An Atomic History Chapter 2

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Chapter Two 19 THE FERMI-SZILARD PILE AND URANIUM RESEARCH

The first government funding for nuclear research was allocated to purchase graphite and uranium oxide for the chain reaction experiments being organized by Fermi and World War II and the Manhattan Project Szilard at Columbia University in February 1940.2 This work, which began in New York 2 City, soon spread to Princeton, the University of Chicago, and research institutions in California.3 Even at this stage, the scientists knew that a chain reaction would need three major components in the right combination: fuel, moderator, and coolant. The fuel would contain the fissile material needed to support the fission process. The neutrons generated by the fission process had to be slowed by the moderator so that they could initiate additional fission reactions. The heat that resulted from this process had to be removed by the coolant. Fermi’s initial research explored the possibility of a chain reaction with natural urani- The 1930s were a time of rapid progress in the development of nuclear physics. um. It was quickly determined that high-purity graphite served as the best neutron moder- Research accelerated in the early years of the Second World War, when new developments ator out of the materials then available.4 After extensive tests throughout 1940 and early were conceived and implemented in the midst of increasing wartime urgency. American 1941, Fermi and Szilard set up the first blocks of graphite at Columbia University in government interest in these developments was limited at first, but increased as the war September 1941. The graphite blocks were called a "pile," a name that was soon extended broadened, and as the possibility of a fission bomb became more probable. After Pearl to all other forms of reactors. Fermi and Szilard’s pile consisted of graphite blocks around Harbor and the final decision to pursue the bomb, the American effort was coordinated and a core of natural uranium. Unfortunately, the pile did not work well, largely because the partially militarized under the aegis of the U.S. Army Corps of Engineers. This led to the graphite blocks were not arranged for optimum results.5 Additional work perfected what establishment of the "Manhattan Engineer District," commonly known as the Manhattan came to be called the "lattice" arrangement, where channels of uranium coursed through a Project. matrix of graphite blocks.6 Another achievement of those early days was a better under- Before Pearl Harbor and direct American involvement in the war, the U.S. govern- standing of the chain reaction itself. In order for a chain reaction to be maintained, each ment’s role in nuclear research was basically that of an observer. Funding began only as fissioned nucleus had to send off at least one neutron that caused another nucleus to fis- Chicago Pile No. 1 was set up in the the promise of success increased in 1940 and 1941. The government certainly provided sion, and so on. A chain reaction that continued indefinitely at a constant rate had a multi- squash court underneath the west little direction during that time; it was the physicists themselves, especially the foreign sci- plication factor ("k") of 1, and was identified as "k = 1." When k was greater than 1, there stands of Stagg Field at the University entists, who organized a restriction on the publication of fission research in late 1939 and of Chicago. Courtesy of Argonne was an increase in both the fission rate and the reactor power level. If k was less than 1, 1 National Laboratory Archives, man- early 1940. Only the scientists knew what was at stake. the reaction could not sustain itself.7 aged and operated by The University The government’s involvement increased by degrees in response to Hitler’s military Even though Fermi and Szilard’s early work in chain reactions failed to achieve k = 1, of Chicago for the U.S. Department of Energy under Contract No. W-31-109- achievements. The first U.S. government agency to oversee nuclear developments, the they learned much from the experience. The usefulness of graphite as a neutron modera- ENG-38, negative 1-785. Advisory Committee on Uranium, was created in October 1939 in response to Einstein’s tor was firmly established. The lattice was found to be the best arrangement for the urani- letter to Roosevelt in August of 1939—and Hitler’s invasion of um and the graphite blocks to achieve maximum neutron efficiency.8 Most importantly, it Poland in September. The National Defense Research Council was learned, or at least affirmed, that piles stocked with natural uranium could produce (NDRC) replaced the Advisory Committee in June 1940, after nuclear energy in the form of heat, but would not produce a workable bomb. Fermi and the fall of France. The NDRC in turn was folded into the Office Szilard’s early work with piles demonstrated that a much higher concentration of uranium- of Scientific Research and Development (OSRD) after the inva- 235 would be needed for that task.9 sion of the Soviet Union in June 1941. In each of these steps, there was a growing coordination between the physicists and their government. More will be said about the agencies that pre- THE SEARCH FOR URANIUM-235 ceded the Manhattan Project, but it would be better to first exam- ine the developments that increased government interest in the Alfred Nier, at the University of Minnesota, first separated uranium-235 from natural two years before Pearl Harbor. Beginning with research into fis- uranium the same month Fermi and Szilard received government support for their chain sion chain reactions and the separation of uranium-235 from nat- reaction work. In March, Nier conclusively demonstrated that uranium-235 was the urani- ural uranium, these developments culminated in the discovery of um isotope responsible for fission.10 Almost immediately, this discovery threw a major the remarkable fissile properties of Element 94, soon to be roadblock in the path of the development of the atomic bomb. As Fermi’s chain reaction known as plutonium. research increasingly demonstrated, a uranium atomic bomb would be possible only with An Atomic History 0-3 8/11/02 7:31 AM Page 18

