" in the wake of the
attack on Pearl Harbor
The attack on Pearl HarborAlso known as the Battle of Pearl Harbor was a surprise military strike by the Imperial Japanese Navy Air Service upon the United States against the naval base at Pearl Harbor in Honolulu, Territory of Hawaii, j ...
and the subsequent
United States declaration of war upon Japan and
then on Germany. Work was proceeding on three different techniques for
isotope separation
Isotope separation is the process of concentrating specific isotopes of a chemical element by removing other isotopes. The use of the nuclides produced is varied. The largest variety is used in research (e.g. in chemistry where atoms of "marker" n ...
to separate uranium-235 from the more abundant
uranium-238
Uranium-238 (238U or U-238) is the most common isotope of uranium found in nature, with a relative abundance of 99%. Unlike uranium-235, it is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. However, it ...
. Lawrence and his team at the
University of California
The University of California (UC) is a public land-grant research university system in the U.S. state of California. The system is composed of the campuses at Berkeley, Davis, Irvine, Los Angeles, Merced, Riverside, San Diego, San Francisco, ...
investigated
electromagnetic separation
Isotope separation is the process of concentrating specific isotopes of a chemical element by removing other isotopes. The use of the nuclides produced is varied. The largest variety is used in research (e.g. in chemistry where atoms of "marker" n ...
, while
Eger Murphree
Eger Vaughan Murphree (November 3, 1898 – October 29, 1962) was an American chemist, best known for his co-invention of the process of fluid catalytic cracking.
Biography
Murphree was born on November 3, 1898, in Bayonne, New Jersey, moving a ...
and
Jesse Wakefield Beams
Jesse Wakefield Beams (December 25, 1898 in Belle Plaine, Kansas – July 23, 1977) was an American physicist at the University of Virginia.
Biography
Beams completed his undergraduate B.A. in physics at Fairmount College in 1921 and his mas ...
's team looked into
gaseous diffusion
Gaseous diffusion is a technology used to produce enriched uranium by forcing gaseous uranium hexafluoride (UF6) through semipermeable membranes. This produces a slight separation between the molecules containing uranium-235 (235U) and uranium-2 ...
at
Columbia University
Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a private research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhatt ...
, and
Philip Abelson directed research into
thermal diffusion at the
Carnegie Institution of Washington and later the
Naval Research Laboratory
The United States Naval Research Laboratory (NRL) is the corporate research laboratory for the United States Navy and the United States Marine Corps. It was founded in 1923 and conducts basic scientific research, applied research, technological ...
.
Murphree was also the head of an unsuccessful separation project using
gas centrifuges.
Meanwhile, there were two lines of research into
nuclear reactor technology, with
Harold Urey
Harold Clayton Urey ( ; April 29, 1893 – January 5, 1981) was an American physical chemist whose pioneering work on isotopes earned him the Nobel Prize in Chemistry in 1934 for the discovery of deuterium. He played a significant role in the d ...
continuing research into
heavy water at Columbia, while Arthur Compton brought the scientists working under his supervision from Columbia, California and
Princeton University
Princeton University is a private university, private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth, New Jersey, Elizabeth as the College of New Jersey, Princeton is the List of Colonial Colleges, fourth-oldest ins ...
to join his team at the
University of Chicago
The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park neighborhood. The University of Chicago is consistently ranked among the b ...
, where he organized the
Metallurgical Laboratory
The Metallurgical Laboratory (or Met Lab) was a scientific laboratory at the University of Chicago that was established in February 1942 to study and use the newly discovered chemical element plutonium. It researched plutonium's chemistry and m ...
in early 1942 to study plutonium and reactors using
graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...
as a
neutron moderator
In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, ideally without capturing any, leaving them as thermal neutrons with only minimal (thermal) kinetic energy. These thermal neutrons are immensely mo ...
. Briggs, Compton, Lawrence, Murphree, and Urey met on 23 May 1942, to finalize the S-1 Committee recommendations, which called for all five technologies to be pursued. This was approved by Bush, Conant, and
Brigadier General
Brigadier general or Brigade general is a military rank used in many countries. It is the lowest ranking general officer in some countries. The rank is usually above a colonel, and below a major general or divisional general. When appointed ...
Wilhelm D. Styer
Wilhelm Delp Styer (22 July 1893 – 26 February 1975) was a lieutenant general in the United States Army during World War II. A graduate of the United States Military Academy at West Point with the class of 1916, he was commissioned into the ...
, the chief of staff of
Major General
Major general (abbreviated MG, maj. gen. and similar) is a military rank used in many countries. It is derived from the older rank of sergeant major general. The disappearance of the "sergeant" in the title explains the apparent confusion of a ...
Brehon B. Somervell's
Services of Supply, who had been designated the Army's representative on nuclear matters.
Bush and Conant then took the recommendation to the Top Policy Group with a budget proposal for $54 million for construction by the
, $31 million for research and development by OSRD and $5 million for contingencies in fiscal year 1943. The Top Policy Group in turn sent it on 17 June 1942, to the President, who approved it by writing "OK FDR" on the document.
[.]
Bomb design concepts
![Los Alamos Primer assembly methods](https://upload.wikimedia.org/wikipedia/commons/4/4e/Los_Alamos_Primer_assembly_methods.png)
Compton asked theoretical physicist
J. Robert Oppenheimer of the University of California to take over research into
fast neutron calculations
The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term ''temperature'' is used, since hot, thermal and cold neutrons are moderated in a medium with ...
—the key to calculations of critical mass and weapon detonation—from
Gregory Breit
Gregory Breit (russian: Григорий Альфредович Брейт-Шнайдер, ''Grigory Alfredovich Breit-Shneider''; July 14, 1899, Mykolaiv, Kherson Governorate – September 13, 1981, Salem, Oregon) was a Russian-born Jewish Am ...
, who had quit on 18 May 1942 because of concerns over lax operational security.
John H. Manley
John Henry Manley (July 21, 1907 – June 11, 1990) was an American physicist who worked with J. Robert Oppenheimer at the University of California, Berkeley before becoming a group leader during the Manhattan Project.
Biography
He was born in ...
, a physicist at the Metallurgical Laboratory, was assigned to assist Oppenheimer by contacting and coordinating experimental physics groups scattered across the country. Oppenheimer and
Robert Serber of the
University of Illinois
The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the University ...
examined the problems of
neutron
The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beh ...
diffusion—how neutrons moved in a nuclear chain reaction—and
hydrodynamics
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) and ...
—how the explosion produced by a chain reaction might behave. To review this work and the general theory of fission reactions, Oppenheimer and
Fermi
Enrico Fermi (; 29 September 1901 – 28 November 1954) was an Italian (later naturalized American) physicist and the creator of the world's first nuclear reactor, the Chicago Pile-1. He has been called the "architect of the nuclear age" and ...
convened meetings at the University of Chicago in June and at the University of California in July 1942 with theoretical physicists
Hans Bethe,
John Van Vleck
John Hasbrouck Van Vleck (March 13, 1899 – October 27, 1980) was an American physicist and mathematician. He was co-awarded the Nobel Prize in Physics in 1977, for his contributions to the understanding of the behavior of electronic magnetism ...
, Edward Teller,
Emil Konopinski
Emil John (Jan) Konopinski (December 25, 1911 in Michigan City, Indiana – May 26, 1990 in Bloomington, Indiana) was an American nuclear scientist , Robert Serber,
Stan Frankel, and
Eldred C. (Carlyle) Nelson, the latter three former students of Oppenheimer, and
experimental physicist
Experimental physics is the category of disciplines and sub-disciplines in the field of physics that are concerned with the observation of physical phenomena and experiments. Methods vary from discipline to discipline, from simple experiments and o ...
s
Emilio Segrè,
Felix Bloch,
Franco Rasetti
Franco Dino Rasetti (August 10, 1901 – December 5, 2001) was an Italian (later naturalized American) physicist, paleontologist and botanist. Together with Enrico Fermi, he discovered key processes leading to nuclear fission. Rasetti refused ...
,
John Henry Manley
John Henry Manley (July 21, 1907 – June 11, 1990) was an American physicist who worked with J. Robert Oppenheimer at the University of California, Berkeley before becoming a group leader during the Manhattan Project.
Biography
He was born in ...
, and
Edwin McMillan. They tentatively confirmed that a fission bomb was theoretically possible.
There were still many unknown factors. The properties of pure uranium-235 were relatively unknown, as were those of plutonium, an element that had only been discovered in February 1941 by
Glenn Seaborg and his team. The scientists at the (July 1942) Berkeley conference envisioned creating plutonium in nuclear reactors where uranium-238 atoms absorbed neutrons that had been emitted from fissioning uranium-235 atoms. At this point no reactor had been built, and only tiny quantities of plutonium were available from
cyclotrons at institutions such as
Washington University in St. Louis
Washington University in St. Louis (WashU or WUSTL) is a private research university with its main campus in St. Louis County, and Clayton, Missouri. Founded in 1853, the university is named after George Washington. Washington University is r ...
. Even by December 1943, only two milligrams had been produced. There were many ways of arranging the fissile material into a critical mass. The simplest was shooting a "cylindrical plug" into a sphere of "active material" with a "tamper"—dense material that would focus neutrons inward and keep the reacting mass together to increase its efficiency. They also explored designs involving
spheroid
A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters. A spheroid has cir ...
s, a primitive form of "
implosion" suggested by
Richard C. Tolman
Richard Chace Tolman (March 4, 1881 – September 5, 1948) was an American mathematical physicist and physical chemist who made many contributions to statistical mechanics. He also made important contributions to theoretical cosmology in t ...
, and the possibility of
autocatalytic methods, which would increase the efficiency of the bomb as it exploded.
Considering the idea of the fission bomb theoretically settled—at least until more experimental data was available—the 1942 Berkeley conference then turned in a different direction. Edward Teller pushed for discussion of a more powerful bomb: the "super", now usually referred to as a "
hydrogen bomb
A thermonuclear weapon, fusion weapon or hydrogen bomb (H bomb) is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a lowe ...
", which would use the explosive force of a detonating fission bomb to ignite a
nuclear fusion reaction in
deuterium
Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two Stable isotope ratio, stable isotopes of hydrogen (the other being Hydrogen atom, protium, or hydrogen-1). The atomic nucleus, nucleus of a deuterium ato ...
and
tritium. Teller proposed scheme after scheme, but Bethe refused each one. The fusion idea was put aside to concentrate on producing fission bombs. Teller also raised the speculative possibility that an atomic bomb might "ignite" the atmosphere because of a hypothetical fusion reaction of nitrogen nuclei. Bethe calculated that it could not happen, and a report co-authored by Teller showed that "no self-propagating chain of nuclear reactions is likely to be started." In Serber's account, Oppenheimer mentioned the possibility of this scenario to
Arthur Compton
Arthur Holly Compton (September 10, 1892 – March 15, 1962) was an American physicist who won the Nobel Prize in Physics in 1927 for his 1923 discovery of the Compton effect, which demonstrated the particle nature of electromagnetic radia ...
, who "didn't have enough sense to shut up about it. It somehow got into a document that went to Washington" and was "never laid to rest".
Organization
Manhattan District
The
Chief of Engineers, Major General
Eugene Reybold
Eugene Reybold (February 13, 1884 – November 21, 1961) was distinguished as the World War II Chief of Engineers who directed the largest United States Army Corps of Engineers in the nation's history.
Reybold was born in Delaware City, Delaware ...
, selected Colonel
James C. Marshall
Brigadier General James Creel Marshall (15 October 1897 – 19 July 1977) was a United States Army Corps of Engineers officer who was initially in charge of the Manhattan Project to build an atomic bomb during World War II.
A member of the Ju ...
to head the Army's part of the project in June 1942. Marshall created a liaison office in Washington, D.C., but established his temporary headquarters on the 18th floor of
270 Broadway
Tower 270 (also known as 270 Broadway, Arthur Levitt State Office Building, 80 Chambers Street, and 86 Chambers Street) is a 28-story mixed use building in the Civic Center and Tribeca neighborhoods of Manhattan, New York City. Completed in 1930 ...
in New York, where he could draw on administrative support from the Corps of Engineers'
North Atlantic Division
The North Atlantic Division of the U.S. Army Corps of Engineers is one of the eight permanent divisions within the Corps.
Made up of roughly 3,500 employees in six districts and a Division headquarters, the North Atlantic Division is a major ...
. It was close to the Manhattan office of
Stone & Webster
Stone & Webster was an American engineering services company based in Stoughton, Massachusetts. It was founded as an electrical testing lab and consulting firm by electrical engineers Charles A. Stone and Edwin S. Webster in 1889. In the early ...
, the principal project contractor, and to Columbia University. He had permission to draw on his former command, the Syracuse District, for staff, and he started with
Lieutenant Colonel
Lieutenant colonel ( , ) is a rank of commissioned officers in the armies, most marine forces and some air forces of the world, above a major and below a colonel. Several police forces in the United States use the rank of lieutenant colone ...
Kenneth Nichols
Major General Kenneth David Nichols CBE (13 November 1907 – 21 February 2000), also known by Nick, was an officer in the United States Army, and a civil engineer who worked on the secret Manhattan Project, which developed the atomic bomb dur ...
, who became his deputy.
[.]
![Manhttan Project Organization Chart](https://upload.wikimedia.org/wikipedia/commons/0/09/Manhttan_Project_Organization_Chart.gif)
Because most of his task involved construction, Marshall worked in cooperation with the head of the Corps of Engineers Construction Division, Major General
Thomas M. Robbins
Thomas may refer to:
People
* List of people with given name Thomas
* Thomas (name)
* Thomas (surname)
* Saint Thomas (disambiguation)
* Thomas Aquinas (1225–1274) Italian Dominican friar, philosopher, and Doctor of the Church
* Thomas the A ...
, and his deputy, Colonel
Leslie Groves
Lieutenant General Leslie Richard Groves Jr. (17 August 1896 – 13 July 1970) was a United States Army Corps of Engineers officer who oversaw the construction of the Pentagon and directed the Manhattan Project, a top secret research project ...
. Reybold, Somervell, and Styer decided to call the project "Development of Substitute Materials", but Groves felt that this would draw attention. Since engineer districts normally carried the name of the city where they were located, Marshall and Groves agreed to name the Army's component of the project the Manhattan District. This became official on 13 August when Reybold issued the order creating the new district. Informally, it was known as the Manhattan Engineer District, or MED. Unlike other districts, it had no geographic boundaries, and Marshall had the authority of a division engineer. Development of Substitute Materials remained as the official codename of the project as a whole, but was supplanted over time by "Manhattan".
Marshall later conceded that, "I had never heard of atomic fission but I did know that you could not build much of a plant, much less four of them for $90 million." A single
TNT plant that Nichols had recently built in Pennsylvania had cost $128 million. Nor were they impressed with estimates to the nearest order of magnitude, which Groves compared with telling a caterer to prepare for between ten and a thousand guests. A survey team from Stone & Webster had already scouted a site for the production plants. The
War Production Board
The War Production Board (WPB) was an agency of the United States government that supervised war production during World War II. President Franklin D. Roosevelt established it in January 1942, with Executive Order 9024. The WPB replaced the Sup ...
recommended sites around
Knoxville, Tennessee
Knoxville is a city in and the county seat of Knox County, Tennessee, Knox County in the U.S. state of Tennessee. As of the 2020 United States census, Knoxville's population was 190,740, making it the largest city in the East Tennessee Grand Di ...
, an isolated area where the
Tennessee Valley Authority
The Tennessee Valley Authority (TVA) is a federally owned electric utility corporation in the United States. TVA's service area covers all of Tennessee, portions of Alabama, Mississippi, and Kentucky, and small areas of Georgia, North Carolina ...
could supply ample electric power and the rivers could provide cooling water for the reactors. After examining several sites, the survey team selected one near
Elza, Tennessee
Elza was a community in Anderson County, Tennessee, that existed before 1942, when the area was acquired for the Manhattan Project. Its site is now part of the city of Oak Ridge, Tennessee.
History
Elza formed around a flagstop on the Louisvi ...
. Conant advised that it be acquired at once and Styer agreed but Marshall temporized, awaiting the results of Conant's reactor experiments before taking action. Of the prospective processes, only Lawrence's electromagnetic separation appeared sufficiently advanced for construction to commence.
