The Manhattan Project, 1942-44
Building an Atomic Infrastructure
• “The Manhattan Project bore no relation to
the industrial or social life of our country; it
was a separate state with…its thousands of
secrets. It had a peculiar sovereignty, one
that could bring about the end, peacefully or
violently, of all other sovereignties.”
– Herbert S. Marks
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Manhattan Project
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Manhattan Project Scientists:
Soldiers out of Uniform
• Their participation in Manhattan Project –
The single most profound experience in the
history of the American scientific
community.
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Back in the U.S…
• Vannevar Bush and the National Defense Research
Council (NRDC) take over US uranium work. James
Conant (chemist and pres. of Harvard put in charge)
Arthur Compton
V. Bush
Karl Compton
A. Loomis
E. Lawrence
J. Conant
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• 1940-41: Money begins to flow
– July 1940 - $40,000 more put into work
• Efforts directed not for bomb but for Enrico
Fermi’s studies of uranium reactor.
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• By fall of 1941, Compton, Conant,
Lawrence, Bush – encouraged by MAUD
report – urge FDR to undertake large bomb
project.
• FDR separates scientists from policy
decisions.
• FDR (informally) authorizes $1.2 million
and urges crash program.
• December 6, 1941: FDR authorizes the
Manhattan Engineering District.
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Manhattan Project Expands
• After Pearl Harbor, FDR OK’s some $1.2
million to be spent.
• American bomb effort re-named the
Manhattan Project
• Put under U.S. Army control in 1942.
– Why the Army?
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Questions for the Manhattan Project
and a mission
• Is a chain reaction possible in practice?
• How to produce bomb-grade uranium and
plutonium?
• A successful bomb project – needs
industrial-scale resources, superior
management, and the will to succeed.
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The Met Lab
• The Metallurgical Laboratory at the
University of Chicago founded early 1942
– Run by Nobel laureate Arthur Compton
– Fermi moves from Columbia to Chicago
• Some of the Met Lab’s goals:
– Prove that a chain reaction is possible
– Develop ways to extract Pu from U
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Fermi and Chicago Pile-1
• Early studies encouraging – probably less
U-235 needed to get a critical mass
• Enrico Fermi leader of group studying chain
reaction.
• Fermi scales up reactor studies.
• By December, 1942 – Fermi & Co. build a
test atomic “pile”
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Stagg Field, Chicago
One of the graphite-uranium layers in CP-1
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Enrico Fermi, 1942
CP-1
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The New World
• James Conant receives
coded message from
Compton:
– “The Italian navigator
has landed in the New
World.”
• First controlled
nuclear reaction.
• Produced miniscule
half a watt of energy.
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Szilard
Fermi
Szilard to Fermi: “This will go down as a black day in the history
of mankind…”
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Two weeks after CP-1 debuts…
• FDR approves another $250 million (about
$3 billion today) to scale up to production.
• American expertise in industrial production
to make U-235 and Pu-239.
– This is an area where America excels.
• The Manhattan Project is now less of a
scientific endeavor than massive
engineering effort.
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Building an Atomic Infrastructure
• Niels Bohr (1939): Building an atomic
bomb “can never be done unless you turn
the United States into one huge factory.”
• This becomes the means to the end.
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Managing the Manhattan Project
• Manhattan Project requires a master
organizer. This is Brig. Gen. Leslie Groves.
• Groves placed in charge of the Manhattan
Project in September 1942.
• Who is Leslie Groves?
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Gen. Leslie R. Groves… “the angriest
officer in the Army.”
• b. 1896 – d.1970
• College education; Army Corps
of Engineers; in charge of
building the Pentagon.
• His assignment – “Draw up
plans for the organization,
construction, operation and
security of the project, and after
approval, take the necessary
steps to put it into effect.”