Chapter Two 19 THE FERMI-SZILARD PILE AND URANIUM RESEARCH

Chapter Two 21 concentrated uranium-235. Natural uranium is composed of two isotopes (over 99% ura- tion of Element 94 would provide a use for all the uranium-238 that otherwise would not nium-238 and less than 0.7% uranium-235), so it is not possible to separate the isotopes be suitable bomb material. Also, because this was a new element, with a different atomic chemically. Isotopes had to be separated physically, atom by atom. In 1940 and 1941, number from any isotope of uranium, it could be separated from uranium by chemical there was no known way to separate isotopes in the quantity needed to make a bomb. means.15 There were, however, various theoretical possibilities. Edwin McMillan and Philip Abelson made the first serious attempts to make Elements A promising method of isotope separation was the electromagnetic method, pioneered 93 and 94 in the laboratory at the University of California’s Radiation Laboratory in early by Alfred Nier and championed by Ernest Lawrence, head of the Radiation Laboratory at 1940. This discovery was featured in the last publication on fission research before the the University of California. This method was based on the theory that uranium atoms in American physics community dropped a curtain on the subject. That publication, howev- gaseous form, when passed through a vacuum and subjected to an electromagnetic field, er, detailed how both man-made elements were the decay products of neutron capture in would tend to separate into lighter and heavier isotopes. The lighter atoms of uranium- uranium-238. Specifically, the researchers found that neutron bombardment of uranium- 235 could then be gathered separately.11 Lawrence’s first prototype for this process was a 238 produced uranium isotope 239, which quickly decayed into Element 93, which in turn converted cyclotron dubbed a "calutron" or "racetrack," perfected in late 1941 and early decayed into Element 94. When this process was complete, Element 94, later identified as (Left to Right) Ernest Lawrence, 1942. The world’s largest electromagnet at that time, the 184-foot-diameter calutron, soon plutonium, proved relatively stable, with a half-life of 24,000 years.16 Arthur Compton, Vannevar Bush, James Conant, Karl Compton and proved to be relatively successful at forcing uranium-235 and 238 atoms into different tra- Research on the nature of Element 94 accelerated throughout the rest of 1940 and Alfred Loomis, 1940. Ernest Orlando jectories, allowing them to land in different receptacles.12 1941 because the new element promised to be more fissionable than uranium-235. Much Lawrence Berkeley National Another method considered for the separation of uranium-235 was gaseous diffusion, of this work was done at the Radiation Laboratory by researchers including Glenn Laboratory, courtesy of AIP Emilio Segré Visual Archives. a technique pioneered in Britain and championed in the United States by John Dunning of Seaborg, Joseph Kennedy, and Arthur Wahl.17 In February and March 1941, Seaborg and Columbia University. In this method uranium gas passes through a series of membranes others succeeded in isolating Element 94 through chemical means. They also found other with openings small enough to block the heavier isotopes of the new element (plutonium-236 and 238).18 The next year Seaborg named the uranium-238 while allowing uranium-235 to pass new elements: Element 93, the first after uranium, was named "neptunium" (Np) after the through. The immediate problem posed by this first planet past Uranus; Element 94 was named for the next planet, Pluto, and was called method, and the problem that continued to plague "plutonium."19 Bucking a tradition that would have mandated "Pl" as the scientific short- this method for years to come, was the difficulty hand of the new element, Seaborg chose "Pu," in large part because of its unfavorable con- of manufacturing a membrane suitable to the notations.20 task.13 Element 94 lived up to "P-U." Research in 1941 suggested and later demonstrated Other methods that surfaced during this peri- that plutonium was 1.7 times more fissionable than uranium-235.21 Heavier and less sta- od included centrifugal separation and liquid ther- ble than uranium, plutonium could also be separated chemically, which meant that its pro- mal diffusion. Jesse Beams of the University of duction might be cheaper than the laborious process of harvesting uranium-235. This Virginia championed the centrifuge method, advantage, however, was offset by a major drawback: the new element was much more while the liquid thermal diffusion method was radioactive than uranium. Every step of the production process would require consider- favored by Philip Abelson of the Carnegie able shielding for the work force. Institute. Both methods were later dropped by Despite this disadvantage, the promise of plutonium was too great to leave untouched the Office of Scientific Research and in the search for fissionable material. In early 1941, Ernest Lawrence turned his cyclotron Development.14 on the new man-made elements to learn more about their fission properties. Lawrence came away from this work convinced that the new element could be produced in large quantities by bombarding uranium-238 with neutrons in Fermi’s pile.22 This discovery THE PROMISE OF PLUTONIUM gave a boost to Fermi and Szilard’s chain reaction research, and to the concept of the pile in general. The discovery of the usefulness of Element 94 provided a purpose for Fermi’s Uranium is the heaviest naturally occurring element on earth. Ever since the 1930s, pile, not yet known as a "reactor." however, it was known, at least in theory, that man-made elements of greater mass could be made by bombarding natural uranium with neutrons. The first two artificial elements were identified as eka-rhenium (Element 93) and eka-osmium (Element 94). In the early EARLY U.S. GOVERNMENT INVOLVEMENT 1940s, they would be formally named neptunium and plutonium, respectively. With the discovery of fission and the possibility of a fission bomb, there was renewed The government’s participation in fission research gained momentum as the results interest in Elements 93 and 94 for a number of reasons. Calculations suggested that became more promising. The first of the Manhattan Project’s predecessors, the Advisory Element 94 would fission just as well as, if not better than uranium-235, and the produc- Committee on Uranium, was not terribly active, as might befit an agency that oversaw a An Atomic History 0-3 8/11/02 7:31 AM Page 20