Marshall and Nichols began assembling the resources they would need. The first step was to obtain a high priority rating for the project. The top ratings were AA-1 through AA-4 in descending order, although there was also a special AAA rating reserved for emergencies. Ratings AA-1 and AA-2 were for essential weapons and equipment, so Colonel
Lucius D. Clay
General Lucius Dubignon Clay (April 23, 1898 – April 16, 1978) was a senior officer of the United States Army who was known for his administration of occupied Germany after World War II. He served as the deputy to General of the Army Dwight D ...
, the deputy chief of staff at Services and Supply for requirements and resources, felt that the highest rating he could assign was AA-3, although he was willing to provide a AAA rating on request for critical materials if the need arose. Nichols and Marshall were disappointed; AA-3 was the same priority as Nichols' TNT plant in Pennsylvania.
[.]
Military Policy Committee
![Trinity Test - Oppenheimer and Groves at Ground Zero 002](https://upload.wikimedia.org/wikipedia/commons/7/7e/Trinity_Test_-_Oppenheimer_and_Groves_at_Ground_Zero_002.jpg)
Vannevar Bush became dissatisfied with Colonel Marshall's failure to get the project moving forward expeditiously, specifically the failure to acquire the Tennessee site, the low priority allocated to the project by the Army and the location of his headquarters in New York City. Bush felt that more aggressive leadership was required, and spoke to
Harvey Bundy
Harvey Hollister Bundy Sr. (March 30, 1888 – October 7, 1963) was an American attorney who served as a special assistant to the Secretary of War during World War II. He was the father of William Bundy and McGeorge Bundy, who both served at hig ...
and Generals Marshall, Somervell, and Styer about his concerns. He wanted the project placed under a senior policy committee, with a prestigious officer, preferably Styer, as overall director.
Somervell and Styer selected Groves for the post, informing him on 17 September of this decision, and that General Marshall ordered that he be promoted to brigadier general,
[.] as it was felt that the title "general" would hold more sway with the academic scientists working on the Manhattan Project.
[.] Groves' orders placed him directly under Somervell rather than Reybold, with Colonel Marshall now answerable to Groves. Groves established his headquarters in Washington, D.C., on the fifth floor of the
New War Department Building, where Colonel Marshall had his liaison office. He assumed command of the Manhattan Project on 23 September 1942. Later that day, he attended a meeting called by Stimson, which established a Military Policy Committee, responsible to the Top Policy Group, consisting of Bush (with Conant as an alternate), Styer and
Rear Admiral
Rear admiral is a senior naval flag officer rank, equivalent to a major general and air vice marshal and above that of a commodore and captain, but below that of a vice admiral. It is regarded as a two star "admiral" rank. It is often regarde ...
William R. Purnell
Rear Admiral William Reynolds Purnell (6 September 1886 – 3 March 1955) was an officer in the United States Navy who served in World War I and World War II. A 1908 graduate of the United States Naval Academy, he captained destroyers during Wo ...
.
Tolman and Conant were later appointed as Groves' scientific advisers.
On 19 September, Groves went to
Donald Nelson
Donald Marr Nelson (1888–1959) was an American business executive and public servant, serving as the executive vice president of Sears Roebuck before accepting the position of director of priorities of the United States Office of Production Man ...
, the chairman of the War Production Board, and asked for broad authority to issue a AAA rating whenever it was required. Nelson initially balked but quickly caved in when Groves threatened to go to the President. Groves promised not to use the AAA rating unless it was necessary. It soon transpired that for the routine requirements of the project the AAA rating was too high but the AA-3 rating was too low. After a long campaign, Groves finally received AA-1 authority on 1 July 1944. According to Groves, "In Washington you became aware of the importance of top priority. Most everything proposed in the Roosevelt administration would have top priority. That would last for about a week or two and then something else would get top priority".
One of Groves' early problems was to find a director for
Project Y, the group that would design and build the bomb. The obvious choice was one of the three laboratory heads, Urey, Lawrence, or Compton, but they could not be spared. Compton recommended Oppenheimer, who was already intimately familiar with the bomb design concepts. However, Oppenheimer had little administrative experience, and, unlike Urey, Lawrence, and Compton, had not won a Nobel Prize, which many scientists felt that the head of such an important laboratory should have. There were also concerns about Oppenheimer's security status, as many of his associates were
communists, including his wife,
Kitty (Katherine Oppenheimer); his girlfriend,
Jean Tatlock
Jean Frances Tatlock (February 21, 1914 – January 4, 1944) was an American psychiatrist and physician. She was a member of the Communist Party of the United States of America and was a reporter and writer for the party's publication ''Western ...
; and his brother,
Frank Oppenheimer
Frank Friedman Oppenheimer (August 14, 1912 – February 3, 1985) was an American particle physicist, cattle rancher, professor of physics at the University of Colorado, and the founder of the Exploratorium in San Francisco.
A younger brother ...
. A long conversation on a train in October 1942 convinced Groves and Nichols that Oppenheimer thoroughly understood the issues involved in setting up a laboratory in a remote area and should be appointed as its director. Groves personally waived the security requirements and issued Oppenheimer a clearance on 20 July 1943.
Collaboration with the United Kingdom
The British and Americans exchanged nuclear information but did not initially combine their efforts. Britain rebuffed attempts by Bush and Conant in 1941 to strengthen cooperation with its own project, codenamed
Tube Alloys
Tube Alloys was the research and development programme authorised by the United Kingdom, with participation from Canada, to develop nuclear weapons during the Second World War. Starting before the Manhattan Project in the United States, the Bri ...
, because it was reluctant to share its technological lead and help the United States develop its own atomic bomb.
[.] An American scientist who brought a personal letter from Roosevelt to Churchill offering to pay for all research and development in an Anglo-American project was poorly treated, and Churchill did not reply to the letter. The United States as a result decided as early as April 1942 that if its offer was rejected, they should proceed alone.
The British, who had made significant contributions early in the war, did not have the resources to carry through such a research program while fighting for their survival. As a result, Tube Alloys soon fell behind its American counterpart. and on 30 July 1942, Sir
John Anderson John Anderson may refer to:
Business
*John Anderson (Scottish businessman) (1747–1820), Scottish merchant and founder of Fermoy, Ireland
* John Byers Anderson (1817–1897), American educator, military officer and railroad executive, mentor of ...
, the minister responsible for Tube Alloys, advised Churchill that: "We must face the fact that ...
urpioneering work ... is a dwindling asset and that, unless we capitalise it quickly, we shall be outstripped. We now have a real contribution to make to a 'merger.' Soon we shall have little or none." That month Churchill and Roosevelt made an informal, unwritten agreement for atomic collaboration.
![Groves and Chadwick 830308](https://upload.wikimedia.org/wikipedia/commons/5/56/Groves_and_Chadwick_830308.jpg)
The opportunity for an equal partnership no longer existed, however, as shown in August 1942 when the British unsuccessfully demanded substantial control over the project while paying none of the costs. By 1943 the roles of the two countries had reversed from late 1941; in January Conant notified the British that they would no longer receive atomic information except in certain areas. While the British were shocked by the abrogation of the Churchill-Roosevelt agreement, head of the Canadian
National Research Council National Research Council may refer to:
* National Research Council (Canada), sponsoring research and development
* National Research Council (Italy), scientific and technological research, Rome
* National Research Council (United States), part of ...
C. J. Mackenzie was less surprised, writing "I can't help feeling that the United Kingdom group
ver Ver or VER may refer to:
* Voluntary Export Restraints, in international trade
* VER, the IATA airport code for General Heriberto Jara International Airport
* Volk's Electric Railway, Brighton, England
* VerPublishing, of the German group VDM Publ ...
emphasizes the importance of their contribution as compared with the Americans."
As Conant and Bush told the British, the order came "from the top".
The British bargaining position had worsened; the American scientists had decided that the United States no longer needed outside help, and they wanted to prevent Britain exploiting post-war commercial applications of atomic energy. The committee supported, and Roosevelt agreed to, restricting the flow of information to what Britain could use during the war—especially not bomb design—even if doing so slowed down the American project. By early 1943 the British stopped sending research and scientists to America, and as a result the Americans stopped all information sharing. The British considered ending the supply of Canadian uranium and heavy water to force the Americans to again share, but Canada needed American supplies to produce them. They investigated the possibility of an independent nuclear program, but determined that it could not be ready in time to affect the outcome of the
war in Europe.
By March 1943 Conant decided that British help would benefit some areas of the project.
James Chadwick and one or two other British scientists were important enough that the bomb design team at Los Alamos needed them, despite the risk of revealing weapon design secrets. In August 1943 Churchill and Roosevelt negotiated the
Quebec Agreement
The Quebec Agreement was a secret agreement between the United Kingdom and the United States outlining the terms for the coordinated development of the science and engineering related to nuclear energy and specifically nuclear weapons. It was s ...
, which resulted in a resumption of cooperation between scientists working on the same problem. Britain, however, agreed to restrictions on data on the building of large-scale production plants necessary for the bomb. The subsequent Hyde Park Agreement in September 1944 extended this cooperation to the postwar period. The Quebec Agreement established the
Combined Policy Committee
The Quebec Agreement was a secret agreement between the United Kingdom and the United States outlining the terms for the coordinated development of the science and engineering related to nuclear energy and specifically nuclear weapons. It was ...
to coordinate the efforts of the United States, United Kingdom and Canada. Stimson, Bush and Conant served as the American members of the Combined Policy Committee, Field Marshal Sir
John Dill and Colonel
J. J. Llewellin were the British members, and
C. D. Howe
Clarence Decatur Howe, (15 January 1886 – 31 December 1960) was an American-born Canadian engineer, businessman and Liberal Party politician. Howe served as a cabinet minister in the governments of prime ministers William Lyon Mackenzie ...
was the Canadian member. Llewellin returned to the United Kingdom at the end of 1943 and was replaced on the committee by Sir
Ronald Ian Campbell
Sir Ronald Ian Campbell (7 June 1890 – 22 April 1983) was a British diplomat.
Campbell was the second son of Sir Guy Campbell, 3rd Baronet (see Campbell baronets), and Nina, daughter of Frederick Lehmann. He was educated at Eton and graduat ...
, who in turn was replaced by the British Ambassador to the United States,
Lord Halifax
Edward Frederick Lindley Wood, 1st Earl of Halifax, (16 April 1881 – 23 December 1959), known as The Lord Irwin from 1925 until 1934 and The Viscount Halifax from 1934 until 1944, was a senior British Conservative politician of the 19 ...
, in early 1945. Sir John Dill died in Washington, D.C., in November 1944 and was replaced both as Chief of the
British Joint Staff Mission
British may refer to:
Peoples, culture, and language
* British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies.
** Britishness, the British identity and common culture
* British English, ...
and as a member of the Combined Policy Committee by Field Marshal Sir
Henry Maitland Wilson.
When cooperation resumed after the Quebec agreement, the Americans' progress and expenditures amazed the British. The United States had already spent more than $1 billion ($ billion today), while in 1943, the United Kingdom had spent about £0.5 million. Chadwick thus pressed for British involvement in the Manhattan Project to the fullest extent and abandoned any hopes of an independent British project during the war. With Churchill's backing, he attempted to ensure that every request from Groves for assistance was honored. The British Mission that arrived in the United States in December 1943 included
Niels Bohr, Otto Frisch,
Klaus Fuchs
Klaus Emil Julius Fuchs (29 December 1911 – 28 January 1988) was a German theoretical physicist and atomic spy who supplied information from the American, British and Canadian Manhattan Project to the Soviet Union during and shortly aft ...
, Rudolf Peierls, and
Ernest Titterton
Sir Ernest William Titterton (4 March 1916 – 8 February 1990) was a British nuclear physicist.
A graduate of the University of Birmingham, Titterton worked in a research position under Mark Oliphant, who recruited him to work on radar ...
. More scientists arrived in early 1944. While those assigned to gaseous diffusion left by the fall of 1944, the 35 working under Oliphant with Lawrence at Berkeley were assigned to existing laboratory groups and most stayed until the end of the war. The 19 sent to Los Alamos also joined existing groups, primarily related to implosion and bomb assembly, but not the plutonium-related ones. Part of the Quebec Agreement specified that nuclear weapons would not be used against another country without the mutual consent of the US and UK. In June 1945, Wilson agreed that the use of nuclear weapons against Japan would be recorded as a decision of the Combined Policy Committee.
The Combined Policy Committee created the
Combined Development Trust The Combined Development Agency (CDA), originally the Combined Development Trust (CDT), was a defense purchasing authority established in 1944 by the governments of the United States and the United Kingdom. Its role was to ensure adequate supplies ...
in June 1944, with Groves as its chairman, to procure uranium and
thorium ores on international markets. The
Belgian Congo
The Belgian Congo (french: Congo belge, ; nl, Belgisch-Congo) was a Belgian colony in Central Africa from 1908 until independence in 1960. The former colony adopted its present name, the Democratic Republic of the Congo (DRC), in 1964.
Colo ...
and Canada held much of the world's uranium outside Eastern Europe, and the
Belgian government in exile
The Belgian Government in London (french: Gouvernement belge à Londres, nl, Belgische regering in Londen), also known as the Pierlot IV Government, was the government in exile of Belgium between October 1940 and September 1944 during World W ...
was in London. Britain agreed to give the United States most of the Belgian ore, as it could not use most of the supply without restricted American research. In 1944, the Trust purchased of uranium oxide ore from companies operating mines in the Belgian Congo. In order to avoid briefing US Secretary of the Treasury
Henry Morgenthau Jr.
Henry Morgenthau Jr. (; May 11, 1891February 6, 1967) was the United States Secretary of the Treasury during most of the administration of Franklin D. Roosevelt. He played a major role in designing and financing the New Deal. After 1937, while ...
on the project, a special account not subject to the usual auditing and controls was used to hold Trust monies. Between 1944 and the time he resigned from the Trust in 1947, Groves deposited a total of $37.5 million into the Trust's account.
Groves appreciated the early British atomic research and the British scientists' contributions to the Manhattan Project, but stated that the United States would have succeeded without them. He also said that Churchill was "the best friend the atomic bomb project had
she kept Roosevelt's interest up ... He just stirred him up all the time by telling him how important he thought the project was."
The British wartime participation was crucial to the success of the United Kingdom's
independent nuclear weapons program after the war when the
McMahon Act of 1946 temporarily ended American nuclear cooperation.
Project sites
Image:Manhattan Project US Canada Map 2.svg, upright=3.2, center, A selection of US and Canadian sites important to the Manhattan Project. Click on the location for more information., alt=Map of the United States and southern Canada with major project sites marked
circle 50 280 20 Berkeley, California
Berkeley ( ) is a city on the eastern shore of San Francisco Bay in northern Alameda County, California, United States. It is named after the 18th-century Irish bishop and philosopher George Berkeley. It borders the cities of Oakland and Emer ...
circle 140 400 20 Inyokern, California
Inyokern (formerly Siding 16 and Magnolia) is a census-designated place (CDP) in Kern County, California, United States. Its name derives from its location near the border between Inyo and Kern Counties. Inyokern is located west of Ridgecrest, a ...
circle 170 100 20 Richland, Washington
circle 220 20 20 Trail, British Columbia
Trail is a city in the West Kootenay region of the Interior of British Columbia, Canada. It was named after the Dewdney Trail, which passed through the area. The town was first called Trail Creek or Trail Creek Landing, and the name was shorten ...
circle 230 270 20 Wendover, Utah
circle 290 360 20 Monticello, Utah
circle 320 360 20 Uravan, Colorado
Uravan (a contraction of uranium/vanadium) is a former uranium mining town in western Montrose County, Colorado, United States, which still appears on some maps. The town was a company town established by U. S. Vanadium Corporation in 1936 to e ...
circle 340 440 20 Los Alamos, New Mexico
Los Alamos is an census-designated place in Los Alamos County, New Mexico, United States, that is recognized as the development and creation place of the atomic bomb—the primary objective of the Manhattan Project by Los Alamos National Labora ...
circle 340 500 20 Alamogordo, New Mexico
Alamogordo () is the seat of Otero County, New Mexico, United States. A city in the Tularosa Basin of the Chihuahuan Desert, it is bordered on the east by the Sacramento Mountains and to the west by Holloman Air Force Base. The population was ...
circle 610 290 20 Ames, Iowa
Ames () is a city in Story County, Iowa, United States, located approximately north of Des Moines in central Iowa. It is best known as the home of Iowa State University (ISU), with leading agriculture, design, engineering, and veterinary medici ...
circle 660 400 20 St Louis, Missouri
St. Louis () is the second-largest city in Missouri, United States. It sits near the confluence of the Mississippi and the Missouri Rivers. In 2020, the city proper had a population of 301,578, while the bi-state metropolitan area, which ...
circle 710 310 20 Chicago, Illinois
(''City in a Garden''); I Will
, image_map =
, map_caption = Interactive Map of Chicago
, coordinates =
, coordinates_footnotes =
, subdivision_type = Country
, subdivision_name ...
circle 730 370 20 Dana, Indiana
circle 800 350 20 Dayton, Ohio
Dayton () is the sixth-largest city in the U.S. state of Ohio and the county seat of Montgomery County. A small part of the city extends into Greene County. The 2020 U.S. census estimate put the city population at 137,644, while Greater Day ...
circle 760 540 20 Sylacauga, Alabama
circle 890 390 20 Morgantown, West Virginia
Morgantown is a city in and the county seat of Monongalia County, West Virginia, Monongalia County, West Virginia, United States, situated along the Monongahela River. The largest city in North-Central West Virginia, Morgantown is best known as th ...
circle 800 460 20 Oak Ridge, Tennessee
Oak Ridge is a city in Anderson and Roane counties in the eastern part of the U.S. state of Tennessee, about west of downtown Knoxville. Oak Ridge's population was 31,402 at the 2020 census. It is part of the Knoxville Metropolitan Area. Oak ...
circle 910 160 20 Chalk River Laboratories
Chalk River Laboratories (french: Laboratoires de Chalk River; also known as CRL, Chalk River Labs and formerly Chalk River Nuclear Laboratories, CRNL) is a Canadian nuclear research facility in Deep River, about north-west of Ottawa.