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Groves’ Challenges
• Choose industrial sites for
uranium and plutonium
production
• Select industrial
contractors
• Keep schedule
• Maintain security
• Nurture relationship with
scientists
– Groves and J. Robert
Oppenheimer
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Groves’ Genius
•
•
•
•
Ability to grasp essentials
Willingness to take risks
Ability to amass and apply resources
Manage the tension between scientists and
military
• Maintain project security
– Compartmentalization, deception (see JRO
letter to LG)
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Building an Atomic Infrastructure
• Groves given incredible latitude and
resources to complete his tasks
• One of the first major tasks – get industrial
scale production of uranium and plutonium
started
• Which to pursue – a uranium or plutonium
bomb?
– Groves: “Both.”
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Building an Atomic Infrastructure
• Groves picks 3 major sites
for building the atomic
bomb
– Oak Ridge, TN – uranium
processing
– Hanford, WA – plutonium
production
– Los Alamos, NM – scientific
research, design, construction,
and testing (operated by Univ.
of Calif.)
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Building an Atomic Infrastructure
Oak Ridge, TN
• Located near Knoxville, TN; sprawling
complex on 59,000 rural acres that Groves
bought
• Groves’ “troops” erect small city of
hundred of buildings employing some
22,000 men and women with its own power
plant.
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Early View of Oak Ridge
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Gaseous diffusion plant; Oak Ridge
$500M; 12,000 workers
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Producing U-235 at Oak Ridge
• Two methods pursued in tandem: gaseous
diffusion and electromagnetic separation.
• As Groves said, “If there is a choice
between two methods, one of which is good
and the other looks promising, then build
both.”
• Both methods based on different
size/weight of U-235 vs. U-238. Goal was a
few ounces of U-235 a day.
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1. Gaseous diffusion done first
– Plant (codename K-25) built at cost of $10.7
billion [2003 dollars]
2. This was then fed into a second stage which
enriched it further
3. Electromagnetic separation (a variation of
what a cyclotron does)
– Plant code-named Y-12 built for $10 billion
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Electromagnetic Separation
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“Calutron” Operators at Oak Ridge
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“Racetrack” for Separating U-235
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What they want…
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Building an Atomic Infrastructure
Hanford, WA
• Located in desert valley of Washington near
Columbia River
– River was key for cooling reactors and providing power
• Hanford became a sprawling atomic boomtown –
Built and operated by DuPont Chemical
Corporation for $1.
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Life at Hanford
• A story of superlatives – Hanford becomes
fourth largest city in WA while reactors are
built.
– Largest general delivery post office in the
world
– Work week – 54 hours over 6 days
– Meals – 50 tons a day – were 69 cents for all
you could eat.
• Science vs. engineering at Hanford
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Building an Atomic Infrastructure
Hanford, WA
One of three reactor plants built at Hanford
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T Plant, Chemical Separation Building,
Hanford, Washington
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Building an Atomic Infrastructure
Hanford, WA
• Plutonium “bred”at Hanford
– U-238 bombarded with neutrons
– Gradually decays to form Pu-239 (with some
Pu-240 as impurity)
• By 1944, Hanford reactors are producing
some 250 megawatts of power (vs. half a
watt two years earlier in Chicago)
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Building an Atomic Infrastructure
• By the end of 1944: both uranium and
plutonium suitable for bombs are being
produced at industrial-scale facilities.
• The bigger picture…by end of 1944,
Germany appears almost
defeated…Question: Why continue with
Manhattan Project?
– Note: Japanese fleet considered a possible
target as early as 1943.
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Building an Atomic Infrastructure
• The bigger picture: Investing several
hundred million dollars into massive
factories producing large amounts of
uranium and plutonium indicated one key
thing:
• The US was permanently committing
itself to atomic weapons.
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War Developments
• Firebombing of Hamburg
(July 1943); 45,000 civilians
killed.
– Stated goal: “To destroy
Hamburg”
– Why? “shortening and winning
the war.”
• One atrocity in escalating
war of atrocities – Bataan,
concentration camps, Soviet
front.
• Dresden, Berlin, Tokyo, etc.
all firebombed.
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Meanwhile, on a desert mesa in
New Mexico…
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