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Copies of this publication areavailable while supply lasts from theOffIce of Scientific and Technical InformationP.O. BOX 62Oak Ridge, TN 37831Attention: Information ServicesTelephone: (423) 576-8401

Also Available: The United StatesDepartment of Energy: A Summary History, 1977-1994

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UNITED STATES DEPARTMENT OF ENERGY

F.G. GoslingHistory DivisionExecutive SecretariatManagement and AdministrationDepartment of Energy

]January 1999 edition

.

DISCLAIMER

This report was prepared as an account of work sponsoredby an agency of the United States Government. Neither theUnited States Government nor any agency thereof, nor anyof their employees, make any warranty, express or implied,or assumes any legal liability or responsibility for the

accuracy, completeness, or usefulness of any information,apparatus, product, or process disclosed, or represents thatits use would not infringe privately owned rights. Referenceherein to any specific commercial product, process, orservice by trade name, trademark, manufacturer, orotherwise does not necessarily constitute or imply itsendorsement, recommendation, or favoring by the UnitedStates Government or any agency thereof. The views andopinions of authors expressed herein do not necessarilystate or reflect those of the United States Government orany agency thereof.

I

DISCLAIMER

Portions of this document may be illegiblein electronic image products. Images areproduced from the best available originaldocument.

1

Foreword

The Department of Energy Organization Act of1977 brought together for the first time in onedepartment most of the Federal Government’s energyprograms. With these programs came a score oforganizational entities, each with its own history andtraditions, from a dozen departments and independentagencies. The History Division has prepared a seriesof monographs on The Origins of the Department ofEnergy. Each explains the history, goals, andachievements of a predecessor agency or a majorprogram of the Department of Energy.

“The Manhattan Project: Making the AtomicBomb” is a short history of the origins and develop-ment of the American atomic bomb program duringWorld War H. Beginning with the scientific develop-ments of the pre-war years, the monograph details therole of United States government in conducting asecret, nationwide enterprise that took science fromthe laboratory and into combat with an entirely newtype of weapon,The monograph concludes with adiscussion of the immediate postwar period, thedebate over the Atomic Energy Act of 1946, and thefounding of the Atomic Energy Commission.

The author wishes to thank Richard G. Hewlett,Jack M. Hell, and Thomas Comwell for reviewingthe manuscript and making numerous valuablesuggestions. He also wishes to thank Glenn Seaborgfor a thorough critique that improved the finalproduct. Others who read and commented on themanuscript include Roger Anders, Terry Fehner,Alice Buck, Betsy Scroger, and Sheila Convis.Finally, the author thanks La Shonda Steward forresearch support, Betsy Scroger for a first-classediting job, and Sheila Convis for project support.

.. .111

Table of Contents

..— —.. . ..Introduction:The Mnstein Letter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vu

Part I: Physics Background, 1919-1939 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Part II: Early Government Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Part III: The Manhattan Engineer District . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Part N The Manhattan Engineer District in Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Part V The Atomic Bomb and American Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Part VI: The Manhattan District in Peacetime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Manhattan Project Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Select Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Manhattan Project Chronology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

v

Introduction

Introduction: The Einstein LetterOn October 11, 1939, Alexander Sachs, Wall

Street economist and longtime friend and unofllcialadvisor to President Franklin Delano Roosevelt, metwith the President to discuss a letter written byAlbert Einstein the previous August. Einstein hadwritten to inform Roosevelt that recent research onchain reactions utilizing uranium made it probablethat large amounts of power could be produced bya chain reaction and that, by harnessing this power,the construction of “extremely powerful bombs...” 1was conceivable. Einstein believed the Germangovernment was actively supporting research in thisarea and urged the United States government to dolikewise. Sachs read from a cover letter he hadprepared and briefed Roosevelt on the main pointscontained in Einstein’s letter. Initially the Presidentwas noncommittal and expressed concern overlocating the necessary funds, but at a secondmeeting over breakfast the next morning Rooseveltbecame convinced of the value of exploring atomicenergy.

Einstein drafted his famous letter with the help ofthe Hungarian emigre physicist Leo Szilard, one ofa number of European scientists who had fled to theUnited States in the 1930s to escape Nazi andFascist repression. Szilard was among the most vocalof those advocating a program to develop bombs

based on recent findings in nuclear physics andchemistry. Those like Szilard and fellow Hungarianrefugee physicists Edward Teller and Eugene Wignerregarded it as their responsibility to alert Americansto the possibility that German scientists might winthe race to build an atomic bomb and to warn thatHitler would be more than willing to resort to sucha weapon. But Roosevelt, preoccupied with events inEurope, took over two months to meet with Sachsafter receiving Einstein’s letter. Szilard and his col-leagues interpreted Roosevelt’s inaction asunwelcome &idence that the President did not takethe threat of nuclear warfare seriously.

Roosevelt wrote Einstein back on October 19,1939, informing the physicist that he had setup acommittee consisting of Sachs and representativesfrom the Army and Navy to study uranium? Eventsproved that the President was a man of considerableaction once he had chosen a direction. In fact,Roosevelt’s approval of uranium research in October1939, based on his belief that the United States couldnot take the risk of allowing Hitler to achieve unilat-eral possession of “extremely powerful bombs,”was merely the frostdecision among many thatultimately led to the establishment of the only atomicbomb effort that succeeded in World War II--theManhattan Project.

The British, who made significant theoretical con-tributions early in the war, did not have theresources to pursue a full-fledged atomic bombreseafch program while fighting for their survival.Consequently, the British acceded, reluctantly, toAmerican leadership and sent scientists to everyManhattan Project facility. The Germans, despiteAllied fears that were not dispelled until the ALSOSmission in 1944? were little nearer to producingatomic weapons at the end of the war than they hadbeen at the beginning of the war. German scientistspursued research on fission, but the government’sattempts to forge a coherent strategy met with littlesuccess.4

The Russians built a program that grew increas-ingly active as the war drew to a conclusion, but thefirst successful Soviet test was not conducted until1949. The Japanese mmanaged to build severalcyclotrons by war’s end, but the atomic bombresearch effort could not maintain a high priority inthe face of increasing scarcities. Only the Americans,late entrants into World War II and protected byoceans on both sides, managed to take the discoveryof fission from the laboratory to the battlefield andgain a shortlived atomic monopoly.

vii

Part I:Physics Background, 1919-1939

The Atomic Solar SystemThe road to the atomic bomb began in 1919 when

the New Zealander Ernest Rutherford, working inthe Cavendish Laboratory at Cambridge Universityin England, achieved the fust artificial transmutationof an element when he changed several atoms ofnitrogen into oxygen. At the time of Rutherford’sbreakthrough, the atom was conceived as aminiature solar system, with extremely light “negatively charged particles, called electrons, in orbitaround the much heavier positively charged nucleus.In the process of changing nitrogen into oxygen,Rutherford detected a high-energy particle with apositive charge that proved to be a hydrogennucleus. The proton, as this subatomic particle wasnamed, joined the electron in the miniature solmsystem. Another addition came in 1932 when JamesChadwick, Rutherford’s colleague at Cambridge,identified a thwd particle, the neutron, so-namedbecause it had no charge.

By the early 1930s the atom was thought to con-sist of a positively charged nucleus, containing bothprotons and neutrons, circled by negatively chargedelectrons equal in number to the protons in thenucleus. The number of protons determined the ele-ment’s atomic number. Hydrogen, with one proton,came first and uranium, with ninety-two protons,last on the periodic table. This simple schemebecame more complicated when chemists discoveredthat many elements existed at different weights even

while displaying identical chemical properties. It wasChadwick’s discovery of the neutron in 1932 thatexplained this mystery. Scientists found that theweight discrepancy between atoms of the same ele-ment resulted because they contained differentnumbers of neutrons. These different classes ofatoms of the same element but with varyingnumbers of neutrons were designated isotopes. Thethree isotopes of uranium, for instance, all haveninety-two protons in their nuclei and ninety-twoelectrons in orbit. But uranium-238, which accountsfor over ninety-nine percent of natural uranium, has146 neutrons in its nucleus, compared with 143neutrons in the rare uranium-235 (.7 percent ofnatural uranium) and 142 neutrons in uranium-234,which is found only in traces in the heavy metal.The slight difference in atomic weight between theuranium-235 and uranium-238 isotopes figuredgreatly in nuclear physics during the 1930s and1940s.

The year 1932 produced other notable events inatomic physics. The Englishman J. D. Cockroft andthe Irishman E. T. S. Walton, working jointly atthe Cavendish Laboratory, were the fwst to split theatom when they bombarded lithium with protonsgenerated by a particle accelerator and changed theresulting lithium nucleus into two helium nuclei.Also in that year, Ernest O. Lawrence and his col-leagues M. Stanley Livingston and Milton Whitesuccessfully operated the first cyclotron on theBerkeley campus of the University of California.

MoonshineLawrence’s cyclotron, the Cockroft-Walton

machine, and the Van de Graaff electrostaticgenerator, developed by Robert J. Van de Graaff atPrinceton University, were particle acceleratorsdesigned to bombard the nuclei of various elementsto disintegrate atoms. Attempts of the early 1930s,however, required huge amounts of energy to splitatoms because the first accelerators used protonbeams and alpha particles as sources of energy.Since protons and alpha particles are positivelychm-ged, they met substantial resistance from thepositively charged target nucleus when they attemp-ted to penetrate atoms. Even high-speed protonsand alpha particles scored direct hits on a nucleusonly approximately once in a million tries. Mostsimply passed by the target nucleus. Not surprising-ly, Ernest Rutherford, Albert Einstein, and NielsBohr regarded particle bombardment as useful infurthering knowledge of nuclear physics but believed

1

I Part k

it unlikely to meet public expectations of harnessingthe power of the atom for practical purposesanytime in the near future. In a 1933 interviewRutherford called such expectations “moonshine.”5Einstein compared particle bombardment withshooting in the dark at scarce birds, while Bohr, theDanish Nobel laureate, agreed that the chances oftaming atomic energy were remote.b

From Protons to Neutrons: FermiRutherford, Einstein, and Bohr proved to be

wrong in this instance, and the proof was not longin coming. Beginning in 1934, the Italian physicistEnrico Fermi began bombarding elements withneutrons instead of protons, theorizing that Chad-wick’s uncharged particles could pass into thenucleus without resistance. Like other scientists atthe time, Fermi paid little attention to the possibilitythat matter might disappear during bombardmentand result in the release of huge amounts of energyin accordance with Einstein’s formula, E= m&,which stated that mass and energy were equivalent.Fermi and his colleagues bombarded sixty-threestable elements and produced thirty-seven newradioactive ones? They also found that carbon andhydrogen proved useful as moderators in slowingthe bombarding neutrons and that slow neutronsproduced the best results since neutrons movingmore slowly remained in the vicinity of the nucleuslonger and were therefore more likely to becaptured.

One element Fermi bombarded with slowneutrons was uranium, the heaviest of the knownelements. Scientists disagreed over what Fermi hadproduced in this transmutation. Some thought thatthe resulting substances were new “transuranic”elements, while others noted that the chemical pro-perties of the substances resembled those of lighterelements. Fermi was himself uncert.zdn.For the nextseveral years, attempts to identify these substancesdominated the research agenda in the internationalscientific community, with the answer coming out ofNazi Germany just before Christmas 1938.

The DEcovery of IIAon:Hahn and Stiwxwnann

The radiochemists Otto Hahn and FritzStrassmann were bombarding elements withneutrons in their Berlin laboratory when they madean unexpected discovery. They found that while the

nuclei of most elements changed somewhat duringneutron bombardment, uranium nuclei changedgreatly and broke into two roughly equal pieces.They split and became not the new transuranicelements that some thought Fermi had discoveredbut radioactive ba-ium isotopes (barium has theatomic number 56) and fragments of the uraniumitself. The substances Fermi had created in his ex-periments, that is, did more than resemble lighterelements; they were lighter elements. Importantly,the products of the Hahn-Strassmann experimentweighed less than that of the original uraniumnucleus, and herein lay the primary significance oftheir findings. For it folIowed from Einstein’s equa-tion that the loss of mass resulting from the splittingprocess must have been converted into energy in theform of kinetic energy that could in turn be con-verted into heat. Calculations made by Hahn’sformer colleague, Lise Meitner, a refugee fromNazism then staying in Sweden, and her nephew,Otto Fnsch, led to the conclusion that so muchenergy had been released that a previously un-discovered kind of process was at work. Frisch, bor-rowing the term for cell division in biology-binaryfission-named the process fission! For his part,Fermi had produced f~sion in 1934 but had notrecognized it.

Chain ReactionIt soon became clear that the process of fission

discovered by Hahn and Strassmann had anotherimportant characteristic besides the immediaterelease of enormous amounts of energy. This wasthe emission of neutrons. The energy released whenfission occurred in uranium caused several neutronsto “boil off” the two main fragments as they flewapart. Given the right set of circumstances, perhapsthese secondary neutrons might collide with otheratoms and release more neutrons, in turn smashinginto other atoms and, at the same time, continuous-ly emitting energy. Beginning with a single uraniumnucleus, fission could not only produce substantialamounts of energy but could also lead to a reactioncreating ever-increasing amounts of ener~. Thepossibility of such a “chain reaction” completelyaltered the prospects for releasing the energy storedin the nucleus. A controlled self-sustaining reactioncould make it possible to generate a large amount ofenergy for heat and power, while an uncheckedreaction could create an explosion of huge force.

2

. —

PhysicsBackground,1919-1939

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FISSIONPRODUCT

Uranium235FwiionChainReaction.Department of Enew.

Fission Comes to America: 1939 replaced individualism in laboratory research. No

News of the Hahn-Strassmann experiments andthe Meitner-Frisch calculations spread rapidly.Meitner and Frisch communicated their results toNiels Bohr, who was in Copenhagen preparing todepart for the United States via Sweden andEngland. Bohr confined the validity of the findingswhile sailing to New York City, arriving onJanuary 16, 1939. Ten days later Bohr, accom-panied by Fermi, communicated the latestdevelopments to some European emigre scientistswho had preceded him to this country and tomembers of the American scientific community atthe opening session of a conference on theoreticalphysics in Washington, D.C.

American physicists quickly grasped the impor-tance of Bohr’s message, having by the 1930sdeveloped into an accomplished scientific communi-ty. While involved in important theoretical work,Americans made their most significant contributionsin experimental physics, where teamwork had

one epitomized the “can do” attitude of Americanphysicists better than Ernest O. Lawrence, whose in-genuity and drive made the Berkeley RadiationLaboratory the unofficial capital of nuclear physicsin the United States. Lawrence staked his claim toAmerican leadership when he built his fwst particleaccelerator, the cyclotron, in 1930. Van de Graafffollowed with his generator in 1931, and from thenon Americans led the way in producing equipmentfor nuclear physics and high-energy physics researchlater.

Early American Work on FissionAmerican scientists became active participants in

attempts to confm and extend Hahn’s andStrassmann’s results, which dominated nuclearphysics in 1939. Bohr and John A. Wheeler advanc-ed the theory of fission in important theoreticalwork done at Princeton University, while Fermi andSzilard collaborated with Waker H. Zinn and

3

Herbert L. Anderson at Columbia University in in-vestigating the possibility of producing a nuclearchain reaction. Given that uranium emitted neutrons(usually two) when it fissioned, the question becamewhether or not a chain reaction in uranium waspossible, and, if so, in which of the three isotopesof the rare metal it was most likely to occur. ByMarch 1940 John R. Dunning and his colleagues atColumbia University, collaborating with Alfred Nierof the University of Minnesota, had demonstratedconclusively that uranium-235, present in only 1 in140 parts of natural uranium, was the isotope thatfissioned with slow neutrons, not the more abundanturanium-238 as Fermi had guessed. This finding wasimportant, for it meant that a chain reaction usingthe slightly lighter uranium-235 was possible, butonly if the isotope could be separated from the

uranium-238 and concentrated into a critical mass, aprocess that posed serious problems. Fermi con-tinued to try to achieve a chain reaction using largeamounts of natural uranium in a pile formation.

Dunning’s and Nier’s demonstration promisednuclear power but not necessarily a bomb. It wasalready known that a bomb would require fission byfast neutrons; a chain reaction using slow neutronsmight not proceed very far before the metal wouldblow itself apart, causing little, if any, damage.Uranium-238 fissioned with fast neutrons but couldnot sustain a chain reaction because it requiredneutrons with higher energy. The crucial questionwas whether uranium-235 could fission with fastneutrons in a chain-reacting manner, but withoutenriched samples of uranium-235, scientists couldnot perform the necessary experiments.

4

Part II:Early Government Support

ENRICHEDPRODUCT

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DEPLETEDMATERIAL

SchematicDkrarn of Flowof ProcessGasin GaseousDiffusionQ.&de. ReprintedfromRichardG. HewlettandOscarE. Anderson,Jr., T7reNewWorld, 1939-IM$ VolumeIofA HiWOIYof the United States Atomic Energy Commission(University Park:PennsylvaniaStateUniversityPres, 1%2).

The Uranium CommitteePresident Roosevelt responded to the call for

government support of uranium research quickly butcautiously. He appointed Lyman J. Bnggs, directorof the National Bureau of Standards, head of theAdvisory Committee on Uranium, which met forthe fust time on October 21, 1939. The committee,including both civilian and military representation,was to coordinate its activities with Sachs and lookinto the current state of research on uranium torecommend an appropriate role for the federalgovernment. In early 1940 the Uranium Committeerecommended that the government fund limitedresearch on isotope separation as well as Fermi’sand Szilard’s work on chain reactions at Columbia.

Isotope SeparationScientists had concluded that enriched samples of

uranium-235 were necessary for further research andthat the isotope might serve as a fuel source for anexplosive device; thus, finding the most effectivemethod of isotope separation was a high priority.Siice uranium-235 and uranium-238 were chemicallyidentical, they could not be separated by chemicalmeans. And with their masses differing by less thanone percent, separation by physical means would beextremely difficult and expensive. Nonetheless, scien-tists pressed forward on several complicated techni-ques of physical separation, all based on the smalldifference in atomic weight between the uraniumisotopes.

The Electromagnetic MethodThe electromagnetic method, pioneered by

Alfred O. Nier of the University of Minnesota, useda mass spectrometer, or spectrograph, to send astream of charged particles through a magnetic field.Atoms of the lighter isotope would be deflectedmore by the magnetic field than those of the heavierisotope, resulting in two streams that could then becollected in different receivers. The electromagneticmethod as it existed in 1940, however, would havetaken far too long to separate quantities sufficient tobe useful in the current war. In fact, twenty-seventhousand years would have been required for asingle spectrometer to separate one gram ofuranium-235.9

Gaseous DiffusionGaseous diffusion appeared more promising.

Based on the well-known principle that molecules ofa lighter isotope would pass through a porous bar-

5

I Part IE I

rier more readily than molecules of a heavier one,this approach proposed to produce by myriadrepetitions a gas increasingly rich in uranium-235 asthe heavier uranium-238 was separated out in asystem of cascades. Theoretically, this process couldachieve high concentrations of uranium-235 but, likethe electromagnetic method, would be extremelycostly. British researchers led the way on gaseousdiffusion, with John R. Dunning and his colleaguesat Columbia University joining the effort in late1940.

CentrifugeMany scientists initially thought the best hope for

isotope separation was the high-speed centrifuge, adevice based on the same principle as the creamseparator. Centrifugal force in a cylinder spinningrapidly on its vertical axis would separate a gaseousmixture of two isotopes since the lighter isotopewould be less affected by the action and could bedrawn off at the center and top of the cylinder. Acascade system composed of hundreds, perhapsthousands, of centrifuges could produce a rich mix-ture. This method, being pursued primarily byJesse W. Beams at the University of Virginia, receiv-ed much of the early isotope separation funding!”

Liquid Thermal DtifusionThe Uranium Committee briefly demonstrated an

interest in a fourth enrichment process during 1940,only to conclude that it would not be worth pursu-ing. This process, liquid thermal diffusion, wasbeing investigated by Philip Abelson at the CarnegieInstitution. Into the space between two concentricvertical pipes Abelson placed pressurized liquiduranium hexafluoride. With the outer wall cooled bya circulating water jacket and the inner heated byhigh-pressure steam, the lighter isotope tended toconcentrate near the hot wall and the heavier nearthe cold. Convection would in time carry the lighterisotope to the top of the column. Taller columnswould produce more separation. Like other enrich-ment methods, liquid thermal diffusion was at anearly stage of development. 11

Limited Government Funding: 1940The Uranium Committee’s fwst report, issued on

November 1, 1939, recommended that, despite theuncertainty of success, the government should im-mediately obtain four tons of graphite and fifty tons

of uranium oxide. This recommendation led to thefust outlay of government funds-$6,000 inFebruary 1940-and reflected the importance attach-ed to the Fermi-Szilard pile experiments alreadyunderway at Columbla University. Building uponthe work performed in 1934 demonstrating the valueof moderators in producing slow neutrons, Fermithought that a mixture of the right moderator andnatural uranium could produce a self-sustainingchain reaction. Fermi and Szilard increasinglyfocused their attention on carbon in the form ofgraphite. Perhaps graphite could slow down, ormoderate, the neutrons coming from the fissionreaction, increasing the probability of their causingadditional fissions in sustaining the chain reaction. Apile containing a large amount of natural uraniumcould then produce enough secondary neutrons tokeep a reaction going.

There was, however, a large theoretical gapbetween building a self-generating pile and buildinga bomb. Although the pile envisioned by Fermi andSzilard could produce large amounts of power andmight have military applications (powering navalvessels, for instance), it would be too big for abomb. It would take separation of uranium-235 orsubstantial enrichment of natural uranium withuranium-235 to create a fast-neutron reaction on asmall enough scale to build a usable bomb. Whilecertain of the chances of success in his graphitepower pile, Fermi, in 1939, thought that there was“little likelihood of an atomic bomb, little proofthat we were not pursuing a chimera_.”*2

The National Defense ResearchCommittee

Shortly after World War II began withman invasion of Poland on Set)tember 1.

the Ger-1939,

Vannevar Bush, president of the Carnegie Founda-tion, became convinced of the need for the govern-ment to marshrdl the forces of science for a war thatwould inevitably involve the United States. Hesounded out other science administrators in thenation’s capital and agreed to act as point man inconvincing the Roosevelt administration to set up anational science organization. Bush struck analliance with Roosevelt’s closest advisor, HarryHopkins, and after clearing his project with thearmed forces and science agencies, met with thePresident and Hopkins. With the imminent fall ofFrance undoubtedly on Roosevelt’s mind, it tookless than ten minutes for Bush to obtain the Presi-dent’s approval and move into action.]3

6

I EarlyGovernmentSupport I

Roosevelt approved in June 1940 the establish-ment of a voice for the scientific community withinthe executive branch. The National DefenseResearch Committee, with Bush at its head,reorganized the Uranium Committee into a scientificbody and eliminated military membership. Notdependent on the military for funds, as the UraniumCommittee had been, the National Defense ResearchCommittee would have more influence and moredirect access to money for nuclear research. In theinterest of security, Bush barred foreign-born scien-tists from committee membership and blocked thefurther publication of articles on uranium research.Retaining programmatic responsibilities for uranium

researchin theneworganizationalsetup(amongtheNational Defense Research Committee’s earlypriorities were studies on radar, proximity fuzes, andanti-submarine warfare), the Uranium Committeerecommended that isotope separation methods andthe chain reaction work continue to receive fundingfor the remainder of 1940. Bush approved the planand allocated the funds.

scientists funded primarily by private foundations.While the federal government began supportinguranium research in 1940, the pace appeared tooleisurely to the scientific community and failed toconvince scientists that their work was of highpriority. Certainly few were more inclined to thisview than Ernest O. Lawrence, director of theRadiation Laboratory at the University of Californiain Berkeley. Lawrence was among those whothought that it was merely a matter of time beforethe United States was drawn into World War II,and he wanted the government to mobilize its scien-tific forces as rapidly as possible.