CRL is a ...
circle 920 260 20 Rochester, New York
Rochester () is a City (New York), city in the U.S. state of New York (state), New York, the county seat, seat of Monroe County, New York, Monroe County, and the fourth-most populous in the state after New York City, Buffalo, New York, Buffalo, ...
circle 950 360 20 Washington, D.C.
)
, image_skyline =
, image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan, ...
desc none
Oak Ridge
![Y-12 Shift Change](https://upload.wikimedia.org/wikipedia/commons/a/ad/Y-12_Shift_Change.jpg)
The day after he took over the project, Groves took a train to Tennessee with Colonel Marshall to inspect the proposed site there, and Groves was impressed. On 29 September 1942,
United States Under Secretary of War
The Under Secretary of War was a position created by an act of 16 December 1940 (54 Stat. 1224). At the same time, section 5a of the National Defense Act (1920) was amended to allow the United States Secretary of War to assign his responsibilities ...
Robert P. Patterson authorized the Corps of Engineers to acquire of land by
eminent domain
Eminent domain (United States, Philippines), land acquisition (India, Malaysia, Singapore), compulsory purchase/acquisition (Australia, New Zealand, Ireland, United Kingdom), resumption (Hong Kong, Uganda), resumption/compulsory acquisition (Austr ...
at a cost of $3.5 million. An additional was subsequently acquired. About 1,000 families were affected by the condemnation order, which came into effect on 7 October. Protests, legal appeals, and a 1943 Congressional inquiry were to no avail.
[.] By mid-November
U.S. Marshals
The United States Marshals Service (USMS) is a federal law enforcement agency in the United States. The USMS is a bureau within the U.S. Department of Justice, operating under the direction of the Attorney General, but serves as the enforceme ...
were tacking notices to vacate on farmhouse doors, and construction contractors were moving in.
[.] Some families were given two weeks' notice to vacate farms that had been their homes for generations; others had settled there after being evicted to make way for the
Great Smoky Mountains National Park
Great Smoky Mountains National Park is an American national park in the southeastern United States, with parts in North Carolina and Tennessee. The park straddles the ridgeline of the Great Smoky Mountains, part of the Blue Ridge Mountains, whi ...
in the 1920s or the
Norris Dam in the 1930s.
The ultimate cost of land acquisition in the area, which was not completed until March 1945, was only about $2.6 million, which worked out to around $47 an acre. When presented with Public Proclamation Number Two, which declared Oak Ridge a total exclusion area that no one could enter without military permission, the
Governor of Tennessee
The governor of Tennessee is the head of government of the U.S. state of Tennessee. The governor is the only official in Tennessee state government who is directly elected by the voters of the entire state.
The current governor is Bill Lee, a ...
,
Prentice Cooper
William Prentice Cooper Jr. (September 28, 1895May 18, 1969) was an American politician and diplomat who served as the 39th governor of Tennessee from 1939 to 1945. He led the state's mobilization efforts for World War II, when over 300,000 Ten ...
, angrily tore it up.
Initially known as the Kingston Demolition Range, the site was officially renamed the
Clinton Engineer Works
The Clinton Engineer Works (CEW) was the production installation of the Manhattan Project that during World War II produced the enriched uranium used in the 1945 bombing of Hiroshima, as well as the first examples of reactor-produced plutoni ...
(CEW) in early 1943. While Stone & Webster concentrated on the production facilities, the architectural and engineering firm
Skidmore, Owings & Merrill
Skidmore, Owings & Merrill (SOM) is an American architectural, urban planning and engineering firm. It was founded in 1936 by Louis Skidmore and Nathaniel A. Owings, Nathaniel Owings in Chicago, Illinois. In 1939, they were joined by engineer Jo ...
designed and built a residential community for 13,000. The community was located on the slopes of Black Oak Ridge, from which the new town of
Oak Ridge got its name. The Army presence at Oak Ridge increased in August 1943 when Nichols replaced Marshall as head of the Manhattan Engineer District. One of his first tasks was to move the district headquarters to Oak Ridge although the name of the district did not change. In September 1943 the administration of community facilities was outsourced to
Turner Construction Company
Turner Construction is an American construction company with presence in 20 countries. It is a subsidiary of the German company Hochtief. It is the largest domestic contractor in the United States as of 2020, with a revenue of $14.41 billion in ...
through a subsidiary, the Roane-Anderson Company (for
Roane Roane is a surname. Notable people with the surname include:
*Anthony Roane (died 1583), English politician
*Archibald Roane (1769–1819), 2nd Governor of Tennessee
*John Roane (1766–1838), American politician
*John Roane (1794–1869), America ...
and
Anderson Counties, in which Oak Ridge was located).
[.] Chemical engineers, including
William J. (Jenkins) Wilcox Jr. (1923–2013) and Warren Fuchs, were part of "frantic efforts" to make 10% to 12% enriched uranium 235, known as the code name "tuballoy tetroxide", with tight security and fast approvals for supplies and materials. The population of Oak Ridge soon expanded well beyond the initial plans, and peaked at 75,000 in May 1945, by which time 82,000 people were employed at the Clinton Engineer Works,
[.] and 10,000 by Roane-Anderson.
Fine-arts photographer,
Josephine Herrick, and her colleague, Mary Steers, helped document the work at Oak Ridge.
Los Alamos
The idea of locating Project Y at Oak Ridge was considered, but in the end it was decided that it should be in a remote location. On Oppenheimer's recommendation, the search for a suitable site was narrowed to the vicinity of
Albuquerque, New Mexico
Albuquerque ( ; ), ; kee, Arawageeki; tow, Vakêêke; zun, Alo:ke:k'ya; apj, Gołgéeki'yé. abbreviated ABQ, is the most populous city in the U.S. state of New Mexico. Its nicknames, The Duke City and Burque, both reference its founding in ...
, where Oppenheimer owned a ranch. In October 1942, Major
John H. Dudley of the Manhattan District was sent to survey the area. He recommended a site near
Jemez Springs, New Mexico. On 16 November, Oppenheimer, Groves, Dudley and others toured the site. Oppenheimer feared that the high cliffs surrounding the site would make his people feel claustrophobic, while the engineers were concerned with the possibility of flooding. The party then moved on to the vicinity of the
Los Alamos Ranch School
Los Alamos Ranch School was a private ranch school for boys in the northeast corner of Sandoval County, New Mexico (since 1949, within Los Alamos County), USA, founded in 1917 near San Ildefonso Pueblo. During World War II, the school was bought ...
. Oppenheimer was impressed and expressed a strong preference for the site, citing its natural beauty and views of the
Sangre de Cristo Mountains
)
, country= United States
, subdivision1_type= States
, subdivision1=
, parent= Rocky Mountains
, geology=
, orogeny=
, area_mi2= 17193
, range_coordinates=
, length_mi= 242
, length_orientation= north-south
, width_mi= 120
, w ...
, which, it was hoped, would inspire those who would work on the project. The engineers were concerned about the poor access road, and whether the water supply would be adequate, but otherwise felt that it was ideal.
![Los Alamos colloquium](https://upload.wikimedia.org/wikipedia/commons/f/fe/Los_Alamos_colloquium.jpg)
Patterson approved the acquisition of the site on 25 November 1942, authorizing $440,000 for the purchase of the site of , all but of which were already owned by the Federal Government.
Secretary of Agriculture
The United States secretary of agriculture is the head of the United States Department of Agriculture. The position carries similar responsibilities to those of agriculture ministers in other governments.
The department includes several organi ...
Claude R. Wickard
Claude Raymond Wickard (February 28, 1893 – April 29, 1967) was a Democratic politician who served as the Secretary of Agriculture during the administrations of Presidents Franklin D. Roosevelt and Harry S. Truman from 1940 to 1945.
Biograph ...
granted use of some of
United States Forest Service
The United States Forest Service (USFS) is an agency of the U.S. Department of Agriculture that administers the nation's 154 national forests and 20 national grasslands. The Forest Service manages of land. Major divisions of the agency inc ...
land to the
War Department "for so long as the military necessity continues". The need for land, for a new road, and later for a right of way for a power line, eventually brought wartime land purchases to , but only $414,971 was spent.
[.] Construction was contracted to the M. M. Sundt Company of
Tucson, Arizona
, "(at the) base of the black ill
, nicknames = "The Old Pueblo", "Optics Valley", "America's biggest small town"
, image_map =
, mapsize = 260px
, map_caption = Interactive map ...
, with
Willard C. Kruger and Associates
Willard Carl Kruger (1910–1984) was an American architect born in Sperry, Texas, who grew up in Raton, New Mexico. (has death date) He founded W. C. Kruger and Associates, which was an American architectural and engineering firm. The firm desi ...
of
Santa Fe, New Mexico
Santa Fe ( ; , Spanish for 'Holy Faith'; tew, Oghá P'o'oge, Tewa for 'white shell water place'; tiw, Hulp'ó'ona, label=Tiwa language, Northern Tiwa; nv, Yootó, Navajo for 'bead + water place') is the capital of the U.S. state of New Mexico. ...
, as architect and engineer. Work commenced in December 1942. Groves initially allocated $300,000 for construction, three times Oppenheimer's estimate, with a planned completion date of 15 March 1943. It soon became clear that the scope of Project Y was greater than expected, and by the time Sundt finished on 30 November 1943, over $7 million had been spent.
![Los Alamos map](https://upload.wikimedia.org/wikipedia/commons/6/65/Los_Alamos_map.gif)
Because it was secret, Los Alamos was referred to as "Site Y" or "the Hill". Birth certificates of babies born in Los Alamos during the war listed their place of birth as PO Box 1663 in Santa Fe. Initially Los Alamos was to have been a military laboratory with Oppenheimer and other researchers commissioned into the Army. Oppenheimer went so far as to order himself a
lieutenant colonel's uniform, but two key physicists,
Robert Bacher
Robert Fox Bacher (August 31, 1905November 18, 2004) was an American nuclear physicist and one of the leaders of the Manhattan Project. Born in Loudonville, Ohio, Bacher obtained his undergraduate degree and doctorate from the University of Mich ...
and
Isidor Rabi, balked at the idea. Conant, Groves and Oppenheimer then devised a compromise whereby the laboratory was operated by the University of California under contract to the War Department.
Chicago
An Army-OSRD council on 25 June 1942 decided to build a
pilot plant for plutonium production in
Red Gate Woods
Red Gate Woods is a forest preserve section within the Palos Forest Preserve, a division of the Forest Preserve District of Cook County, Illinois. It is located near where the Cal-Sag Channel meets the Chicago Sanitary and Ship Canal. In the wo ...
southwest of Chicago. In July, Nichols arranged for a lease of from the
Cook County Forest Preserve District
The Forest Preserve District of Cook County is a governmental commission in Cook County, Illinois, that owns and manages a network of open spaces, containing forest, prairie, wetland, streams, and lakes, that are mostly set aside as natural areas ...
, and Captain James F. Grafton (1908-1969) was appointed Chicago area engineer. It soon became apparent that the scale of operations was too great for the area, and it was decided to build the plant at Oak Ridge, and keep a research and testing facility in Chicago.
Delays in establishing the plant in Red Gate Woods led Compton to authorize the Metallurgical Laboratory to construct the first nuclear reactor beneath the
bleachers of
Stagg Field
Amos Alonzo Stagg Field is the name of two successive football fields for the University of Chicago. Beyond sports, the first Stagg Field (1893–1957) is remembered for its role in a landmark scientific achievement of Enrico Fermi and the Metall ...
at the University of Chicago. The reactor required an enormous amount of
graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...
blocks and uranium pellets. At the time, there was a limited source of pure
uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...
.
Frank Spedding
Frank Harold Spedding (22 October 1902 – 15 December 1984) was a Canadian American chemist. He was a renowned expert on rare earth elements, and on extraction of metals from minerals. The uranium extraction process helped make it possible for ...
of
Iowa State University
Iowa State University of Science and Technology (Iowa State University, Iowa State, or ISU) is a public land-grant research university in Ames, Iowa. Founded in 1858 as the Iowa Agricultural College and Model Farm, Iowa State became one of the n ...
was able to produce only two
short ton
The short ton (symbol tn) is a measurement unit equal to . It is commonly used in the United States, where it is known simply as a ton,
although the term is ambiguous, the single word being variously used for short, long, and metric ton.
The vari ...
s of pure uranium. Additional three short tons of uranium metal was supplied by
Westinghouse Lamp Plant which was produced in a rush with makeshift process. A large square balloon was constructed by
Goodyear Tire to encase the reactor. On 2 December 1942, a team led by Enrico Fermi initiated the first artificial self-sustaining nuclear chain reaction in an experimental reactor known as
Chicago Pile-1
Chicago Pile-1 (CP-1) was the world's first artificial nuclear reactor. On 2 December 1942, the first human-made self-sustaining nuclear chain reaction was initiated in CP-1, during an experiment led by Enrico Fermi. The secret development of t ...
. The point at which a reaction becomes self-sustaining became known as "going critical". Compton reported the success to Conant in Washington, D.C., by a coded phone call, saying, "The Italian navigator
ermi
The Xiongnu (, ) were a tribal confederation of nomadic peoples who, according to ancient Chinese sources, inhabited the eastern Eurasian Steppe from the 3rd century BC to the late 1st century AD. Modu Chanyu, the supreme leader after 209 ...
has just landed in the new world."
In January 1943, Grafton's successor, Major
Arthur V. Peterson, ordered Chicago Pile-1 dismantled and reassembled at Red Gate Woods, as he regarded the operation of a reactor as too hazardous for a densely populated area. At the Argonne site,
Chicago Pile-3
Chicago Pile-3 (CP-3) was the world's first heavy water reactor. One of the first research reactors, it was built in 1943 near Palos Hills, Illinois, original site of Argonne National Laboratory. Joining CP-1/CP-2, it first went critical on 15 ...
, the first heavy water reactor, went critical on 15 May 1944.
After the war, the operations that remained at Red Gate moved to the new site of the
Argonne National Laboratory
Argonne National Laboratory is a science and engineering research United States Department of Energy National Labs, national laboratory operated by University of Chicago, UChicago Argonne LLC for the United States Department of Energy. The facil ...
about away.