Chapter Two 23 process that, at the end of 1939, was almost wholly theoretical and potentially expensive.23 ered. Estimates were projected on how much uranium-235 would be required for a fis- In early 1940, the committee recommended that the government become directly involved sion bomb and that this amount could be gathered through the various uranium separation in funding fission research, specifically concentrating on uranium-235 separation and techniques at an estimated cost of between 50 and 100 million dollars. The following Fermi and Szilard’s chain reaction work at Columbia University.24 month, on December 7, 1941, the Japanese attacked Pearl Harbor. Four days later, Hitler In June 1940, the Uranium Committee was folded into a much larger umbrella organi- declared war against the United States as well. When Roosevelt approved the OSRD zation, the National Defense Research Council (NDRC), established to oversee and coor- report in January of 1942, there was an increased urgency to the fission programs that dinate military and civilian scientific work that might prove useful if the United States would only intensify over the next few months, as the government sought to organize an entered the war. This action was in response to recent successes in uranium work, as well atomic bomb program. It was also during this confusing period that plutonium was for- as the invasion of Western Europe by the Germans. The NDRC was headed by Dr. mally included as one of the viable options for a fission bomb.29 Vannevar Bush, president of the Carnegie Institute. Fission work still concentrated on iso- With Roosevelt’s consent, Vannevar Bush implemented the first reorganization of the tope separation and nuclear chain reactions, but there was a growing emphasis on plutoni- American nuclear effort in December 1941 and January 1942. First, there was a decision (Left to Right) Ernest Lawrence, um research.25 On June 28, 1941, just days after the Germans invaded Russia, the NDRC to make an all-out effort for the bomb. Next, the NDRC, which previously ran the Glenn Seaborg, and Robert Oppenheimer at control panel of 184 was subsumed by a new organization with broader scope and greater powers, the Office of Uranium Section (S-1) for the OSRD, was determined to be inadequate for this effort. S-1 inch cyclotron, circa 1942. Ernest Scientific Research and Development (OSRD), established by Executive Order. Vannevar was placed directly under the OSRD.30 Eger Murphree, a chemical engineer with Orlando Lawrence Berkeley National Laboratory, courtesy of AIP Emilio Bush was again placed in charge, this time with a mandate to report directly to Standard Oil, was put in charge of engineering studies and pilot plant construction. Ernest Segré Visual Archives. Roosevelt.26 Lawrence, Arthur Compton, and Harold Urey were made program chiefs. Lawrence was Despite all of these organizational changes, and made overseer of electromagnetic and plutonium research. Compton was placed over the remarkable developments in the various pro- chain reaction and weapons theory research, while Urey headed up work on gaseous diffu- posed methods for harvesting uranium-235 or pro- sion, centrifuge work, and heavy water development. Bush himself coordinated the engi- ducing plutonium, no one at the governmental level neering and scientific work, and made the final decisions for all construction contracts. was at all certain that any of these methods would The planning and construction of the pilot plants led to the first cooperation between the produce fissionable material on an industrial scale. OSRD and the Army Corps of Engineers.31 This uncertainty began to change with the appear- Compton, the new head of chain reaction work, was now directly in charge of the ance of the MAUD report in July of 1941. graphite and uranium-lattice research. In January 1942, Compton decided to transfer all MAUD was a British committee of scientists pile research to Chicago. This led to the creation of the Metallurgical Laboratory on the and government officials established to study the grounds of the University of Chicago. Fermi, Szilard, and Seaborg were among the physi- possibility of a fission bomb. A meaningless cists who moved to the new facility in the months that followed.32 The primary goal of acronym adopted as a wartime safeguard, "MAUD" the Metallurgical Laboratory, soon known as Met Lab, was the development of ways to was first organized in June 1940, during the dark transmute uranium into plutonium on an industrial scale.33 days after Dunkirk. In the months that followed, it As the war intensified in the early months of 1942, with Japanese advances through- charted the developments of nuclear fission research out the Pacific and German U-boats unchecked in the North Atlantic, it was soon clear that on both sides of the Atlantic.27 The committee even this level of organization was not sufficient to guarantee the success of the fission released its report in July 1941, when it appeared bomb project. Rather, an increased level of militarization and engineering know-how the Soviet Union was in imminent danger of col- would be required to safeguard the project and see it through to completion. This led to lapse. The MAUD report called for a fission bomb the direct involvement of the U.S. Army Corps of Engineers and the creation of the based on the use of gaseous diffusion of uranium, and dismissed other methods including Manhattan Project. thermal diffusion, centrifuge, electromagnetic racetracks, or the use of plutonium. It also Ironically, just as the American bomb program was about to go into high gear, the stated that close cooperation with the United States was essential to the success of the German program was being demoted. German fission research, which looked so threaten- enterprise. Even though American physicists disputed the report’s concentration on ing before the veil of secrecy went down in early 1940, took a number of wrong turns in gaseous diffusion, MAUD had great and positive impact in the United States. The report the crucial early years of the war, not the least of which was the faulty assumption that concluded that a nuclear fission bomb was not only feasible, but also possible within a graphite would not work as a reactor moderator. There is also evidence that crucial physi- time frame of two years, making it available for use in the present war.28 cists involved in the program, such as Heisenberg and Weizsacker, either dragged their feet In November of 1941, the OSRD, drawing on the MAUD report and subsequent or misled those in authority as to the potential for the bomb. Either way, in the summer of reports by the National Academy of Sciences, made its own recommendations to President 1942, the High Command decided that the fission bomb was too much of a long shot, Roosevelt on the feasibility of a fission bomb using uranium-235. Unlike the MAUD given Germany’s economic over-extension and the projected time frame of the war itself; report, which favored gaseous diffusion, the other separation methods were fully consid- fission research was removed from immediate military supervision.34 Unknown to the An Atomic History 0-3 8/11/02 7:31 AM Page 22

Chapter Two 25 allies at the time, the Germans never really got close to making an atom bomb, in large Marshall proved to be a good coordinator, but that was not enough. The program part because it would have been too expensive given the state of their economy. needed someone to cut through the logjam of military-supply restrictions, and through the dissonance of the scientists themselves, who could not reach a consensus on the best way to produce fissionable material. Bush himself realized this, and was instrumental in get- THE MANHATTAN PROJECT ting Marshall replaced by a more dynamic leader.41 Even though Marshall retained the title of District Engineer until well into 1943, his effective replacement was Leslie Groves, Early on, Niels Bohr discounted the possibility who had achieved renown by building the Pentagon in record time.42 Anticipating an of making an atomic bomb by saying that it could overseas assignment, Groves was not pleased to be put in charge of a project that many only be done by diverting the resources of an entire military experts considered a pipe dream.43 Like it or not, Groves assumed formal com- nation.35 He was not far wrong. Only a large and mand on September 23, 1942.44 powerful nation could gear up for the effort and This lack of faith in the project sometimes worked to Groves’ advantage. He was drive it to conclusion. The Manhattan Project made brigadier general to help break the military supply problem, and he was given huge proved to be such an effort, one that the United leeway in directing the work of S-1. Otherwise, he States was in the best position to achieve. The coun- was left alone, since many of his superiors wanted try had a huge industrial and capital base, as well as to avoid all responsibility for what they thought a skilled work force. It also had no shortage of bril- would be its inevitable failure. As Groves himself liant scientists, many of whom were refugees from put it in later years, he was the impresario of "a two Hitler’s Europe. They not only supported the effort, billion dollar grand opera with thousands of tem- but also were in the forefront of the push to see the peramental stars in all walks of life."45 He himself program through. Finally, there was the U.S. Army had no idea if the project could be made to work. Corps of Engineers, trained to design and construct As he stated, "if our gadget proves to be a dud, I large projects and to provide the leadership needed and all of the principal Army officers of the project to see them to completion.36 . . . will spend the rest of our lives so far back in a In the early summer of 1942, when the Army Fort Leavenworth dungeon that they’ll have to pipe Corps was brought into the program, leadership and sunlight in to us."46 General Groves and Robert organization were unresolved. When Col. James C. Marshall was called to head up the Groves moved on several fronts simultaneously. Oppenheimer reviewing report, world program on June 17, 1942, it was still called "S-1," the old NDRC nomenclature for the He got the triple-A rating required to give MED top map in the background suggests the 37 global nature of their endeavor. uranium research project. Marshall was commissioned to build the facilities needed to priority in the allocation of supplies and equipment. Courtesy of SRS History Project. produce an atomic bomb, and reorganize the effort so that it would be done as quickly as He purchased a large supply of uranium from the possible. Belgian Congo. He also acquired the 52,000-acre tract near Clinton, Tennessee, as the S-1 Committee Meeting. September Marshall did not have the clout to get top priority in the struggle for wartime supplies. manufacturing site for the various processes needed to produce fissionable material.47 13, 1942 at Bohemian Grove, California. (Left to Right) Harold In mid-July, the S-1 project got a rather low-priority AA-3 rating, largely because the pro- Working closely with Robert Oppenheimer, the man who would direct the making of the Urey, Ernest Lawrence, James Conant, gram was considered such a long shot.38 In other respects, the project dragged. bomb, Groves selected the site of the bomb design laboratory at Los Alamos, New Lyman Briggs, Eger Murphree, and 48 Arthur Compton. Ernest Orlando Marshall’s first scientific meeting with Vannevar Bush and the S-1 Executive Committee Mexico, in November of 1942. Lawrence Berkeley National of the OSRD, did not take place until July 25. At that time, the scientists were urging the The science end of the project was more difficult to resolve. While the plutonium Laboratory, courtesy of AIP Emilio acquisition of a large tract of land in east Tennessee, near the town of Clinton, for the site program seemed relatively secure, Groves was not pleased to have four different methods Segré Visual Archives. of all major nuclear manufacturing. Marshall later described the tract as "four isolated (electromagnetic, gaseous diffusion, thermal diffusion, and centrifuge) for producing ura- sites in one big isolated site."39 No action was taken to acquire the land. nium-235. He wanted one method designated the clear front runner to avoid what prom- In an effort to better coordinate the efforts of the S-1 project, Marshall put the pro- ised to be an exorbitantly expensive program.49 Unfortunately, there was no clear choice. gram under the umbrella of a formally instituted corps district, like those established for As late as May, the S-1 Executive Committee had de-emphasized the potential of thermal specific geographical areas throughout the country. Unlike other corps districts, however, diffusion, but still recommended that the other three—electromagnetic, gaseous diffusion, this one would have no territorial boundaries. On August 16, 1942, S-1 was folded into and the centrifuge—all proceed to the pilot plant stage.50 In November, Groves was the "Manhattan Engineer District" or MED, with headquarters in New York City.40 Even unable to get a consensus from the physicists involved in the various uranium-235 pro- though project headquarters was soon moved from New York to Washington, DC, the orig- grams, but he was able to narrow the field. The electromagnetic method emerged from the inal name stuck. Few today remember the Manhattan Engineer District, but the program fray the favored method—both a pilot plant and the regular plant were approved for con- to make the first atomic bomb is still called the "Manhattan Project." struction at Clinton. Gaseous diffusion still had promise, and it too went forward, even An Atomic History 0-3 8/11/02 7:31 AM Page 24