Specitieally what Lawrence had on his mind in

early1941wereexperimentstakingplacein hisownlaboratory using samples produced in the cyclotron.Studies on uranium f~sion fragments by Edwin M.McMillan and Philip H. Abelson led to the chemicalidentification of element 93, neptunium, whileresearch by Glenn T. Seaborg revealed that anisotope of neptunium decayed to yet another tran-suraniurn (man-made) element. In February,

A Push From LawrenceSeaborg identified this as element 94, which he laternamed plutonium. By May he had proven that

During 1939 and 1940 most of the work done on plutonium-239 was 1.7 times as likely asisotope separation and the chain reaction pile was uranium-235 to fission. This finding made theperformed in university laboratories by academic Fermi-Szilard experiment more important than ever

Fmt MassSpectrographComponentsin 37-InchCyclotronTank.ReprintedfromRichardG. HewlettandOscarE. Anderson,Jr., TheNew World, 1939-1946 VolumeI ofA History of the United States Atomic Eneigy Commksion (University Park PennsylvaniaStateUniversityPress,1%2).

7

PartIL

as it suggested the possibility of producing largeagIounts of the f~sionable plutonium in a uraniumpile using plentiful uranium-238 and then separatingit chemically. Surely this would be less expensiveand simpler than building isotope-separation plants.

Lawrence, demonstrating his characteristic energyand impatience, launched a campaign to speed upuranium research. He began by proposing to con-vert his smaller cyclotron into a spectrograph to pro-duce uranium-235. Siice both the cyclotron and thespectrograph used a vacuum chamber and elec-tromagnet, this conversion would be relatively un-complicated. Lawrence then took his case to Karl T.Compton and Alfred L. Loomis at Harvard Univer-sity, both doing radar work for the NationalDefense Research Committee and benefiting fromLawrence’s advice in staffing their laboratories. In-fected by Lawrence’s enthusiasm, Compton for-warded Lawrence’s optimistic assessment onuranium research to Bush, warning that Germanywas undoubtedly making progress and that Briggsand the Uranium Committee were moving too slow-ly. Compton also noted that the British were aheadof their American colleagues, even though, in hisopinion, they were inferior in both numbers andability.

ProgramReview:Summer1941Bush and Lawrence met in New York City.

Though he continued to support the Uranium Com-mittee, Bush recognized that Lawrence’s assessmentwas not far off the mark. Bush shrewdly decided toappoint Lawrence as an advisor to Briggs-a movethat quickly resulted in funding for plutonium workat Berkeley and for Nler’s mass spectrograph atMinnesota-and also asked the National Academyof Sciences to review the uranium research program.Headed by Arthur Compton of the University ofChicago and including Lawrence, this committeesubmitted its unanimous report on May 17. Comp-ton’s committee, however, failed to provide thepractical-minded Bush with the evidence he neededthat uranium research would pay off in the eventthe United States went to war in the near future.Compton’sgroupthought that increased uraniumfunding could produce radioactive material thatcould be dropped on an enemy by 1943, a pile thatcould power naval vessels in three or four years, anda bomb of enormous power at an indeterminatepoint, but certainly not before 1945. Compton’sreport discussed bomb production only in connec-tion with slow neutrons, a clear indication thatmuch more scientific work remained to be done

ErnestLawrence.ArthurCompton,VannevarBush,JamesConant,KarlLoomis,andAlfredLoomis.ReprintedfromRichardG.HewlettandOs&rE. Anderson,Jr., TheNewWorf~ 1939-1946VolumeI ofA Hktou of the United State Atomic EnerOCommission (thdversily Park:PennsylvaniaStateUniversityPress,1%2).

8

EarlyGovernmentSupport

before an explosive device could be detonated}4

BushreconstitutedtheNationalAcademyofSciences committee and instructed it to assess therecommendations contained in the frost report froman engineering standpoint. On July 11 the secondcommittee endorsed the frst report and supportedcontinuation of isotope separation work and pileresearch for scientific reasons, though it admittedthat it could promise no immediate applications.The second report, like the f~st, was a disappointingdocument from Bush’s point of view?5

The Office of Scientific Research andDevelopment

By the time Bush received the second NationalAcademy of Sciences report, he had assumed theposition of director of the Office of ScientificResearch and Development. Established by an ex-ecutive order on June 28, 1941—six days after Ger-man troops invaded the Soviet Union-the Office ofScientific Research and Development strengthenedthe scientific presence in the federal government.Bush, who had lobbied hard for the new setup, nowreported directly to the President and could invokethe prestige of the White House in his dealings withother federal agencies. The National DefenseResearch Committee, now headed by James B. Co-nant, president of Harvard University, became anadvisory body responsible for making research anddevelopment recommendations to the Office ofScientific Research and Development. The UraniumCommittee became the Office of Scientific Researchand Development Section on Uranium and wascodenamed S-1 (Section One of the Office of Scien-tific Research and Development).

Turning the Corner: The MAUD ReportBush’s disappointment with the July 11 National

Academy of Sciences report did not last long.Several days later he and Conant received a copy ofa draft report forwarded from the National DefenseResearch Committee liaison office in London. Thereport, prepared by a group codenamed the MAUDCommittee and set up by the British in spring 1940to study the possibility of developing a nuclearweapon, maintained that a sufficiently purifiedcritical mass of uranium-235 could fission even withfast neutrons!G Building upon theoretical work onatomic bombs performed by refugee physicistsRudolf Peierls and Otto Frisch in 1940 and 1941,the MAUD report estimated that a critical mass of

ten kilograms would be large enough to produce an

enormousexplosion.Abombthissiiecouldbeloaded on existing aircraft and be ready in approx-imately two. years.17

Americans had been in touch with the MAUDCommittee since fall 1940, but it was the July 1941MAUD report that helped the American bomb ef-fort turn the corner. Here were specific plans forproducing a bomb, produced by a distinguishedgroup of scientists with high credibfity in the UnitedStates, not only with Bush and Conant but with thePresident!s The MAUD report dismissed plutoniumproduction, thermal diffusion, the electromagneticmethod, and the centrifuge and called for gaseousdiffusion of uranium-235 on a massive scale. TheBritish believed that uranium research could lead tothe production of a bomb in time to effect the out-come of the war. While the MAUD report providedencouragement to Americans advocating a more ex-tensive uranium research program, it also served asa sobering reminder that f~sion had been discoveredin Nazi Germany almost three years earlier and thatsince spring 1940 a large part of the Kaiser WilhelmInstitute in Berlin had been set aside for uraniumresearch.

Bush andConantimmediatelywentto work.After strengthening the Uranium Committee, par-ticularly with the addition of Fermi as head oftheoretical studies and Harold C. Urey as head ofisotope separation and heavy water research (heavywater was highly regarded as a moderator), Bushasked yet another reconstituted National Academyof Sciences committee to evaluate the uranium pro-gram. This time he gave Compton specific instruc-tions to address technical questions of critical massand destructive capability, partially to verify theMAUD results.

Bush Reports to RooseveltWithout waiting for Compton’s committee to

ftish its work, Bush went to see the President. OnOctober 9 Bush met with Roosevelt and VicePresident Henry A. WaUace (briefed on uraniumresearch in July). Bush summarized the Britishfindings, discussed cost and duration of a bombproject, and emphasized the uncertainty of the situa-tion. He also received the President’s permission toexplore construction needs with the Army. Rooseveltinstructed him to move as quickly as possible butnot to go beyond research and development. Bush,then, was to fmd out if a bomb could be built andat what cost but not to proceed to the production

9

Partm

stage without further presidential authorization.Roosevelt indicated that he could fmd a way tofinance the project and asked Bush to draft a letterso that the British government could be approached“at the top. ”lg

Compton repoited back on November 6, just onemonth and a day before the Japanese attack onPearl Harbor on December 7, 1941, brought theUnited States into World War II (Germany andItaly declared war on the United States three dayslater). Compton’s committee concluded that acritical mass of between two and 100 kilograms ofuranium-235 would produce a powerful fissionbomb and that for $50-100 million isotope separa-tion in sufficient quantities could be accomplished.Although the Americans were less optimistic thanthe British, they confirmed the basic conclusions ofthe MAUD committee and convinced Bush to for-ward their findings to Roosevelt under a cover letteron November 27. Roosevelt did not respond untilJanuary 19, 1942 when he did, it was as com-mander in chief of a nation at war. The President’shariiten fiote read, “V. B. OK—returned-Ithink you had best keep this in your own safeFDR-~Y20

Moving Into ActionBy the time Roosevelt responded, Bush had set

the wheels in motion. He put Eger V. Murphree, achemical engineer with the Standard Oil Company,in charge of a group responsiblefor overseeingengineering studies and supervising pilot plant con-struction and any laboratory-scale investigations.And he appointed Urey, Lawrence, and Comptonas program chiefs. Urey headed up work includingdiffusion and centrifuge methods and heavy-waterstudies. Lawrence took electromagnetic andplutonium responsibilities, and Compton ran chainreaction and weapon! theory programs. Bush’sresponsibility was to coordinate engineering andscientific efforts and make final decisions on recom-mendations for construction contracts. In accor-dance with the instructions he received fromRoosevelt, Bush removed all uranium work fromthe National Defense Research Committee. Fromthis point forward, broad policy decisions relating touranium were primarily the responsibility of the TopPolicy Group, composed of Bush, Conant, VicePresident Wallace, Secretary of War Henry L. Stim-son, and Army Chief of Staff George C. Marshall.21A high-level conference convened by Wallace on

December 16 put the seal of approval on these ar-rangements. Two days later the S-1 Committee gaveLawrence $400,000 to continue his electromagneticwork.

With the United States now at war and with thefear that the American bomb effort was behindNazi Germany’s, a sense of urgency permeated thefederal government’s science enterprise. Even asBush tried to free-tune the organizational apparatus,new scientific information poured in fromlaboratories to be analyzed and incorporated intoplanning for the upcoming design and constructionstage. By spring 1942, as American naval forcesslowed the Japanese advance in the Pacific with anApril victory in the battle of the Coral Sea, thesituation had changed from one of too little moneyand no deadlines to one of a clear goal, plenty ofmoney, but too little time. The race for the bombwas on.

Continuing Efforts on Isotope SeparationDuring the frst half of 1942 several routes to a

bomb were explored. At Columbia, Urey worked onthe gaseous diffusion and centrifuge systems forisotope separation in the codenamed SAM(Substitute or Special Alloy Metals) Laboratory. AtBerkeley, Lawrence continued his investigations onelectromagnetic separation using the mass spec-trograph he had converted from his thirty-seven-inchcyclotron. Compton patched together facilities at theUniversity of Chicago’s Metallurgical Laboratory forpile experiments aimed at producing plutonium.Meanwhile Murphree’s group hurriedly studied waysto move from laboratory experiments to productionfacilities.

Research on uranium required uranium ore, andobtaining sufficient supplies was the responsibility ofMurphree and his group. Fortunately, enough orewas on hand to meet the projected need of 150 tonsthrough rnid-1944. Twelve hundred tons of high-grade ore were stored on Staten Island, andMurphree made arrangements to obtain additionalsupplies from Canada and the Colorado Plateau,the only American source. Uranium in the form ofhexafluoride was also needed as feed material forthe centrifuge and the gaseous and thermal diffusionprocesses. Abelson, who had moved from theCarnegie Institution to the Naval ResearchLaboratory, was producing small quantities, andMurphree made arrangements with E. I. du Pent deNemours and Company and the Harshaw Chemical

10

EarlyGovernmentSupport

Company of Cleveland to produce hexafluoride ona scale sufficient to keep the vital isotope separationresearch going.

Lawrence was so successful in producing enrichedsamples of uranium-235 electromagnetically with hisconverted cyclotron that Bush sent a special progressreport to Roosevelt on March 9, 1942. Bush told thePresident that Lawrence’s work might lead to ashort cut to the bomb, especially in light of newcalculations indicating that the critical mass requiredmight well be smaller than previously predicted.Bush also emphasized that the efficiency of theweapon would probably be greater than earlierestimated and expressed more confidence that itcould be detonated successfully. Bush thought thatif matters were expedited a bomb was possible in1944. Two days later the President responded: “Ithink the whole thing should be pushed not only inregard to development, but also with due regard totime.This isverymuchof theessence.”22

In the meantime, however, isotope separationstudks at Columbia quickly confronted seriousengineering difficulties. Not only were the specifica-tions for the centrifuge demanding, but, dependingupon rotor size, it was estimated that it would re-quire tens of thousands of centrifuges to produceenough uranium-235 to be of value. Gaseous diffu-sion immediately ran into trouble as well. Fabrica-tion of an effective barrier to separate the uraniumisotopes seemed so difficult as to relegate gaseousdiffusion to a lower priority (the barrier had to be acorrosion-resistant membrane containing millions ofsubmicroscopic holes per square inch). Both separa-tion methods demanded the design and constructionof new technoloses and required that parts, manyof them never before produced, be ftihed totolerances not previously imposed on Americanindustry.

In Chicago, Compton decided to combine all pileresearch by stages. “Initiallyhe funded Fermi’s pile atColumbia and the theoretical work of EugeneWigner at Princeton and J. Robert Oppenheimer atBerkeley. He appointed Szilard head of materials ac-quisition and arranged for Seaborg to move hisplutonium work from Berkeley to Chicago in April1942. Compton secured space wherever he couldfind it, including a racket court under the westgrandstand at Stagg Field, where Samuel K. Allisonbegan building a graphite and uranium pile.Although it was recognized that heavy water wouldprovide a moderator superior to graphite, the only

available supply was a small amount that the Britishhad smuggled out of France. In a decision typical ofthe new climate of urgency, Compton decided toforge ahead with graphite, a decision made easier byFermi’s increasingly satisfactory results at Columbiaand Allison’s even better results in Chicago. In lightof recent calculations that cast doubt on the MAUDreport’s negative assessment of plutonium produc-tion, Compton hoped that Allison’s pile would pro-vide plutonium that could be used as material for aweapon.

By May 1942 Bush decided that production plan-ning could wait no longer, and he instructed Conantto meet with the S-1 section leaders and makerecommendations on all approaches to the bomb,regardless of cost. Analyzing the status of the fourmethods of isotope seprmation then under considera-tion-gaseous diffusion, centrifuge, electromagnetic,and pile-the committee decided on May 23 torecommend that all be pushed as fast as possible.This decision reflected the inability of the committeeto distinguish a clear front-runner and its consequentunwillingness to abandon any method. With fundsreadily available and the outcome of the war con-ceivably hanging in the balance, the S-1 leadershiprecommended that all four methods proceed to thepilot plant stage and to full production planning.

Enter the ArmyThe decision to proceed with production planning

led directly to the involvement of the Army,specifically the Corps of Engineers. Roosevelt hadapproved Army involvement on October 9, 1941,and Bush had arranged for Army participation atS-1 meetings beginning in March 1942. The need forsecurity suggested placing the S-1 program withinone of the armed forces, and the construction exper-tise of the Corps of Engineers made it the logicalchoice to build the production facilities envisioned inthe Conant report of May 23.

By orchestrating some delicate negotiationsbetween the Office of Scientific Research andDevelopment and the Army, Bush was able totransfer the responsibility for process development,materials procurement, engineering design, and siteselection to the Corps of Engineers and to earmarkapproximately sixty percent of the proposed 1943budget, or $54 million, for these functions. AnArmy officer would be in overaIl command of theentire project. This new arrangement left S-1, with a

11

PartE

budget of approximately $30 million, in charge of developments that might influence engineering con-only university research and pilot plant studies. Ad- siderations or plant design?3 With this reorganiza-ditional reorganization created an S-1 Executive tion in place, the nature of the American atomicCommittee, composed of Conant, Briggs, Compton, bomb effort changed from one dominated byLawrence, Murphree, and Urey. This group would research scientists to one in which scientists played aoversee all Office of Scientii3c Research and supporting role in the construction enterprise run byDevelopment work and keep abreast of technical the United States Army Corps of Engineers.

12

Part III:The Manhattan EngineerDistrict

Initial ProblemsSummer 1942—during which the American island-

hopping campaign in the Pacific began atGuadalcanal-proved to be a troublesome one forthe fledgling bomb project. Colonel James C. Mar-shall received the assignment of directing theLaboratory for the Development of SubstituteMetals, or DSM. Marshall immediately moved fromSyracuse to New York City, where he set up theManhattan Engineer District, established by generalorder on August 13. Marshall, like most other Armyofficers, knew nothing of nuclear physics. Further-more, Marshall and his Army superiors were dispos-ed to move cautiously. In one case, for instance,Marshall delayed purchase of an excellent produc-tion site in Tennessee pending further study, whilethe scientists who had been involved in the projectfrom the start were pressing for immediate purchase.While Bush had carefully managed the transition toArmy control, there was not yet a mechanism to ar-bitrate disagreements between S-1 and the military.The resulting lack of coordination complicated at-tempts to gain a higher priority for scarce materialsand boded ill for the future of the entire bombproject.

Reorganization of the ManhattanEngineer D~trict:Groves and the Military PolicycornInittee

Decisions made in September provided ad-ministrative clarity and renewed the project’s senseof urgency. Bush and the Army agreed that an of-ficer other than Marshall should be given the assign-ment of overseeing the entire atomic project, whichby now was referred to as the Manhattan Project.On September 17, the Army appointed ColonelLeslieR, Groves(promotedto BrigadierGeneraliidays later) to head the effort. Groves was anengineer with impressive credentials, inchdingbuilding of the Pentagon, and, most importantly,had strong administrative abilities. Within two daysGroves acted to obtain the Tennessee site andsecured a higher priority rating for project materials.In addition, Groves moved the Manhattan ErwineerDistrict headquarters from New York to “Washington. He quickly recognized the talents of

GeneralLeslieR. Groves.ReprintedfromVincentC. Jones,Manhattan: 7%eArmy and the Atomic Bomb (Washington,D,C.:U.S.GovernmentPrintingOffice,198S).

13

Part ~

Marshall’s deputy, Colonel Kenneth D. Nichols, andarranged for Nichols to work as “hischief aide andtroubleshooter throughout the war.

Bush, with the help and authority of Secretary ofWar Henry L. Stimson, setup the Military PolicyCommittee, including one representative each fromthe Army, the Navy, and the Office of ScientificResearch and Development. Bush hoped that scien-tists would have better access to decision making inthe new structure than they had enjoyed when DSMand S-1 operated as parallel but separate units. WithGroves in overall command (Marshall remained asDistrict Engineer, where his cautious nature provedusefhl in later decision making) and the MilitaryPolicy Committee in place (the Top Policy Groupretained broad policy authority), Bush felt that early

organizational deficiencies had been remedied.24During summer and fall 1942 technical and

administrative difficulties were still severe. Each ofthe four isotope separation processes remainedunder consideration, but a full-scale commitment toall four posed serious problems even with the pro-ject’s high priority. When Groves took command inmid-September, he made it clear that by late 1942decisions would be made as to which process orprocesses promised to produce a bomb in theshortest amount of time. The exigencies of war,Groves held, required scientists to move fromlaboratory research to development and productionin record time. Though traditional scientific cautionmight be short-circuited in the process, there was noalternative if a bomb was to be built in time to beused in the current conflict. As everyone involved inthe Manhattan Project soon learned, Groves neverlost sight of this goal and made all his decisionsaccordingly.

Isotope Separation Methods: Fall 1942Groves made good on his timetable when he

scheduled a meeting of the Military Policy Commit-tee on November 12 and a meeting of the S-1 Ex-ecutive Committee on November 14. The scientistsat each of the institutions doing isotope separationresearch knew these meetings would determine theseparation method to be used in the bomb project;therefore, the keen competition among the institu-tions added to the sense of urgency created by thewar. Berkeley remained a hotbed of activity asLawrence and his staff pushed the electromagneticmethod into the lead. The S-1 Executive Committeeeven toyed with the idea of placing all its money onLawrence but was dissuaded by Conant.

Throughout the summer and fall, Lawrence refinedhis new 184-inch magnet and huge cyclotron to pro-duce calutrons, as the tanks were called in honor ofthe University of California, capable of reliablebeam resolution and containing improved collectorsfor trapping the enriched uranium-235. The S-1 Ex-ecutive Committee visited Berkeley on September 13and subsequently recommended building both apilot plant and a large section of a full-scale plant inTennessee.

The centrifuge being developed by Jesse Beams atthe University of Virginia was the big loser in theNovember meetings. Westinghouse had been unableto overcome problems with its model centrifuge.Parts failed with discouraging regularity due tosevere vibrations during trial runs; consequently, apilot plant and subsequent production stages ap-peared impractical in the near future. Conant hadalready concluded that the centrifuge was likely tobe dropped when he reported to Bush on October 26.The meetings of November 12 and 14 confinedhis analysis.

Gaseous diffusion held some promise and remain-ed a live option, although the Dunning group atColumbia had not yet produced any uranium-235 bythe November meetings. The major problem con-tinued to be the barrier; nickel was the leading can-didate for barrier material, but there was seriousdoubt as to whether a reliable nickel barrier couldbe ready in sufficient quantity by the end of thewar.

While the centrifuge was cancelled and gaseousdiffusion received mixed reviews, optimism prevailedamong the pile proponents at the MetallurgicalLaboratory in Chicago. Shortages of uranium andgraphite delayed construction of the Stagg Fieldpile-CP-l (Chicago Pile Number One)—but thisfrustration was tempered by calculations indicatingthat a completed pile would produce a chain reac-tion. With Fermi’s move to Chicago in April, allpile research was now being conducted at theMetallurgical Laboratory as Compton had planned,and Fermi and his team anticipated a successful ex-periment by the end of the year. Further optimismstemmed from Seaborg’s inventive work withplutonium, particukuly his investigations onplutonium’s oxidation states that seemed to providea way to separate plutonium from the irradiateduranium to be produced in the pile. In AugustSeaborg’s team produced a microscopic sample ofpure plutonium, a major chemical achievement andone fully justifying further work on the pile. The

14

I The ManhattanEngineerD~trict I

onlycloudin theChicagoskywasthescientists’disappointment when they learned that constructionand operation of the production facilities, now to bebuilt near the Clinch River in Tennessee at Site X,would be turned over to a private fm. An ex-perimental pile would be built in the Argome ForestPreserve just outside Chicago, but the MetallurgicalLaboratory scientists would have to cede their ckdmto pile technology to an organization experiencedenough to take the process into construction andoperation.

The Luminaries Report From BerkeleyWhileeach of the four processes fought to

demonstrate its “workability” during summer andfall 1942 equally important theoretical studieswere being conducted that greatly influenced thedecisions made in November. Robert Oppenheimerheaded the work of a group of theoretical physicistshe called the luminaries, which included Felix Bloch,Hans Bethe, Edward Teller, and Robert Serber,while John H. Manley assisted him by coordinatingnationwide fission research and instrument andmeasurement studies from the Metallurgical

J, RobertOppenheimer.Reprintedbypetilon of theJ. RobertOppenheimerMemorialCommittee.