Hanford
By December 1942 there were concerns that even Oak Ridge was too close to a major population center (Knoxville) in the unlikely event of a major nuclear accident. Groves recruited
DuPont
DuPont de Nemours, Inc., commonly shortened to DuPont, is an American multinational chemical company first formed in 1802 by French-American chemist and industrialist Éleuthère Irénée du Pont de Nemours. The company played a major role in ...
in November 1942 to be the prime contractor for the construction of the plutonium production complex. DuPont was offered a standard
cost plus fixed-fee contract, but the President of the company,
Walter S. Carpenter, Jr.
Walter Samuel Carpenter Jr. (January 8, 1888 – February 2, 1976) was an American corporate executive from Wilmington, Delaware, who oversaw the DuPont company's involvement in the Manhattan Project to produce an atomic bomb for use during W ...
, wanted no profit of any kind, and asked for the proposed contract to be amended to explicitly exclude the company from acquiring any patent rights. This was accepted, but for legal reasons a nominal fee of one dollar was agreed upon. After the war, DuPont asked to be released from the contract early, and had to return 33 cents.
![Hanford workers](https://upload.wikimedia.org/wikipedia/commons/0/0a/Hanford_workers.jpg)
DuPont recommended that the site be located far from the existing uranium production facility at Oak Ridge. In December 1942, Groves dispatched Colonel
Franklin Matthias
Franklin Thompson Matthias (13 March 1908 – 3 December 1993) was an American civil engineer who directed the construction of the Hanford nuclear site, a key facility of the Manhattan Project during World War II.
A graduate of the University ...
and DuPont engineers to scout potential sites. Matthias reported that
Hanford Site near
Richland, Washington, was "ideal in virtually all respects". It was isolated and near the
Columbia River
The Columbia River (Upper Chinook: ' or '; Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, C ...
, which could supply sufficient water to cool the reactors that would produce the plutonium. Groves visited the site in January and established the Hanford Engineer Works (HEW), codenamed "Site W".
Under Secretary Patterson gave his approval on 9 February, allocating $5 million for the acquisition of of land in the area. The federal government relocated some 1,500 residents of
White Bluffs and
Hanford, and nearby settlements, as well as the
Wanapum
The Wanapum tribe of Native Americans formerly lived along the Columbia River from above Priest Rapids down to the mouth of the Snake River in what is now the US state of Washington. About 60 Wanapum still live near the present day site of Priest ...
and other tribes using the area. A dispute arose with farmers over compensation for crops, which had already been planted before the land was acquired. Where schedules allowed, the Army allowed the crops to be harvested, but this was not always possible.
[.] The land acquisition process dragged on and was not completed before the end of the Manhattan Project in December 1946.
The dispute did not delay work. Although progress on the reactor design at Metallurgical Laboratory and DuPont was not sufficiently advanced to accurately predict the scope of the project, a start was made in April 1943 on facilities for an estimated 25,000 workers, half of whom were expected to live on-site. By July 1944, some 1,200 buildings had been erected and nearly 51,000 people were living in the construction camp. As area engineer, Matthias exercised overall control of the site. At its peak, the construction camp was the third most populous town in Washington state. Hanford operated a fleet of over 900 buses, more than the city of Chicago. Like Los Alamos and Oak Ridge, Richland was a gated community with restricted access, but it looked more like a typical wartime American boomtown: the military profile was lower, and physical security elements like high fences, towers, and guard dogs were less evident.
Canadian sites
British Columbia
Cominco had produced electrolytic hydrogen at
Trail, British Columbia
Trail is a city in the West Kootenay region of the Interior of British Columbia, Canada. It was named after the Dewdney Trail, which passed through the area. The town was first called Trail Creek or Trail Creek Landing, and the name was shorten ...
, since 1930. Urey suggested in 1941 that it could produce heavy water. To the existing $10 million plant consisting of 3,215 cells consuming 75 MW of hydroelectric power, secondary electrolysis cells were added to increase the deuterium concentration in the water from 2.3% to 99.8%. For this process,
Hugh Taylor of Princeton developed a platinum-on-carbon
catalyst
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
for the first three stages while Urey developed a nickel-
chromia
In Greek mythology, Chromia (; Ancient Greek: , ''Khrōmía'') was the daughter of Itonus, son of Amphictyon, himself son of Deucalion. She was also, in some traditions, the mother of Aetolus, Paeon, Epeius and Eurycyda by Endymion.
The poem ''E ...
one for the fourth stage tower. The final cost was $2.8 million. The Canadian Government did not officially learn of the project until August 1942. Trail's heavy water production started in January 1944 and continued until 1956. Heavy water from Trail was used for
Chicago Pile 3
Chicago Pile-3 (CP-3) was the world's first heavy water reactor. One of the first research reactors, it was built in 1943 near Palos Hills, Illinois, original site of Argonne National Laboratory. Joining CP-1/CP-2, it first went critical on 15 ...
, the first reactor using heavy water and natural uranium, which went critical on 15 May 1944.
[.]
Ontario
The
Chalk River, Ontario
Chalk River (2016 population: 1029) is a small rural village, part of the Laurentian Hills municipality in Renfrew County, Ontario, Canada. It is located in the Upper Ottawa Valley along Highway 17 (Trans-Canada Highway), inland (west) from ...
, site was established to rehouse the Allied effort at the
Montreal Laboratory
The Montreal Laboratory in Montreal, Quebec, Canada, was established by the National Research Council of Canada during World War II to undertake nuclear research in collaboration with the United Kingdom, and to absorb some of the scientists and ...
away from an urban area. A new community was built at
Deep River, Ontario
Deep River is a town in Renfrew County, Ontario, Canada. Located along the Ottawa River, it lies about north-west of Ottawa on the Trans-Canada Highway. Deep River is opposite the Laurentian Mountains and the Province of Quebec. The name ''Deep R ...
, to provide residences and facilities for the team members. The site was chosen for its proximity to the industrial manufacturing area of Ontario and Quebec, and proximity to a rail head adjacent to a large military base,
Camp Petawawa
Garrison Petawawa is located in Petawawa, Ontario. It is operated as an army base by the Canadian Army.
Garrison facts
The Garrison is located in the Ottawa Valley in Renfrew County, northwest of Ottawa along the western bank of the Ottawa ...
. Located on the Ottawa River, it had access to abundant water. The first director of the new laboratory was
Hans von Halban. He was replaced by John Cockcroft in May 1944, who in turn was succeeded by
Bennett Lewis
Wilfrid Bennett Lewis, (June 24, 1908 – January 10, 1987) was a Canadian nuclear scientist and administrator, and was centrally involved in the development of the CANDU reactor.
Born in Castle Carrock, Cumberland, England, he earned a doc ...
in September 1946. A pilot reactor known as
ZEEP
The ZEEP (Zero Energy Experimental Pile) reactor was a nuclear reactor built at the Chalk River Laboratories near Chalk River, Ontario, Canada (which superseded the Montreal Laboratory for nuclear research in Canada). ZEEP first went critical a ...
(zero-energy experimental pile) became the first Canadian reactor, and the first to be completed outside the United States, when it went critical in September 1945, ZEEP remained in use by researchers until 1970. A larger 10 MW
NRX
NRX (National Research Experimental) was a heavy-water-moderated, light-water-cooled, nuclear research reactor at the Canadian Chalk River Laboratories, which came into operation in 1947 at a design power rating of 10 MW (thermal), increasing to ...
reactor, which was designed during the war, was completed and went critical in July 1947.
Northwest Territories
The
Eldorado Mine at
Port Radium was a source of uranium ore.
Heavy water sites
Although DuPont's preferred designs for the nuclear reactors were helium cooled and used graphite as a moderator, DuPont still expressed an interest in using heavy water as a backup, in case the graphite reactor design proved infeasible for some reason. For this purpose, it was estimated that of heavy water would be required per month. The ''
P-9 Project
The P-9 Project was the codename given during World War II to the Manhattan Project's heavy water production program. The Cominco operation at Trail, British Columbia, was upgraded to produce heavy water. DuPont built three plants in the Unite ...
'' was the government's code name for the heavy water production program. As the plant at Trail, which was then under construction, could produce per month, additional capacity was required. Groves therefore authorized DuPont to establish heavy water facilities at the Morgantown Ordnance Works, near
Morgantown, West Virginia
Morgantown is a city in and the county seat of Monongalia County, West Virginia, Monongalia County, West Virginia, United States, situated along the Monongahela River. The largest city in North-Central West Virginia, Morgantown is best known as th ...
; at the
Wabash River Ordnance Works, near
Dana and
Newport, Indiana
Newport is a town in Vermillion Township, Vermillion County, in the U.S. state of Indiana. The population was 515 at the 2010 census. The town is the county seat of Vermillion County.
History
A post office has been in operation at Newport since ...
; and at the
Alabama Ordnance Works, near
Childersburg
Childersburg is a city in Talladega County in the U.S. state of Alabama. It was incorporated in 1889. At the 2020 census, the population was 4,754. It has a history dating back before 1540, when it was noted as a village of the Coosa Nation vi ...
and
Sylacauga, Alabama. Although known as Ordnance Works and paid for under
Ordnance Department contracts, they were built and operated by the Army Corps of Engineers. The American plants used a process different from Trail's; heavy water was extracted by distillation, taking advantage of the slightly higher boiling point of heavy water.
Uranium
Ore
![Shinkolobwe](https://upload.wikimedia.org/wikipedia/commons/c/c6/Shinkolobwe.jpg)
The key raw material for the project was uranium, which was used as fuel for the reactors, as feed that was transformed into plutonium, and, in its enriched form, in the atomic bomb itself. There were four known major deposits of uranium in 1940: in Colorado, in northern Canada, in
Joachimsthal in Czechoslovakia, and in the
Belgian Congo
The Belgian Congo (french: Congo belge, ; nl, Belgisch-Congo) was a Belgian colony in Central Africa from 1908 until independence in 1960. The former colony adopted its present name, the Democratic Republic of the Congo (DRC), in 1964.
Colo ...
. All but Joachimstal were in Allied hands. A November 1942 survey determined that sufficient quantities of uranium were available to satisfy the project's requirements. Nichols arranged with the
State Department
The United States Department of State (DOS), or State Department, is an United States federal executive departments, executive department of the Federal government of the United States, U.S. federal government responsible for the country's fore ...
for export controls to be placed on
uranium oxide and negotiated for the purchase of of uranium ore from the Belgian Congo that was being stored in a warehouse on
Staten Island
Staten Island ( ) is a borough of New York City, coextensive with Richmond County, in the U.S. state of New York. Located in the city's southwest portion, the borough is separated from New Jersey by the Arthur Kill and the Kill Van Kull an ...
and the remaining stocks of mined ore stored in the Congo. He negotiated with
Eldorado Gold Mines
Eldorado Resources was a Canadian mining company active between 1926 and 1988. The company was originally established by brothers Charles and Gilbert LaBine as a gold mining enterprise in 1926, but transitioned to focus on radium in the 1930s a ...
for the purchase of ore from its refinery in Port Hope, Ontario, and its shipment in 100-ton lots. The Canadian government subsequently bought up the company's stock until it acquired a controlling interest.
While these purchases assured a sufficient supply to meet wartime needs, the American and British leaders concluded that it was in their countries' interest to gain control of as much of the world's uranium deposits as possible. The richest source of ore was the
Shinkolobwe mine in the Belgian Congo, but it was flooded and closed. Nichols unsuccessfully attempted to negotiate its reopening and the sale of the entire future output to the United States with
Edgar Sengier, the director of the company that owned the mine, the
Union Minière du Haut-Katanga. The matter was then taken up by the Combined Policy Committee. As 30 percent of Union Minière's stock was controlled by British interests, the British took the lead in negotiations. Sir John Anderson and Ambassador
John Winant hammered out a deal with Sengier and the Belgian government in May 1944 for the mine to be reopened and of ore to be purchased at $1.45 a pound. To avoid dependence on the British and Canadians for ore, Groves also arranged for the purchase of US Vanadium Corporation's stockpile in
Uravan, Colorado
Uravan (a contraction of uranium/vanadium) is a former uranium mining town in western Montrose County, Colorado, United States, which still appears on some maps. The town was a company town established by U. S. Vanadium Corporation in 1936 to e ...
.
Uranium mining in Colorado yielded about of ore.
Mallinckrodt Incorporated
Mallinckrodt Pharmaceuticals is an American-Irish domiciled manufacturer of specialty pharmaceuticals (namely, adrenocorticotropic hormone), generic drugs and imaging agents. In 2017 it generated 90% of its sales from the U.S. healthcare system. ...
in St. Louis, Missouri, took the raw ore and dissolved it in
nitric acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...
to produce
uranyl nitrate.
Ether
In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be c ...
was then added in a
liquid–liquid extraction
Liquid–liquid extraction (LLE), also known as solvent extraction and partitioning, is a method to separate compounds or metal complexes, based on their relative solubilities in two different immiscible liquids, usually water (polar) and an org ...
process to separate the impurities from the uranyl nitrate. This was then heated to form
uranium trioxide, which was reduced to highly pure
uranium dioxide
Uranium dioxide or uranium(IV) oxide (), also known as urania or uranous oxide, is an oxide of uranium, and is a black, radioactive, crystalline powder that naturally occurs in the mineral uraninite. It is used in nuclear fuel rods in nuclear rea ...
. By July 1942, Mallinckrodt was producing a ton of highly pure oxide a day, but turning this into uranium metal initially proved more difficult for contractors
Westinghouse and Metal Hydrides. Production was too slow and quality was unacceptably low. A special branch of the Metallurgical Laboratory was established at
Iowa State College in
Ames, Iowa
Ames () is a city in Story County, Iowa, United States, located approximately north of Des Moines in central Iowa. It is best known as the home of Iowa State University (ISU), with leading agriculture, design, engineering, and veterinary medici ...
, under Frank Spedding to investigate alternatives. This became known as the
Ames Project
The Ames Project was a research and development project that was part of the larger Manhattan Project to build the first atomic bombs during World War II. It was founded by Frank Spedding from Iowa State College in Ames, Iowa as an offshoot of ...
, and its
Ames process became available in 1943.
File:Ames Process pressure vessel lower.jpg, A "bomb" (pressure vessel
A pressure vessel is a container designed to hold gases or liquids at a pressure substantially different from the ambient pressure.
Construction methods and materials may be chosen to suit the pressure application, and will depend on the size o ...
) containing uranium halide and sacrificial metal, probably magnesium, being lowered into a furnace
File:Ames Process pressure vessel remnant slag after reaction.jpg, After the reaction, the interior of a bomb coated with remnant slag
Slag is a by-product of smelting (pyrometallurgical) ores and used metals. Broadly, it can be classified as ferrous (by-products of processing iron and steel), ferroalloy (by-product of ferroalloy production) or non-ferrous/base metals (by-prod ...
File:Ames Process uranium biscuit.jpg, A uranium metal "biscuit" from the reduction reaction
Isotope separation
Natural uranium consists of 99.3% uranium-238 and 0.7% uranium-235, but only the latter is
fissile. The chemically identical uranium-235 has to be physically separated from the more plentiful isotope. Various methods were considered for
uranium enrichment
Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235U) has been increased through the process of isotope separation. Naturally occurring uranium is composed of three major isotopes: uranium-238 (238U ...
, most of which was carried out at Oak Ridge.
The most obvious technology, the centrifuge, failed, but electromagnetic separation, gaseous diffusion, and thermal diffusion technologies were all successful and contributed to the project. In February 1943, Groves came up with the idea of using the output of some plants as the input for others.
Centrifuges
The centrifuge process was regarded as the only promising separation method in April 1942.
Jesse Beams had developed such a process at the
University of Virginia
The University of Virginia (UVA) is a Public university#United States, public research university in Charlottesville, Virginia. Founded in 1819 by Thomas Jefferson, the university is ranked among the top academic institutions in the United S ...
during the 1930s, but had encountered technical difficulties. The process required high rotational speeds, but at certain speeds harmonic vibrations developed that threatened to tear the machinery apart. It was therefore necessary to accelerate quickly through these speeds. In 1941 he began working with
uranium hexafluoride
Uranium hexafluoride (), (sometimes called "hex") is an inorganic compound with the formula UF6. Uranium hexafluoride is a volatile white solid that reacts with water, releasing corrosive hydrofluoric acid. The compound reacts mildly with alumin ...