Chapter Two 27 though no one knew how to make the necessary filtration membrane. Thermal diffusion The success of Fermi’s pile was further complemented by advances in the chemical was de-emphasized, and the centrifuge was eliminated altogether.51 separations work that would have to be an integral part of the plutonium project. The first By the end of November 1942, there were three top contenders for making fissionable chemical separation of plutonium from uranium-238 was achieved on August 20, 1942. It material: electromagnetic and gaseous-diffusion methods for harvesting uranium-235, and was also the first occasion where there was enough plutonium to be seen with the naked the pile or reactor method for producing plutonium. For these three methods, full-scale eye.62 Additional work by Seaborg and others established that a separation matrix of lan- production was recommended.52 Up until November, it was assumed that the Clinton site thanum fluoride and other materials would successfully separate the plutonium from the in Tennessee would contain all manufacturing work required to produce fissile material for other irradiated materials.63 The separation work would still be difficult, especially at the the bomb. In that month, however, it was decided that the plutonium manufacturing works industrial level, but it was now established that it could be done. should be kept separate from the other processes. Even though Hanford in Washington The Manhattan Project was ready to jump from the laboratory to industrial operation. State would not be selected as the plutonium site until early 1943, the selection process The results of the project to date, as well as the industrial plans, were laid before President was well underway by the end of 1942.53 Roosevelt at the end of 1942. In late December, the Manhattan Project was authorized to In keeping with accepted military tradition—and to the annoyance of some of the proceed full-steam with industrial production, using the three methods for obtaining fis- physicists—Groves courted large private firms to run the various aspects of what would be sionable material.64 Clinton had already been selected as the site of the electromagnetic a huge industrial complex.54 Tennessee Eastman, which had already done work at Holston and gaseous diffusion plants, as well as the plutonium pile semi-works. Los Alamos had Ordnance Works, was retained to run the electromagnetic plant at Clinton. The M. W. been chosen as the intellectual nerve center and bomb assembly point for the project, and Kellogg Company and Union Carbide and Carbon Corporation were detailed for the Hanford was about to be selected as the site for the nuclear reactors and the chemical sep- gaseous diffusion plant, also to be at Clinton. E. I. du Pont de Nemours and Company, arations plants.65 The Manhattan Project was on the verge of take-off. commonly referred to as Du Pont, was retained for the operation of the plutonium works, no longer to be at Clinton, but not yet assigned to Hanford.55 Groves succeeded in getting Du Pont to assume the responsibility for the operation of PRODUCING THE FISSION MATERIAL the plutonium works plant in November of 1942.56 Groves was particularly interested in getting the giant chemical firm to carry out this part of the project. Not only did Du Pont By the time the first atomic bombs were detonated in the summer of 1945, the have a history of explosives manufacture and long association with the U.S. military, but Manhattan Project had cost around two billion dollars. The bulk of that money was spent the company also had the organizational strength and design and engineering capabilities creating three top-secret government facilities devoted to production of the fissionable to do the work. Since Du Pont specialized in chemical processes, it was ideally suited to material and the creation of the bomb mechanisms needed to detonate that material: the the chemical separation of plutonium from the irradiated materials that would leave the Clinton Engineer Works, later known as Oak Ridge; the Hanford Works; and the Los piles or reactors.57 Alamos Scientific Laboratory. While much of this work went on simultaneously, the bulk The reactor work that Du Pont was scheduled to perform got a serious boost when of the fissionable material production had to take place before the bomb could be assem- Fermi’s pile went critical on December 2, 1942. This was the first time a self-sustaining bled. For ease of presentation, the uranium-235 production facilities at Clinton will be chain reaction had ever been created. This achievement was the result of almost a year of discussed first, followed by the plutonium pilot plant at Clinton and the large plutonium research at the Metallurgical Laboratory on the grounds of the University of Chicago. production facility at Hanford. This in turn will be followed by the work at Los Alamos, Fermi himself had moved to Chicago in April of 1942, bringing together all pile research where the uranium and plutonium bombs were designed and assembled. at the Met Lab. Final design work for the pile was begun that summer, followed by instru- ment design, the machining of the graphite blocks, and the creation of dies needed to press the uranium oxide into suitable forms.58 The pile itself was set up in the squash court URANIUM FACILITIES AT OAK RIDGE underneath the west stands of Stagg Field and was designated Chicago Pile No. 1 or CP- 1.59 Shaped like a flattened sphere, CP-1 was 25 feet wide in the middle, 20 feet high, and The Clinton Engineer Works, now known as Oak Ridge, was the designated location composed of 57 layers of graphite block.60 Arranged in a lattice formation, the pile con- for the production of uranium-235. Built in late 1942 and early 1943 on 59,000 acres west sisted of 400 tons of graphite, 6 tons of uranium metal, and another 50 tons of uranium of Knoxville, there were two large-scale facilities at Oak Ridge for the production of ura- oxide. When the pile went critical on December 2, it reached a power level of one-half nium-235: the electromagnetic plant, designated Y-12; and the gaseous-diffusion plant, watt.61 Even though the power level was inconsequential, the results of the test pile were designated K-25.66 The experimental plutonium pile and separation facility, X-10, will be extraordinary. Fermi’s pile demonstrated that a nuclear chain reaction with uranium was discussed in the next section. possible, and it paved the way for the large-scale nuclear reactors that would be able to Planned by Ernest Lawrence and other researchers at Berkeley, Y-12 was built by turn uranium to plutonium. Among those present on that day was Crawford Greenewalt, Stone and Webster of Boston, for operation by Tennessee Eastman Corporation. the man slated to head Du Pont’s technical efforts at Hanford, and, after the war, to Excavation began in February 1943; operation commenced in October of that same year. become president of Du Pont itself. The heart of the Y-12 area were the two electromagnetic racetracks that separated urani- An Atomic History 0-3 8/11/02 7:31 AM Page 26