Laboratoryin Chicago.Despiteinconsistentex-perimental results, the consensus emerging atBerkeley was that approximately twice as much fis-sionable material would be required for a bombthan had been estimated six months earlier. Thiswas disturbing, especially in light of the military’sview that it would take more than one bomb to winthe war. The goal of mass-producing fissionablematerial, which still appeared questionable in late1942, seemed even more unrealistic given Op-penheimer’s estimates. Oppenheimer did report, withsome enthusiasm, that fusion explosions usingdeuterium (heavy hydrogen) might be possible. Thepossibility of thermonuclear (fusion) bombsgenerated some optimism since deutenum supplies,while not abundant, were certainly larger and moreeasily supplemented than were those of uranium andplutonium. S-1 immediately authorized basicresearch on other light elements.

Input From DuPontFinal input for the November meetings of the

Military Policy Committee and the S-1 ExecutiveCommittee came from DuPont. One of the fustthings Groves did when he took over in Septemberwas to begin courting DuPont, hoping that the giantchemical fm would undertake construction andoperation of the plutonium separation plant to bebuilt in Tennessee. He appealed to patriotism, infor-ming the company that the bomb project had highpriority with the President and maintaining that asuccessful effort could affeet the outcome of thewar. DuPont managers resisted but did not refusethe task, and in the process they provided an objec-tive appraisal of the pile project. Noting that it wasnot even known if the chain reaction would work,DuPont stated that under the best of circumstancesplutonium could be mass-produced by 1945, and itemphasized that it thought the chances of this hap-pening were low. This appraisal did not discourageGroves, who was confident that DuPont would takethe assignment if offered.

Time for DecisionsThe MilitaryPolicy Committee met on Novem-

ber 12, 1942, and its deeisions were ratified by theS-1 Executive Committee two days later. The MilitaryPolicy Committee, acting on Groves’s and Conant’srecommendations, eancelled the centrifuge project.Gaseous diffusion, the pile, and the electromagneticmethod were to proceed directly to full-scale,

15

I Part m I

eliminating the pilot plant stage. The S-1 ExecutiveCommittee approved these recommendations andagreed that the gaseous diffusion facility was oflower priority than either the pile or the elec-tromagnetic plant but ahead of a second pile. Thescientilc committee also asked DuPont to look intomethods for increasing American supplies of heavywater in case it was needed to serve as a moderatorfor one of the new piles.

A Brief ScareAnxious as he was to get moving, Groves decided

to make one final quality control check before ac-ting of the decisions of November 12 and 14. Thisdecision seemed imperative after a brief scare sur-rounding the pile project. While Fermi’s calculationsprovided reasonable assurance against such apossibility, the vision of a chain reaction runningwild in heavily-populated Chicago arose when theS-1 Executive Committee found that Compton wasbuilding the experimental pile at Stagg Field, a deci-sion he had made without informing either the com-mittee or Groves. In addition, information fromBritish scientists raised serious questions about thefeasibility of deriving plutonium from the pile. Ittook several days for Groves and a committee ofscientists including Lawrence and Oppenheimer tosatisfy themselves that the pile experiment posed lit-tle danger, was justified by sound theory, and wouldin all probability produce plutonium as predicted.

One Last Look: The Lewis CommitteeOn November 18, Groves appointed Warren K.

Lewis of the Massachusetts Institute of Technologyto head a final review committee, comprised ofhimself and three DuPont representatives. Duringthe next two weeks, the committee traveled fromNew York to Chicago to Berkeley and back againthrough Chicago. It endorsed the work on gaseousdiffusion at Columbia, though it made someorganizational recommendations; in fact, the Lewiscommittee elevated gaseous diffusion to fwst priorityand expressed reservations about the electromagneticprogram despite an impassioned presentation byLawrence in Berkeley. Upon returning to Chicago,Crawford H. Greenewalt, a member of the Lewiscommittee, was present at Stagg Field when, at 3:20p.m. on December 2, 1942, Fermi’s massive latticepile of 400 tons of graphite, six tons of uraniummetal, and fifty tons of uranium oxide achieved thefust self-sustaining chain reaction, operating initially

at a power level of one-half watt (increased to 20025 As Compton reported to Co-watts ten days later).

nant, “the Italian navigator has just landed in thenew world.” To Conant’s question, “Were thenatives friendly?” Compton answered, “Everyonelanded safe and happy.”26 Significant as this mo-ment was in the history of physics, it came after theLewis committee had endorsed moving to the pilotstage and one day after Groves had instructed Du-Pont to move into design and construction onDecember 1.27

No Turning Back: Final Decisions andPresidential Approval

The S-1 Executive Committee met to consider theLewis report on December 9, 1942, just weeks afterAllied troops landed in North Africa. Most of themorning session was spent evaluating the controver-sial recommendation that only a small electro-magnetic plant be built. Lewis and his colleaguesbased their recommendation on the belief thatLawrence could not produce enough uranium-235 tobe of military significance. But since the calutroncould provide enriched samples quickly, the commit-tee supported the construction of a small elec-tromagnetic plant. Conant disagreed with the Lewiscommittee’s assessment, believing that uranium hadmore weapon potential than plutonium. And sincehe knew that gaseous diffusion could not provideany enriched uranium until the gaseous diffusionplant was in full operation, he supported the onemethod that might, if all went well, produce enoughuranium to build a bomb in 1944. During the after-noon, the S-1 Executive Committee went over adraft Groves had prepared for Bush to send to thePresident. It supported the Lewis committee’s reportexcept that it recommended skipping the pilot plantstage for the pile. After Conant and the Lewis com-mittee met on December 10 and reached a com-promise on the electromagnetic method, Groves’sdraft was amended and forwarded to Bush?s

On December 28, 1942, President Roosevelt ap-proved the establishment of what ultimately becamea government investment in excess of $2 billion, $.5billion of which was itemized in Bush’s report sub-mitted on December 16. The Manhattan Project wasauthorized to build full-scale gaseous diffusion andplutonium plants and the compromise electro-magnetic plant, as well as heavy water productionfacilities. In his report, Bush reaffmed his beliefthat bombs possibly could be produced during thefwst half of 1945 but cautioned that an earlier

16

The ManhattanEngineerD~trict

delivery was unlikely. No schedtde could guaranteethat the. United States wouId overtake Germany inthe race for the bomb, but by the beginning of 1943the Manhattan Project had the complete support ofPresident Roosevelt and the military leadership, theservices of some of the nation’s most distinguishedscientists, and a sense of urgency driven by fear.Much had been achieved in the year between PearlHarbor and the end of 1942.

NosingledecisioncreatedtheAmericanatomicbomb project. Roosevelt’s December 28 decisionwas inevitable in light of numerous earlier ones that,in incremental fashion, committed the United Statesto pursuing atomic weapons. In fact, the essentialpieces were in place when Roosevelt approved

Bush’s November 9, 1941, report on January 19,1942. At that time, there was a science organizationat the highest level of the federal government and aTop Policy Group with direct access to the Presi-dent. Funds were authorized, and the participationof the Corps of Engineers had been approved inprinciple. In addition, the country was at war andits scientific leadership-as well as its President-hadthe belief, born of the MAUI) report, that the pro-jectcouldresultina significantcontributionto thewareffort. Roosevelt’s approval of $500 million inlate December 1942 was a step that followed directlyfrom the commitments made in January of that yearand stemmed logically from the President’s earliesttentative decisions in late 1939.

17

Part IV:The Manhattan EngineerDistrict in Operation

The Manhattan ProjectIn many ways the Manhattan Engineer District

operated like any other large construction company.It purchased and prepared sites, let contracts, hiredpersonnel and subcontractors, built and maintainedhousing and service facilities, placed orders formaterials, developed administrative and accountingprocedures, and established communications net-works. By the end of the war Groves and his staffhad spent approximately $2.2 billion on productionfacilities and towns built in the states of Tennessee,Washington, and New Mexico, as well as onresearch in university laboratories from Columbia toBerkeley. What made the Manhattan Project unlikeother companies performing similar functions wasthat, because of the necessity of moving quickly, itinvested hundreds of millions of dollars in unprovenand hitherto unknown processes and did so entirelyin secret. Speed and secrecy were the watchwords ofthe Manhattan Project.

Secrecy proved to be a blessing in dis@se.Although it dictated remote site locations, requiredsubterfuge in obtaining labor and supplies, and serv-ed as a constant irritant to the academic scientists onthe project, it had one overwhelming advantage:Secrecy made it possible to make decisions with littleregard for normal peacetime political considerations.Groves knew that as long as he had the backing ofthe White House money would be available and hecould devote his considerable energies entirely to

running the bomb project. Secrecy in the ManhattanProject was so complete that many people workingfor the organization did not know what they were ,working on until they heard about the bombing ofHiroshima on the radio. The need for haste clarifiedpriorities and shaped decision making. Unfiishedresearch on three separate, unproven processes hadto be used to freeze design plans for productionfacilities, even though it was recognized that laterfindings inevitably would dictate changes. The pilotplant stage was eliminated entirely, violating allmanufacturing practices and leading to intermittentshutdowns and endless troubleshooting during trialruns in production facilities. The inherent problemsof collapsing the stages between the laboratory andfull production created an emotionally charged at-mosphere with optimism and despair alternatingwith confusing frequency.

Despite Bush’s assertion that a bomb could prob-ably be produced by 1945, he and the other prin-cipals associated with the project recognized themagnitude of the task before them. For any largeorganization to take laboratory research into design,construction, operation, and product delivery intwo-and-a-half years (from early 1943 to Hiroshima)would be a major industrial achievement. Whetherthe Manhattan Project would be able to producebombs in time to affect the current conflict was anopen question as 1943 began. (Obvious though itseems in retrospect, it must be remembered that noone at the time knew that the war would end in1945 or who the remaining contestants would be ifand when the atomic bomb was ready for use).

Clinton Engineer Works (Oak Ridge)By the time President Roosevelt authorized the

Manhattan Project on December 28, 1942, work onthe east Tennessee site where the fwst productionfacilities were to be built was already underway. Thefinal quarter of 1942 saw the acquisition of theroughly ninety-square-mile parcel (59,000 acres) inthe ridges just west of Knoxville, the removal of therelatively few families on the marginal farmland,and extensive site preparation to provide thetransportation, communications, and utility needs ofthe town and production plants that would occupythe previously underdeveloped area. Original planscalled for the Clinton Engineer Works, as themilitary reservation was named, to house approx-imately 13,000 people in prefabricated housing,trailers, and wood dormitories. By the time theManhattan Engineer District headquarters were

19

moved from Washington to Tennessee in the sum-mer of 1943 (Groves kept the Manhati Project’soffice in Washington and placed Nichols in com-mand in Temessee), estimates for the town of OakRidge had been revised upward to 4045,000 people.(The name Oak Ridge did not come into usage untilafter World War II but will be used hereto avoidconfusion). At the end of the war, Oak Ridge wasthe fifth largest town in Tennessee, and the ClintonEngineer Works was consuming one-seventh of allthe power being produced in the nation?g While theArmy and its contractors tried to keep up with therapid influx of workers and their families, servicesalways lagged behind demand, though morale re-mained high in the atomic boomtown.

The three production facility sites were located invalleys away from the town. This provided securityand containment in case of explosions. The Y-12area, home of the electromagnetic plant, was closestto Oak Ridge, being but one ridge away to thesouth. Farther to the south and west lay both the

X-10 area, which contained the experimentalplutonium pile and separation facilities, and K-25,site of the gaseous diffusion plant and later the S-50thermal diffusion plat. Y-12 and X-10 were begunslightly earlier in 1943 than was K-25, but all threewere well along by the end of the year.

The Y-12 Electromagnetic Plant: FinalDecisions

Although the Lewis report had placed gaseousdiffusion ahead of the electromagnetic approach,many were still betting in early 1943 that Lawrenceand his mass spectrograph would eventuallypredominate. Lawrence and his laboratory ofmechanics at Berkeley continued to experiment withthe giant 184-inch magnet, trying to reach a consen-sus on which shims, sources, and collectors to incor-porate into Y-12 design for the Oak Ridge plant.Research on magnet size and placement and beamresolution eventually led to a racetrack configuration

ClintonEngineerWorks.ReprintedfromVincentC. Jones,Manhattan: I’7zeArmy and the Atomic Bomb (Washington,D.C.:U.S.OovermnentPrintingOffice,1985).

20

The ManhattanEngineerD~trict in Operation

of two magnets with forty-eight gaps containing twovacuum tanks each per building, with ten buildingsbeing necessary to provide the 2,000 sources andcollectors needed to separate 100 grams ofuranium-235 daily. It was hoped that improvementsin calutron design, or placing multiple sources andcollectors in each tank, might increase efficiency andreduce the number of tanks and buildings required,but experimental results were inconclusive even asStone & Webster of Boston, the Y-12 contractor atOak Ridge, prepared to break ground.

At a meeting of Groves, Lawrence, and John R.

LotzofStone&WebsterinBerkeleylateinDecember 1942, Y-12 plans took shape. It wasagreed that Stone & Webster would take over designand construction of a 500-tank facility, whileLawrence’s laboratory would play a supporting roleby supplying experimental data. By the time anothersummit conference on Y-12 took place in Berkeleyon January 13 and 14, Groves had persuaded theTennessee Eastman Corporation to sign on as plantoperator and arranged for various parts of the elec-tromagnetic equipment to be manufactured by theWestinghouse Electric and Manufacturing Com-

pany, the Allis-Chalmers Manufacturing Company,and the Chapman Valve Manufacturing Company.General Eleetric agreed to provide electricalequipment.

On January 14, after a day of presentations and ademonstration of the experimental tanks in thecyclotron building, Groves stunned the Y-12 con-tractors by insiiting that the fwst racetrack of ninety-six tanks be in operation by July 1 and that 500tanks be delivered by year’s end. Given that eachracetrack was 122 feet long, 77 feet wide and 15 feethigh; that the completed plant was to be the size of

threetwo-storybuildings;thattankdeignwasMlinflux;and that chemical extraction facilities alsowould have to be built, Groves’s demands were littleless than shocking. Nonetheless, Groves maintainedthat his schedule could be met~”

For the next two months Lawrence, the contrac-tors, and the Army negotiated over the final design.While all involved could see possible improvements,there simply was not enough time to incorporateevery suggested modification. Y-12 design wasfinalized at a March 17 meeting in Boston, with onemajor modification-the inclusion of a second stage

Y-12AlphaRacetrackat Clinton.SpareMagnetsin LeftForeground.Repfited fromRichardG. HewlettandOscarE. Anderson,Jr.,The New World 1939-19/4 VolumeI ofA Histoty of the United States Atomic Energy Commission (University Park PennsylvaniaStateUniversityPress,1%2).

21

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of the electromagnetic process. The purpose of thissecond stage was to take the enriched uranium-235derived from several runs of the frost stage and useit as the sole feed material for a second stage ofracetracks containing tanks approximately haIf thesize of those in the fwst. Groves approved this ar-rangement and work began on both the Alpha(fnst-stage) and Beta (second-stage) tracks.

Construction of Y-12Groundbreaking for the Alpha plant took place

on February 18, 1943. Soon blueprints could not beproduced fast enough to keep up with constructionas Stone & Webster labored to meet Groves’sdeadline. The Beta facility was actually begun beforeformal authorization. while laborers were ag-gressively recruited, there was always a shortage ofworkers skilled enough to perform jobs according tothe rigid specifications. (A fhrther complication wasthat some tasks could be performed only by workers

with special clearances). Huge amounts of materialhad to be obtained (38 million board feet of lumber,for instance), and the magnets needed so much cop-per for windings that the Army had to borrowalmost 15,000 tons of silver bullion from the UnitedStates Treasury to fabricate into strips and wind onto coils as a substitute for copper.31 Treasury silverwas also used to manufacture the busbars that ranaround the to~ of the racetracks.

Replacing copper with silver solved the immediateproblem of the magnets and busbars, but persistentshortages of electronic tubes, generators, regulators,and other equipment pla~ed the electromagneticproject and posed the most serious threat toGroves’s deadline. Furthermore, last-minute designchanges continued to frustrate equipment manufac-turers. Nonetheless, when Lawrence toured withY-12 contractors in May 1943, he was impressed bythe scaIe of operations. Lawrence returned toBerkeley rededicated to the “awful job” of fiishingthe racetracks on time?2

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Y-12 Electromagnetic PlantUnderConstructionat Clinton.ReprintedfromRichardG. HewlettandOscarE. Anderson,Jr., The NewWorld 1939-1946 VolumeI of A H.isto~ of the United States Atomic Energy Commission (University Park:PennsylvaniaStateUniversityPress,1%2).

22

The ManhattanEngineerDistrictin Operation

Design Changes at Y-12Lawrence and his colleagues continued to look for

wajw to improve the electromagnetic process.Lawrence found that hot (high positive voltage) elec-trical sources could replace the single cold (ground-ed) source in future pkmts, providing more efficientuse of power, reducing insulator failure, and makingh possible to use multiple rather than singlebeams~3 Meanwhile, receiver design evolved quicklyenough in spring and summer 1943 to be incor-porated into the Alpha plant. Work at the Radia-tion Laboratory picked up additional speed inMarch with the authorization of the Beta process.With Alpha technology far from perfected,Lawrence and his staff now had to participate inplanning for an unanticipated stage of the elec-tromagnetic process.

While the scientists in Berkeley studied changesthat would be required in the down-sized Betaracetracks, engineering work at Oak Ridge prescrib-ed specific design modifications. For a variety ofreasons, including simplicity of maintenance, Ten-nessee Eastman decided that the Beta plant wouldconsist of a rectangular, rather than oval, arrange-ment of two tracks of thirty-six tanks each. Factor-ing this configuration into their edculations,Lawrence and his coworkers bent their efforts todeveloping chemical processing techniques thatwould minimize the loss of enriched uranium duringBeta production runs. To make certain that Alphahad enough feed material, Lawrence arranged forresearch on an alternate method at Brown Universi-ty and expanded efforts at Berkeley. With what wasleft of his time and money in early 1943 Lawrencebuilt prototypes of Alpha and Beta units for testing

Y-12BetaRacetrackat Clinton.ReprintedfromRichardG.HewlettandOscarE. Anderson,Jr., Z7reNewWorld1939-1946,VolumeI of A Hiwov of the United States AtomicEnergy Commission (UniversityPark PennsylvaniaStateUniversityPress,1%2).

and training operating persomel. Meanwhile Ten-nessee Eastman, running behind schedule, raced tocomplete experimental models so that training andtest runs could be performed at Oak Ridge.

Warning From Los AlamosBut in the midst of encouraging progress in con-

struction and research on the electromagnetic pro-cess in July came discouraging news fromOppenheimer’s isolated laboratory in Los Akunos,New Mexico, set up in spring 1943 to consolidatework on atomic weapons. Oppenheimer warned thatthree times more fissionable material would be re-quired for a bomb than earlier estimates had in-dicated. Even with satisfactory performance of theracetracks, it was possible that they might not pro-duce enough purified uranium-235 in time.Lawrence responded to this crisis in characteristicfashion: He immediately lobbied Groves to incor-porate multiple sources into the racetracks underconstruction and to build more racetracks. Grovesdecided to build the fwst four as planned but, afterreceiving favorable reports from both Stone &Webster and Tennessee Eastman, allowed a four-beam source in the fifth. Convinced that the elec-tromagnetic process would work and sensing thatestimates from Los Alamos might be reviseddownward in the future, Groves let Lawrence talkhim into building a new plant-in effect, doublingthe size of the electromagnetic complex. The newfacility, Groves reported to the Military Policy Com-mittee on September 9, would consist of twobuildings, each with two rectangular racetracks ofninety-six tanks operating with four-beam sources.

Shakedown at Y-12During summer and fall 1943 the fwst elec-

tromagnetic plant began to take shape. The hugebuilding to house the operating equipment wasreadied as manufacturers began delivering everythingfrom electrical switches to motors, valves, andtanks. While construction and outfitting proceeded,ahnost 5,000 operating and maintenance personnelwere hired and trained. Then, between October andmid-December, Y-12 paid the price for being a newtechnology that had not been put through its pacesin a pilot plant. Vacuum tanks in the fwst Alpharacetrack leaked and shimmied out of line due tomagnetic pressure, welds failed, electrical circuitsmalfunctioned, and operators made frequentmistakes. Most seriously, the magnet coils shortedout because of rust and sediment in the cooling oil.

23

Part w

Groves arrived on December 15 and shut theracetrack down. The coils were sent to Allis-Chalmers with hope that they could be cleanedwithout being dismantled entirely, while measureswere taken to prevent recurrence of the shortingproblem. The second Alpha track now bore theweight of the electromagnetic effort. In spite ofprecautions aimed at correcting the electrical and oil-related problems that had shut down the fiistracetrack, the second Alpha fared little better whenit started up in mid-January 1944. While all tanksoperated at least for short periods, performance wassporadic and maintenance could not keep up withelectrical failures and defective parts. Like itspredecessor, Alpha 2 was a maintenance nightmare.

Alpha 2 produced about 200 grams of twelve-percent uranium-235 by the end of February,enough to send samples to Los Alarnos and feed thefwst Beta unit but not enough to satisfy estimates ofweapon requirements. The fiist four Alpha tracksdid not operate together until April, a full fourmonths late. While maintenance improved, outputwas well under previous expectations. The openingof the Beta building on March 11 led to furtherdisappointment. Beam resolution was so unsatisfac-tory that complete redesign was required. To makematters worse, word spread that the K-25 gaseousdiffusion process was in deep trouble because of itsongoing barrier crisis. K-25 had been counted uponto provide uranium enriched enough to serve as feedmaterial for Beta. Now it would be producing suchslight enrichment that the Alpha tracks would haveto process K-25’s material, requiring extensiveredesign and retooling of tanks, doors, and liners,particularly in units that would be wired to run ashot, rather than as cold, electrical sources.sl

Reworking the RacetracksIt became clear to Groves that he would have to

fmd a way for a combination of isotope separationprocesses to produce enough fissionable material forbombs. This meant making changes in theracetracks so that they could process the slightlyenriched material produced by K-25. He thenconcentrated on further expansion of the electro-magnetic facilities. Lawrence, seconded by Op-penheimer, believed that four more racetracksshould be built to accompany the nine alreadyf~hed or under construction. Groves agreed withthis approach, though he was not sure that the addi-tional racetracks could be built in time.

As K-25 stock continued to drop and plutoniumprospects remained uncertain, Lawrence lobbied yetagain for further expansion of Y-12, arguing that itprovided the only possible avenue to a bomb by1945. His plan was to convert all tanks to multiplebeams and to build two more racetracks. By thistime even the British had given up on gaseous diffu-sion and urged acceptance of Lawrence’s plan.

Time was running out, and an element ofdesperation crept into decisions made at a meetingon July 4, 1944. Groves met with the Oak Ridgecontractors to consider proposals Lawrence hadprepared after assessing once again the resourcesand abilities of the Radiation Laboratory. There wasto be no change in the completed racetracks; theresimply was not enough time. Some improvementswere to be made in the racetracks then under con-struction. In the most important decision made atthe meeting, Lawrence was to throw all he had intoa completely new type of calutron that would use athirty-beam source. Technical support would comefrom both Westinghouse and General Electric,which would cease work on four-beam development.It was a gamble in a high-stakes game, but stickingwith the Alpha and Beta racetracks might have beenan even greater gamble.

The K-25 Gaseous Diffusion PlantEleven miles southwest of Oak Ridge on the

Clinch River was the site of the K-25 gaseous diffu-sion plant upon which so much hope had restedwhen it was authorized in late 1942. Championed bythe British and placed fwst by the Lewis committee,gaseous diffusion seemed to be based on soundtheory but had not yet produced samples of enrich-ed uranium-235.