, the only known gaseous compound of uranium, and was able to separate uranium-235. At Columbia, Urey had
Karl P. Cohen
Karl Paley Cohen (February 5, 1913 – April 6, 2012) was a physical chemist who became a mathematical physicist and helped usher in the age of nuclear energy and reactor development. He began his career in 1937 making scientific advances in urani ...
investigate the process, and he produced a body of mathematical theory making it possible to design a centrifugal separation unit, which Westinghouse undertook to construct.
Scaling this up to a production plant presented a formidable technical challenge. Urey and Cohen estimated that producing a kilogram (2.2 lb) of uranium-235 per day would require up to 50,000 centrifuges with rotors, or 10,000 centrifuges with rotors, assuming that 4-meter rotors could be built. The prospect of keeping so many rotors operating continuously at high speed appeared daunting, and when Beams ran his experimental apparatus, he obtained only 60% of the predicted yield, indicating that more centrifuges would be required. Beams, Urey and Cohen then began work on a series of improvements which promised to increase the efficiency of the process. However, frequent failures of motors, shafts and bearings at high speeds delayed work on the pilot plant. In November 1942 the centrifuge process was abandoned by the Military Policy Committee following a recommendation by Conant, Nichols and August C. Klein of Stone & Webster.
Although the centrifuge method was abandoned by the Manhattan Project, research into it advanced significantly after the war with the introduction of the
Zippe-type centrifuge
The Zippe-type centrifuge is a gas centrifuge designed to enrich the rare fissile isotope uranium-235 (235U) from the mixture of isotopes found in naturally occurring uranium compounds. The isotopic separation is based on the slight difference in m ...
, which was developed in the Soviet Union by Soviet and captured German engineers. It eventually became the preferred method of Uranium isotope separation, being far more economical than the other separation methods used during World War II.
Electromagnetic separation
Electromagnetic isotope separation was developed by Lawrence at the University of California Radiation Laboratory. This method employed devices known as
calutron
A calutron is a mass spectrometer originally designed and used for separating the isotopes of uranium. It was developed by Ernest Lawrence during the Manhattan Project and was based on his earlier invention, the cyclotron. Its name was derived ...
s, a hybrid of the standard laboratory
mass spectrometer and the cyclotron magnet. The name was derived from the words ''California'', ''university'' and ''cyclotron''.
[.] In the electromagnetic process, a magnetic field deflected charged particles according to mass. The process was neither scientifically elegant nor industrially efficient.
[.] Compared with a gaseous diffusion plant or a nuclear reactor, an electromagnetic separation plant would consume more scarce materials, require more manpower to operate, and cost more to build. Nonetheless, the process was approved because it was based on proven technology and therefore represented less risk. Moreover, it could be built in stages, and rapidly reach industrial capacity.
![Alpha 1 racetrack, Uranium 235 electromagnetic separation plant, Manhattan Project, Y-12 Oak Ridge](https://upload.wikimedia.org/wikipedia/commons/c/ce/Alpha_1_racetrack%2C_Uranium_235_electromagnetic_separation_plant%2C_Manhattan_Project%2C_Y-12_Oak_Ridge.jpg)
Marshall and Nichols discovered that the electromagnetic isotope separation process would require of copper, which was in desperately short supply. However, silver could be substituted, in an 11:10 ratio. On 3 August 1942, Nichols met with
Under Secretary of the Treasury Daniel W. Bell
Daniel Wafena Bell (July 23, 1891 – October 4, 1971) was an American civil servant and businessman. Born in Kinderhook, Illinois, he was acting director of the Bureau of the Budget (now the Office of Management and Budget) from September 1, 193 ...
and asked for the transfer of 6,000 tons of silver bullion from the
West Point Bullion Depository
The West Point Mint is a U.S. Mint production and depository facility erected in 1937 near the U.S. Military Academy in West Point, New York, United States. the mint holds 22% of the United States' gold reserves, or approximately 54 million oun ...
. "Young man," Bell told him, "you may think of silver in tons but the Treasury will always think of silver in
troy ounces!" Ultimately were used.
The silver bars were cast into cylindrical billets and taken to
Phelps Dodge in Bayway, New Jersey, where they were extruded into strips thick, wide and long. These were wound onto magnetic coils by
Allis-Chalmers
Allis-Chalmers was a U.S. manufacturer of machinery for various industries. Its business lines included agricultural equipment, construction equipment, power generation and power transmission equipment, and machinery for use in industrial setti ...
in Milwaukee, Wisconsin. After the war, all the machinery was dismantled and cleaned and the floorboards beneath the machinery were ripped up and burned to recover minute amounts of silver. In the end, only 1/3,600,000th was lost.
[.] The last silver was returned in May 1970.
Responsibility for the design and construction of the electromagnetic separation plant, which came to be called
Y-12, was assigned to Stone & Webster by the S-1 Committee in June 1942. The design called for five first-stage processing units, known as Alpha racetracks, and two units for final processing, known as Beta racetracks. In September 1943 Groves authorized construction of four more racetracks, known as Alpha II. Construction began in February 1943.
When the plant was started up for testing on schedule in October, the 14-ton vacuum tanks crept out of alignment because of the power of the magnets, and had to be fastened more securely. A more serious problem arose when the magnetic coils started shorting out. In December Groves ordered a magnet to be broken open, and handfuls of rust were found inside. Groves then ordered the racetracks to be torn down and the magnets sent back to the factory to be cleaned. A pickling plant was established on-site to clean the pipes and fittings.
The second Alpha I was not operational until the end of January 1944, the first Beta and first and third Alpha I's came online in March, and the fourth Alpha I was operational in April. The four Alpha II racetracks were completed between July and October 1944.
Tennessee Eastman
Eastman Chemical Company is an American company primarily involved in the chemical industry. Once a subsidiary of Kodak, today it is an independent global specialty materials company that produces a broad range of advanced materials, chemicals and ...
was contracted to manage Y-12 on the usual cost plus fixed-fee basis, with a fee of $22,500 per month plus $7,500 per racetrack for the first seven racetracks and $4,000 per additional racetrack. The calutrons were initially operated by scientists from Berkeley to remove bugs and achieve a reasonable operating rate. They were then turned over to trained Tennessee Eastman operators who had only a high school education. Nichols compared unit production data, and pointed out to Lawrence that the young "
hillbilly
Hillbilly is a term (often derogatory) for people who dwell in rural, mountainous areas in the United States, primarily in southern Appalachia and the Ozarks. The term was later used to refer to people from other rural and mountainous areas west ...
" girl operators, known as
Calutron Girls
The Calutron Girls were a group of young women, mostly high school graduates, who joined the Manhattan Project, the World War II efforts to develop nuclear weapons at the United States government facility located at Oak Ridge, Tennessee, betwe ...
, were outperforming his PhDs. They agreed to a production race and Lawrence lost, a morale boost for the Tennessee Eastman workers and supervisors. The girls were "trained like soldiers not to reason why", while "the scientists could not refrain from time-consuming investigation of the cause of even minor fluctuations of the dials."
Y-12 initially enriched the uranium-235 content to between 13% and 15%, and shipped the first few hundred grams of this to Los Alamos in March 1944. Only 1 part in 5,825 of the uranium feed emerged as final product. Much of the rest was splattered over equipment in the process. Strenuous recovery efforts helped raise production to 10% of the uranium-235 feed by January 1945. In February the Alpha racetracks began receiving slightly enriched (1.4%) feed from the new S-50 thermal diffusion plant. The next month it received enhanced (5%) feed from the K-25 gaseous diffusion plant. By August K-25 was producing uranium sufficiently enriched to feed directly into the Beta tracks.
Gaseous diffusion
The most promising but also the most challenging method of isotope separation was gaseous diffusion.
Graham's law
Graham's law of effusion (also called Graham's law of diffusion) was formulated by Scottish physical chemist Thomas Graham (chemist), Thomas Graham in 1848.Keith J. Laidler and John M. Meiser, ''Physical Chemistry'' (Benjamin/Cummings 1982), pp.&n ...
states that the rate of
effusion
In physics and chemistry, effusion is the process in which a gas escapes from a container through a hole of diameter considerably smaller than the mean free path of the molecules. Such a hole is often described as a ''pinhole'' and the escape ...
of a gas is inversely proportional to the square root of its
molecular mass
The molecular mass (''m'') is the mass of a given molecule: it is measured in daltons (Da or u). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The related quanti ...
, so in a box containing a semi-permeable membrane and a mixture of two gases, the lighter molecules will pass out of the container more rapidly than the heavier molecules. The gas leaving the container is somewhat enriched in the lighter molecules, while the residual gas is somewhat depleted. The idea was that such boxes could be formed into a cascade of pumps and membranes, with each successive stage containing a slightly more enriched mixture. Research into the process was carried out at Columbia University by a group that included Harold Urey,
Karl P. Cohen
Karl Paley Cohen (February 5, 1913 – April 6, 2012) was a physical chemist who became a mathematical physicist and helped usher in the age of nuclear energy and reactor development. He began his career in 1937 making scientific advances in urani ...
, and
John R. Dunning
John Ray Dunning (September 24, 1907 – August 25, 1975) was an American physicist who played key roles in the Manhattan Project that developed the first atomic bombs. He specialized in neutron physics, and did pioneering work in gaseous diffusio ...
.
![K-25 aerial view](https://upload.wikimedia.org/wikipedia/commons/a/ac/K-25_aerial_view.jpg)
In November 1942 the Military Policy Committee approved the construction of a 600-stage gaseous diffusion plant. On 14 December,
M. W. Kellogg
KBR, Inc. (formerly Kellogg Brown & Root) is a U.S. based company operating in fields of science, technology and engineering. KBR works in various markets including aerospace, defense, industrial and intelligence. After Halliburton acquired Dress ...
accepted an offer to construct the plant, which was codenamed K-25. A cost plus fixed-fee contract was negotiated, eventually totaling $2.5 million. A separate corporate entity called Kellex was created for the project, headed by Percival C. Keith, one of Kellogg's vice presidents. The process faced formidable technical difficulties. The highly corrosive gas uranium hexafluoride would have to be used, as no substitute could be found, and the motors and pumps would have to be vacuum tight and enclosed in inert gas. The biggest problem was the design of the barrier, which would have to be strong, porous and resistant to corrosion by uranium hexafluoride. The best choice for this seemed to be nickel. Edward Adler and Edward Norris created a mesh barrier from electroplated nickel. A six-stage pilot plant was built at Columbia to test the process, but the Norris-Adler prototype proved to be too brittle. A rival barrier was developed from powdered nickel by Kellex, the
Bell Telephone Laboratories and the
Bakelite
Polyoxybenzylmethylenglycolanhydride, better known as Bakelite ( ), is a thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde. The first plastic made from synthetic components, it was developed ...
Corporation. In January 1944, Groves ordered the Kellex barrier into production.
Kellex's design for K-25 called for a four-story long U-shaped structure containing 54 contiguous buildings. These were divided into nine sections. Within these were cells of six stages. The cells could be operated independently, or consecutively within a section. Similarly, the sections could be operated separately or as part of a single cascade. A survey party began construction by marking out the site in May 1943. Work on the main building began in October 1943, and the six-stage pilot plant was ready for operation on 17 April 1944. In 1945 Groves canceled the upper stages of the plant, directing Kellex to instead design and build a 540-stage side feed unit, which became known as K-27. Kellex transferred the last unit to the operating contractor,
Union Carbide
Union Carbide Corporation is an American chemical corporation wholly owned subsidiary (since February 6, 2001) by Dow Chemical Company. Union Carbide produces chemicals and polymers that undergo one or more further conversions by customers befor ...
and Carbon, on 11 September 1945. The total cost, including the K-27 plant completed after the war, came to $480 million.
The production plant commenced operation in February 1945, and as cascade after cascade came online, the quality of the product increased. By April 1945, K-25 had attained a 1.1% enrichment and the output of the S-50 thermal diffusion plant began being used as feed. Some product produced the next month reached nearly 7% enrichment. In August, the last of the 2,892 stages commenced operation. K-25 and K-27 achieved their full potential in the early postwar period, when they eclipsed the other production plants and became the prototypes for a new generation of plants.
Thermal diffusion
The thermal diffusion process was based on
Sydney Chapman and
David Enskog 250px
David Enskog (22 April 1884, Västra Ämtervik, Sunne – 1 June 1947, Stockholm) was a Swedish mathematical physicist. Enskog helped develop the kinetic theory of gases by extending the Maxwell–Boltzmann equations.
Biography
Af ...
's
theory
A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may be s ...
, which explained that when a mixed gas passes through a temperature gradient, the heavier one tends to concentrate at the cold end and the lighter one at the warm end. Since hot gases tend to rise and cool ones tend to fall, this can be used as a means of isotope separation. This process was first demonstrated by
Klaus Clusius
Klaus Paul Alfred Clusius (19 March 1903 – 28 May 1963) was a German physical chemist from Breslau (Wrocław), Silesia. During World War II, he worked on the German nuclear energy project, also known as the Uranium Club; he worked on isotope ...
and
Gerhard Dickel
Gerhard Dickel (28 October 1913 – 3 November 2017) was a German chemist and physicist. He developed a thermal diffusion method of separating isotopes with Klaus Clusius in 1938, sometimes referred to as Clusius-Dickel separation.
Biography
H ...
in Germany in 1938. It was developed by US Navy scientists, but was not one of the enrichment technologies initially selected for use in the Manhattan Project. This was primarily due to doubts about its technical feasibility, but the inter-service rivalry between the Army and Navy also played a part.
![S50plant](https://upload.wikimedia.org/wikipedia/commons/6/67/S50plant.jpg)
The Naval Research Laboratory continued the research under Philip Abelson's direction, but there was little contact with the Manhattan Project until April 1944, when
Captain
Captain is a title, an appellative for the commanding officer of a military unit; the supreme leader of a navy ship, merchant ship, aeroplane, spacecraft, or other vessel; or the commander of a port, fire or police department, election precinct, e ...
William S. Parsons
Rear Admiral William Sterling "Deak" Parsons (26 November 1901 – 5 December 1953) was an American naval officer who worked as an ordnance expert on the Manhattan Project during World War II. He is best known for being the weaponeer on the ''En ...
, the naval officer in charge of ordnance development at Los Alamos, brought Oppenheimer news of encouraging progress in the Navy's experiments on thermal diffusion. Oppenheimer wrote to Groves suggesting that the output of a thermal diffusion plant could be fed into Y-12. Groves set up a committee consisting of
Warren K. Lewis, Eger Murphree and Richard Tolman to investigate the idea, and they estimated that a thermal diffusion plant costing $3.5 million could enrich of uranium per week to nearly 0.9% uranium-235. Groves approved its construction on 24 June 1944.
Groves contracted with the H. K. Ferguson Company of
Cleveland
Cleveland ( ), officially the City of Cleveland, is a city in the U.S. state of Ohio and the county seat of Cuyahoga County. Located in the northeastern part of the state, it is situated along the southern shore of Lake Erie, across the U.S. ...
, Ohio, to build the thermal diffusion plant, which was designated S-50. Groves's advisers, Karl Cohen and W. I. Thompson from
Standard Oil
Standard Oil Company, Inc., was an American oil production, transportation, refining, and marketing company that operated from 1870 to 1911. At its height, Standard Oil was the largest petroleum company in the world, and its success made its co-f ...
, estimated that it would take six months to build. Groves gave Ferguson just four. Plans called for the installation of 2,142 diffusion columns arranged in 21 racks. Inside each column were three concentric tubes. Steam, obtained from the nearby K-25 powerhouse at a pressure of and temperature of , flowed downward through the innermost nickel pipe, while water at flowed upward through the outermost iron pipe. The uranium hexafluoride flowed in the middle copper pipe, and isotope separation of the uranium occurred between the nickel and copper pipes.
Work commenced on 9 July 1944, and S-50 began partial operation in September. Ferguson operated the plant through a subsidiary known as Fercleve. The plant produced just of 0.852% uranium-235 in October. Leaks limited production and forced shutdowns over the next few months, but in June 1945 it produced . By March 1945, all 21 production racks were operating. Initially the output of S-50 was fed into Y-12, but starting in March 1945 all three enrichment processes were run in series. S-50 became the first stage, enriching from 0.71% to 0.89%. This material was fed into the gaseous diffusion process in the K-25 plant, which produced a product enriched to about 23%. This was, in turn, fed into Y-12, which boosted it to about 89%, sufficient for nuclear weapons.
[.]