Chapter Two 29 um-235 from natural uranium. The two racetracks were designated Alpha and Beta, and each track was 122 feet long, 77 feet wide, and 15 feet high. Alpha provided the first step in the separation of uranium-235, while Beta took that material and further enriched it.67 “All In One Lifetime" - Jimmy F. Byrnes The gaseous diffusion plant, K-25, got off to a later start. Planned by physicists from Columbia University and by Kellex Corporation, K-25

Of all the South Carolina political figures who would play a role in ship’s alliance with Franklin Delano Roosevelt’s administration. was built by J. A. Jones Construction and Ford, Bacon the rooting of nuclear industry in his home state, Jimmy Byrnes was Byrnes, Charleston’s Mayor Burnet R. Maybank, and Governor & Davis. It was to be operated by M. W. Kellogg the most knowledgeable about what was ahead. Known as Franklin Blackwood successfully lobbied for the Santee Cooper Project. It was Company and Union Carbide and Carbon Corporation. Delano Roosevelt’s "assistant president," Byrnes, under the titles of the largest New Deal project the state received. Excavation for this facility did not begin until the sum- Director of Economic Stabilization and, later, Director of War In 1944, Byrnes was hopeful that he would be Roosevelt’s vice mer of 1943, after which the huge U-shaped building Mobilization, ran the country while FDR dealt with the war and foreign presidential candidate for his fourth term and Roosevelt encouraged took shape. Each wing of the building was 400 feet affairs. Described as "a small, wiry, neatly made man," who had the him along those lines. However, when push came to shove, the wide, and a half-mile long. Uranium hexafluoride gas ability to place issues before his personal agenda, Byrnes also acted Missourian, Harry S. Truman, was selected. Despite his work as was to be pumped through 11 miles of tubes and literal- as a buffer between the influential Bernard Baruch, another native son "assistant president," Byrnes’ politics and background as a conserva- ly thousands of porous barriers, perforated with billions of South Carolina, and the president. After Roosevelt’s death, Byrnes tive Democrat from the Deep South was considered a liability. of holes, all designed to select for uranium-235 atoms, served as Secretary of State under Truman, bringing his considerable Within twenty-four hours of Roosevelt’s death, two men told his which would tend to travel through the process slightly skill in negotiation and political maneuvering to the job. successor, Harry Truman, about the race for the atom bomb. The first faster than uranium-238. Even at this point, it was not Byrnes, a Charlestonian, was born in 1879 was Henry Stimson, the Secretary of War; the known how to produce the barrier or "membrane" that to Irish-American parents. His mother, " I had often heard naval officers second was Jimmy Byrnes, then a private citi- 68 Elizabeth E. Byrnes, who learned dressmaking say that a new defensive weapon zen of South Carolina. Truman selected Byrnes was at the very heart of the separation process. to support her family after her husband’s death, was developed for every offensive as his Secretary of State shortly afterward and By the spring and summer of 1944, there was a cri- 69 raised him. At age fourteen he found a job in a weapon. I asked the scientists what requested that he serve on the "Interim sis in the operation of both Y-12 and K-25. At Y-12, Charleston law firm as an office boy where a defense there could be against the Committee" a top-secret group in charge of problems began to crop up almost immediately after the member of the firm took an interest in him and atom bomb. But these distinguished establishing American policy on when and how Alpha track went on line in October 1943. The vacuum tanks leaked and were pulled out Meeting prior to the start of the “Big acted as his mentor. Seven years later Byrnes gentlemen, who had directed the the bomb would be used in the war, its testing, of alignment by the force of the magnets. In addition, rust formed in the magnetic coils, Three” at Potsdam, Wednesday, July 18, 1945. In the foreground, left to was appointed to the position of court reporter in advisory work on the bomb, could and its postwar applications. As a member of which tended to short out, forcing a closure of the racetrack in December of 1943 for right, Generalissimo Stalin, President Aiken for the 2nd Judicial Circuit, a job he think of no defense. They did antici- the Interim Committee, Byrnes rubbed elbows extensive repairs. Even after these problems were addressed, there remained the matter of Truman, Secretary of State Byrnes, enjoyed for eight years. During that time, he pate the development of still larger with members of the scientific community that and Foreign Commissar Molotov on gathering the uranium-235. Not enough thought had been devoted to the physical process the lawn outside of Stalin’s residence continued with his education at night, studying and more destructive bombs. I asked created the bomb and the Secretaries of War of isotope recovery; much of the uranium-235 was located on the walls of the vacuum in Babelsburg, Soviet Union. James F. in the office of attorney James Aldrich. He them if I should believe the only and of the Navy. He also met with the industri- tanks, and it was found to be difficult to collect.70 Byrnes Papers, Mss 90, negative passed the bar in 1903, and began practicing defense against further development alists and engineers who created Oak Ridge 49965. Courtesy of the Special If possible, K-25 was in worse shape. When the gaseous diffusion plant was con- Collections, Clemson University law in Aiken, seeking election as a solicitor in was to kill off all the scientists. This and Hanford to learn about what was entailed in structed, it was not even known how to make the porous membrane needed to separate Libraries, Clemson, South Carolina. 1908 in the Aiken circuit. He married Maude suggestion did not appeal to them." their operations. 71 Busch, a local woman and became editor of On July 3, 1945, he became Secretary of uranium-235 from 238, the very crux of the whole procedure. Continuing problems with Aiken’s weekly newspaper, The Aiken Journal and Review. State. In that capacity, he accompanied Truman to the Potsdam the membrane soon made it apparent that K-25 could not produce uranium with a high He was elected to Congress in 1910, in 1930 to the Senate. He Conference. Between 1945 and 1947, he earned an international rep- concentration of uranium-235. In desperation, the Army turned to thermal diffusion, a is credited with helping establish the first national highway system–U.S. utation for his role in world events, that ranged from policy making on process that had been dropped by the Manhattan Project, but one favored by the Navy. Highway 1–that runs through Aiken. An active supporter of Franklin the bomb to postwar control over atomic energy. Byrnes remained with Groves took the Navy’s thermal-diffusion process and had a small plant called S-50 built Delano Roosevelt, then governor of New York in 1928, Byrnes worked the post until 1947, after which he retired to South Carolina. He had at K-25 to handle the work. Able to provide massive quantities of slightly enriched urani- as a speechwriter for Roosevelt during the 1932 campaign. Byrnes served with distinction in all three branches of federal government and um, S-50 essentially saved the gaseous-diffusion process. Even with this help, however, was part of the Roosevelt team but he was not in favor of all of he played a significant role at Yalta and Potsdam, as a key player in the K-25 could only produce 50% enriched uranium, suitable only as feed material for the Y- Roosevelt’s domestic policies. His support for Roosevelt and the New Truman cabinet effecting an end to World War II, and setting out the 12 plants.72 Deal measures he advocated did land him a seat on the United States foundation for early Cold War policy. After solutions were found to the problems associated with Y-12, the electromagnetic Supreme Court in 1941. One year later, he resigned to assume his process was enlarged in scope to provide most of the fission material for the uranium-235 position as "Economic Czar" within the wartime emergency program of Source: James F. Byrnes Papers, Mss 90, Special Collections, atomic bomb that would be dropped on Hiroshima in August of 1945.73 Even before that wage and price. South Carolina benefited from Byrnes’ presence in Clemson University Libraries, Clemson, South Carolina. Secondary time, however, the uranium-235 work was somewhat overshadowed by the plutonium the White House. The state received over $400 million in federal assis- Source: www.byrnesscholars.org. (Inset) Source: James F. Byrnes, tance during the Depression, a result of the state’s political leader- Speaking Frankly, (New York: Harper, 1947), 260. process, which promised an even more powerful bomb. But this process too had its share of problems. An Atomic History 0-3 8/11/02 7:31 AM Page 28