At Oak Ridge, on a relatively flat area of about5,000 acres, site preparation for the K-25 powerpkmtbegan in June. Throughout the summer, contractorscontended with primitive roads as they shipped inthe materials needed to build what became theworld’s largest steam electric plant. In Septemberwork began on the cascade building, plans forwhich had changed dramatically since the spring.Now there were to be fifty four-story buildings(2,000,000 square feet) in a U-shape measuring halfa mile by 1,000 feet. Innovative foundation techni-ques were required to avoid setting thousands ofconcrete piers to support load-bearing walls.

Since it was eleven miles from the headquarters atOak Ridge, the K-25 site developed into a satellite

24

The ManhattanEngineerDistrictin Operation I

K-25GaseousDiffusionPlantUnderConstructionat Clinton.ReprintedfromRichardG. HewlettandOscarE. Anderson,Jr.,ZheNewWorld, 1939-1946 VolumeI of A Histow of theUnited States Atomic Energy Commission (LJniversi&ParkPennsylvaniaStateUniversityPress,1%2).

town. Housing was supplied, as was a full array ofservice facilities for the population that reached15,000. Dubbed Happy Valley by the inhabitants,the town had housing similar to that in Oak Ridge,but, like headquarters, it too experienced chronicshortages. Even with a contractor camp withfacilities for 2,000 employees nearby, half of HappyValley’s workers had to commute to the construc-tion site daily.

Downgrading K-25In late summer 1943 it was decided that K-25

would play a lesser role than originally intended. In-stead of producing fully enriched uranium-235, thegaseous diffusion plant would now provide aroundfifty percent enrichment for use as feed material inY-12. This would be accomplished by eliminatingthe more troublesome upper part of the easeade.Even this level of enrichment was not assured sincea barrier for the diffusion plant still dld not exist.The decision to downgrade K-25 was part of the

K-25fromOppositeEnd.WhiteBuildingin Centerof PreviousPictureDueernibleat FarEnd.ReprintedfromRichardG.HewlettandOscarE. Anderson,Jr., 77zeNew World,1939-1944 VolumeI of A Histoty of the United States AtomicEne~ Commission (Universiw Park PennsylvaniaState ‘UniversityPress,1%2).

larger decision to double Y-12 capacity and fit withGroves’s new strategy of utilizing a combination ofmethods to produce enough f~sionable material forbombs as soon as possible.

There was no doubt in Groves’s mind thatgaseous diffusion still had to be pursued vigorously.Not only had major resources already been expend-ed on the program, but there was ako the possibilitythat it might yet prove successful. Y-12 was in trou-ble as 1944 began, and the plutonium pile projectswere just getting underway. A workable barrierdesign might put K-25 ahead in the race for thebomb. Unfortunately, no one had been able tofabricate barrier of sufficient quality. The only altern-ative remaining was to increase production enoughto compensate for the low percentage of barrier thatmet specifications. As Lawrence prepared to throw

25

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I Part m I

everything he had into a thirty-beam source forY-12, Groves ordered a crash barrier program, hop-ing to prevent K-25 from standing idle as “theracefor the bomb continued.

Help From the NavyAs problems with both Y-12 and K-25 reached

crisis proportions in spring and summer 1944,the Manhattan Project received help from an unex-pected source-the United States Navy. PresidentRoosevelt had instructed that the atomic bomb ef-fort bean Army program and that the Navy be ex-cluded from deliberations. Navy research on atomicpower, conducted primarily for submarines, receivedno direct aid from Groves, who, in fact, was notup-to-date on the state of Navy efforts when hereceived a letter on the subject from Oppenheimerlate in April 1944.

Oppenheimer informed Groves that PhilipAbelson’s experiments on thermal diffusion at thePhiladelphia Naval Yrud deserved a closer look.Abelson was building a plant to produce enricheduranium to be completed in early July. It might bepossible, Oppenheimer thought, to help Abelsoncomplete and expand his plant and use its slightlyenriched product as feed for Y-12 until problemswith K-25 could be resolved.

The liquid thermal diffusion process had beenevaluated in 1940 by the Uranium Committee, whenAbelson was at the National Bureau of Standards.In 1941 he moved to the Naval ResearchLaboratory, where there was more support for hiswork. During summer 1942 Bush and Conantreceived reports about Abelson’s research but con-cluded that it would take too long for the thermaldiffusion process to make a major contribution tothe bomb effort, especially since the electromagneticand pile projects were making satisfactory progress.After a visit with Abelson in January 1943, Bushencouraged the Navy to increase its support of ther-mal diffusion. A thorough review of Abelson’s pro-ject early in 1943, however, concluded that thermaldiffusion work should be expanded but should notbe considered as a replacement for gaseous diffu-sion, which was better understood theoretically.Abelson continued his work independently of theManhattan Project. He obtained authorization tobuild a new plant at the Philadelphia Naval Yard,where construction began in January 1944.

Groves immediately saw the value of Oppen-heimer’s suggestion and sent a group to Philadelphiato visit Abelson’s plant. A quick analysis

demonstrated that a thermal diffusion plant couldbe built at Oak Ridge and placed in operation byearly 1945. The steam needed in the convection col-umns was already at hand in the form of the almostcompleted K-25 powerplant. It would be a relativelysimple matter to provide steam to the thermal diffu-sion plant and produce enriched uranium, whileproviding electricity for the K-25 plant when it wasftished. Groves gave the contractor, H. K.Ferguson Company of Cleveland, just ninety daysfrom September 27 to bring a 2,142-cohunn planton line (Abelson’s plant contained 100 columns).There was no time to waste as Happy Valley braceditself for a new influx of workers.

The Metallurgical LaboratoryOneof the most important branches of the far-

flung Manhattan Project was the MetallurgicalLaboratory (Met Lab) in Chicago, which wascounted on to design a production pile forplutonium. Here again the job was to design equip-ment for a technology that was not well understoodeven in the laboratory. The Fermi pile, important asit was historically, provided little technical guidanceother than to suggest a lattice arrangement ofgraphite and uranium. Any pile producing morepower than the few watts generated in Fermi’sfamous experiment would require elaborate controls,radiation shielding, and a cooling system. Theseengineering features would all contribute to a reduc-tion in neutron multiplication (neutron multiplica-tion being represented by k); so it was imperative todetermine which pile design would be safe and con-trollable and still have a k high enough to sustain anongoing reaction.35

Pile DesignA group headed by Compton’s chief engineer,

Thomas V. Moore, began designing the productionpile in June 1942. Moore’s fwst goals were to fmdthe best methods of extracting plutonium from theirradiated uranium and for cooling the uranium. Itquickly became clear that a production pile woulddiffer significantly in design from Fermi’s exper-imental reactor, possibly by extending uranium rodsinto and through the graphite next to cooling tubesand building a radiation and containment shield.Although experimental reactors like Fermi’s did notgenerate enough power to need cooling systems,piles built to produce plutonium would operate athigh power levels and require coolants. The MetLab group considered the full range of gases and li-quids in a search to isolate the substances with the

26

The ManhattanEngineerDistrictin Operation

best nuclear characteristics, with hydrogen andhelium standing out among the gases andwater-even with its marginal nuclear properties andtendency to corrode uranium-as the best liquid.

During the summer, Moore and his group beganplanning a helium-cooled pilot pile for the ArgonneForest Preserve near Chicago, built by Stone&Webster, and on September 25 they reported toCompton. The proposal was for a 460-ton cube ofgraphite to be pierced by 376 vertieal columns con-taining twenty-two cartridges of uranium andgraphite. Cooling would be provided by circulatinghelium from top to bottom through the pile. A wallof graphite surrounding the reactor would provideradiation containment, while a series of sphericalsegments that gave the design the nickname MaeWest would make up the outer shell.

By the time Compton received Moore’s report, hehad two other pile designs to consider. One was awater-cooled model developed by Eugene Wignerand Gale Young, a former colleague of Compton’s.Wigner and Young proposed a twelve-foot bytwenty-five-foot cylinder of graphite with pipes ofuranium extendkg from a water tank above,through the cylinder, and into a second water tankunderneath. Coolant would circulate continuouslythrough the system, and corrosion would beminimized by coating interior surfaces or lining theuranium pipes.

A second alternative to Mae West was more dar-ing. Szilard thought that liquid metal would be suchan efficient coolant that, in combination with anelectromagnetic pump having no moving parts(adapted from a design he and Einstein hadcreated), it would be possible to achieve high powerlevels in a considerably smaller pile. Szilard hadtrouble obtaining supplies for his experiment,primarily because bismuth, the metal he preferred asthe coolant, was rare.

Groves Steps InOctober1942foundGrovesin Chicagoreadyto

force a showdown on pile design. Szilard was noisilycomplahing that deckions had to be made so thatdesign could move to procurement and construction.Compton’s delay reflected uncertainty of thesuperiority of the helium pile and awareness that,engineering studies could not be deftitive until theprecise value of k had been established. Some scien-tists at the Met Lab urged that a full production pilebe built immediately, while others advocated amulti-step process, perhaps beginning with an exter-nally cooled reactor proposed by Fermi. The situa-

tion was tailor-made for a man with Groves’stemperament. On October 5 Groves exhorted theMet Lab to decide on pile design within a week.Even wrong decisions were better than no decisions,Groves claimed, and since time was more valuablethan money, more than one approach should bepursued if no single design stood out. While Grovesdid not mandate a specific decision, his imposeddeadline forced the Met Lab scientists to reach aconsensus.

Compton decided on compromise. Fermi wouldstudy the fundamentals of pile operation on a smallexperimental unit to be completed and in operationby the end of the year. Hopefldly he could deter-mine the precise value of k and make a significantadvance in pile engineering possible. An intermediatepile with external cooling would be built at Argonneand operated until June 1, 1943, when it would betaken down for plutonium extraction. The helium-cooled Mae West, designed to produce 100 grams ofplutonium a day, would be built and operating byMarch 1944. Studies on liquid-cooled reactors wouldcontinue, including Szilard’s work on liquid metals.

Seaborg and Plutonium ChemistryWhilethe Met Lab labored to make headway on

pile design, Seaborg and his coworkers tried to gainenough information about transuranium chemistryto insure that plutonium produced could be suc-cessfully extracted from the irradiated uranium.Using lanthanum fluoride as a carrier, Seaborgisolated a weighable sample of plutonium in August1942. At the same time, Isadore Perlman andWilliam J. Knox explored the peroxide method ofseparation; John E. Willard studied variousmaterials to determine which best adsorbedplutonium;36 Theodore T. Magel and Daniel K.Koshland, Jr., researched solvent-extraction pro-cesses; and Harrison S. Brown and Orville F. Hillperformed experiments into volatility reactions.Basic research on plutonium’s chemistry continuedas did work on radiation and fission products.

Seaborg’s discovery and subsequent isolation ofplutonium were major events in the history ofchemistry, but, like Fermi’s achievement, it remain-ed to be seen whether they could be translated intoa production process useful to the bomb effort. Infact, Seaborg’s challenge seemed even more daunt-ing, for while piles had to be scaled up ten to twen-ty times, a separation plant for plutonium wouldinvolve a scale-up of the laboratory experiment onthe order of a btion-fold.

27

Partw

Collaboration with DuPont’s Charles M. Cooperand his staff on plutonium separation facilitiesbegan.even before Seaborg succeeded in isolating asample of plutonium. Seaborg was reluctant to dropany of the approaches then under consideration, andCooper agreed. The two decided to pursue all fourmethods of plutonium separation but put fwstpriority on the lanthanum fluoride process Seaborghad already developed. Cooper’s staff ran into pro-blems with the lanthanum fluoride method in late1942, but by then Seaborg had become interested inphosphate carriers. Work led by Stanley G. Thomp-son found that bismuth phosphate retained overninety-eight percent plutonium in a precipitate. Withbismuth phosphate as a backup for the lanthanumfluoride, Cooper moved ahead on a serniworks nearStagg Field.

DuPont Joins the TeamCompton’s original plans to build the experiment-

al pile and chemical separation plant on the Univer-sity of Chicago campus changed during fall1942. The S-1 Executive Committee concurred thatit would be safer to put Fermi’s pile in Argonne andbuild the pilot plant and separation facilities in OakRidge than to place these experiments in a populousarea. On October 3 DuPont agreed to design andbuild the chemical separation plant. Groves tried toentice further DuPont participation at Oak Ridge byhaving the f~ prepare an appraisal of the pile pro-ject and by placing three DuPont staff members onthe Lewis committee. Because DuPont was sensitiveabout its public image (the company was still smart-ing from charges that it profiteered during WorldWar I), Groves ultimately obtained the services ofthe giant chemical company for the sum of onedollar over actual costs. In addition, DuPont vowedto stay out of the bomb business after the war andoffered all patents to the United States government.

Groves had done well in convincing DuPont tojoin the Manhattan Project. DuPont’s proven ad-ministrative structure assured excellent coordination(Crawford Greenewalt was given the responsibilityof coordinating DuPont and Met Lab planning),and Groves and Compton welcomed the company’sdemand that it be put in fidl charge of the OakRidge plutonium project. DuPont had a strongorganization and had studied every aspect of theMet Lab’s program thoroughly before accepting theassignment. While deeply involved in the overall wareffort, DuPont expected to be able to divert person-nel and other resources from explosives work in

time to throw its full weight into the Oak Ridgeproject.

Moving the pilot plutonium plant to Oak Ridgeleft too little room for the full-scale productionplant at the X-10 site and also left too littlegenerating power for yet another major facility. Fur-thermore, the site was uncomfortably close to Knox-ville should a catastrophe occur. Thus the search foran alternate location for the full-scale plutoniumfacility began soon after DuPont joined the produc-tion team. Compton’s scientists needed an area ofapproximately 225 square miles. Three or four pilesand one or two chemical separation complexeswould be at least a mile apart for security purposes,while nothing would be allowed within four miles ofthe separation complexes for fear of radioactive ac-cidents. Towns, highways, rail lines, and laboratorieswould be several miles further away.

HanfordDecember 16, 1942, found Colonel Franklin T.

Matthias of Groves’s staff and two DuPontengineers headed for the Pacific Northwest andsouthern California to investigate possible produc-tion sites. Of the possible sites available, none had abetter combination of isolation, long constructionseason, and abundant water for hydroelectric powerthan those found along the Columbia and ColoradoRivers. After viewing six locations in Washington,Oregon, and California, the group agreed that thearea around Hanford, Washington, best met thecriteria established by the Met Lab scientists andDuPont engineers. The Grand Coulee and Bon-neville Dams offered substantial hydroelectric power,while the flat but rocky terrain would provide ex-cellent support for the huge plutonium productionbuildings. The ample site of nearly one-half millionacres was far enough inland to meet security re-quirements, while existing transportation facilitiescould quickly be improved and labor was readilyavailable. Pleased with the committee’s unanimousreport, Groves accepted its recommendation andauthorized the establishment of the HanfordEngineer Works, codenamed Site W.

Now that DuPont would be building theplutonium production complex in the Northwest,Compton saw no reason for any pile facilities inOak Ridge and proposed to conduct Met Labresearch in either Chicago or Argonne. DuPont, onthe other hand, continued to support a serniworks atOak Ridge and asked the Met Lab scientists tooperate it. Compton demurred on the grounds that

28

The ManhattanEngineerDistrictin Operation

he did not have sufficient technical staff, but he was simply did not have sufficient expertise to operatealso reluctant because his scientists complained that the semiworks on its own. The University oftheir laboratory was becoming little more than a Chicago administration supported Compton’s deci-subsidiary of DuPont. In the end, Compton knew ‘sion in early March.the Met Lab would have to support DuPont, which

UKII—,. –

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HanfordEngineerWorks.ReprintedfromViicentC. Jones,Manhattan: l%e Army and the Atomic Bomb(Washington,D.C.:U.S. GovernmentPrintingOffice,1985).

29

Pile Design: Changing PrioritiesThe fall 1942 planning sessions at the Met Lab led

to the decidon to build a second Fermi pile at

Argonne as soon as his experiments on the fwst werecompleted and to proceed on design of the MaeWest helium-cooled unit. When DuPont engineersassessed the Met Lab’s plans in the late fall, theyagreed that helium should be given f~st priority.They placed heavy water second and urged an aU-out effort to produce more of this highly effectivemoderator. Bkmuth and water were ranked thirdand fourth in DuPont’s analysis. Priorities changedwhen Fermi’s calculations demonstrated a highervalue for k than anyone had anticipated. Met Labscientists concluded that a water-cooled pile wasnow feasible, while DuPont shifted its interest to air

cooling. Since a helium-cooled unit shared importantdesign characteristics with an air-cooled one,Greenewalt thought that an air-cooled serniworks at

Oak Ridge would contribute significantly to design-ing the full-scale facilities at Hanford.

DuPont established the general specifications forthe air-cooled semiworks and chemical separationfacilities in early 1943. A massive graphite block,protected by several feet of concrete, would containhundreds of horizontal channels ftied with uraniumslugs surrounded by cooling air. New slugs would bepushed intothechannelson thefaceof thepile,forcing irradiated ones at the rear to fall into anunderwater bucket. The buckets of irradiated slugswould undergo radioactive decay for several weeks,then be moved by underground canal into thechemical separation facility where the plutoniumwould be extracted with remote control equipment.

Met Lab activities focused on designing a water-cooled pile for the full-scale plutonium plant. Tak-ing their cue from the DuPont engineers, who utiliz-ed a horizontal design for the air-cooled semiworks,Met Lab scientists abandoned the vertical arrange-ment with water tanks, which had posed seriousengineering difficulties. Instead they proposed to

place uranium slugs sealed in aluminum cans insideahuninurn tubes. The tubes, laid horizontallythrough a graphite block, would cool the pile withwater injected into each tube. The pile, containing200 tons of uranium and 1,200 tons of graphite,would need 75,000 gallons of water per minute forcooling.

Decision on Pile DesignGreenewalt’s initial response to the water-cooled

design was guarded. He worried about pressure pro-blems that might lead to boiling water in individualtubes, corrosion of slugs and tubes, and the one-percent margin of safety fork. But he was evenmore worried about the proposed helium-cooledmodel. He feared that the compressors would not beready in time for Hanford, that the shell could notbe made vacuum-tight, and that the pile would beextremely difficult to operate. DuPont engineersconceded that Greenewalt’s fears were well--grounded. Late in February, Greenewalt reluctantlyconcluded that the Met Lab’s model, while it had itsproblems, was superior to DuPont’s own helium-cooled design and decided to adopt the water-cooledapproach.

The Met Lab’s victory in the pile design competi-tion came as its status within the Manhattan Projectwas changing. Still an exciting place intellectually,the Met Lab occupied a less central place in thebomb project as Oak Ridge and Hanford rose toprominence. Fermi continued to work on the StaggField pile (CP-1), hoping to determine the exactvalue of k. Subsequent experiments at the Argonnesite using CP-2, built with material from CP-1,focused on neutroncaptureprobabilities,controlsystems,andinstrumentreliability.Oncetheproduc-tion facilities at Oak Ridge and Hanford wereunderway, however, Met Lab research became in-creasingly unimportant in the race for the bomb andthe scientists found themselves serving primarily asconsultants for DuPont.

Decision on Chemical ExtractionWhile the Met Lab physicists chafed under Du-

Pont domination, a smoother and quieter relation-ship existed between the chemists and DuPont.Seaborg and Cooper continued to work welltogether, and enough progress was made in thesemiworks for the lanthanum fluoride process in late1942 that DuPont moved into the plant design stageand converted the serniworks for the bismuthphosphate method. DuPont pressed for a decisionon plutonium extraction methods in late May.Greenewalt chose bismuth phosphate, though evenSeaborg admitted he could find little to distinguishbetween the two. Greenewalt based his decision on

30

TheManhattanEngineerDistrictin Operation

the corrosiveness of lanthanum fluoride and onSeaborg’s guarantee that he could extract at leastfifty percent of the plutonium using bismuthphosphate. DuPont began constructing the chemicalseparation pilot plant at Oak Ridge, while Seaborgcontinued refining the bismuth phosphate method.

It was now Cooper’s job to design the pile as wellas the plutonium extraction facilities at Clinton,both complicated engineering tasks made even moredifficult by high levels of radiation produced by theprocess. Not only did Cooper have to oversee thedesign and fabrication of parts for yet another newManhattanProjecttechnology,hehadto do sowithan eye toward planning the Hanford facility. Safety

In July 1942 Compton setup a health division atthe Met Lab and put Robert S. Stone in charge.Stone established emission standards and conductedexperiments on radiation hazards, providing valuableplanning information for the Oak Ridge and Han-ford facilities.

Construction at Oak RidgeDuPont broke ground for the X-10 complex at

Oak Ridge in February 1943. The site would includean air-cooled experimental pile, a pilot chemicalseparation plant, and support facilities. Cooper pro-duced blueprints for the chemical separation plantsin time for construction to begin in March. A series

was a major consideration because of the hazards of of huge underground concrete cells, the f~st ofworking with plutonium, which was highly radioac- which sat under the pile, extended to one storytive. Uranium, a much less active element than above ground. Aluminum cans containing uraniumplutonium, posed far fewer safety problems. slugs would drop into the fust cell of the chemical

7 ce

I

Air-CooledPileBuiltin X-10Areaat Clinton.ReprintedfromRichardG. HewlettandOscarE. Anderson,Jr., TheNW World,1939-194~VolumeI ofA History of the United States Atomic Enetgy Commission (University Park PennsylvaniaStateUniversityPress,1%2).

31

I Partm I

separation facility and dissolve and then go throughthe extraction process. The pile buil@ng went upduring the spring and summer, a huge concrete shellseven feet thick with hundreds of holes for uraniumslug placement. Slugs were to plutonium piles whatbarrier was to gaseous diffusio~ that is, an obstaclethat could shut down the entire process. TheAluminum Company of American (Alcoa) was theonly fm left working on a process to enclose.yranium-235 in aluminum sheaths, and it was stillhaving problems. Initial production provided mixedresults, with many cans failing vacuum tests becauseof faulty welds.

WorkersLoadingUraniumSlugIntoFaceof Air-CooledPile.ReprintedfromRichardG. HewlettandOscarE. Anderson,Jr., TheNW World 1939-1946VolumeI ofA History of theUnited States Atomic Energy Commission (University Park:PennsylvaniaStateUrdveHityPress,1%2).

X-10 in Operation: Fall 1943The moment everyone had been waiting for came

in late October when DuPont completed construc-tion and tests of the X-10 pile at Clinton EngineerWorks. After thousands of slugs were loaded, thepile went critical in the early morning of Nov-ember 4 and produced plutonium by the end of themonth. Criticality was achieved with only half of the

channels ffled with uranium. During the nextseveral months, Compton gradually raised the powerlevel of the pile and increased its plutonium yield.Chemical separation techniques using the bismuthphosphate process were so successful that LosAlamos received plutonium samples beginning in thespring. Fission studies of these samples at LosAkunos during summer 1944 heavily influencedbomb design.

Hanford Take-sShapeColonel Matthias returned to the Hanford area to

set up a temporary office on February 22, 1943. Hisorders were to purchase half a million acres in andaround the Hanford-Pasco-White Bluffs area, asparsely populated region where sheep ranching andfarming were the main economic activities. Many ofthe area’s landowners rejected initial offers on theirland and took the Army to court seeking more ac-ceptable appraisals. Matthias adopted a strategy ofsettling out of court to save time, time being a moreimportant commodity than money to the ManhattanProject.