Aggregate U-235 production
About of uranium enriched to 89% uranium-235 was delivered to Los Alamos by July 1945.
The entire 50 kg, along with some 50%-enriched, averaging out to about 85% enriched, were used in
Little Boy
"Little Boy" was the type of atomic bomb dropped on the Japanese city of Hiroshima on 6 August 1945 during World War II, making it the first nuclear weapon used in warfare. The bomb was dropped by the Boeing B-29 Superfortress ''Enola Gay'' p ...
.
Plutonium
The second line of development pursued by the Manhattan Project used the fissile element plutonium. Although small amounts of plutonium exist in nature, the best way to obtain large quantities of the element is in a nuclear reactor, in which natural uranium is bombarded by neutrons. The uranium-238 is
transmuted into uranium-239, which rapidly decays, first into neptunium-239 and then into plutonium-239.
Only a small amount of the uranium-238 will be transformed, so the plutonium must be chemically separated from the remaining uranium, from any initial impurities, and from fission products.
[.]
X-10 Graphite Reactor
![X10 Reactor Face](https://upload.wikimedia.org/wikipedia/commons/1/16/X10_Reactor_Face.jpg)
In March 1943, DuPont began construction of a plutonium plant on a site at Oak Ridge. Intended as a pilot plant for the larger production facilities at Hanford, it included the air-cooled
X-10 Graphite Reactor, a chemical separation plant, and support facilities. Because of the subsequent decision to construct water-cooled reactors at Hanford, only the chemical separation plant operated as a true pilot.
[.] The X-10 Graphite Reactor consisted of a huge block of graphite, long on each side, weighing around , surrounded by of high-density concrete as a radiation shield.
The greatest difficulty was encountered with the uranium slugs produced by Mallinckrodt and Metal Hydrides. These somehow had to be coated in aluminum to avoid corrosion and the escape of fission products into the cooling system. The Grasselli Chemical Company attempted to develop a tinning#Hot-dipping, hot dipping process without success. Meanwhile, Alcoa tried canning. A new process for flux-less welding was developed, and 97% of the cans passed a standard vacuum test, but high temperature tests indicated a failure rate of more than 50%. Nonetheless, production began in June 1943. The Metallurgical Laboratory eventually developed an improved welding technique with the help of General Electric, which was incorporated into the production process in October 1943.
Watched by Fermi and Compton, the X-10 Graphite Reactor went critical on 4 November 1943 with about of uranium. A week later the load was increased to , raising its power generation to 500 kW, and by the end of the month the first 500 mg of plutonium was created. Modifications over time raised the power to 4,000 kW in July 1944. X-10 operated as a production plant until January 1945, when it was turned over to research activities.
[.]
Hanford reactors
Although an air-cooled design was chosen for the reactor at Oak Ridge to facilitate rapid construction, it was recognized that this would be impractical for the much larger production reactors. Initial designs by the Metallurgical Laboratory and DuPont used helium for cooling, before they determined that a water-cooled reactor would be simpler, cheaper and quicker to build. The design did not become available until 4 October 1943; in the meantime, Matthias concentrated on improving the Hanford Site by erecting accommodations, improving the roads, building a railway switch line, and upgrading the electricity, water and telephone lines.
![Hanford B-Reactor Area 1944](https://upload.wikimedia.org/wikipedia/commons/5/55/Hanford_B-Reactor_Area_1944.jpg)
As at Oak Ridge, the most difficulty was encountered while canning the uranium slugs, which commenced at Hanford in March 1944. They were pickling (metal), pickled to remove dirt and impurities, dipped in molten bronze, tin, and silumin, aluminum-silicon alloy, canned using hydraulic presses, and then capped using arc welding under an argon atmosphere. Finally, they were subjected to a series of tests to detect holes or faulty welds. Disappointingly, most canned slugs initially failed the tests, resulting in an output of only a handful of canned slugs per day. But steady progress was made and by June 1944 production increased to the point where it appeared that enough canned slugs would be available to start B-Reactor, Reactor B on schedule in August 1944.
Work began on Reactor B, the first of six planned 250 MW reactors, on 10 October 1943. The reactor complexes were given letter designations A through F, with B, D and F sites chosen to be developed first, as this maximised the distance between the reactors. They would be the only ones constructed during the Manhattan Project. Some of steel, of concrete, 50,000 concrete blocks and 71,000 concrete bricks were used to construct the high building.
Construction of the reactor itself commenced in February 1944. Watched by Compton, Matthias, DuPont's Crawford Greenewalt, Leona Woods and Fermi, who inserted the first slug, the reactor was powered up beginning on 13 September 1944. Over the next few days, 838 tubes were loaded and the reactor went critical. Shortly after midnight on 27 September, the operators began to withdraw the control rods to initiate production. At first all appeared well but around 03:00 the power level started to drop and by 06:30 the reactor had shut down completely. The cooling water was investigated to see if there was a leak or contamination. The next day the reactor started up again, only to shut down once more.
[.]
Fermi contacted Chien-Shiung Wu, who identified the cause of the problem as neutron poisoning from xenon-135, which has a half-life of 9.2 hours. Fermi, Woods, Donald J. Hughes and John Archibald Wheeler then calculated the nuclear cross section of xenon-135, which turned out to be 30,000 times that of uranium. DuPont engineer George Graves had deviated from the Metallurgical Laboratory's original design in which the reactor had 1,500 tubes arranged in a circle, and had added an additional 504 tubes to fill in the corners. The scientists had originally considered this overengineering a waste of time and money, but Fermi realized that by loading all 2,004 tubes, the reactor could reach the required power level and efficiently produce plutonium. Reactor D was started on 17 December 1944 and Reactor F on 25 February 1945.
[.]
Separation process
![Hanford Engineer Works](https://upload.wikimedia.org/wikipedia/commons/5/5c/Hanford_Engineer_Works.png)
Meanwhile, the chemists considered the problem of how plutonium could be separated from uranium when its chemical properties were not known. Working with the minute quantities of plutonium available at the Metallurgical Laboratory in 1942, a team under Charles M. Cooper developed a fluoride selective electrode, lanthanum fluoride process for separating uranium and plutonium, which was chosen for the pilot separation plant. A second separation process, the
bismuth phosphate process
The bismuth-phosphate process was used to extract plutonium from irradiated uranium taken from nuclear reactors. It was developed during World War II by Stanley G. Thompson, a chemist working for the Manhattan Project at the University of Califor ...
, was subsequently developed by Seaborg and Stanly G. Thomson. This process worked by toggling plutonium between its +4 and +6 oxidation states in solutions of bismuth phosphate. In the former state, the plutonium was precipitated; in the latter, it stayed in solution and the other products were precipitated.
Greenewalt favored the bismuth phosphate process due to the corrosive nature of lanthanum fluoride, and it was selected for the Hanford separation plants. Once X-10 began producing plutonium, the pilot separation plant was put to the test. The first batch was processed at 40% efficiency but over the next few months this was raised to 90%.
At Hanford, top priority was initially given to the installations in the 300 area. This contained buildings for testing materials, preparing uranium, and assembling and calibrating instrumentation. One of the buildings housed the canning equipment for the uranium slugs, while another contained a small test reactor. Notwithstanding the high priority allocated to it, work on the 300 area fell behind schedule due to the unique and complex nature of the 300 area facilities, and wartime shortages of labor and materials.
Early plans called for the construction of two separation plants in each of the areas known as 200-West and 200-East. This was subsequently reduced to two, the T and U plants, in 200-West and one, the B plant, at 200-East. Each separation plant consisted of four buildings: a process cell building or "canyon" (known as 221), a concentration building (224), a purification building (231) and a magazine store (213). The canyons were each long and wide. Each consisted of forty cells.
Work began on 221-T and 221-U in January 1944, with the former completed in September and the latter in December. The 221-B building followed in March 1945. Because of the high levels of radioactivity involved, all work in the separation plants had to be conducted by remote control using closed-circuit television, something unheard of in 1943. Maintenance was carried out with the aid of an overhead crane and specially designed tools. The 224 buildings were smaller because they had less material to process, and it was less radioactive. The 224-T and 224-U buildings were completed on 8 October 1944, and 224-B followed on 10 February 1945. The purification methods that were eventually used in 231-W were still unknown when construction commenced on 8 April 1944, but the plant was complete and the methods were selected by the end of the year. On 5 February 1945, Matthias hand-delivered the first shipment of 80 g of 95%-pure plutonium nitrate to a Los Alamos courier in Los Angeles.
Weapon design
![Thin Man plutonium gun bomb casings](https://upload.wikimedia.org/wikipedia/commons/c/ce/Thin_Man_plutonium_gun_bomb_casings.jpg)
In 1943, development efforts were directed to a
gun-type fission weapon
Gun-type fission weapons are fission-based nuclear weapons whose design assembles their fissile material into a supercritical mass by the use of the "gun" method: shooting one piece of sub-critical material into another. Although this is sometim ...
with plutonium called
Thin Man. Initial research on the properties of plutonium was done using cyclotron-generated plutonium-239, which was extremely pure, but could only be created in very small amounts. Los Alamos received the first sample of plutonium from the Clinton X-10 reactor in April 1944 and within days Emilio Segrè discovered a problem: the reactor-bred plutonium had a higher concentration of plutonium-240, resulting in up to five times the spontaneous fission rate of cyclotron plutonium. Seaborg had correctly predicted in March 1943 that some of the plutonium-239 would absorb a neutron and become plutonium-240.
This made reactor plutonium unsuitable for use in a gun-type weapon. The plutonium-240 would start the chain reaction too quickly, causing a predetonation that would release enough energy to disperse the critical mass with a minimal amount of plutonium reacted (a fizzle (nuclear test), fizzle). A faster gun was suggested but found to be impractical. The possibility of separating the isotopes was considered and rejected, as plutonium-240 is even harder to separate from plutonium-239 than uranium-235 from uranium-238.
Work on an alternative method of bomb design, known as implosion, had begun earlier under the direction of the physicist Seth Neddermeyer. Implosion used explosives to crush a subcritical sphere of fissile material into a smaller and denser form. When the fissile atoms are packed closer together, the rate of neutron capture increases, and the mass becomes a critical mass. The metal needs to travel only a very short distance, so the critical mass is assembled in much less time than it would take with the gun method. Neddermeyer's 1943 and early 1944 investigations into implosion showed promise, but also made it clear that the problem would be much more difficult from a theoretical and engineering perspective than the gun design. In September 1943, John von Neumann, who had experience with shaped charges used in armor-piercing shells, argued that not only would implosion reduce the danger of predetonation and fizzle, but would make more efficient use of the fissionable material. He proposed using a spherical configuration instead of the cylindrical one that Neddermeyer was working on.
![Fat Man design model](https://upload.wikimedia.org/wikipedia/commons/1/16/Fat_Man_design_model.png)
By July 1944, Oppenheimer had concluded plutonium could not be used in a gun design, and opted for implosion. The accelerated effort on an implosion design, codenamed
Fat Man
"Fat Man" (also known as Mark III) is the codename for the type of nuclear bomb the United States detonated over the Japanese city of Nagasaki on 9 August 1945. It was the second of the only two nuclear weapons ever used in warfare, the fir ...
, began in August 1944 when Oppenheimer implemented a sweeping reorganization of the Los Alamos laboratory to focus on implosion. Two new groups were created at Los Alamos to develop the implosion weapon, X (for explosives) Division headed by explosives expert George Kistiakowsky and G (for gadget) Division under Robert Bacher. The new design that von Neumann and T (for theoretical) Division, most notably Rudolf Peierls, had devised used explosive lenses to focus the explosion onto a spherical shape using a combination of both slow and fast high explosives.
The design of lenses that detonated with the proper shape and velocity turned out to be slow, difficult and frustrating.
Various explosives were tested before settling on composition B as the fast explosive and baratol as the slow explosive. The final design resembled a soccer ball, with 20 hexagonal and 12 pentagonal lenses, each weighing about . Getting the detonation just right required fast, reliable and safe electrical detonators, of which there were two for each lens for reliability.
It was therefore decided to use exploding-bridgewire detonators, a new invention developed at Los Alamos by a group led by Luis Walter Alvarez, Luis Alvarez. A contract for their manufacture was given to Raytheon.
To study the behavior of converging shock waves, Robert Serber devised the RaLa Experiment, which used the short-lived radioisotope lanthanum-140, a potent source of gamma radiation. The gamma ray source was placed in the center of a metal sphere surrounded by the explosive lenses, which in turn were inside in an ionization chamber. This allowed the taking of an X-ray movie of the implosion. The lenses were designed primarily using this series of tests. In his history of the Los Alamos project, David Hawkins (philosopher), David Hawkins wrote: "RaLa became the most important single experiment affecting the final bomb design".
Within the explosives was the thick aluminum pusher, which provided a smooth transition from the relatively low density explosive to the next layer, the thick tamper of natural uranium. Its main job was to hold the critical mass together as long as possible, but it would also reflect neutrons back into the core. Some part of it might fission as well. To prevent predetonation by an external neutron, the tamper was coated in a thin layer of boron.
A polonium-beryllium modulated neutron initiator, known as an "urchin" because its shape resembled a sea urchin, was developed to start the chain reaction at precisely the right moment. This work with the chemistry and metallurgy of radioactive polonium was directed by Charles Allen Thomas of the Monsanto Company and became known as the Dayton Project. Testing required up to 500 Curie (unit), curies per month of polonium, which Monsanto was able to deliver. The whole assembly was encased in a duralumin bomb casing to protect it from bullets and flak.
[.]
![Remote handling of a kilocurie source of radiolanthanum](https://upload.wikimedia.org/wikipedia/commons/8/80/Remote_handling_of_a_kilocurie_source_of_radiolanthanum.jpg)
The ultimate task of the metallurgists was to determine how to cast plutonium into a sphere. The difficulties became apparent when attempts to measure the density of plutonium gave inconsistent results. At first contamination was believed to be the cause, but it was soon determined that there were multiple allotropes of plutonium. The brittle α phase that exists at room temperature changes to the plastic β phase at higher temperatures. Attention then shifted to the even more malleable δ phase that normally exists in the 300 °C to 450 °C range. It was found that this was stable at room temperature when alloyed with aluminum, but aluminum emits neutrons when bombarded with alpha particles, which would exacerbate the pre-ignition problem. The metallurgists then hit upon a plutonium-gallium alloy, which stabilized the δ phase and could be hot pressing, hot pressed into the desired spherical shape. As plutonium was found to corrode readily, the sphere was coated with nickel.
The work proved dangerous. By the end of the war, half the experienced chemists and metallurgists had to be removed from work with plutonium when unacceptably high levels of the element appeared in their urine. A minor fire at Los Alamos in January 1945 led to a fear that a fire in the plutonium laboratory might contaminate the whole town, and Groves authorized the construction of a new facility for plutonium chemistry and metallurgy, which became known as the DP-site. The hemispheres for the first plutonium pit (nuclear weapon), pit (or core) were produced and delivered on 2 July 1945. Three more hemispheres followed on 23 July and were delivered three days later.
Trinity
Because of the complexity of an implosion-style weapon, it was decided that, despite the waste of fissile material, an initial test would be required. Groves approved the test, subject to the active material being recovered. Consideration was therefore given to a controlled fizzle, but Oppenheimer opted instead for a full-scale nuclear test, codenamed "Trinity".
![Trinity device readied](https://upload.wikimedia.org/wikipedia/commons/8/88/Trinity_device_readied.jpg)
In March 1944, planning for the test was assigned to Kenneth Bainbridge, a professor of physics at Harvard, working under Kistiakowsky. Bainbridge selected the Alamogordo Bombing Range, bombing range near Alamogordo Army Airfield as the site for the test. Bainbridge worked with Captain Samuel P. Davalos on the construction of the Trinity Base Camp and its facilities, which included barracks, warehouses, workshops, an explosive magazine and a commissary.
Groves did not relish the prospect of explaining to a Senate committee the loss of a billion dollars worth of plutonium, so a cylindrical containment vessel codenamed "Jumbo" was constructed to recover the active material in the event of a failure. Measuring long and wide, it was fabricated at great expense from of iron and steel by Babcock & Wilcox in Barberton, Ohio. Brought in a special railroad car to a siding in Pope, New Mexico, it was transported the last to the test site on a trailer pulled by two tractors. By the time it arrived, however, confidence in the implosion method was high enough, and the availability of plutonium was sufficient, that Oppenheimer decided not to use it. Instead, it was placed atop a steel tower from the weapon as a rough measure of how powerful the explosion would be. In the end, Jumbo survived, although its tower did not, adding credence to the belief that Jumbo would have successfully contained a fizzled explosion.