Chapter Two 31 THE PLUTONIUM PROCESS: ARGONNE AND OAK RIDGE’S X-10 PILE Undoubtedly, one reason for the reluctance of Fermi and others at the Met Lab to wel- come Du Pont into the nuclear fold was Du Pont’s reputation as an explosives manufactur- The first stage in the plutonium process was the pile or reactor, and the seat of that knowl- er. The Du Pont family, based in Delaware, had been involved in making gunpowder since edge during the Manhattan Project—and for many years to come—was the Metallurgical the early 1800s, and had a long association with the U.S. military as a munitions manufac- Laboratory run by the University of Chicago. Shortly after the success of Fermi’s pile in turer. Anti-trust legislation in the early 1900s forced the Du Pont company to split into December 1942, all Met Lab reactor research was transferred to the greater safety of the three firms, but this did not keep Du Pont from making great profits after the First World Argonne Forest section of the Palos Park Forest Preserve on the outskirts of Chicago. It War broke out in Europe in 1914. Du Pont sold high explosives to Britain and France, and was the Met Lab at Argonne that developed the pile designs used in the plutonium pilot later, after the United States entered the war, filled all the Army and Navy orders for pow- works at Oak Ridge, and in the much larger facility at Hanford.74 der. It has been estimated that the company provided 40 percent of all the explosives 83 Fermi’s first successful pile was relatively primitive, and it was material used by the Allies in the First World War. the work of the Met Lab to improve the designs of new reactors. This This led to huge profits for the company, and enabled it to expand further into chemi- included new safety features and the best possible use of the available cal work, which had proven so useful during the war. In particular, research was directed neutrons, a concept called "neutron efficiency." The pile designs toward nitrocellulose, previously used for gun cotton. Breakthroughs in various highly worked out by the Met Lab included reactors with moderators that marketable plastics, such as Duco, rayon, cellophane, and the biggest seller of all, nylon, 84 ranged from graphite to heavy water. Coolants included helium, air, followed. About this same time, in 1934, Senate committee hearings on exorbitant heavy water, and light water. When the Du Pont engineers came on wartime profits tarred the company as infamous "merchants of death," a label Du Pont felt board the plutonium project, they had their own preferences: the plu- was unjustified and anachronistic. Hoping to avoid bad press in the aftermath of a project tonium semi-works at Oak Ridge, known as X-10, would be air- that would make World War I munitions look like a pop gun, Du Pont insisted on a con- cooled, with a graphite moderator.75 As a back-up for both moderator tract with the government that would earn it a profit of one dollar. and coolant, Groves insisted on the production of heavy water at a X-10 pile was a graphite cube, 24 feet number of distillation plants, the largest of which was the Wabash to a side, with 1248 separate channels River Ordnance Works, near Dana, Indiana.76 for the insertion of nuclear materials. Courtesy of Oak Ridge National Construction work on X-10 began in February 1943 and was fin- Laboratory. ished in October of that same year. In addition to an air-cooled experimental pile, there was a pilot plant for chemical separation.77 Built by Du Pont and supervised by Met Lab, the X-10 pile was a graphite cube, 24 feet to a side, with 1248 separate channels for the insertion of nuclear materials.78 The X-10 reactor was designed to produce small amounts of plutonium, which could then be used in various separations experiments.79 When the reactor went critical on November Fourth anniversary reunion of CP-1 4, 1943, it became the world’s second nuclear reactor, and the first one dedicated to pro- scientists. Courtesy of Argonne duction.80 In the months that followed, X-10 was a training ground for Du Pont personnel National Laboratory Archives, managed and operated by The University who would later run the much larger and more complex facilities at Hanford. X-10 would of Chicago for the U.S. Department of continue to serve in this fashion long after the war, when it became part of the Clinton Energy under Contract No. W-31-109- 81 ENG-38, negative 201-5282. Laboratories and finally Oak Ridge National Laboratory.