Matthias received his assignment in late March.The three water-cooled piles, designated by the let-ters B, D, and F, would be built about six milesapart on the south bank of the Columbia River.The four chemical separation plants, built in pairs,would be nearly ten miles south of the piles, while afacility to produce slugs and perform tests would beapproximately twenty miles southeast of the separa-tion plants near Richkmd. Temporary quarters forconstruction workers would be put up in Hanford,while permanent facilities for other personnel wouldbe located down the road in Richland, safely remov-ed from the production and separation plants.

During summer 1943, Hanford became theManhattan Project’s newest atomic boomtown.Thousands of workers poured into the town, manyof them to leave in discontent. Well situated from alogistical point of view, Hanford was a sea of tentsand barracks where workers had little to do andnowhere to go. DuPont and the Army coordinatedefforts to recruit laborers from all over the countryfor Hanford, but even with a relative labor surplusin the Pacific Northwest, shortages plagued the pro-ject. Conditions improved significantly during thesecond half of the year, with the addhion of recrea-tional facilities, higher pay, and better overall ser-vic~ for Hanford’s population, which reached50,000 by summer 1944. Hanford still resembled thefrontier and mining towns once common in the

32

I The ManhattanEngineerDistrictin Operation I

AerialViewof HanfordCommunity.ReprintedfromRichardG. HewlettandOscarE. Anderson,Jr., Z7zeNewWor14 1939-1946VolumeI ofA Historyof the UnitedStatesAtomicEnew Commission(UniversityPark PennsylvaniaStateUniversityPress,1%2).

west, but the rate of worker turnover droppedsubstantially.

Groundbreaking for the water-cooling plant forthe 1OO-Bpile, the westernmost of the three, tookplace on August 27, less than two weeks beforeItaly’s surrender to the Allies on September 8. Workon the pile itself began in February, with the baseand shield being completed by mid-May. It tookanother month to place the graphite pile and installthe top shield and two more months to wire andpipe the pile and connect it to the various monitor-ing and control devices.

At Hanford, irradiated uranium slugs would dropinto water pools behind the piles and then be movedby remote<ontrolled rail cars to a storage facilityfive miles away for transportation to their final

destination at one of the two chemical separationlocations, designated 200-West and 200-East. The Tand U plants were located at 200-West, while asingle plant, the B unit, made up the 200-East com-plex (the planned fourth chemical separation plantwas not built). The Hanford chemical separationfacilitie+were massive scaled-up versions of thoseat Oak Ridge, each containing separation and con-centration buildings in addition to ventilation (toeliminate radioactive and poisonous gases) and wastestorage areas. Labor shortages and the lack of fma.1blueprints forced DuPont to stop work on the 200areas in summer 1943 and concentrate its forces on1OO-B,with the result that 1943 construction pro-gress on chemical separation was limited to diggingtwo huge holes in the ground~7

33

I Part w

PileD at Hanford.Pilein Foreground,WaterTreatmentPlantin Rear.ReprintedfromRichardG. HewlettandOscarE. Anderson,Jr., TheNewWorld 193$1944VolumeI ofA History of the United States Atomic Energy Commission (Universi~ ParkPennsylvaniaStateUniversityPress,1%2).

The Chemical Separation Buildings(Queen Marys)

Both 221T and 221U, the chemical separationbuildings in the 200-West complex, were ffished byDecember 1944. 221B, their counterpart in 200-East,was completed in spring 1945. Nicknamed QueenMarys by the workers who built them, the separa-tion buikiings were awesome canyon-like structures800 feet long, 65 feet wide, and 80 feet high con-taining forty process pools. The interior had an eeriequality as operators behind thick concrete shieldingmanipulated remote control equipment by lookingthrough television monitors and periscopes from anupper gallery. Even with massive concrete lids onthe process pools, precautions against radiation ex-posure were necessary and influenced all aspects ofplant design.38

Construction of the chemical concentrationbuildings (224-T, -U, and -B) was a less dauntingtask because relatively little radioactivity was involv-ed, and the work was not started until very late1944. The 200-West units were ftished in early Oc-tober, the East unit in February 1945. In the QueenMarys, bismuth phosphate carried the plutoniumthrough the long succession of process pooIs. The

ChemicalSeparationPlant(QueenMary)UnderConstructionatHanford.ReprintedfromRichardG. HewlettandOscarE.Anderson,Jr., i%eNewWorld, 19391944 VolumeI ofAHirtoty of the United Stat~ Atomic Energy Commission(University Park PennsylvaniaStateUniversityPress,1%2).

34

I The ManhattanEngineerDistrictin Operation I

CompletedQueen Mary at Hanford. Reprinted from Richard G. Hewlett and Oscar E. Anderson, Jr., The New World, 1939-1946,Volume I of A History of the United States Atomic Energy Commission (University Park Pennsylvania State University Press, 1962).

concentration stage was designed to separate the twochemicals. The normal relationship between pilotplant and”production plant was realized when theOak Ridge pilot plant reported that bismuthphosphate was not suitable for the concentrationprocess but that Seaborg’s original choice, lan-thanum fluoride, worked quite well. Hanford,accordingly,incorporatedthissugg~tionintotheconcentrationfacilities.Thefinalstepin plutoniumextraction was isolation, performed in a more typicallaboratory setting with little radiation present. HerePerlman’s earlier research on the peroxide methodpaid off and was applied to produce pure plutoniumnitrate. The nitrate would be converted to metal inLos Alamos, New Mexico.

Los AlamosThe final link in the Manhattan Project’s farflung

network was the Los Alamos Scientific Laboratoryin Los Alamos, New Mexico. The laboratory thatdesigned and fabricated the fust atomic bombs,codenamed Project Y, began to take shape in spring1942 when Conant suggested to Bush that the Officeof Scientific and Research Development and theArmy form a committee to study bomb develop-ment. Bush agreed and forwarded the recommenda-tion to Vice President Wallace, Secretary of War

Stirnson,and General Marshall (the Top PolicyGroup). By the time of his appointment in lateSeptember, Groves had orders to setup a committeeto study military applications of the bomb. Mean-while, sentiment was growing among the Manhattanscientists that research on the bomb project neededto be better coordinated. Oppenheimer, amongothers, advocated a central facility where theoreticaland experimental work could be conducted accor-ding to standard scientific protocols. This wouldinsure accuracy and speed progress. Oppenheimersuggested that the bomb laboratory operate secretlyin an isolated area but allow free exchange of ideasamong the scientists on the staff. Groves acceptedOppenheimer’s suggestion and began seeking an ap-propriate location.

The search for a bomb laboratory site quicklynarrowed to two places in northern New Mexico,Jemez Springs and the Los Alamos Boys RanchSchool, locations Oppenheimer knew well since hehad a ranch nearby in the Pecos Valley of theSangre de Cristo Mountains. In mid-November, Op-penheimer, Groves, Edwin M. McMilkm, andLieutenant Colonel W. H. Dudley visited the twosites and chose Los Akunos. Located on a mesaabout thirty miles northwest of Santa Fe, LosAlarnos was virtually inaccessible. It would have to

35

I IPart m

be provided with better water and power facilities, buy. By the end of 1942 the district engineer inbut the laboratory community was not expected to Albuquerque had orders to begin construction, andbeverylarge.Theboys’schooloccupyingthesite theU~versityof Californiahadcontractedto‘pro-was eager to sell, and Groves was equally eager to tide supplies and persomel.

\l f—~ -

Los Alamos Site. Reprinted from Vincent C. Jones, Manhattan: Tile Army and the Atomic Bomb(Washington, D.C.:U.S. GovernmentPrintingOffice,1985).

36

The ManhattanEngineerDistrictin Operation

Oppenheimer and GrovesOppenheimer,selectedto head the new

laboratory, proved to be an excellent director despiteinitial concerns about his administrative inex-perience, leftist political sympathies, and lack of aNobel Prize when several scientists he would bedrecting were prizewinners. Groves worked wellwith Oppenheimer although the two were fun-damentally different in temperament. Groves was apractical-minded military man, brusque and goal-oriented. His aide, Colonel Nichols, characterizedhis heavyset boss as ruthless, egotistical, and confi-dent, “the biggest S.O.B. I have ever worked for. Heis most demanding. He is most critical. He is alwaysa driver, never a praiser. He is abrasive and sar-castic,” Nichols admitted, however, that if he had itto do over again, he would once again “pickGeneral Groves [as his boss]” because of his un-questioned ability?g Groves demanded that theManhattan Project scientists spend all their time onthe bomb and resist the temptation, harmlessenough in peacetime, to follow lines of research thathad no direct applicability to immediate problems.In constrast to Groves, Oppenheimer was aphilosophical man, attracted to Eastern mysticismand of a decidedly theoretical inclination and sen-sitive nature. A chain-smoker given to long workinghours, Oppenheimer appeared almost emaciated.The Groves-Oppenheimer alliance, though not oneof intimacy, was marked by mutual respect and wasa major factor in the success of the ManhattanProject.

Oppenheimer insisted, with some success, thatscientists at Los Alamos remain as much anacademic community as possible, and he provedadept at satisfying the emotional and intellectualneeds of his highly distinguished staff. Hans Bethe,head of the theoretical division, remembered thatnobody else in that laboratory”. . . even cameclose to him. In his knowledge. There washuman warmth as well. Everybody certainlyhad the impression that Oppenheimer caredwhat each particular person was doing. In talk-ing to someone he made it clear that that per-son’s work was important for the success ofthe whole project.”4°

Oppenheimer had a chance to display his per-suasive abilities early when he had to convince scien-tists, many of them already deeply involved in war-related research in university laboratories, to join hisnew organization. Complicating his task were the

Groves and Oppenheimer.Reptited fromLeslieR. Groves,Now It tin Be Told (New York Harper&Row,1%2).

earlyplansto operateLosAkunosas a militarylaboratory. Oppenheimer accepted Groves’s rationalefor this arrangement but soon found that scientistsobjected to working as commissioned officers andfeared that the military chain of command was ill-suited to scientific decision making. The issue cameto a head when Oppenheimer tried to convinceRobert F. Bather and Isidor I. Rabi of theMassachusetts Institute of Technology’s RadiationLaboratory to join the Los Alarnos team. Neitherthought a military environment was conducive toscientific research. At Oppenheimer’s request, Con-ant and Groves wrote a letter explaining that thesecret weapon-related research had pr~identialauthority and was of the utmost national impor-tance. The letter promised that the laboratory wouldremain civilian through 1943, when it was believedthat the requirements of security would requiremilitarization of the final stages of the project (in

37

Part m

fact, militarization never took place). Oppenheimerwould supervise all scientific work, and the militarywould maintain the post and provide security.

Recruiting the StaffOppenheimer spent the f~st three months of 1943

tirelessly crisscrossing the country in an attempt to

put together a fwst-rate staff, an effort that provedfighly successful!l Even Bather signed on, thoughhe promised to resign the moment militarization oc-curred; Rabi, though he did not move to LosAlamos, became a valuable consultant. As soon asOppenheimer arrived at Los Alamos in mid-March,recruits began arriving from universities across theUnited States, including California, Minnesota,Chicago, Princeton, Stanford, Purdue, Columbia,IowaState,andtheMassachusetts Institute ofTechnology, while still others came from theMetLab and the National Bureau of Standards. Virtual-ly overnight Los Akunos became an ivory towerfrontier boomtown, as scientists and their families,along with nuclear physics equipment, including twoVan de Graaffs, a Cockroft-Walton accelerator, anda cyclotron, arrived caravan fashion at the Santa Ferailroad station and then made their way “up to themesa along the single primitive road. It was a mostremarkable collection of talent and machinery thatsettled this remote outpost of the ManhattanProject.

Theory and the “Gadget”The initial spartan environment of “the Hill”

(which included box lunches and temporary housing)was without doubt quite a contrast to the comfor-table campus settings so familiar to many on thestaff. But the laboratory’s work began even as theCorps of Engineers struggled to provide theamenities of civilized life. The properties of uraniumwere reasonably well understood, those ofplutonium less so, and knowledge of fission explo-sions entirely theoretical. That 2.2 secondaryneutrons were produced when uranium-235 fissionedwas accepted, but while Seaborg’s team had provenin March 1941 that plutonium underwent neutron-induced f~sion, it was not known yet if plutoniumreleased secondary neutrons during bombardment.The theoretical consensus was that chain reactionstook place with sufficient speed to produce powerfulreleases of energy and not simply explosions of thecritical mass itself, but only experiments could test

the theory. The optimum size of the critical mass re-mained to be established, as did the optimum shape.When enough data were gathered to establishop-timum critical mass, optimum effective mass stillhad to be determined. That is, it was not enoughsimply to start a chain reaction in a critical mass; itwas necessary to start one in a mass that wouldrelease the greatest possible amount of energy beforeit was destroyed in the explosion.

In addition to calculations on uranium andplutonium fission, chain reactions, and critical andeffective masses, work needed to be done on theordnance aspects of the bomb, or “gadget” as itcame to be known. Two subcritical masses of fis-sionable material would have to come together toform a supercritical mass for an explosion to occur.Furthermore, they had to come together in a precisemanner and at high speed. Measures also had to betaken to insurethat thehighlyunstablesubcriticalmasses did not predetonate because ofspontaneously emitted neutrons or neutrons produc-ed by alpha particles reacting with lightweight im-purities. The chances of predetonation could bereduced by purification of the fissionable materialand by using a high-speed ftig system capable ofachieving velocities of 3,000 feet per second. A con-ventional artillery method of ftig one subcriticalmass into the other was under consideration foruranium-235, but this method would work forplutonium only if absolute purification of plutoniumcould be achieved.

A variation of the explosion method was designedfor uranium. Bomb designers, unable to solve thepurification problem, turned to the relativelyunknown implosion method for plutonium. Withimplosion, symmetrical shockwaves directed inwardwould compress a subcritical mass of plutoniumpacked in a nickel casing (tarnper), releasingneutrons and causing a chain reaction.

Always in the background loomed the hydrogenbomb, a thermonuclear device considerably morepowerful than either a uranium or plutonium devicebut one that needed a nuclear fission bomb as adetonator. Research on the hydrogen bomb, orSuper, was always a distant second in priority atLos Alamos, but Oppenheimer concluded that itwas too important to ignore. After considerablethought, he gave Teller permission to devote himselfto the Super. To make up for Teller’s absence,Rudolf Peierls, one of a group of British scientistswho reinforced the Los Alamos staff at the begin-ning of 1944, was added to Bethe’s theory group inmid-1944. Another member of the British contingent

38

I The ManhattanEngineerD~trict in Operation I

was the Soviet agent Klaus Fuchs, who had beenpassing nuclear information to the Russians since1942 and continued doing so until 1949 when hewas caught and convicted of espionage (and subse-quently exchanged) .42

AnotherLewisCommitteeThe fwst few months at Los Alamos were oc-

cupied with bnefmgs on nuclear physics for thetechnical staff and with planning research prioritiesand organizing the laboratory. Groves called onceagain on Warren Lewis to head a committee, thistime to evaluate the Los Akunos program. Thecommittee’s recommendations resulted in the coor-dinated effort envisioned by those who advocated aunified laboratory for bomb research. Fermi tookcontrol of critical mass experiments and standardiza-tion of measurement techniques. Plutoniumpurification work, begun at the Met Lab, becamehigh priority at Los Alamos, and increased attentionwas paid to metallurgy. The committee also recom-mended that an engineering divi.4on be organized tocollaborate with physicists on bomb design andfabrication. The laboratory was thus organized intofour divisions: theoretical (Hans A. Bethe); ex-perimental physics (Robert F. Bather); chemistryand metallurgy (Joseph W. Kennedy); and ordnance(Navy Captain William S. “Deke” Parsons). Likeother Manhattan Project installations, Los Alamossoonbeganto expandbeyondinitialexpectations.

Asdirector,Oppenheimershoulderedburdensboth large and small, including numerous mundanematters such as living quarters, mail censorship,salaries, promotions, and other “quality of life”issues inevitable in an intellectual pressure-cookerwith few social amenities. Oppenheimer relied on agroup of advisers to help him keep the “big picture”in focus, while a committee made up of Los Alamosgroup leaders provided day-today communicationsbetween divisions.

Early ProgressEarly experiments on both uranium and

plutonium provided welcome results. Uranium emit-ted neutrons in less than a billionth of a second—just enough time, in the world of nuclear physics,for an efficient explosion. Ernilio Segre later provid-ed an additional cushion with his dkcovery inDecembek 1943 that, if cosmic rays were eliminated,

the subcritical uranium masses would not have to bebrought together as quickly as previously thought;nor would the uranium have to be as pure. Muzzlevelocity for the scaleddown artillery piece could belower, and the gun could be shorter and lighter.43Segre’s tests on the fust samples of plutoniumdemonstrated that plutonium emitted even more

neutronsthanuraniumdueto thespontaneousfis-sion of plutoniurn-240. Both theory and experiment-al data now agreed that a bomb using either ele-ment would detonate if it could be designed andfabricated into the correct size and shape. But manydetails remained to be worked out, includingcalculations to determine how much uranium-235 orplutonium would be needed for an explosive device.

Bather’s engineering ditilon patiently generatedthe essential cross-sectional measurements needed tocalculate critical and efficient mass. (The cross sec-tion is a measurement that indicates the probabilityof a nuclear reaction taking place). The same grouputilized particle accelerators to produce the largenumbers of neutrons needed for its cross-sectionalexperiments. Bather’s group also compiled data thathelped identify tamper materials that would most ef-fectively push neutrons back to the core andenhance the efficiency of the explosion. Despite LosAlamos’s postwar reputation as a mysterious retreatwhere brilliant scientists performed miracles ofnuclear physics, much of the work that led to theatomic bombs was extremely tedious.

Thechemists’job wasto purifytheuranium-235andplutonium,reducethemto metals,andprocessthe tamper material. Only highly purified uraniumand plutonium would be safe from predetonation.Fortunately purification standards for uranium wererelatively modest, and the chemical division was ableto focus its effort on the lesser known plutoniumand make substantial progress on a multi-stepprecipitation process by summer 1944. Themetallurgy division had to turn the purifieduranium-235 and plutonium into metal. Here, too,significant progress was made by summer as themetallurgists adapted a stationary-bomb techniqueinitially developed at Iowa State University.

Parsons, in charge of ordnance engineering,directed his staff to design two artillery pieces ofrelatively standard specifications except for their ex-tremely light barrels-one for a uranium weaponand one for a plutonium bomb. The weapons need-ed to achieve high velocities, but they would nothave to be durable since they would only be fwedonce. Here again early efforts centered on the more

39

problematicplutoniumweapon,whichrequiredahigher velocity due to its higher risk of predetona-tion. Two plutonium guns arrived in March andwere field-tested successfully. In the same month,two uranium guns were ordered.

Early Implosion WorkParsons assigned implosion studies a low priority

and placed the emphasis on the more familiar ar-tillery method. Consequently, Seth H. Neddermeyerperformed his early implosion tests in relativeobscurity. Neddemeyer found it difficult to achievesymmetrical implosions at the low velocities he hadachieved. When the Princeton mathematician Johnvon Neumann, a Hungarian refugee, visited LosAlarnos late in 1943, he suggested that high-speedassembly and high velocities would preventpredetonation and achieve more symmetrical explo-sions. A relatively small, subcritical mass could beplaced under so much pressure by a symmetrical im-plosion that an efficient detonation would occur.Less critical material would be required, bombscould be ready earlier, and extreme purification ofplutonium would be unnecessary. Von Neumann’stheories excited Oppenheimer, who assigned Par-sons’s deputy, George B. Kistiakowsky, the task ofperfecting implosion techniques. Because Parsonsand Neddemeyer did not get along, it wasKistiakowsky who worked with the scientists on theimplosion project. While experiments on implosionand explosion continued, Parsons directed much ofhis effort toward developing bomb hardware, in-cluding arming and wiring mechanisms and fuzingdevices. Working with the Army Air Force, Par-sons’s group developed two bomb models by March1944 and began testing them with B-29s. Thin Man,named for President Roosevelt, utilized theplutonium gun design, while Fat Man, named afterWinston Churchill, was an implosion prototype.(Segre’s lighter, smaller uranium gadget became Lit-tle Boy, Thin Man’s brother).

Elimination of Thin ManThin Man was eliminated four months later

because of the plutonium-240 contamination pro-blem. Seaborg had warned that when plutonium-

239wasirradiatedfora lengthof timeitwaslikelyto pick up an additional neutron, transformingit into plutonium-240 and increasing the dangerof predetonation (the bullet and target in theplutonium weapon would melt before comingtogether). Measurements taken at Clinton confinedthe presence of plutonium-240 in the plutonium pro-duced in the experimental pile. On July 17 the dif-ficult decision was made to cease work on theplutonium gun method. Plutonium could be usedonly in an implosion device, but in summer 1944 animplosion weapon looked like a long shot.

Abandonment of the plutonium gun projecteliminated a shortcut to the bomb. “Thisnecessitateda revision of the estimates of weapon delivery Bushhad given the President in 1943. The new timetable,presented to General Marshall by Groves on August7,1944+wo months after the Allied invasion ofFrance began at Normandy on June 6—promisedsmall implosion weapons of uranium or plutoniumin the second quarter of 1945 if experiments provedsatisfactory. More certain was the delivery of auranium gun bomb by Augxut 1, 1945, and thedelivery of one or two more by the end of that year.Marshall and Groves acknowledged that Germansurrender might take place by summer 1945, thusmaking it probable that Japan would be the targetof any atomic bombs ready at that time.

Question Marks: Summer 1944It was still unclear if even the August 1 deadline

could be met. While expenditures reached $100million per month by mid-1944, the Manhattan Pro-ject’s goal of producing weapons for the current warwas not assured.OperationalproblemsplaguedtheY-12 electromagnetic facility just coming on line.The K-25 gaseous diffusion plant threatened tobecome an expensive white elephant if suitable bar-rier could not be fabricated. And the Hanford pilesand separation facilities faced an equally seriousthreat as not enough of the uranium-containingslugs to feed the pile were available. Even assumingthat enough uranium or plutonium could bedelivered by the production facilities built in suchgreat haste, there was no guarantee that the LosAlarnos laboratory would be able to design andfabricate weapons in time. Only the most optimisticin the Manhattan Project would have predicted, asGroves did when he met with Marshall, that a bombor bombs powerful enough to make a difference inthe current war would be ready by August 1, 1945.

40

The ManhattanEngineerDistrictin Operation 1

Progress at Oak RidgeDuring winter 1944-45 there was substantial

progress at Oak Ridge, thanks to improved perfor-mance in each of the production facilities andNichols’s work in coordinating a complicated feedschedule that maximized output of enriched uraniumby utilizing the electromagnetic, thermal diffusion,and gaseous diffusion processes in tandem. NineAlpha and three Beta racetracks were operationaland, while not producing up to design potential,were becoming significantly more reliable because ofmaintenance improvements and chemicalrefinements introduced by Tennessee Eastman. TheS-50 thermal diffusion plant being built by the H.K. Ferguson Company was almost complete and

Seetion of S-50 Liquid l’hennal Diffusion Plant at Clinton.Reprinted from Richard G. Hewlett and Oscar E. Anderson, Jr.,The New World, 1939-1946jVolume I of A HLstoty of theUnited States Atomic Enenjy Commission (University ParkPennsylvania State University Press, 1%2).

was producing small amounts of enriched materialin the ftihed racks, and the K-25 gaseous diffusionplant, complete with barriers, was undergoing fma.1leak tests. By March 1945, Union Carbide hadworked out most of the kinks in K-25 and hadstarted recycling uranium hexafluoride through thesystem. S-50 was ftihed at the same time that theY-12 racetracks were demonstrating increased effi-ciency. The Beta calutrons at the electromagneticplant were producing weapon-grade uranium-235using feed from the modified Alpha racetracks andthe small output from the gaseous diffusion andthermal diffusion facilities. Oak Ridge was now send-ing enough enriched uranium-235 to Los Ahtmosto meet experimental needs. To increase production,Grove-sproposed an additional gaseous diffusionplant (K-27) for low-level enrichment and a fourthBeta track for high-level enrichment, both to becompleted by February 1946, in time to contributeto the war against Japan, which many thoughtwould not conclude before summer 1946.