[.]
A pre-test explosion was conducted on 7 May 1945 to calibrate the instruments. A wooden test platform was erected from Ground Zero and piled with of TNT spiked with nuclear fission products in the form of an irradiated uranium slug from Hanford, which was dissolved and poured into tubing inside the explosive. This explosion was observed by Oppenheimer and Groves's new deputy commander, Brigadier General Thomas Farrell (general), Thomas Farrell. The pre-test produced data that proved vital for the Trinity test.
![Trinity Detonation T&B](https://upload.wikimedia.org/wikipedia/commons/f/fc/Trinity_Detonation_T%26B.jpg)
For the actual test, the weapon, nicknamed "the gadget", was hoisted to the top of a steel tower, as detonation at that height would give a better indication of how the weapon would behave when dropped from a bomber. Detonation in the air maximized the energy applied directly to the target, and generated less nuclear fallout. The gadget was assembled under the supervision of Norris Bradbury at the nearby McDonald Ranch House on 13 July, and precariously winched up the tower the following day. Observers included Bush, Chadwick, Conant, Farrell, Fermi, Groves, Lawrence, Oppenheimer and Tolman. At 05:30 on 16 July 1945 the gadget exploded with an TNT equivalent, energy equivalent of around 20 kilotons of TNT, leaving a crater of Trinitite (radioactive glass) in the desert wide. The shock wave was felt over away, and the mushroom cloud reached in height. It was heard as far away as El Paso, Texas, so Groves issued a cover story about an ammunition magazine explosion at Alamogordo Field.
Oppenheimer later recalled that, while witnessing the explosion, he thought of a verse from the Hindu holy book, the ''Bhagavad Gita'' (XI,12):
Years later he would explain that another verse had also entered his head at that time:
Personnel
In June 1944, the Manhattan Project employed some 129,000 workers, of whom 84,500 were construction workers, 40,500 were plant operators and 1,800 were military personnel. As construction activity fell off, the workforce declined to 100,000 a year later, but the number of military personnel increased to 5,600. Procuring the required numbers of workers, especially highly skilled workers, in competition with other vital wartime programs proved very difficult. In 1943, Groves obtained a special temporary priority for labor from the War Manpower Commission. In March 1944, both the War Production Board and the War Manpower Commission gave the project their highest priority. The Kansas commission director stated that from April to July 1944 every qualified applicant in the state who visited a United States Employment Service office was urged to work at the Hanford Site. No other job was offered until the applicant definitively rejected the offer.
![Leslie Groves at Oak Ridge](https://upload.wikimedia.org/wikipedia/commons/6/67/Leslie_Groves_at_Oak_Ridge.jpg)
Tolman and Conant, in their role as the project's scientific advisers, drew up a list of candidate scientists and had them rated by scientists already working on the project. Groves then sent a personal letter to the head of their university or company asking for them to be released for essential war work. At the University of Wisconsin–Madison, Stanislaw Ulam gave one of his students, Joan Hinton, an exam early, so she could leave to do war work. A few weeks later, Ulam received a letter from Hans Bethe, inviting him to join the project. Conant personally persuaded Kistiakowsky to join the project.
One source of skilled personnel was the Army itself, particularly the Army Specialized Training Program. In 1943, the MED created the Special Engineer Detachment (SED), with an authorized strength of 675. Technicians and skilled workers drafted into the Army were assigned to the SED. Another source was the Women's Army Corps (WAC). Initially intended for clerical tasks handling classified material, the WACs were soon tapped for technical and scientific tasks as well. On 1 February 1945, all military personnel assigned to the MED, including all SED detachments, were assigned to the 9812th Technical Service Unit, except at Los Alamos, where military personnel other than SED, including the WACs and Military Police, were assigned to the 4817th Service Command Unit.
An Associate Professor of Radiology at the University of Rochester School of Medicine, Stafford L. Warren, was commissioned as a colonel in the United States Army Medical Corps, and appointed as chief of the MED's Medical Section and Groves' medical advisor. Warren's initial task was to staff hospitals at Oak Ridge, Richland and Los Alamos. The Medical Section was responsible for medical research, but also for the MED's health and safety programs. This presented an enormous challenge, because workers were handling a variety of toxic chemicals, using hazardous liquids and gases under high pressures, working with high voltages, and performing experiments involving explosives, not to mention the largely unknown dangers presented by radioactivity and handling fissile materials. Yet in December 1945, the National Safety Council presented the Manhattan Project with the Award of Honor for Distinguished Service to Safety in recognition of its safety record. Between January 1943 and June 1945, there were 62 fatalities and 3,879 disabling injuries, which was about 62 percent below the rate of private industry.
Secrecy
![Oak Ridge Wise Monkeys](https://upload.wikimedia.org/wikipedia/commons/7/74/Oak_Ridge_Wise_Monkeys.jpg)
A 1945 ''Life (magazine), Life'' article estimated that before the Hiroshima and Nagasaki bombings "probably no more than a few dozen men in the entire country knew the full meaning of the Manhattan Project, and perhaps only a thousand others even were aware that work on atoms was involved." The magazine wrote that the more than 100,000 others employed with the project "worked like moles in the dark". Warned that disclosing the project's secrets was punishable by 10 years in prison or a fine of , they saw enormous quantities of raw materials enter factories with nothing coming out and monitored "dials and switches while behind thick concrete walls mysterious reactions took place" without knowing the purpose of their jobs.
In December 1945 the United States Army published a secret report analysing and assessing the security apparatus surrounding the Manhattan Project. The report states that the Manhattan Project was "more drastically guarded than any other highly secret war development." The security infrastructure surrounding the Manhattan Project was so vast and thorough that in the early days of the project in 1943, security investigators vetted 400,000 potential employees and 600 companies that would be involved in all aspects of the project for potential security risks. Although at times the most important employer in the nation for government bureaucrats assigning manpower, they only knew of the "Pasco, Washington, Pasco secret project"; one said that until Hiroshima "we had no idea what was being made".
Oak Ridge security personnel considered any private party with more than seven people as suspicious, and residents—who believed that US government agents were secretly among them—avoided repeatedly inviting the same guests. Although original residents of the area could be buried in existing cemeteries, every coffin was reportedly opened for inspection.
Everyone, including top military officials, and their automobiles were searched when entering and exiting project facilities. One Oak Ridge worker stated that "if you got inquisitive, you were called on the carpet within two hours by government secret agents. Usually those summoned to explain were then escorted bag and baggage to the gate and ordered to keep going".
Despite being told that their work would help end the war and perhaps all future wars,
not seeing or understanding the results of their often tedious duties—or even typical side effects of factory work such as smoke from smokestacks—and the war in Europe ending without the use of their work, caused serious morale problems among workers and caused many rumors to spread. One manager stated after the war:
Another worker told of how, working in a laundry, she every day held "a special instrument" to uniforms and listened for "a clicking noise". She learned only after the war that she had been performing the important task of checking for radiation with a geiger counter. To improve morale among such workers Oak Ridge created an extensive system of intramural sports leagues, including 10 baseball teams, 81 softball teams, and 26 football teams.
Censorship
Voluntary censorship of atomic information began before the Manhattan Project. After the start of the European war in 1939 American scientists began avoiding publishing military-related research, and in 1940 scientific journals began asking the National Academy of Sciences to clear articles. William L. Laurence of ''The New York Times'', who wrote an article on atomic fission in ''The Saturday Evening Post'' of 7 September 1940, later learned that government officials asked librarians nationwide in 1943 to withdraw the issue. The Soviets noticed the silence, however. In April 1942 nuclear physicist Georgy Flyorov wrote to Josef Stalin on the absence of articles on nuclear fission in American journals; this resulted in the Soviet Union establishing its own atomic bomb project.
The Manhattan Project operated under tight security lest its discovery induce Axis powers, especially Germany, to accelerate their own nuclear projects or undertake covert operations against the project. The government's Office of Censorship, by contrast, relied on the press to comply with a voluntary code of conduct it published, and the project at first avoided notifying the office. By early 1943 newspapers began publishing reports of large construction in Tennessee and Washington based on public records, and the office began discussing with the project how to maintain secrecy. In June the Office of Censorship asked newspapers and broadcasters to avoid discussing "atom smashing, atomic energy, atomic fission, atomic splitting, or any of their equivalents. The use for military purposes of radium or radioactive materials, heavy water, high voltage discharge equipment, cyclotrons." The office also asked to avoid discussion of "polonium, uranium, ytterbium, hafnium, protactinium, radium, rhenium, thorium, deuterium"; only uranium was sensitive, but was listed with other elements to hide its importance.
Soviet spies
The prospect of sabotage was always present, and sometimes suspected when there were equipment failures. While there were some problems believed to be the result of careless or disgruntled employees, there were no confirmed instances of Axis-instigated sabotage. However, on 10 March 1945, a Japanese fire balloon struck a power line, and the resulting power surge caused the three reactors at Hanford to be temporarily shut down. With so many people involved, security was a difficult task. A special Counter Intelligence Corps detachment was formed to handle the project's security issues. By 1943, it was clear that the Soviet Union was attempting to penetrate the project. Lieutenant Colonel Boris T. Pash, the head of the Counter Intelligence Branch of the Western Defense Command, investigated suspected Soviet espionage at the Radiation Laboratory in Berkeley. Oppenheimer informed Pash that he had been approached by a fellow professor at Berkeley, Haakon Chevalier, about passing information to the Soviet Union.
The most successful Soviet spy was
Klaus Fuchs
Klaus Emil Julius Fuchs (29 December 1911 – 28 January 1988) was a German theoretical physicist and atomic spy who supplied information from the American, British and Canadian Manhattan Project to the Soviet Union during and shortly aft ...
, a member of the British Mission who played an important part at Los Alamos. The 1950 revelation of his espionage activities damaged the United States' nuclear cooperation with Britain and Canada. Subsequently, other instances of espionage were uncovered, leading to the arrest of Harry Gold, David Greenglass, and Julius and Ethel Rosenberg. Other spies like George Koval and Theodore Hall remained unknown for decades. The value of the espionage is difficult to quantify, as the principal constraint on the Soviet atomic bomb project was a shortage of uranium ore. The consensus is that espionage saved the Soviets one or two years of effort.
Foreign intelligence
![German Experimental Pile - Haigerloch - April 1945](https://upload.wikimedia.org/wikipedia/commons/2/21/German_Experimental_Pile_-_Haigerloch_-_April_1945.jpg)
In addition to developing the atomic bomb, the Manhattan Project was charged with gathering intelligence on the German nuclear energy project. It was believed that the Japanese nuclear weapons program was not far advanced because Japan had little access to uranium ore, but it was initially feared that Germany was very close to developing its own weapons. At the instigation of the Manhattan Project, a Norwegian heavy water sabotage, bombing and sabotage campaign was carried out against heavy water plants in German-occupied Norway. A small mission was created, jointly staffed by the Office of Naval Intelligence, OSRD, the Manhattan Project, and Army Intelligence (G-2), to investigate enemy scientific developments. It was not restricted to those involving nuclear weapons. The Chief of Army Intelligence, Major General George V. Strong, appointed Boris Pash to command the unit, which was codenamed "Alsos", a Greek word meaning "grove".
The Alsos Mission to Italy questioned staff of the physics laboratory at the Sapienza University of Rome, University of Rome following the capture of the city in June 1944. Meanwhile, Pash formed a combined British and American Alsos mission in London under the command of Captain Horace K. Calvert to participate in Operation Overlord. Groves considered the risk that the Germans might attempt to disrupt the Normandy landings with radioactive poisons was sufficient to warn General Dwight D. Eisenhower and send an officer to brief his chief of staff, Lieutenant General Walter Bedell Smith. Under the codename Operation Peppermint, special equipment was prepared and Chemical Warfare Service teams were trained in its use.
Following in the wake of the advancing Allied armies, Pash and Calvert interviewed Frédéric Joliot-Curie about the activities of German scientists. They spoke to officials at Union Minière du Haut Katanga about uranium shipments to Germany. They tracked down 68 tons of ore in Belgium and 30 tons in France. The interrogation of German prisoners indicated that uranium and thorium were being processed in Oranienburg, 20 miles north of Berlin, so Groves Auergesellschaft#Russian Alsos, arranged for it to be bombed on 15 March 1945.
An Alsos team went to Stassfurt in the Soviet Occupation Zone and retrieved 11 tons of ore from WIFO (Nazi company), WIFO. In April 1945, Pash, in command of a composite force known as T-Force, conducted Operation Harborage, a sweep behind enemy lines of the cities of Hechingen, Bisingen, and Haigerloch that were the heart of the German nuclear effort. T-Force captured the nuclear laboratories, documents, equipment and supplies, including heavy water and 1.5 tons of metallic uranium.
Alsos teams rounded up German scientists including Kurt Diebner,
Otto Hahn, Walther Gerlach, Werner Heisenberg, and Carl Friedrich von Weizsäcker, who were taken to England where they were interned at Farm Hall, a bugged house in Godmanchester. After the bombs were detonated in Japan, the Germans were forced to confront the fact that the Allies had done what they could not.
Atomic bombings of Hiroshima and Nagasaki
Preparations
![CGP-JPAP-112](https://upload.wikimedia.org/wikipedia/commons/a/a9/CGP-JPAP-112.jpg)
Starting in November 1943, the Air Force Materiel Command, Army Air Forces Materiel Command at Wright Field, Ohio, began Silverplate, the codename modification of B-29s to carry the bombs. Test drops were carried out at Edwards Air Force Base, Muroc Army Air Field, California, and the Naval Air Weapons Station China Lake, Naval Ordnance Test Station at Inyokern, California. Groves met with the Chief of United States Army Air Forces (USAAF), General Henry H. Arnold, in March 1944 to discuss the delivery of the finished bombs to their targets.
[.] The only Allied aircraft capable of carrying the long Thin Man or the wide Fat Man was the British Avro Lancaster, but using a British aircraft would have caused difficulties with maintenance.
Groves hoped that the American Boeing B-29 Superfortress could be modified to carry Thin Man by joining its two bomb bays together.
Arnold promised that no effort would be spared to modify B-29s to do the job, and designated Major General Oliver P. Echols as the USAAF liaison to the Manhattan Project. In turn, Echols named Colonel Roscoe C. Wilson as his alternate, and Wilson became Manhattan Project's main USAAF contact.
President Roosevelt instructed Groves that if the atomic bombs were ready before the war with Germany ended, he should be ready to drop them on Germany.
The 509th Composite Group was activated on 17 December 1944 at Wendover Army Air Field, Utah, under the command of Colonel Paul W. Tibbets. This base, close to the border with Nevada, was codenamed "Kingman" or "W-47". Training was conducted at Wendover and at Batista Army Airfield, Cuba, where the 393d Bomb Squadron, 393d Bombardment Squadron practiced long-distance flights over water, and dropping dummy pumpkin bombs. A special unit known as Project Alberta was formed at Los Alamos under Navy Captain
William S. Parsons
Rear Admiral William Sterling "Deak" Parsons (26 November 1901 – 5 December 1953) was an American naval officer who worked as an ordnance expert on the Manhattan Project during World War II. He is best known for being the weaponeer on the ''En ...
from Project Y as part of the Manhattan Project to assist in preparing and delivering the bombs. Commander Frederick L. Ashworth from Alberta met with Fleet Admiral Chester W. Nimitz on Guam in February 1945 to inform him of the project. While he was there, Ashworth selected North Field (Tinian), North Field on the Pacific Island Tinian as a base for the 509th Composite Group, and reserved space for the group and its buildings. The group deployed there in July 1945. Farrell arrived at Tinian on 30 July as the Manhattan Project representative.