THE PLUTONIUM WORKS II: DU PONT AND HANFORD

At Groves’ behest, the Du Pont company had come on board to design, build, and operate the plutonium works required for the Manhattan Project. It was a decision that did not find favor with the Metallurgical Laboratory, especially Fermi and Compton, who wanted to do much of the work themselves, or at least preferred General Electric or Westinghouse for the task.82 Groves stood by his choice, and the manager chosen by Du Pont, Crawford Greenewalt—and these were probably the wisest of his many sage decisions. An Atomic History 0-3 8/11/02 7:31 AM Page 30

THE PLUTONIUM WORKS II: DU PONT AND HANFORD

Chapter Two 33 Groves selected Du Pont for a number of reasons. Du Pont was a large company with Just as important as the reactors were the three separations buildings, each 800 feet a healthy corporate structure capable of handling the plutonium project. The company long, 65 feet wide, and 80 feet tall. Dubbed "Queen Marys" due to their size, they were also had engineering and design capabilities that would be essential at Hanford. As a more commonly referred to as "canyons," a term still used today for such buildings. Two chemical company, it would be not only capable of, but also comfortable with, the basic of the three canyons were put into operation; the third was held in reserve for emergency industrial procedures that would have to be used to separate plutonium from the irradiated use. Inside the canyons were 40 process pools designed to mix the radioactive batch with material that would come out of the reactors. Because of its industrial experience with the the chemicals that would separate and purify the plutonium. For that work, Greenewalt chose bismuth phosphate for the bulk of the separation work, and lanthanum fluoride for the final concentration. The end product, plutonium nitrate, would then be shipped to Los Alamos, where it would be converted to plutonium metal.93 Organizational flow chart for the Manhattan Project showing the pro- Before anything could be shipped, however, the reactors had to transmute uranium- duction complex between 1942 and 238 into plutonium, and the reactors at first seemed destined to fail. In September 1944, 1946. Source: U.S. Department of twelve hours after B Reactor was loaded with uranium slugs and went critical for the first Energy, Office of Environmental Management, Linking Legacies: time, the reaction died down, ran again for a while, and died again. Upon examination, it Connecting the Cold War Nuclear was determined that the culprit was xenon, which was created as a byproduct of the fission Weapons Productions Processes to their Environmental Consequences, reaction. Even though xenon had a short half-life, it was a powerful neutron absorber. Report No. DOE/EM-0319 Productivity would be greatly reduced if the reactors had to endure such oscillations.94 (Washington, DC: GPO, 1997).

As part of the Manhattan Project, Du manufacture of gunpowder, Du Pont had an obsession with worker safety, and the plutoni- Pont designed, constructed, and oper- um works at Hanford were going to require all the safety measures that could be brought ated the world’s first production-scale reactors at Hanford. Photograph taken to bear. by U.S. Army Signal Corps, courtesy Hanford, one of the largest of the Manhattan Project engineering feats, was the last to of the Collections of the Library of get started. In December of 1942, it was known only that the plutonium site would be Congress, negative US762, 101676, 211317. along the Columbia River, near the Bonneville and Grand Coulee dams.85 The real estate appraisals began in January 1943,86 and the Hanford site itself was not formally selected until February. Construction, however, proceeded quickly, and was well under way by summer, months before it was known whether the X-10 pilot reactor would even work.87 Construction continued non-stop for a year, when the construction force peaked out at 42,400 in June of 1944.88 By that time, the total population at Hanford, counting both construction and operating force, was around 50,000 people.89 The project itself cost 400 million dollars.90 By the time the dust settled, there were three graphite piles or reactors, three separations buildings, and a host of auxiliary buildings, all designed to create and process plutonium. The three Hanford reactors were designated "B," "D," and "F." All three were water- cooled and graphite-moderated, and were designed to operate at a power level of 250 megawatts.91 Essential components of these piles were the solid uranium cylinders or "slugs" encased in aluminum that were loaded into the reactors through openings built into the graphite core.92 An Atomic History 0-3 8/11/02 7:31 AM Page 32