Hanford’s RoleWith the abandonment of the plutonium gm

bomb in July 1944, planning at Hanford becamemore complicated. Pile 1OO-Bwas almost complete,as was the fwst chemical separation plant, while pileD was at the halfway point. Pile F was not yetunder construction. If implosion devices usingplutonium could be developed at Los Alamos, thethree piles would probably produce enoughplutonium for the weapons required, but as yet noone was sure of the amount needed.

Pile OperationExcitement mounted at Hanford as the date for

pile start-up approached. Fermi placed the fwst slugin pile 1OO-Bon September 13, 1944. Final checkson the pile had been uneventful. The scientists couldonly hope they were accurate, since once the pilewas operational the intense radioactivity wouldmake maintenance of many components impossible.Loading slugs and taking measurements took twoweeks. From just after midnight until approximately3:00 a.m. on September 27, the pile ran without in-cident at a power level higher than any previouschain reaction (though only at a fraction of designcapacity). The operators were elated, but their ex-citement turned to astonishment when the power

41

Part m 1

level began falling after three hours. It fell con-tinuously until the pile ceased operating entirely onthe evening of the 28th. By the next morning thereaction began again, reached the previous day’slevel, then dropped.

Xenon PoisoningHanford scientists were at a loss to explain the

pile’s failure to maintain a chain reaction. Only theforesight of DuPont’s engineers made it possible toresolve the crisii. The cause of the strangephenomenon proved to be xenon poisoning. Xenon,a f~sion product isotope with a mass of 135, wasproduced as the pile operated. It captured neutronsfaster than the pile could produce them, causing agradual shutdown. With shutdown, the xenondecayed, neutron flow began, and the pile started upagain. Fortuitously, despite the objections of somescientists who complained of DuPont’s excessivecaution, the company had installed a large numberof extra tubes. This design feature meant that pile1OO-Bcould be expanded to reach a power level suf-ficient to overwhehn the xenon poisoning. Successwas achieved when the fwst irradiated slugs weredischarged from pile 10@Bon Christmas Day, 1944.The irradiated slugs, after several weeks of storage,went to the chemical separation and concentrationfacilities. By the end of January 1945, the highlypurified plutonium underwent further concentrationin the completed chemical isolation building, whereremaining impurities were removed successfully. LosAkunos received its fust plutonium on February 2.M

Reorganizing for the Final PushOppenheimer acted quickly to maximize the

laboratory’s efforts to master implosion. Only if theimplosion method could be perfected would theplutonium produced at Hanford come into play.Without either a plutonium gun bomb or implosionweapon, the burden would fall entirely on uraniumand the less efficient gun method. Oppenheimerdirected a major reorganization of Los Akunos inJuly 1944 that prepared the way for the finaldevelopment of an implosion bomb. Robert Bathertook over G DivMon (for gadget) to experimentwith implosion and design a bomb; GeorgeKistiakowsky led X DivMon (for explosives) in workon the explosive components; Hans Bethe continuedto head up theoretical studies; and “Deke” Parsonsnow focused on overall bomb construction and

delivery.

Field tests performed with uranium-235 pro-totypes in late 1944 eased doubts about the artillerymethod to be employed in the uranium bomb. Itwas clear that the uranium-235 from Oak Ridgewould be used in a gun-type nuclear device to meetthe August 1 deadline Groves had given GeneralMarshall and the Joint Chiefs of Staff. Theplutonium produced at such expense and effort atHanford would not fit into wartime planning unlessa breakthrough in implosion technology occurred.

At the same time, Los Alamos shifted fkomresearch to development and production. Time wasof the essence, though laboratory research had notyet charted a clear path to the final product. ArmyAir Force training could wait no longer, and inSeptember at Wendover Field in western Utah, Col-onel Paul Tibbets began drilling the 393rd Bombard-ment Squadron, the heart of the 509th CompositeWing, in test drops with 5,500-pound orange dum-my bombs, nicknamed pumpkins. In June 1945,Tibbets and his command moved to Tinian Island inthe Marianas, where the Navy SeaBees had built theworld’s largest airport to accommodate Boeing’snew B-29 Superfortresses.

Taking Care of BusinessPersonnel shortages, particularly of physicists, and

supply problems complicated Oppenheimer’s task.The procurement system, designed to protect thesecrecy of the Los Akunos project, led to frustratingdelays and, when combined with persistent late warshortages, proved a constant headache. The lack ofcontact between the remote laboratory and its sup-ply sources exacerbated the problem, as did therelative lack of experience the academic scientistshad with logistical matters.

Groves and Conant were determined not to letmundane problems compromise the bomb effort,and in fall 1944 they made several changes toprevent-this possibility. Conant shipped as manyscientists as could be spared from Chicago and OakRidge to Los Alamos, hired every civilian machinisthe could lay his hands on, and arranged for Armyenlisted men to supplement the work force (theseGIs were known as SEDS, for Special EngineeringDetachment). Hartley Rowe, an experienced in-dustrial engineer, provided help in easing the transi-tion from research to production. Los Alamos alsoarranged for a rocket research team at the Califor-nia Institute of Technology to aid in procurement,

42

The Manhattan Engineer District in Operation I

test fuzes, and contribute to component develop-ment. These changes kept Los Akunos on track asweapon design reached its final stages.

Freezing Weapon DesignWeapon design for the uranium gun bomb was

frozen in February 1945. Confidence in the weaponwas high enough that a test prior to combat use was

seenasunnecessary.Thedesignforanimplosiondevice was approved in March with a test of themore problematic plutonium weapon scheduled forJuly 4. Oppenheimer shifted the laboratory into highgear and assigned Allison, Bather, and Kistiakowskyto the CowPuncher Committee to “ride herd” on theimplosion weapon. He placed Kenneth T. Bain-bridge in charge of Project Trinity, a new divisionto oversee the July test ftig. Parsons headed Pro-ject Alberta, known as Project A, which had theresponsibility for preparing and delivering weaponsfor combat.

During these critical months much depended uponthe ability of the chemists and metallurgists to pro-

cess the uranium and plutonium into metak andcraft them into the correct shape and size.Plutonium posed by far the greater obstacle. It ex-isted in different states, depending upon tempera-ture, and was extremely toxic. Working under in-tense pressure, the chemists and metallurgistsmanaged to develop precise techniques for process-ing plutonium just before it arrived in quantitybeginning in May.

As a result of progress at Oak Ridge andmetallurgicalandchemicalrefinementsonplutoniumthat improvedimplosion’schances,the Inine months between July 1944 and April 1945 sawthe American bomb projeet progress from doubtfulto probable. The August 1 delivery date for the Lit-tle Boy uranium bomb certainly appeared more like-ly than it had when Groves briefed Marshall. Therewould be no implosion weapons in the fust half of1945 as Groves had hoped, but developments inApril boded well for the scheduled summer test ofthe Fat Man plutonium bomb. And recent edcula-tions provided by Bethe’s theoretical group gavehope that the yield for the fwst weapon would be inthe vicinity of 5,000 tons of TNT rather than the1,000-ton estimate provided in fall 1944.

Part V:The Atomic Bomb and AmericanStrategy

With the Manhattan Project on the brink of suc-cess in spring 1945, the atomic bomb became an in-creasingly important element in American strategy.A long hoped-for weapon now seemed within reachat a time when hard decisions were being made, notonly on ending the war in the Pacific, but also onthe shape of the postwar international order.

From Roosevelt to TrumanOn April 12, only weeks before Germany’s un-

conditional surrender on May 7, President Rooseveltdied suddenly in Warm Springs, Georgia, bringingVice President Harry S. Truman, a veteran of theUnited States Senate, to the presidency. Truman wasnot privy to many of the secret war effortsRoosevelt had undertaken and had to be briefed ex-tensively in his first weeks in office. One of thesebriefings, provided by Secretary of War Stimson onApril 25, concerned S-1 (the Manhattan Project).Stimson, with Groves present during part of themeeting, traced the history of the Manhattan Pro-ject, summarized its status, and detailed thetimetable for testing and combat delivery. Trumanasked numerous questions during the forty-five-

rninute meeting and made it clear that heunderstood the relevance of the atomic bomb to up-coming diplomatic andmilitaryinitiatives.

By the time Truman took office, Japan was neardefeat. American aircraft were attacking Japanesecities at will. A single fmebomb raid in March killednearly 100,000 people and injured over a million inTokyo. A second air attack on Tokyo in May killed83,000. Meanwhile, the United States Navy had cutthe islands’ supply lines. But because of the general-ly accepted view that the Japanese would fight tothe bitter end, a costly invasion of the home islandsseemed likely, though some American policy makersheld that successful combat delivery of one or moreatomic bombs might convince the Japanese that fur-ther resistance was futile.

The Interim Committee ReportOn June 6 Stimson again briefed Truman on S-1.

The briefing summarized the consensus of anInterim Committee meeting held on May 31. TheInterim Committee was an advisory group onatomic research composed of Bush, Conant, Comp-ton, Under Secretary of the Navy Ralph A. Bard,Assistant Secretary of State William L. Clayton, andfuture Secretary of State James F. Bymes. Op-penheimer, Fermi, Compton, and Lawrence servedas scientific advisors (the Scientific Panel), whileMarshall represented the military. A second meetingon June 1 with Walter S. Carpenter of DuPont,James C. White of Tennessee Eastman, George H.Bucher of Westinghouse, and James A. Rafferty ofUnion Carbide provided input from the businessside. The Interim Committee was charged withrecommending the proper use of atomic weapons inwartime and developing a position for the UnitedStates on postwar atomic policy. The May 31meeting concluded that the United States should tryto retain superiority of nuclear weapons in case in-ternational relations detenorated!5 Most present atthe meeting thought that the United States shouldprotect its monopoly for the present, though theyconceded that the secrets could not be held long. Itwas only a matter of time before another country,presumably Russia, would be capable of producingatomic weapons.

There was some discussion of free exchange ofnuclear research for peaceful purposes and the inter-national inspection system that such an exchangewould require. Lawrence’s suggestion that ademonstration of the atomic bomb might possibly

45

convince the Japanese to surrender was discussedover lunch and rejected. The bomb might be a dud,the Japanese might put American prisoners of warin the area, or shoot down the plane, and the shockvalue of the new weapon would be lost. Thesereasons and others convinced the group that thebomb should be dropped without warning on a dualtarget-a war plant surrounded by workers’ homes.The meeting with the industrialists on June 1 furtherconvinced the Interim Committee that the UnitedStates had a lead of three to ten years on the SovietUnion in production facilities for bomb fabrication.

On June 6 Stimson informed the President thatthe Interim Committee recommended keeping S-1 asecret until Japan had been bombed. The attackshould take place as soon as possible and withoutwarning. Truman and Stirnson agreed that the Presi-dent would stall if approached about atomicweapons in Berlin, but that it might be possible togain concessions from Russia later in return for pro-viding technical information. Stimson told Trumanthat the Interim Committee was consideringdomestic legislation and that its members generallyheld the position that international agreementsshould be made in which all nuclear research wouldbe made public and a system of inspections wouldbe devised. In case international agreements werenot forthcoming, the United States should continueto produce as much Fusionable material as possibleto take advantage of its current position ofsuperiority.

Planning for SurrenderStrategies for forcing Japanese capitulation oc-

cupied center stage in June. Truman gained Chineseconcurrence in the Yalta agreements by assuring T.V. Soong, the Chinese foreign minister, thatRussia’s intentions in the Far East were benevolent,smoothing the way for the entrance of the RedArmy. Joseph C. Grew, acting secretary of state,clarified the deftition of unconditional surrender.Japan need not fear total annihilation, Grew stated.Once demilitarized, Japan would be free to chooseits political system and would be allowed to developa vibrant economy. Grew hoped that a public state-ment to Japan would lead to surrender before acostly invasion would have to be launched. TheJoint Chiefs of Staff continued to advocate the in-vasion of Kyushu, a plan identified as OperationOlympic. Stimson hoped that an invasion could beavoided, either by redeftig the surrender terms or

by using the atomic bomb.Indicative of the wide range of his responsibilities

was Groves’s position as head of a bomb targetselection group set up in late April, a responsibilityhe shared with General Thomas Farrell, appointedGroves’s military aide in February 1945. In late Maythe committee of scientists and Army Air Force of-ficers listed Kokura Arsenal, Hiroshima, Niigata,and Kyoto as the four best @gets, believing that at-tacks on these cities-none of which had yet beenbombed by Curtis LeMay’s Twentieth Air Force(which planned to eliminate all major Japanese citiesby January 1, 1946)-would make a profoundpsychological impression on the Japanese andweaken military resistance. Stimson vetoed Kyoto,Japan’s most cherished cultural center, andNagasaki replaced the ancient capital in the directiveissued to the Army Air Force on JuIy 25$6

The Franck Report and Its CriticsMeanwhile the Met Lab was beginning to stir.

The Scientific Panel of the Interim Committee wasthe comection between the scientists and the policymakers, and Compton was convinced that theremust be a high level of participation in the decision-making process. His June 2 briefiig of the Met Labstaff regarding the findings of the Interim Committ-ee led to a flurry of activity. The Met Lab’s Com-mittee on the Social and Political Implications of theAtomic Bomb, chaired by James Franck and in-cluding Seaborg and Szilard, issued a report advo-cating international control of atomic power asthe only way to stop the arms race that would be in-evitable if the United States bombed Japan withoutfust demonstrating the weapon in an uninhabitedam.

The Scientific Panel disagreed with the FranckReport, as the Met Lab study was known, and con-cluded that no technical test would convince Japanto surrender. The Panel concluded that such amilitary demonstration of the bomb might best fur-ther the cause of peace but held that such ademonstration should take place only after theUnited States informed its allies. On June 21 the In-terim Committee sided with the position advancedby the Scientific Panel. The bomb should be used assoon as possible, without warning, and against awar plant surrounded by additional buildings. As toinforming allies, the Committee concluded thatTruman should mention that the United States waspreparing to use a new kind of weapon againstJapan when he went to Berlin in July. On July 2,

46

—.

IiI

TheAtomicBombandAmerican5tmtegy

1945,PresidentTruman listened as Stimson outlined Stimson returned on July 3 and suggested thatthe peace terms for Japan, including demilitarization Truman broach the issue of the bomb with Stalinand prosecution of war criminals in exchange for and tell the Soviet leader that it could become aeconomic and governmental freedom of choice. force for peace with mo~er ameements47.

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LiuuLy 1~L mw, wprmtett rrom vtncent C. Jones, Manhattan: I’7zeArmy and the Atomic Bomb (Washington,D.C.:U.S.GovernmentPrintingOffice,1985).

47

Part v I

The Trinity Test

Meanwhile, the test of the plutonium weapon,named Trinity by Oppenheimer (a name inspired bythe poems of John Donne), was rescheduled for Ju-ly 16 at a barren site on the Alamogordo BombingRange known as the Jomada del Muerto, orJourney of Death, 210 miles south of Los Alamos.A test explosion had been conducted on May 7 witha smalI amount of f~sionable material to check pro-cedures and fine-tune equipment. Preparations con-tinued through May and June and were complete bythe beginning of July. Three observation bunkerslocated 10,000 yards north, west, and south of theftig tower at ground zero would attempt tomeasure critical aspects of the reaction. Specifically,scientists would try to determine the symmetry ofthe implosion and the amount of energy released.Additional measurements would be taken to deter-mine damage estimates, and equipment wouldrecord the behavior of the f~ebaU. The biggest con-cern was control of the radioactivity the test devicewould release. Not entirely content to trust favorablemeteorological conditions to carry the radioactivityinto the upper atmosphere, the Army stood ready toevacuate the people in surrounding areas.

On July 12 the plutonium core was taken to thetest area in an army sedan. The non-nuclear com-ponents left for the test site at 12:01 a.m., Fridaythe 13th. During the day on the 13th, final assemblyof the gadget took place in the McDonald ranchhouse. By 5:00 p.m. on the 15th, the device hadbeen assembled and hoisted atop the one-hundred-foot firing tower. Groves, Bush, Conant, Lawrence,Farrell, Chadwick @ad of theBritishcontingentatLos Alamos and discoverer of the neutron), andothers arrived in the test area, where it was pouringrain. Groves and Oppenheimer, standing at theS-10,OOOcontrol bunker, discussed what to do if theweather did not break in time for the scheduled 400a.m. test. At 3:30 they pushed the time back to5:30; at 400 the rain stopped. Kistiakowsky and histeam armed the device shortly after 5:00 a.m. andretreated to S-10,OOO.In accordance with his policythat each observe from different locations in case ofan accident, Groves left Oppenheimer and joinedBush and Conant at base camp. Those in sheltersheard the countdown over the public addresssystem, while observers at base camp picked it upon an FM radio signal.48

The Dawn of the Atomic Age

At precisely 5:30 a.m. on Monday, July 16, 1945,the atomic age began. While Manhattan staffmembers watched anxiously, the device explodedover the New Mexico desert, vaporizing the towerand turning asphalt around the base of the tower togreen sand. The bomb released approximately 18.6kilotons of power, and the New Mexico sky wassuddenly brighter than many suns. Some observerssuffered temporay blindness even though they look-ed at the brilliant light through smoked glass.Seconds after the explosion came a huge bkwt, sen-ding searing heat across the desert and knockingsome observers to the ground. A steel containerweighing over 200 tons, standing a half-mile fromground zero, was knocked ajar. (Nicknamed Jum-bo, the huge container had been ordered for theplutonium test and transported to the test site buteliminated during fmrd planning). As the orange andyellow fueball stretched up and spread, a secondcolumn, narrower than the f~st, rose and flattenedinto a mushroom shape, thus providing the atomicage with a visual image that has become imprintedon the human consciousness as a symbol of powerand awesome destruction.@

Tower For Trinity Test. Department of Ene~.

48

The Atomic Bomb and AmericanStrategy

At base camp, Bush, Conant, and Groves shookhands. Oppenheimer reported later that the ex-perience edled to his mind the legend of Pro-metheus, punished by Zeus for giving man fwe. Healso thought fleetingly of Alfred Nobel’s vain hopethat dynamite would end wars. The terrifyingdestructive power of atomic weapons and the usesto which they might be put were to haunt many ofthe Manhattan Project scientists for the remainderof their lives.50

The success of the Trinity test meant that a se-cond type of atomic bomb could be readied for useagainst Japan. In addition to the uranium gunmodel, which was not tested prior to being used incombat, the plutonium implosion device detonatedat Trinity now figured in American Far Easternstrategy. In the end Little Boy, the untested uraniumbomb, was dropped f’i.ist at Hiroshima on August 6,1945, while the plutonium weapon Fat Man followedthree days later at Nagasaki on August 9.

.

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Trinity Device Being Readied. Reprinted from Richard G.Hewlett and Oscar E. kderson, Jr., i%e New World,1939-194~ Volume I of A History of the United States AtomicEnergy CommLwion (University Park Pennsylvania StateUniversity Press, 1%2).

----

Remainsof TrinityTestTowerFootings.OppenheimerandGrovesat Center.Depatimentof Energy,

PotsdamThe beriean contingent to the Big Three con-

ference, headed by Truman, Byrne-s,and Stirnson,arrived in Berlin on July 15 and spent most of thenext two days. grappling with the interrelated issuesof Russian participation in the Far Eastern conflictand the wording of an early surrender offer thatmight be presented to the Japanese. This draft sur-render document received considerable attention, thesticking point being the term “unconditional.” It wasclear that the Japanese would fight on rather thanaccept terms that would eliminate the ImperialHouse or demean the warrior tradition, butAmerican policy makers feared that anything lessthan a more democratic political system and totaldemilitarization might lead to Japanese aggression inthe future. Much effort went into finding the preciseformula that would satisfy Ameriean war k ihthe Pacific without requiring a costly invasion of theJapanese mainland. In an attempt to achieve sur-render with honor, the emperor had instructed hisministers to open negotiations with Russia. TheUnited States intercepted and decoded messages be-tween Tokyo and Moscow that made it un-mistakably clear that the Japanese were searchingfor an alternative to unconditional surrender.

Reports on TrinityStalin arrived in Berlin a day late, leaving Stimson

July 16 to mull over questions of postwar Germanadministration and the Far Eastern situation. Aftersending Truman and Byrnes a memorandum ad-

49

Part V: I

vocating an early warning to Japan and setting out abargaining strategy for Russian entry in the Pacificwar, Stimson received a cable from George L. Har-rison, his special consultant in Washington, thatread:Operated on this morning. Diagnosis not yetcomplete but results seem satisfactory and

already exceed expectations. Local press releasenecessary as interest extends great distance. Dr.Groves pleased. He returns tomorrow. I willkeep you posted~l

Stimson immediately informed Truman and Byrnesthat the Trinity test had been successful. The nextday Stimson informed Churchill of the test. Theprime minister expressed great delight and arguedforcefully against informing the Russians, though helater relented. On July 18, while debate continuedover the wording of the surrender message, focusingon whether or not to guarantee the place of theemperor, Stirnson received a second cable fromHarrisorc

Doctor has just returned most enthusiastic andconildent that the little boy is as husky as hisbig brother. The light in his eyes discerniblefrom here to HighhoId and I could have heardhis screams from here to my farm.52

Translation Groves thought the plutonium weaponwould be as powerful as the uranium device andthat the Trinity test could be seen as far away as 250miles and the noise heard for ftity miles. Initialmeasurements taken at the Alamogordo site sug-gested a yield in excess of 5,000 tons of TNT.Truman went back to the bargaining table with anew card in his hand.

Further information on the Trinity test arrived onJuly 21 in the form of a long and uncharacteris-tically excited report from Groves. Los Alarnosscientists now agreed that the blast had been theequivalent of between 15,000 and 20,000 tons ofTNT, higher than anyone had predicted. Grovesreported that glass shattered 125 miles away, thatthe firebail was brighter than several suns at midd-ay, and that the steel tower had been vaporized.Though he had previously believed it impregnable,Groves stated that he did not consider the Pentagonsafe from atomic attack.53 Stirnson informed Mar-shall and then read the entire report to Truman andByrnes. Stimson recorded that Truman was“tremendously pepped up” and that the documentgave him an entirely new feeling of confidence.”54The next day Stimson, informed that the uraniumbomb would be ready in early August, discussed

Grove’s report at great length with Churchill. TheBritish prime minister was elated and said that henow understood why Truman had been so forcefulwith Stalin the previous day, especially in his opposi-tion to Russian designs on Eastern Europe andGermany. Churchill then told Truman that the bombcould lead to Japanese surrender without an invasionand eliminate the necessity for Russian military help.He recommended that the President continue to takea hard line with Stalin. Truman and his advisorsshared Churchill’s views. The success of the Trinitytest stiffened Truman’s resolve, and he refused toaccede to Stalin’s new demands for concessions inTurkey and the Medherranean.