Most of the components for Little Boy left San Francisco on the cruiser on 16 July and arrived on Tinian on 26 July. Four days later the ship was sunk by a Japanese submarine. The remaining components, which included six uranium-235 rings, were delivered by three Douglas C-54 Skymaster, C-54 Skymasters of the 509th Group's 320th Troop Carrier Squadron. Two Fat Man assemblies travelled to Tinian in specially modified 509th Composite Group B-29s. The first plutonium core went in a special C-54. In late April, a joint targeting committee of the Manhattan District and USAAF was established to determine which cities in Japan should be targets, and recommended Kokura, Hiroshima, Niigata (city), Niigata, and Kyoto. At this point, Secretary of War Henry L. Stimson intervened, announcing that he would be making the targeting decision, and that he would not authorize the bombing of Kyoto on the grounds of its historical and religious significance. Groves therefore asked Arnold to remove Kyoto not just from the list of nuclear targets, but from targets for conventional bombing as well. One of Kyoto's substitutes was Nagasaki.
Bombings
In May 1945, the Interim Committee was created to advise on wartime and postwar use of nuclear energy. The committee was chaired by Stimson, with James F. Byrnes, a former US Senator soon to be United States Secretary of State, Secretary of State, as President Harry S. Truman's personal representative; Ralph A. Bard, the Under Secretary of the Navy; William L. Clayton, the Assistant Secretary of State; Vannevar Bush; Karl T. Compton; James B. Conant; and George L. Harrison, an assistant to Stimson and president of New York Life Insurance Company. The Interim Committee in turn established a scientific panel consisting of Arthur Compton, Fermi, Lawrence and Oppenheimer to advise it on scientific issues. In its presentation to the Interim Committee, the scientific panel offered its opinion not just on the likely physical effects of an atomic bomb, but on its probable military and political impact.
At the Potsdam Conference in Germany, Truman was informed that the Trinity test had been successful. He told Stalin, the leader of the Soviet Union, that the US had a new superweapon, without giving any details. This was the first official communication to the Soviet Union about the bomb, but Stalin already knew about it from spies. With the authorization to use the bomb against Japan already given, no alternatives were considered after the Japanese rejection of the Potsdam Declaration.
![Atomic bombing of Japan](https://upload.wikimedia.org/wikipedia/commons/5/54/Atomic_bombing_of_Japan.jpg)
On 6 August 1945, a Boeing B-29 Superfortress (''Enola Gay'') of the 393d Bombardment Squadron, piloted by Tibbets, lifted off from North Field with a Little Boy in its bomb bay. Hiroshima, the headquarters of the 2nd General Army and 5th Division (Imperial Japanese Army), Fifth Division and a port of embarkation, was the primary target of the mission, with Kokura and Nagasaki as alternatives. With Farrell's permission, Parsons, the weaponeer in charge of the mission, completed the bomb assembly in the air to minimize the risks of a nuclear explosion in the event of a crash during takeoff. The bomb detonated at an altitude of with a blast that was later estimated to be the equivalent of 13 kilotons of TNT. An area of approximately was destroyed. Japanese officials determined that 69% of Hiroshima's buildings were destroyed and another 6–7% damaged. About 70,000 to 80,000 people, of whom 20,000 were Japanese combatants and 20,000 were Korean slave laborers, or some 30% of the population of Hiroshima, were killed immediately, and another 70,000 injured.
On the morning of 9 August 1945, a second B-29 (''Bockscar''), piloted by the 393d Bombardment Squadron's commander, Major Charles W. Sweeney, lifted off with a Fat Man on board. This time, Ashworth served as weaponeer and Kokura was the primary target. Sweeney took off with the weapon already armed but with the electrical safety plugs still engaged. When they reached Kokura, they found cloud cover had obscured the city, prohibiting the visual attack required by orders. After three runs over the city, and with fuel running low, they headed for the secondary target, Nagasaki. Ashworth decided that a radar approach would be used if the target was obscured, but a last-minute break in the clouds over Nagasaki allowed a visual approach as ordered. The Fat Man was dropped over the city's industrial valley midway between the Mitsubishi Steel and Arms Works in the south and the Mitsubishi-Urakami Ordnance Works in the north. The resulting explosion had a blast yield equivalent to 21 kilotons of TNT, roughly the same as the Trinity blast, but was confined to the Urakami Valley, and a major portion of the city was protected by the intervening hills, resulting in the destruction of about 44% of the city. The bombing also crippled the city's industrial production extensively and killed 23,200–28,200 Japanese industrial workers and 150 Japanese soldiers. Overall, an estimated 35,000–40,000 people were killed and 60,000 injured.
Groves expected to have another atomic bomb ready for use on 19 August, with three more in September and a further three in October.
Two more Fat Man assemblies were readied, and scheduled to leave Kirtland Air Force Base, Kirtland Field for Tinian on 11 and 14 August.
At Los Alamos, technicians worked 24 hours straight to cast Demon core, another plutonium core. Although cast, it still needed to be pressed and coated, which would take until 16 August. It could therefore have been ready for use on 19 August. On 10 August, Truman secretly requested that additional atomic bombs not be dropped on Japan without his express authority.
Groves suspended the third core's shipment on his own authority on 13 August.
On 11 August, Groves phoned Warren with orders to organize a survey team to report on the damage and radioactivity at Hiroshima and Nagasaki. A party equipped with portable Geiger counters arrived in Hiroshima on 8 September headed by Farrell and Warren, with Japanese Rear Admiral Masao Tsuzuki, who acted as a translator. They remained in Hiroshima until 14 September and then surveyed Nagasaki from 19 September to 8 October. This and other scientific missions to Japan provided valuable scientific and historical data.
The necessity of the bombings of Hiroshima and Nagasaki became a debate over the atomic bombings of Hiroshima and Nagasaki, subject of controversy among historians. Some questioned whether an "atomic diplomacy" would not have attained the same goals and disputed whether the bombings or the Soviet–Japanese War (1945), Soviet declaration of war on Japan was decisive.
The Franck Report was the most notable effort pushing for a demonstration but was turned down by the Interim Committee's scientific panel. The Szilárd petition, drafted in July 1945 and signed by dozens of scientists working on the Manhattan Project, was a late attempt at warning President Harry S. Truman about his responsibility in using such weapons.
After the war
![Army-Navy E Award Ceremony 68997](https://upload.wikimedia.org/wikipedia/commons/f/f6/Army-Navy_E_Award_Ceremony_68997.jpg)
Seeing the work they had not understood produce the Hiroshima and Nagasaki bombs amazed the workers of the Manhattan Project as much as the rest of the world; newspapers in Oak Ridge announcing the Hiroshima bomb sold for $1 ($ today).
Although the bombs' existence was public, secrecy continued, and many workers remained ignorant of their jobs; one stated in 1946, "I don't know what the hell I'm doing besides looking into a ——— and turning a ——— alongside a ———. I don't know anything about it, and there's nothing to say". Many residents continued to avoid discussion of "the stuff" in ordinary conversation despite it being the reason for their town's existence.
In anticipation of the bombings, Groves had Henry DeWolf Smyth prepare a history for public consumption. ''Smyth Report, Atomic Energy for Military Purposes'', better known as the "Smyth Report", was released to the public on 12 August 1945. Groves and Nichols presented Army–Navy "E" Awards to key contractors, whose involvement had hitherto been secret. Over 20 awards of the Presidential Medal for Merit were made to key contractors and scientists, including Bush and Oppenheimer. Military personnel received the Legion of Merit, including the commander of the Women's Army Corps detachment, Captain Arlene G. Scheidenhelm.
At Hanford, plutonium production fell off as Reactors B, D and F wore out, poisoned by fission products and swelling of the graphite moderator known as the Wigner effect. The swelling damaged the charging tubes where the uranium was irradiated to produce plutonium, rendering them unusable. In order to maintain the supply of polonium for the urchin initiators, production was curtailed and the oldest unit, B pile, was closed down so at least one reactor would be available in the future. Research continued, with DuPont and the Metallurgical Laboratory developing a redox solvent extraction process as an alternative nuclear reprocessing, plutonium extraction technique to the bismuth phosphate process, which left unspent uranium in a state from which it could not easily be recovered.
[.]
Bomb engineering was carried out by the Z Division, named for its director, Dr. Jerrold R. Zacharias from Los Alamos. Z Division was initially located at Wendover Field but moved to Oxnard Field, New Mexico, in September 1945 to be closer to Los Alamos. This marked the beginning of Sandia Base. Nearby Kirtland Field was used as a B-29 base for aircraft compatibility and drop tests. By October, all the staff and facilities at Wendover had been transferred to Sandia.
[.] As reservist officers were demobilized, they were replaced by about fifty hand-picked regular officers.
Nichols recommended that S-50 and the Alpha tracks at Y-12 be closed down. This was done in September. Although performing better than ever, the Alpha tracks could not compete with K-25 and the new K-27, which had commenced operation in January 1946. In December, the Y-12 plant was closed, thereby cutting the Tennessee Eastman payroll from 8,600 to 1,500 and saving $2 million a month.
![Atomic Energy Act of 1946 signing](https://upload.wikimedia.org/wikipedia/commons/4/40/Atomic_Energy_Act_of_1946_signing.jpg)
Nowhere was demobilization more of a problem than at Los Alamos, where there was an exodus of talent. Much remained to be done. The bombs used on Hiroshima and Nagasaki were like laboratory pieces; work would be required to make them simpler, safer and more reliable. Implosion methods needed to be developed for uranium in place of the wasteful gun method, and composite uranium-plutonium cores were needed now that plutonium was in short supply because of the problems with the reactors. However, uncertainty about the future of the laboratory made it hard to induce people to stay. Oppenheimer returned to his job at the University of California and Groves appointed Norris Bradbury as an interim replacement; Bradbury remained in the post for the next 25 years.
Groves attempted to combat the dissatisfaction caused by the lack of amenities with a construction program that included an improved water supply, three hundred houses, and recreation facilities.
Two Fat Man-type detonations were conducted at
Bikini Atoll in July 1946 as part of
Operation Crossroads to investigate the effect of nuclear weapons on warships. Able was detonated on 1 July 1946. The more spectacular Baker was detonated underwater on 25 July 1946.
After the bombings at Hiroshima and Nagasaki, a number of Manhattan Project physicists founded the ''Bulletin of the Atomic Scientists'', which began as an emergency action undertaken by scientists who saw urgent need for an immediate educational program about atomic weapons. In the face of the destructiveness of the new weapons and in anticipation of the nuclear arms race several project members including Bohr, Bush and Conant expressed the view that it was necessary to reach agreement on international control of nuclear research and atomic weapons. The Baruch Plan, unveiled in a speech to the newly formed United Nations Atomic Energy Commission (UNAEC) in June 1946, proposed the establishment of an international atomic development authority, but was not adopted.
Following a domestic debate over the permanent management of the nuclear program, the
United States Atomic Energy Commission
The United States Atomic Energy Commission (AEC) was an agency of the United States government established after World War II by U.S. Congress to foster and control the peacetime development of atomic science and technology. President H ...
(AEC) was created by the Atomic Energy Act of 1946 to take over the functions and assets of the Manhattan Project. It established civilian control over atomic development, and separated the development, production and control of atomic weapons from the military. Military aspects were taken over by the Armed Forces Special Weapons Project (AFSWP). Although the Manhattan Project ceased to exist on 31 December 1946, the Manhattan District was not abolished until 15 August 1947.
Cost
The project expenditure through 1 October 1945 was $1.845 billion, equivalent to less than nine days of wartime spending, and was $2.191 billion when the AEC assumed control on 1 January 1947. Total allocation was $2.4 billion. Over 90% of the cost was for building plants and producing the fissionable materials, and less than 10% for development and production of the weapons.
A total of four weapons (the Trinity gadget, Little Boy, Fat Man, and an unused Fat Man bomb) were produced by the end of 1945, making the average cost per bomb around $500 million in 1945 dollars. By comparison, the project's total cost by the end of 1945 was about 90% of the total spent on the production of US small arms (not including ammunition) and 34% of the total spent on US tanks during the same period.
Overall, it was the second most expensive weapons project undertaken by the United States in World War II, behind only the design and production of the Boeing B-29 Superfortress.
Legacy
![Aerial view of Niagara Falls Storage Site, Lewiston, New York (2002)](https://upload.wikimedia.org/wikipedia/commons/b/b4/Aerial_view_of_Niagara_Falls_Storage_Site%2C_Lewiston%2C_New_York_%282002%29.jpg)
The political and cultural impacts of the development of nuclear weapons were profound and far-reaching. William Laurence of ''The New York Times'', the first to use the phrase "Atomic Age",
became the official correspondent for the Manhattan Project in spring 1945. In 1943 and 1944 he unsuccessfully attempted to persuade the Office of Censorship to permit writing about the explosive potential of uranium, and government officials felt that he had earned the right to report on the biggest secret of the war. Laurence witnessed both the Trinity test and the bombing of Nagasaki and wrote the official press releases prepared for them. He went on to write a series of articles extolling the virtues of the new weapon. His reporting before and after the bombings helped to spur public awareness of the potential of nuclear technology and motivated its development in the United States and the Soviet Union.
The wartime Manhattan Project left a legacy in the form of the network of United States Department of Energy national laboratories, national laboratories: the Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, Oak Ridge National Laboratory,
Argonne National Laboratory
Argonne National Laboratory is a science and engineering research United States Department of Energy National Labs, national laboratory operated by University of Chicago, UChicago Argonne LLC for the United States Department of Energy. The facil ...
, and Ames Laboratory. Two more were established by Groves soon after the war, the Brookhaven National Laboratory at Upton, New York, and the Sandia National Laboratories at Albuquerque, New Mexico. Groves allocated $72 million to them for research activities in fiscal year 1946–1947. They would be in the vanguard of the kind of large-scale research that Alvin Weinberg, the director of the Oak Ridge National Laboratory, would call Big Science.
The Naval Research Laboratory had long been interested in the prospect of using nuclear power for warship propulsion, and sought to create its own nuclear project. In May 1946, Nimitz, now Chief of Naval Operations, decided that the Navy should instead work with the Manhattan Project. A group of naval officers were assigned to Oak Ridge, the most senior of whom was Captain Hyman G. Rickover, who became assistant director there. They immersed themselves in the study of nuclear energy, laying the foundations for a nuclear navy, nuclear-powered navy. A similar group of Air Force personnel arrived at Oak Ridge in September 1946 with the aim of developing nuclear aircraft. Their Aircraft Nuclear Propulsion, Nuclear Energy for the Propulsion of Aircraft (NEPA) project ran into formidable technical difficulties, and was ultimately cancelled.
The ability of the new reactors to create radioactive isotopes in previously unheard-of quantities sparked a revolution in nuclear medicine in the immediate postwar years. Starting in mid-1946, Oak Ridge began distributing radioisotopes to hospitals and universities. Most of the orders were for iodine-131 and phosphorus-32, which were used in the diagnosis and treatment of cancer. In addition to medicine, isotopes were also used in biological, industrial and agricultural research.
On handing over control to the Atomic Energy Commission, Groves bid farewell to the people who had worked on the Manhattan Project:
In 2014, the United States Congress passed a law providing for a national park dedicated to the history of the Manhattan Project. The Manhattan Project National Historical Park was established on 10 November 2015.
Notes
Explanatory footnotes
Citations
General and cited references
General, administrative, and diplomatic histories
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* Dave Lindorff, Lindorff, Dave, "Brothers Against the Federal Bureau of Investigation, Bureau: Theodore Hall, Ted Hall, the Soviet Union's youngest atomic spy, his rocket scientist brother Edward N. Hall, Ed, and the untold story of how J. Edgar Hoover's biggest Manhattan Project bust was shut down", ''The Nation'', vol. 314, no. 1 (10–17 January 2022), pp. 26–31. Published online a
"One Brother Gave the Soviets the A-Bomb. The Other Got a Medal."*
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Technical histories
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* (1967 interview with Groves)
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* (Available on commons:File:Los Alamos Primer.pdf, Wikimedia Commons)
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Participant accounts
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External links
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* Features hundreds of audio/visual interviews with Manhattan Project veterans.
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Manhattan Project and Allied Scientists Collectionsat th
University of Chicago Special Collections Research Center
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Manhattan Project,
1942 establishments in the United States
1946 disestablishments in the United States
American secret government programs
Atomic bombings of Hiroshima and Nagasaki
Explosives engineering
History of the Manhattan Project
Military history of Canada during World War II
Military history of the United Kingdom during World War II
Military history of the United States during World War II
Nuclear history of the United States
Nuclear weapons program of the United States
Projects established in 1942
Secret military programs