Chapter Two 35 Fortunately, the solution had already been built into each of the reactor cores. The In the beginning, it was assumed that both the uranium and the plutonium bombs Met Lab had mandated a total of 1500 reactor openings to admit the uranium slugs, the would be detonated using the "artillery method." This entailed a "cannon" that would fire neutron fuel rods, and the control rods. Du Pont insisted on adding another 500 openings a sub-critical mass of fissionable material into another sub-critical mass, and trigger a in the corners of each reactor as a precautionary measure. It was this extra feature that chain reaction almost instantaneously in thousands of generations, creating a nuclear saved the plutonium project. By loading the extra 500 slots, the Du Pont engineers were explosion. This method was perfectly adequate for the uranium bomb, dubbed "Little able to simply override the effect of the xenon.95 Boy," which was improved from an initial gun length of 17 feet, to one that only required After the necessary corrections were made to the reactors, they were quickly placed 6 feet.103 The plutonium bomb was a different matter. From the beginning, there were on line. Both B and D went critical in December 1944, followed by F in February 1945.96 difficulties with the plutonium gun design, referred to as "Thin Man." The gun method By early 1945, Los Alamos was getting regular amounts of plutonium from Hanford, as was simply too inefficient, and there were problems with the unwanted plutonium-240, an well as uranium-235 from Oak Ridge. It was now up to the scientists at Los Alamos to almost unavoidable consequence of the original irradiation. As a result, Thin Man was create the devices needed to house and detonate the fission material. eliminated as a feasible bomb design as early as July of 1944. This left the "implosion" method for the plutonium bomb, and "Fat Man," as this device was called, was fraught with challenges that no one had ever thought to solve.104 LOS ALAMOS AND THE ATOMIC BOMBS The basic problem with a plutonium bomb was that the core, reacting to countless generations of chain reactions within a split second, would expand too fast to achieve the While the uranium facilities at Oak Ridge and the plutonium plant at Hanford all optimum explosion. Seth Neddermeyer came up with the solution when he proposed worked their way through production problems in the course of 1944, problems of a differ- packing a spherical layer of high explosives around an assembly that consisted of a tamper ent sort plagued the physicists assigned to create bomb devices at Los Alamos. When inside of which was a hollow spherical core of fissionable but subcritical plutonium. The Groves spoke of the Manhattan Project as a grand opera with temperamental stars, he high explosives would blast inward, creating an "implosion" that would squeeze the tamp- Portrait of Robert Oppenheimer, head probably had Los Alamos in mind. He once told his military staff that, "at great expense, er from all sides. This would likewise reduce the hollow sphere of plutonium to a solid of the Los Alamos Scientific we have gathered on this mesa the largest collection of crackpots ever seen."97 ball of fissionable material that would achieve criticality far faster than possible with the Laboratory. Source: Los Alamos 105 National Laboratory. Considering the difficulties involved, it was certainly one of Robert Oppenheimer’s crown- gun method. The problem remained of how to create such a device. ing achievements to have managed Los Alamos so successfully.98 It was a job that The push for an implosion device led to the final shift at Los Alamos from research to entailed staying on top of the many scientific problems, as well as smoothing the ruffled production.106 The shock waves created by the sphere of surrounding explosives had to be (Opposite page) Four frames of feathers of a great many scientists. coordinated to the microsecond, and they had to have just the right magnitude. This employee badge photographs for Los Los Alamos began operation in the spring of 1943, when Oppenheimer and his staff required highly sophisticated calculations, and led to the first use of computers at Los Alamos Scientific Laboratory. Hans 107 Bethe is shown in the top frame. moved into the facilities. Among the people in charge of crucial aspects of the program Alamos. IBM calculation equipment arrived at the laboratory in April 1944. Source: Los Alamos National were Hans Bethe (theoretical physics), Robert Bacher (experimental physics), Joseph The successful completion of the implosion device was one of the great achievements Laboratory. Kennedy (chemistry and metallurgy), William "Deke" Parsons (ordnance), Felix Bloch, of the Manhattan Project. When the bombs were finally ready, in the summer of 1945, the and Edward Teller.99 The Los Alamos Scientific Laboratory, as it was officially known, war was already over in Europe, but Japan was still a potential target. There was little was the nerve center of the Manhattan Project. Production of fission material was coordi- doubt that the uranium bomb, Little Boy, would work as planned. The plutonium bomb, nated here, plutonium was purified, and finally, but certainly not least, the bombs them- Fat Man, was more problematical. Even though an implosion device had been created, no selves, known as "gadgets," were designed and made.100 one could know if it would work without a test run. This was arranged at the Trinity Test In addition to the scientific laboratory, operated by Oppenheimer and the University Site within the Alamogordo Bombing Range in New Mexico. There, a plutonium bomb of California, Los Alamos was also guarded by the Army. Security was tight, and often was set up on a 100-foot tower, and was detonated successfully on July 16, 1945, yielding resented, creating tension between the civilian scientists and the military force required to an explosive force equal to 21 kilotons of TNT.108 Groves, Oppenheimer, and all that guard them. It was not until late 1944, when Groves put Colonel Gerald Tyler in charge of were present for the Trinity test, knew immediately that the atomic bombs could end the the military side of Los Alamos, that matters were brought under some control.101 war. Some suspected, even then, that it would cast a long shadow over the world to come. By early 1945, regular shipments of uranium-235 and plutonium-239 were arriving at The first bomb to be dropped on Japan was the uranium device. On August 6, 1945, a Los Alamos. This material first had to be purified and stored in a safe configuration to B-29 bomber named the Enola Gay dropped a 9700-pound Little Boy over Hiroshima, a prevent inadvertent criticality. The metallurgy section then turned the fission material into city of 300,000 inhabitants. The device went off at 1900 feet with a force of between 15 metal form for bomb use.102 Long before this occurred, however, Los Alamos was and 20 thousand tons of TNT. Seventy thousand died outright, with another 70,000 embroiled in one of the main problems of the Manhattan Project: how to assemble a pluto- injured. By the end of the year, another 70,000 would be dead due to burns and radiation nium fission bomb. It was a dilemma that plagued work throughout 1944, and was not poisoning. Within five years, the total death toll would rise to 200,000.109 Three days solved until well into 1945. later, on August 9, the 10,000-pound plutonium implosion device, Fat Man, was dropped on Nagasaki with a force of between 20 and 21 thousand tons of TNT. The loss of life An Atomic History 0-3 8/11/02 7:31 AM Page 34

Chapter Two 37 was less than that of the uranium bomb only because Nagasaki’s hilly terrain blunted the Asia. One of the biggest factors in this new contest was the atomic bomb, a device more full effects of the blast. powerful than any previous ordnance by many orders of magnitude. And that was just the Little Boy and Fat Man convinced the Japanese to capitulate. On August 10, they beginning. Waiting in the wings was the fusion bomb, many times more powerful than the conveyed their desire to surrender on condition that the emperor could be retained. When fission devices dropped on Japan. The theoretical workings of this device were studied at the United States concurred the following day, the Japanese government surrendered on Los Alamos well before Hiroshima and Nagasaki.111 The atomic genie was out of the bot- August 14. Formal surrender documents were signed on September 2 aboard the USS tle, but it would be a few years before it was ready to mature. Missouri in Tokyo Bay.110 Two atomic bombs ended the Second World War, a global con- flict that had killed more soldiers and civilians than any other war in world history. Many believed, and many more hoped, that the close of the war would mark the beginning of a new era of peace. Certainly the United Nations, organized in San Francisco that same year, was established with this goal in mind. However, it would not be long before the two wartime superpowers, the United States and the Soviet Union, would be at odds over the postwar arrangements that each inherited in Europe and East

Aerial view of damage from the fission bomb dropped on Nagasaki. Courtesy of the Collections of the Library of Congress, negative US762, 104726. An Atomic History 0-3 8/11/02 7:31 AM Page 36

Aerial view of damage from the fission bomb dropped on Nagasaki. Courtesy of the Collections of the Library of Congress, negative US762, 104726.