On July 24 Stimson met with Truman. He told thePresident that Marshall no longer saw any need forRussian help, and he briefed the President on thelatest S-1 situation. The uranium bomb might beready as early as August 1 and was a certainty byAugust 10. The plutonium weapon would be avail-able by August 6. Stimson continued to favor makingsome sort of commitment to the Japanese emperor,though the draft already shown to the Chinese wassilent on this issue.

Truman Informs StalinAmerican and British coordination for an inva-

sion of Japan continued, with November 1 standingas the landing date. At a meeting with Americanand British military strategists at Potsdam, the Rus-sians reported that their troops were moving into theFar East and could enter the war in mid-August.They would drive the Japanese out of Manchuriaand withdraw at the end of hostilities. Nothing wassaid about the bomb. This was left for Truman,who, on the evening of July 24, approached Stalinwithout an interpreter to inform the Generalissimothat the United States had a new and powerfulweapon. Stalin casually responded that he hopedthat it would be used against Japan to good effect.The reason for Stalin’s composure became clearlater when it was learned that Russian intelligencehad been receiving information about the S-1 pro-ject from Klaus Fuchs and other agents since sum-mer 1942.

The Potsdam ProclamationA directive, written by Groves and issued by

Stirnson and Marshall on July 25, ordered the ArmyAir Force’s 509th Composite Group to attackHiroshima, Kokura, Niigata, or Nagasaki “after

50

I The AtomicBomb and AmerieanStrategy

about” August 3, or as soon as weather permitted.55The 509th was ready. Tests with ddes had beenconducted successfully, and Operation Bronx, whichbrought the gun and uranium-235 projectile to Ti-tian aboard the U,S.S, hiitznapolis and the othercomponents on three C-54s, was complete. OnJuly 26 the United States learned of Churchill’s elec-toral defeat and Chiang Kai-Shek’s concurrence inthe warning to Japan. Within hours the warningwas issued in the name of the President of theUnited States, the president of China, and the primeminister of Great Britain (now Clement AttIee). TheRussians were not informed in advance. This pro-cedure was technically correct since the Russians

werenotatwarwithJapan,butit wasanotherin-dication of the new American attitude that theSoviet Union’s aid in the present conflict no longerwas needed. The message called for the Japanese tosurrender unconditionally or face “prompt and utterdestruction.”sb The Potsdarn Proclamation left theemperor’s status unclear by making no reference tothe royal house in the section that promised theJapanese that they could design their new gover-nmentas long as it was peaceful and moredemocratic. While anti-war sentiment was growingin Japanese dec~lon-making circles, it could notcarry the day as long as unconditional surrender leftthe emperor’s position in jeopardy. The Japanese re-jected the offer on July 29.

Intercepted messages between Tokyo and Moscowrevealed that the Japanese wanted to surrender butfelt they could not accept the terms offered in thePotsdam Proclamation. American policy makers,however, anxious to end the war without committ-ing American servicemen to an invasion of theJapanese homeland, were not inclined to undertakerevisions of the unconditional surrender formula andcause further delay. A Russian declaration of warmight convince Japan to surrender, but it carried apotentially prohibitive price tag as Stalin would ex-pect to share in the postwar administration ofJapan, a situation that would threaten Americanplans in the Far East. A blockade of Japan combin-ed with conventional bombing was rejected as tootime-consuming and an invasion of the islands astoo costly. And few believed that a demonstrationof the atomic bomb would convince the Japanese togive up. Primarily upon these grounds, Americanpolicy makers concluded that the atomic bomb mustbe used. Information that Hiroshima might be theonly prime target city without American prisoners inthe vicinity placed it fwst on the list. As the final

touches were put on the message Truman wouldissue after the attack, word earne that the fwst bombcould be dropped as early as August 1. With theend now in sight, poor weather led to several days’delay.

HiroshimaIn the early morning hours of August 6, 1945, a

B-29 bomber attached to the 590th CompositeGroup took off from Tinkm Island and headednorth by northwest toward the Japanese Islandsover 1,500 miles away. Its primary target wasHiroshima, an important military and communicat-ions center with a population of nearly 300,000located in the deltas of southwestern Honshu Islandfacing the Inland Sea. The Enokz Gay, piloted byColonel Paul Tibbets, flew at low altitude onautomatic pilot before climbmg to 31,000 feet as itneared the target area. As the observation andphotography escorts dropped back, the Enola Gayreleased a 9,700-pound uranium bomb, nicknamedLittle Boy, at approximately 8:15 a.m. Hiroshimatime. Tibbets im.rnediately dove away to avoid theanticipated shockwaves of the blast. Forty-threeseconds later a huge explosion lit the morning sky asLittle Boy detonated 1900 feet above the city, direct-ly over a parade field where the Japanese SecondArmy was doing calisthenics. Though already elevenand a half miles away, the Enola Gay was rockedby the blast. At f~st Tibbets thought he was takingflak. After a second shockwave hit the Diane, thecrew looked back at Hiroshima. “The ~ity w-mhid-den by that awfld cloud . . .boiling up, mushroom-ing, terrible and incredibly tall,” Tibbets recaUed.57Little Boy killed 70,000 people (including abouttwenty Arneriea.n airmen being held as POWs) andinjured another 70,000. By the end of 1945, theHiroshima death toti rose to 140,000 as radiation-sickness deaths mounted. Five years later the totalreached 200,000. The bomb caused total devastationfor five square miles, with almost all of thebuildings in the city either destroyed or darnaged.

Within hours of the attack, radio stations beganreading a prepared statement from President HarryTruman informing the American public that theUnited States had dropped an entirely new type ofbomb on the Japanese city of Hiroshima-anatomic bomb with more power than 15,000 tons ofTNT?s Truman warned that if Japan still refused tosurrender unconditionally as demanded by thePot.sdam Proclamation of July 26, the United States

51

Part v. I

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52

The AtomicBomb and American Strategy

1----

Model of Little Boy UraniumBomb.ReprintedfromRichardG. HewlettandOscarE. Anderson,Jr., TheNW World 193$W?413Volume I of A Hirtory of the United Stater Atomic EneW Commission (Universi@Park: Pennsylvania State University Press, 1%2).

would attack additional targets with equallydevastating results. Two days later, on August 8, theSoviet Union declared war on Japan and attackedJapanese forces in Manchuria, ending Americanhopes that the war would end before Russian entryinto the Pacific theater.

:$f/Fat Man Plutonium Bomb Being Readied at Tinian. Los AlamosNationalLaboratoy.

NagasakiFactional struggles and communications problems

prevented Japan from meeting Allied terms in theimmediate aftermath of Hiroshima. In the absenceof a surrender announcement, conventional bomb-ing raids on additional Japanese cities continued asscheduled. Then, on August 9, a second atomic at-tack took place. Taking off from Tinian at 3:47a.m., Bock% Car (named after its usual pilot) head-ed for its primary target, Kolcura Arsenal, locatedon the northern coast of Kyushu Island. PilotCharles Sweeney found unacceptable weather condi-tions and unwelcome flak above Kokura. Sweeneymade three passes over Kokura, then decided toswitch to his secondary target even though he hadonly enough fuel remaining for a sihgle bombingrun. Clouds greeted 130ck’sCar as it approachedNagasaki, home to the Mitsubishi plant that hadmanufactured the torpedoes used at Pearl Harbor.At the last minute, a brief break in the cloudcovermade possible a visual targeting at 29,000 feet andBock% Car dropped her single payload, a plutoniumbomb weighing 10,000 pounds and nicknamed FatMan, at 11:01 a.m. The plane then veered off andheaded to Okinawa for an emergency landing. FatMan exploded 1,650 feet above the slopes of the citywith a force of 21,000 tons of TNT.59 Fat Man kill-

53

ed 40,000 people and injured 60,000 more. Threesquare miles of the city were destroyed, less thanHiroshima because of the steep hills surroundingNagasaki. By January 1946, 70,000 people had diedin Nagasaki. The total eventually reached 140,000,with a death rate similar to that of Hiroshima.Go

SurrenderStill the Japanese leadership struggled to come to

a deckion, with military extremists con-tinuing to ad-vocate a policy of resistance to the end. Word fina-llyreached Washington from Switzerland andSweden early on August 10 that the Japanese, in ac-cordance with Hirohito’s wishes, would accept thesurrender terms, provided the emperor retain hisposition. Truman held up a third atomic attackwhile the United States considered a response, final-ly taking a middle course and acknowledging theemperor by stating that his authority after the sur-render would be exercised under the authority of theSupreme Commander of the Allied Powers. WithBritish, ‘Chinese, and Russian concurrence, theUnited States answered the Japanese on August 11.Japan surrendered on August 14, 1945, ending thewar that began for the United States with the sur-prise attack at Pearl Harbor on December 7, 1941.The United States had been celebrating for almostthree weeks when the formal papers were signedaboard the U.S.S. Missouri on September 2.

The Bomb Goes PublicThe veil of secrecy that had hidden the atomic

bomb project was lifted on August 6 when PresidentTruman announced the Hiroshima raid to theAmerican people. The release of the Smyth Reporton August 12, which contained general technical in-

formation calculated to satisfy public curiositywithout disclosing any atomic secrets, brought the

Manhattan Project into fuller View.blAmericanswere astounded to learn of the existence of a far-flung, government-run, top secret operation with aphysical plant, payroll, and labor force comparablein size to the American automobile industry. Ap-proximately 130,000 people were employed by theproject at its peak, among them many of thenation’s leading scientists and engineers.

In retrospect, it is remarkable that the atomicbomb was built in time to be used in World War II.Most of the theoretical breakthroughs in nuclearphysics dated back less than twenty-five years, andwith new findings occurring faster than they couldbe absorbed by practitioners in the field, many fun-damental concepts in nuclear physics and chemistryhad yet to be confined by laboratory experimenta-tion. Nor was there any conception initially of thedesign and engineering difficulties that would be in-volved in translating what was known theoreticallyinto working devices capable of releasing the enor-mous energy of the atomic nucleus in a predictablefashion. In fact, the Manhattan Project was asmuch a triumph of engineering as of science.Without the imovative work of the talented LeslieGroves, as well as that of Crawford Greenewalt ofDuPont and others, the revolutionary breakthroughsin nuclear science achieved by Enrico Fermi, NielsBohr, Ernest Lawrence, and their colleagues wouldnot have produced the atomic bomb during WorldWar II. Despite numerous obstacles, the UnitedStates was able to combine the forces of science,government, military, and industry into an organiza-tion that took nuclear physics from the laboratoryand into battle with a weapon of awesome destruc-tive capability, making clear the importance of basicscientific research to natiomd defense.

54

PartVI:The Manhattan DistrictinPeacetime

FromthetimeS-1becamepublicknowledgeuntiithe Atomic Energy Commission succeeded it onJanuary 1, 1947, the Manhattan Engineer Districtcontrolled the nation’s nuclear program. Groves re-mained in command, intent upon protectingAmerica’s lead in nuclear weapons by completingand consolidating the organization he had presidedover for three years in challenging wartime condi-tions. He soon found that peacetime held its ownchallenges.

According to a plan approved by Stimson andMarshall in late August 1945, Groves shut down thethermal diffusion plant in the K-25 area onSeptember 9 and put the Alpha tracks at Y-12 onstandby during September as well. The improvedK-25 gaseous diffusion plant now provided feeddirectly to the Beta units. Hanford’s three piles con-tinued in operation, but one of the two chemicalseparation areas was closed. Los Alamos was assign-ed the task of producing a stockpile of atomicweapons. Actual weapon assembly was to be doneat Sandia Base in Albuquerque, where engineeringand technical personnel were relocated with the staffpreviously stationed at Wendover Field in westernUtah.

Operation CrossroadsIn July 1946, during Operation Crossroads, the

Manhattan Project tested its third and fourthplutonium bombs (Trinity and Nagasaki were the

fust two)witha large,invitedaudienceof jour-nalists,scientists,militaryofficers,congressmen,andforeign observers at Bikini Atoll in the Pacific. ShotAble, dropped from a B-29 on July 1, sank threeships and performed as well as its two predecessorsfrom a technical standpoint, though it failed tofulffl its pretest publicity buildup. Shot Baker wasdetonated from ninety feet underwater on the morn-ing of July 15. Baker produced a spectacular displayas it wreaked havoc on a seventy-four-vessel fleet ofempty ships and spewed thousands of tons of waterinto the air. Both Able and Baker yielded explosionsequivalent to 21,000 tons of TNT, though Baker in-troduced the most subtle hazard of the atomicage—radiation faUout$2 Able and Baker were thefma.1weapon tests conducted by the Manhattan Pro-ject and the last Anerican tests until the AtomicEnergy Commission’s Sandstone series began inspring 1948.

Superpower ChillBetween August 1945 and January 1947, while

Groves fought to maintain the high priority of theatomic program in a peacetime environment, theeuphoria that swept the United States at the end ofWorld War II dissipated as Americans foundthemselves embroiled in a new global struggle, thistime with the Soviet Union. The United States helda monopoly on atomic weapons during the sixteenmonths of Groves’s peacetime tenure, but less thanthree years after the Atomic Energy Commissionsucceeded the Manhattan Engineer District, the Rus-sians’ secret atomic bomb program achieved successwith the 1949 test of Joe I (which the Americansnamed after Joseph Stalin). During the 1950s rela-tions between the two superpowers remained strain-ed, and both added the hydrogen bomb to theirarsenals in an attempt to achieve militarysuperiority.

Postwar PlanningThe beginning of the Cold War in the late 1940s

was linked to the failure of the World War II alliesto reach agreements on international controls respec-ting nuclear research and atomic weapons. Postwarplanning in the United States began in earnest inJuly 1944, when Met Lab scientists in Chicagoissued a “Prospectus on Nucleonics,” which includedplans for atomic research and advocated the creationof an international organization to prevent nuclearconflict. In August the Military Policy Committee

55

,. >...- . . . ,,,-, .’-.. ,: ’.,..: ,,, ,.“;,.;-.-. . ,. ?.’> ,., .. -— —.- -.. _ .— - . .-,, .,-’ ,—-> L_- .’,—,

Partvk

set up a Postwar Policy Committee, charged withmaking recommendations on the proper governmentrole in postwar atomic research and development.The committee, composed of Richard Tolman(chairman), Warren Lewis, Henry Smyth, and RearAdmiral Earle W. Mills, recommended that the bestway for the government to maintain a vigorousnuclear program was to set up a peacetime versionof the Office of Scientific Research and Develop-ment. Nlels Bohr, aware that the Russians hadknown about the Manhattan Project since 1942 andconvinced that the Soviet Union would spare no ef-fort to catch up with the United States, advocated apolicy of full publicity and internationalcooperation.

Roosevelt and Churchill included postwar plan-ning on their agenda when they met at Hyde Parkin September 1944. They immediately vetoed theidea of an open atomic world (Churchill adamantlyrejecting Bohr’s recommendation). Bush and Con-ant, meanwhile, contacted Stirnson on September 19and spoke to the necessity of releasing selected in-formation on the bomb project, reasoning that in afree country the secret could not be kept long.When Roosevelt asked Bush for a briefing on S-1severaldayslater,Bushdiscoveredthat Roosevelthad signed an “aide-memoire” with Churchill,pledging to continue bilateral research with Englandin certain areas of atomic technology$3 Bush fearedthat Roosevelt would institute full interchange withGreat Britain without consulting his own atomicpower experts. Bush argued, prophetically, that leav-ing the Russians out of such an arrangement mightwell lead to an arms race among the Allied victors.

The Baruch PlanBush and Conant presented their views more fully

on September 30. They held that the American andBritish lead would last no more than three or fouryears and that security against the bigger bombs thatsurely would result from a worldwide arms racecould be gained only through internationala~eements aimed at preventing secret research andsurprise attacks. Bush and Conant’s basicphilosophy found expression in the Acheson-Lilienthal report of March 1946, fashioned primarilyby Oppenheimer and evolving into the formalAmerican proposal for the intemationaJ control ofatomic energy known as the Baruch Plan.

Bernard Baruch, the elder statesman who hadserved American presidents in various capacitiessince World War I, unveiled the United States plan

in a speech to the newly-created United NationsAtomic Energy Commission on June 14, 1946.Baruch proposed the establishment of an interna-tional atomic development authority along the linesproposed by the Acheson-Lilienthal report, one thatwould control aU activities dangerous to worldsecurity and possess the power to license and inspectall other nuclear projects. Once such an authoritywas established, no more bombs should be built andexisting bombs should be destroyed. Abolishingatomic weapons could lay the groundwork forreducing and subsequently eliminating all weapons,thus outlawing war altogether. The Baruch Plan, inBaruch’s words “the last, best hope of earth,”deviated from the optimistic tone of the Acheson-Lilienthal plan, which had intentionally remainedsilent on enforcement, and set specific penalties forviolations such as illegally owning atomic bombs.b4IMruch argued that the United Nations should notallow members to use the veto to protect themselvesfrom penalties for atomic energy violations; he heldthat simple majority rule should prevail in this area.As on enforcement, the Acheson-Lilienthal reporthad studiously avoided comment on the veto issue.65

Not surprisingly, the Soviet Union, a non-nuclearpower,insisteduponretainingitsUnitedNationsvetoandarguedthat theabolitionof atomicweapons should precede the establishment of an in-ternational authority. Negotiations could not pro-ceed fairly, the Russians maintained, as long as theUnited States could use its atomic monopoly tocoerce other nations into accepting its plan. TheBaruch Pkm proposed that the United States reduceits atomic arsenal by carefully defined stages linkedto the degree of international agreement on control.Only after each stage of international control wasimplemented would the United States take the nextstep in reducing its stockpile. The United Statesposition, then, was that international agreementmust precede any American reductions, while theSoviets maintained that the bomb must be bannedbefore meaningful negotiations could take place.

The debate in the United Nations was a debate inname only; neither side budged an inch in the sixmonths following Baruch’s United Nations speech.In the end, the Soviet Union, unwilling to surrenderits veto power, abstained from the December 31,1946, vote on Baruch’s proposal on the groundsthat it did not prohibit the bomb, and the Americanplan became a dead letter by early 1947–thoughtoken debate on the American plan continued into1948. The United States, believing that Soviet troopsposed a threat to eastern Europe and recognizing

56

1 The ManhattanDistrictin Peacetime

that American conventional forces were rapidlydemobilizing, refused to surrender its atomic deter-rent without adequate international controls andcontinued to develop its nuclear arsenal. In an at-mosphere of mutual suspicion the Cold War set in.

The Debate Over Domestic LegislationWhile the international situation grew more

ominous due to deteriorating relations between theUnited States and the Soviet Union, a domesticdebate was taking place over the permanentmanagement of America’s nuclear program. Theterms of the debate were framed by the InterimCommittee in July 1945 when it wrote draft legisla-tion proposing a peacetime organization withresponsibilities very similar to those of the Manhat-tan Project, The draft legislation provided for astrong military presence on a nine-member board ofcommissioners and strongly advocated the federalgovernment’s continued dominance in nuclearresearch and development.

The May-Johnson BillThe Interim Committee’s draft legislation reached

President Truman via the State Department shortlyafter the armistice. After affected federal agenciesapproved, Truman advocated speedy passage of thecongressional version of the bill, the May-Johnsonbill, on October 3, 1945. Groves, Bush, and Conanttestified at hearings in the House of Representativesthat the sweeping powers granted the proposed com-mission were necessary and that only governmentcontrol of atomic power could prevent its misuse.Although Lawrence, Fermi, and Oppenheimer (withsome misgivings) regarded the bill as acceptable,many of the scientists at the Met Lab and at OakRidge complained that the bill was objectionablebecause it was designed to maintain military controlover nuclear research, a situation that had beentolerable during the war but was unacceptable dur-ing peacetime when free scientific interchange shouldbe resumed. Particularly onerous to the scientificopponents were the proposed penalties for securityviolations contained in the May-Johnson bill-tenyears in prison and a $100,000 fine. Organized scien-tific opposition in Washington slowed the bill’s pro-gress, and Arthur H. Vandenberg of Michigan heldit up in the Senate through a parliamentarymaneuver.

The McMahon BillAssupport for the May-Johnson bill eroded in

late 1945, President Truman withdrew his support.Vandenberg’s attempt to establish a joint House-Senate special committee failed, but BrienMcMahon of Connecticut successfully created andbecame chair of the Senate’s Special Committee onAtomic Energy. Daily hearings took place untilDecember 20, when McMahon introduced asubstitute to the May-Johnson bill. Hearings on thenew McMahon bill began in January. Groves op-posed McMahon’s bill, citing weak security provi-sions, the low military presence, and the stipulationthat commission members be full-time (Grovesthought that more eminent commissioners could beobtained if work was part-time). Groves ako ob-jected to the bill’s provision that atomic weapons beheld in civilian rather than military custody. Never-theless, the Senate approved the McMahon bti onJune 1, 1946, and the House approved it onJuly 20, with a subsequent conference committeeeliminating most substantive amendments. Thesometimes bitter debate between those who ad-vocated continued military stewardship of America’satomic arsenal and those who saw continuedmilitary control as inimical to American traditionsended in victory for supporters of civilian authority.President Truman signed the McMahon Act, knownofficially as the Atomic Energy Act of 1946, onAugust 1. The bill called for the transfer of author-ity from the United States Army to the United StatesAtomic Ener~ Commission, a five-member civilianboard serving full-time and assisted by a general ad-visory committee and a military liaison comrnittee.GGThe Atomic Energy Act entrusted the AtomicEnergy Commission with the government monopolyin the field of atomic research and developmentpreviously held by its wartime predecessor.6T

ConclusionThe Manhattan Project, its wartime mission com-

pleted, gave way to the civilian Atomic EnergyCommission. How well the Atomic Energy Commiss-ion would be able to manage the nuclear arsenal ina Cold War environment and whether it could suc-cessfully develop the peaceful uses of atomic energy,only time would tell. What was clear as the AtomicEnergy Commission took over at the beginning of1947 was that the success of the Manhattan Projecthad helped cement the bond between basic scientificresearch and national security. Science had gone towar and contributed mightily to the outcome. Thechallenge confronting American policy makers in thepostwar years was to enlist the forces of science inthe battle to defend the peace.

57

1

ManhattanProjectChart

I

TOP POLICYGROUP

THE PRESIDENT

I

MILITARYPOLICY COMMllTEE lsEcR”ARyOF!!$w&lI

‘.=CHIEF OFSTAFF

GENERAL H.H. ARNOLD MAJOR GENERAL(USAAF) L.R. GROVES I

(Nichols: Administrative matters;Groves: Other matters)

PLANNING FORMILITARY OPERATIONSBRIGADIER GENERAL MANHAITAN DISTRICT

T.F. FARRELL, DEPUTY COL. K.D. NICHOLS

I

1 I I IOTHER

CLINTON HANFORDENGINEER ENGINEER

LOSESTABLISHMENTS WORKS WORKS

ALAMOS

SimplifiedChartof ManhattanProject.AdaptedfromLeslieR. Groves,NOWIt CanBe Told(NewYork:Harper8ZRow,1%2).

58

Notes

1.

2,

3,

4.

5.

6,

7,

8,

9,

10.

The Einstein letter is reprinted in Vincent C. Jones,Manhattan: The Army and the Atomic Bomb(Washington, D.C.: U.S. Government Printing Office,1985), 609-10.Roosevelt to Einstein, October 19, 1939.

The United States had little reliable intelligence on theGerman bomb effort until late in the war. Thus it was notknown until the ALSOS counterintelligence mission thatthe German program had not proceeded beyond thelaboratory stage and had foundered by mid-1942. Fordetails of the ALSOS mission see Richard Rhodes, 77zeMaking of the Atomic Bomb (New York: Sirnon &Schuster, 1986), pp. 605-10.

For details on the German research effort see McGeorge13undy, DangerandSurvival:Choices About the Bomb inthe Fimt Fvty Years (New York: Random House, 1988),pp. 14-23.

Lawrence Badash, “Introduction,” in Reminkcenct?rofLos A1amos, 1943-1945, edited by Lawrence Badash,Joseph O. Hirschfelder, and Herbert P. Broida (Dordrecht,Holland: D. Reidel Publishing Company, 1980), xi.

Rhodes, Making of the Atomic Bomb, p. 228.

William R. Shea, “Introduction: From Rutherford toHahn,” in Otto Hahn ond the Rise of Nuclear Physics,edited by WWm R. Shea (Dordrecht, Holland: D.ReidelPublishing Company, 1983), p. 15.

Ibid.

Jones, Manhattan, p. 10.

Richard G. Hewlett and Oscar E. Anderson, Jr., The NewWorld, 1939-1946. Volume I, A Hktoty of the UnitedStates Atomic Energy Commksion (University Park,Pennsylvania Pennsylvania State University Press, 1962),pp. 30-31.

11. Ibid., p. 168.

12. Laura Fermi, Atoms in the Family: My Ll~e With EnricoFermi (Chicagm University of Chicago Press, 1954),

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.24.

25,

26.

27.

28.29.

30.

31.

32.

33.

34.35.

36.

37.38.39.

40.41.

42.

p. 164.

Rhodes, Making of the Atomic Bomb, pp. 336-38.

Hewlett and Anderson, New World, p. 37.

Zbid., p. 39.

MAUD, while it appears to be an acronym, is not. It issimplya codename.

Rhodes, Making of the Atomic Bomb, pp. 321-25 and 369.

Bundy, Danger and Survivalj pp. 4849.

Hewlett and Anderson, New World, P. 46.

Ibid., p. 49.

Ibid., p. 48.

Ibid., p. 406.

Ibid., pp. 74-75.

Ibid., pp. 82-83.

HenryD. Smyth,A GeneralAccotJntof theDeveiopnen?of Methodsof UsingAtomicEnergyfor MilitavPurpowUnder the Auspices of the United States Government,1940-1945 (Washington, D.C.: U. S. Government Printingoffice, 1945), p. 70.Rhodes, Moking of the Atomic Bomb, p. 442.

Ibid.

Hewlett and Anderson, New World, p. 113.

Kemeth D. Nichots, The Road to Trinity (New York:William Morrow and Company, Inc., 1987), pp. 121 and146.

Hewlett and Anderson, New World, p. 149.

Nichols recounts his adventure in borrowing the silver inRoad to Trinity, p. 42.

Hewlett and Anderson, New World, p. 155.

Ibid.

Ibid., p. 165.

For more on k see Rhodes, Making of the Atomic Bomb,p. 397.

Adso@ion is a process whereby gases, liquids, or d~olvedsubstances are gathered on a surface in a condensed layer.

Jones, Manhattan, P. 218.

Hewlett and Anderson, New World, p. 220.Nichols, Road to Trini@, p. 108.

Rhodes, Making of the Atomic Bomb, p. 570.

In the Matter of J. Robert Oppenheimer: Transcript ofHearing Before Pezsonne[ SecuriV Board, Washington,D. C., April 12, 1954, Through May 6, 1954 (Washington,D.C.: Government Printing Office, 1954), pp. 12-13.

For details on Fuchs see Robert C. Wtiams, KIaus Fuchs,Atom Spy (Cambridge: Harvard University Press, 1987).

43. Rhodes, Making of the Atomic Bomb, pp. 540-41.

44. Ibid., pp. 30548.

45. Ibid., pp. 64445.

46. Jones, Manhattan, p. 530.

47. The Franck report, the response of the Scientific Panel,and the Interim Committee recommendations are discussedin Ibid., pp. 365-72.

48. Rhodes, Making of the Atomic Bomb, Pp. 571-72.

49. Ibid., p. 676.

50. See Ibid., pp. 668-78, for more on the Trinity test and theresponses of those present.

51. Hewlett and Anderson, New World, p. 383.

52. Zbid., p. 386.

53. Groves, Leslie R., Now It Can Be Told, (New YorkHarper & Row, 1962), p. 434.

54. Herbert Feis, The Atomic Bomb and the End of WorldWar 11 (Princeton: Princeton University Press, 1966),p. 85.

55. The directive is reprinted in Rhodes, Making of the AtomicBomb, p. 691.

56. Hewlett and Anderson, New World, p. 395.

57. Paul W. Tibbets,“Howto Dropan AtomBomb,”SaturdayEveningPost218(June8, 1946),p. 136.

58. Theofficialyieldof LhtleBoy,as listedin the Departmentof Energy’s“AnnouncedUnitedStatesNuclearTests,July1945ThroughDecember1986,”page2, January 1987, was15,000 tons of TNT (15 kilotons).

59. The official yield of Fat Man listed in Ibid. Descriptions ofthe bombmgs of Hwoshima and Nagasaki derived fromRhodes, Making of the Atomic Bomb, pp. 710 and 739-40.

60. Summaries of Hiroshima and Nagasaki casualty rates anddamage estimates appear in Rhodes, Making of the AtomicBomb, pp. 733-34,740,74Z Groves,NowIt Clrn Be Told,pp. 319, 329-30, 3@ and Jones, Manhattan, pp. 5454.

61. The Smyth report is cited in footnote 24.

62. For details of the Baker fallout see Barton C. Hacker, TheDragon’s Tail: Radiation SafeQ in the Manhattan Project,1942-1946 (Berkeley University of California Press, 1987),pp. 135-53.

63. Hewlett and Anderson, New World, pp. 326-27.

64. Ibid., p. 579.

65. Bundy, DangerandSurvivaljPp. 158-66.

66. The McMahon bti is reprinted in Hewlett and Anderson,New World, pp. 714-22.

67. The Manhattan Project ended with the transfer of powerfrom the Manhattan Engineer District to the AtomicEnergy Commission, though the Manhattan EngineerDktrict itself was not abolished until August 15, 1947. TheTop Policy Group and the Military Policy Committee hadalready ceased to exist by the time the Atomic Energycommission took over on January 1, 1947.

1

60

SelectBibliography

Bundy, McGeorge, Danger and Survival: ChoicesAbout the Bomb in the First F~@ Yeans (NewYork: Random House, 1988).

Cantelon, Philip L. and Robert C. Williams,editors, The American Atom: A DocumentaryHktory of NuclearPoliciesfrom the Dkcovery ofFission to the Present, 1939-1984 (PMladelphkxUniversity of Pennsylvania Press, 1984).

Groves,LeslieR.,NowIt Can Be Told (New York:Harper & Row, 1962).

Hersey, John, Hiroshima (New York: Knopf, 1946).

Hewlett, Richard G. and Oscar Anderson, Jr., 27zeNew World, 1939-1946Volume I of A History ofthe UnitedStatesAtomic Energy Commission(University Park: Pennsylvania State Universi@Press, 1962).

Jones, Vincent C., Manhattan: The Army and theAtomic Bomb (Washington, D.C.: U. S. Govern-ment Printing Office, 1985).

Rhodes, Richard, The Making of the Atomic Bomb(New York: Simon & Schuster, 1986).

Smyth, Henry D., Atomic Energyfor Military Pur-poses: The OfficialReport on the Development ofthe Atomic Bomb Under the Auspice of the United

States Government 194(11945(Washington, D. C.:U. S. Government Printing Office, 1945).

UnitedStatesAtomicEnergyCommission,In theMatter of J. Robert Oppenheimer:TranscriptofHearingBefore Pe~onnel Securi@BoardWmhington, D. C., April 12, 1954, Through May (ij1954 (Washington, D, C.: U. S. Government Print-ing office, 1954).

61

ManhattanProjectChronology

Date

1919

1930

1931

1932

1932

1932

1934

December1938

December1938

January26,1939

August2,1939

Events

Ernest Rutherford discovers theproton by artificially transmutingan element (nitrogen into oxygen).

Ernest O. Lawrence builds thefirst cyclotron in Berkeley.

Robert J. Van de Graaff developsthe electrostatic generator.

James Chadwick discovers theneutron.

J. D. Cockroft and E. T. S.Walton first split the atom.

Lawrence, M. Stanley Livingston,and Milton White operate the firstcyclotron.

Enrico Fermi produces fission.

Otto Hahn and Fritz Strassmanndiscover the process of fission inuranium.

Lk Meitner and Otto Frisch comfirm the Hahn-Strassmanndiscovery and communicate theirtindings to Niels Bohr.

Bohr reports on the Hahn-Strassman results at a meeting ontheoretical physics in Washington,D. C.

Albert Einstein writes PresidentFranklin D. Roosevek, alerting thePresident to the importance ofresearch on chain reactions andthe possibility that research mightlead to developing powerfulbombs.

August19,1939

Septemi3er1, 1939

October11-12, 1939

October 21, 1939

November 1, 2939

March 1940

Spring-Smnmer 1940

June 1940

February 24, 1941

March 28, 1941

May 3.941

May 17, 1941

June 22, 1941

Jtute 28, 1941

July 2, 1941

Jtdy 11, 1941

July 14, 3941

October 9, 1941

Roosevelt informs Einstein that hehas set up a committee to studyuranium.

Germany invades Poland.

Alexander Sachs discusses Eins-tein’s letter with President “Roosevelt. Roosevelt decides to actand appoints Lyman J. Briggshead of the Advisory Committeeon Uranium.

The Uranium Committee meetsfor the first time.

The Uranium Committee recom-mends that the government pur-chase graphhe and uranium oxidefor fission research.

John R. Dunning and his col-leagues demonstrate that fission ismore readily produced in the rareuranium-235 isotope, not the moreplentiful uranium-238.

Isotope separation methods areinvestigated.

Varmevar Bush is named head ofthe National Defense ResearchCommittee. The Uranium Com-mittee becomes a scientific sub-committee of Bush’s organization.

Glenn T. Seaborg’s research groupdiscovers plutonium.

Seaborg’s gm.rp demonstrates thatplutonium is f~ionable.

Scaborg proves plutonium is moretilomble than uranium-235.

A National Academy of Sciencesreport emphasizes the necessity offurther research.

Germany invades the Soviet Union.

Bush is named head of the Office ofscientific Research and Development.James B. Conant replaces Bush atthe National Defense Research Com-mittee, which becomes an advisovbody to the Office of ScientificResearch and Development.

The British MAUD report concludesthat an atomic bomb is feasible.

A second National Academy ofSciences report confkrns the findingsof the fti.

Bush and Conant receive the MAUDreport.

Bush briefs Roosevelt and V& Presi-dent Henry A. Wallace on the stateof atomic bomb research. Roosevelt

62

November 9, 1941

November 27, 1941

December 7, 1941

December 10, 1941

December 16, 1941

December 18, 1941

January 19, 1942

March9,1942

May23,1942

June 1942

June 171943

.hdy 1942

August 7, 1942

instructs Bush to fmd out if a bombcan be built and at what cost. Bushreceives Petilon to explore con-struction needs with the Army.

A third Nationrd Academy ofsciences report agrees with theMAUD report that an atomic bombis feasible,

Bush forwards the third NationalAcademy of sciences report to thePresident.

The Japanese attack Pead Harbor.

Germany rmd Italy deelare war onthe United States.

The Top Policy Committee becomesprimarily responsible for makingbroad policy decKons relating touranium research.

The S-1 Executive committee (whichreplaced the Uranium Committee inthe Office of scientific and ResearchDevelopment) gives Lawrence$400,000 to continue electromagneticresearch.

Roosevelt responds to Bush’sNovember 27 report and approvesproduction of the atomic bomb.

Bush gives Roosevelt an optimisticreport on the possibtity of producinga bomb.

The S-1 Exomtive Committee recom-mends that the project move to thepilot plant stage and build one ortwo piles (reactors) to produceplutonium and electromagnetic, cen-trifuge, and gaseous diffusion plantsto produce uranium-235.

Production piIe designs are developedat the Metallurgical Laboratory inChicago.

President Roosevelt approves the S-1Exeeutive Committee recommenda-tion to proceed to the pilot plantstage and instructs that plant con-struction be the responsibtity of theArmy. The Office of ScientificResearch and Development continuesto direct nuclear research, while theArmy delegates the task of plantconstruction to the Corps ofEngineers.

Kenneth Cole establishes the healthditilon at the MetallurgicalLaboratory.

The Amenean island-hopping eam-ptign in the Pacific beghs with thelanding at Guadaleanal.

August 13, 1942

August 1942

September13,1942

September 17, 1942

September 19, 1942

September 23, 1942

October 3, 1942

October 5, 1942

Fall 1942

October 19, 2942

October 26,1942

November 22, 1942

November 14, 1942

November 1942

November 2S, 1942

Deeember 2,1942

The Manhattan Engineer District isestablished in New York City, Col-onel James C. Marshall command-ing.

Seaborg produces a microscopic sarn-pIe of pure plutonium.

The S-1EweutiveCommitteetitsLawrence’s Berkeley laboratory andrecommends buikiing an elec-tromagnetic pilot plant and a seetionof a fidkcale plant in Tennessee.

Colonel Leslie R. Groves is ap-pointed head of the ManhattanEngineer District. He is promoted toBrigadier General six days later.

Groves selects the Oak Ridge, Ten-nessee site for the pilot plant.

Secretary of War Henry Stimsoncreates a Military Policy Committeeto help make deeisiom for theManhattan Project.

E. I. du Pent de Nemours and Com-pany agrees to build the chernkxdseparation plant at Oak Ridge.

Compton recommends an in-termediate piIe at Argonne.

J. Robert Oppenheimer and theluminaries report from Berkeley thatmore fissionable material may beneeded than previously thought.

Groves decides to establish a separateseiendfic laboratory to design anatomic bomb.

Conrmt recommends dropping thecenbifuge method.

On the recommendation of Grovesand Conant, the Military PolicyCommittee decides to skip the pilotplant stage on the plutonium, elec-tromagnetic, and gaseous diffusionprojects and go directly from theresearch stage to industrial-scaleproduction.

The Committee also decides not tobuild a centrifuge.plant.

The S-1 Executive Committee en-dorses the recommendations of theMilitary Policy committee.

TheAlliesinvadeNorthAfrica.GrovesselectsLosAIamos,NewMexico as the bomb laboratory(codenamed Projeet Y). Oppen-heimer is chosen laboratory direetor.

Scientists led by Enrico Fermi achievethe fmt self-sustained nuclear chrdnreaction in Chicago.

63

December 10, 1942

December 2$, 2942

hmmry 13-14,1943

kunlary 14-24,1943

Wmary 3943

February 18, 1943

Febmary 3943

March 2943

April 1943

June 1943

Summer 3943

July 3943

August 27,3943

September 8, 2943

September 9, 2943

September 27,2943

November 4, 1943

The Lewis committee compromiseson the electromagnetic method. TheMilitary policy Committee decides tobuild the plutonium productionfacilities at a site other than OakRidge.

Roosevelt approves detailed plans forbuilding production facilities andproducing atomic weapons.

Plans for the Y-12 electromagneticplant are discussed. Groves insiststhat Y-12’s first racetrack be finishedby Jdy 1.

At the Casablanca Conference,Roosevelt and British Prime MinisterChurchill agree upon unconditionalsurrender for the h powers.

Groves selects Hanford, Washingtonas the site for the plutonium produc-tion facilities. Eventually three reac-tors, called B, D, and F, are built atHanford.

Bush encourages Philip Abelson’sresearch on the thermal diftilonprocess.

Construction of Y-12 begins at OakRidge.

Groundbreaking for the X-10plutonium pilot plant takes place atOak Ridge.

Researchers begin arxiving at LosAlamos.

Bomb design work begins at LosAlaInos.

Site preparation for the K-25 gaseousdiffusion plant commences at OakRidge.

The Manhattan Engineer Districtmoves its headquarters to Oak Ridge.

Oppenheimer reports that three timesas much fmionable material maybenemssary than thought nine monthsearlier.

Groundbreaking for the l~Bplutonium production pile at Han-ford takes place.

Italy surrenders to Allied forces.

Groves decides to double the size ofY-12.

Construction begins on K-25 at OakRidge.

The X-10 pile goes critical and pro-duces plutonium by the end of themonth.

Late 1943

December 15, 1943

.kmuary 3944

January 1944

February 3944

March 2944

March 1944

April 2944

June 6,2944

June 21,1944

July 4, 2944

JuIy 17, 19t4

July 1944

July 1944

August 7, 1944

September 1944

September 13, 1944

September 2944

John von Neumann tilts LosAlamos to aid implosion research.

The first Alpha racetrack is shutdown due to maintenance problems.

The second Alpha racetrack is startedand demonstrates maintenance pro-blems similar to those that disabledthe first.

Construction begins on Abelson’sthermal difti.uion plant at thePhiladelphia Naval Yard.

Y-12 sends 200 grams ofuranium-235 to Los AklIIIOS.

The Beta building at Y-12 is com-pleted.

Bomb models are tested at LosAlamos.

Oppenheimer informs Groves aboutAbelson’s thermal diffusion researchin Philadelphia.

Nied forces launch the Normandyinvasion.

Groves orders the construction of theS-50 thermal diftilon plant at OakRidge.

The deciion is made to work on acalutron with a 30-beam source foruse in Y-12.

The plutonium gun bomb (codenarn-ed Thin Man) is abandoned.

A major reorganization to maximizeimplosion research occurs at LosAkunos.

Scientists at the MetallurgicalLaboratory issue the “Prospectus onNucleonics,” concerning the intern-ationalcontrol of atomic energy.

Bush briefs General George C. Mar-shall, informing him that small imp-losion bombs might be ready bymid-1945 and that a uranium bombwill almost certainly be ready by

August1, 1945.

ColonelPaulTlbbets’s393rdBom-bardmentSquadronbeginstestdropswithdummybombscalledPUmPkins.

The first slug is placed in pile lCOBat Hanford.

Roosevelt and Churchill meet inHyde Park and sign an “aide-memoire” pledging to continuebdaterd research on atomictechnology.

64

Summer 1944-Spring 1945 The Manhattan Project’s chances for—

September 27, 1944

September 30, 1944

December 1944

February 2, 1945

February 4-11, 1945

March 1945

March 1945

March 12,1945

April 12, 1945

ApriI25,1945

May 1945

May 7, 1945

May 23, 3945

May 31-June 1, 1945

June 6, 1945

June 1945

SUCCSS tiVWX fiOrn doubtful toprobable as Oak Ridge and Hanfordproduce increasing amounts of fis-sionable material, and Los Alarnosmakes progress in chemistry,metallurgy, and weapon design.

The 1OO-Breactor goes critical andbegins operation.

Bush and Conant Xh0G3te interna-tional agreements on atomic researchto prevent an arms race.

The chemical separation plants(Queen Marys) are ftihed atHanford.

Los Akunos receives its fmtplutonium.

Roosevelt, Churchill, and SovietPremier Joseph Stalin meet at Yalta.

S-50 begins operation at Oak Ridge.

Tokyo is fwebombed, resulting inIoo,ooo casualties.

K-25 begins production at OakRidge.

President Roosevelt dies.

Stimson and Groves brief PresidentTruman on the Manhattan Project.

Strdin tells Harry Hopkins that he iswilling to meet with Truman andproposes Berlin as the location.

The German armed forces in Europesurrender to the Allies.

Tokyo is fwebombed again, thk timeresulting in 83,000 deaths.

The Interim Committee meets tomake recommendations on wartimeuse of atomic weapons, internationalregulation of atomic information,and legislation regarding domesticcontrol of the atomic enterprise (theCommittee’s draft legislationbecomes the basis for the May-Johnson bfl).

Stimson informs President Trumanthat the Interim Committee recom-mends keeping the atomic bomb asecret and using it as soon as possiblewithout Warning.

Scientists at the MetallurgicalLaboratory issue the Franck Report,advocating international control ofatomic research and proposing ademonstration of the atomic bombpfior to its combat use.

June 14,1945

June 21,1945

July 2-3, 1945

Jdy 16, 1945

Jdy 17-August 2, 394S

July 21,1945

JuIy 24,1945

Jldy 25, 1945

JuIy 26, 1945

~ldy 29, 1945

August 6, 1945

August 8,1945

August 9, l!w

August 12, I!)4s

August 14, 1945

September 2, 1945

September 9,1945

September 1945October 3, 1945

Groves submits the target selectiongroup’s recommendation to Marshall.

The Inteti Committee, Supportingits Scientific Panel, rejects the FranckReport reeornmendation that thebomb be demonstrated prior tocombat.

Stimon briefs Truman on the In-terim Committee’s deliberations andoutlines the peace terms for Japan.

Los Alamos scientists successfully testa plutonium implosion bomb in theTrinity shot at Alamogordo, NewMexico.

Truman, Churchill, and StaJin meetin Potsdam.

Groves sends Stimson a report on theTrinity test.

Stimson again briefs Truman on theManhattan Project and peace termsfor Japan. In an evening session,Truman informs Stalin that theUnited States has tested a powertidnew weapon.

The 509th Composite Group isordered to attack Japan with anatomic bomb “after about” I@I,UX

3.

Truman, Chinese President ChiangKai-Shek, and new British PrimeMinister Clement Atlee issue thePotsdam Proclamation, calling forJapan to surrender unconditionally.

The Japanese reject the PotsdamProclamation.

The gun model uranium bomb, call-ed Liffle Boy, is dropped onHiroshima. Truman announces theraid to the American public.

Russia declares war on Japan and in-vades Manchuria.

The implosion model plutoniumbomb, calkd Fat Man, is droppedon Nagasaki.

The Smyth Report, containingunclassified technical information onthe bomb project, is released.

Japan surrenders.

The Japanese sign articles of sur-render aboard the U.S.S. Mksow-i.

S-50 shuts down.

Y-12 shutdown begins.Truman advocates passage of theMay-Johnson bti.

65

December 20, W

January 1946

June M, 1946

July 1, 1946

July 15, U46

August 1, 1946

December 1946-wmary 1947

kumary 1, 1947

August 15, l!M7

December 31, 1947

Senator Brien McMahon introduces asubstitute to the May-Johnson bfl,which had been losing support, in-cluding Tmman’s.

Hearings on the McMahon btibqjn.

Bernard Baruch presents theAmerican plan for international con-trol of atomic research.

Operation Crossroads begins withShot Able, a plutonium bomb drop-ped from a B-29, at Bti Atoll.

Operation Crossroads continues withShot Baker, a plutonium bombdetonated underwater, at B&Atoll.

President Truman signs the AtomicEnergy Act of 1946, a slightlyamended version of the McMahonbti.

The Soviet Union opposes theBaruch Plan, rendering it useless.

In accordance with the AtomicEnergy Act of 1946, all atomicenergy activities are transferred fromthe Manhattan Engineer District tothe newly created United StatesAtomic Energy Cotilon. TheTop Policy Group and the MilitaryPolicy Ccmunittee had alreadydisbanded.

The Manhattan Engineer District isabolished.

The National Defense ResearchCommittee and the Office of Scien-titlc Research and Development areabolished. Their functions aretransferred to the Department ofDefense.

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