MANHATTAN PROJECT

5. Manhattan Project: 

 

The Manhattan Project was the codename for a project conducted during World War II to develop the first atomic bomb. The project was led by the United States, and included participation from the United Kingdom and Canada.Formally designated as the Manhattan Engineer District (MED), it refers specifically to the period of the project from 1942–1946 under the control of the U.S. Army Corps of Engineers, under the administration of General Leslie R. Groves. The scientific research was directed by American physicist J. Robert Oppenheimer. The project’s roots lay in scientists’ fears since the 1930s that Nazi Germany was also investigating nuclear weapons of its own. Born out of a small research program in 1939, the Manhattan Project eventually employed more than 130,000 people and cost nearly US$2 billion ($22 billion in current value). It resulted in the creation of multiple production and research sites that operated in secret. With the total involved, this makes it one of the largest conspiracies in history. Entire towns were built for short periods of time, employing people, all under secrecy and top national secrecy at that. The government never admitted to it, the media never reported on it, and people had no idea for over 25 years. Project research took place at over thirty sites across the United States, Canada, and the United Kingdom. The three primary research and production sites of the project were the plutonium-production facility at what is now the Hanford Site, the uranium-enrichment facilities at Oak Ridge, Tennessee, and the weapons research and design laboratory now known as Los Alamos National Laboratory. The MED maintained control over U.S. weapons production until the formation of the Atomic Energy Commission in January 1947. 

 

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The Manhattan Project : ( source : [1] )

 

was a research and development program by the United States with the United Kingdom and Canada that produced the firstatomic bomb during World War II. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the US Army Corps of Engineers. The Army component of the project was designated the Manhattan District; "Manhattan" gradually superseded the official codename, "Development of Substitute Materials", for the entire project. Along the way, the Manhattan Project absorbed its earlier British counterpart, Tube Alloys. The Manhattan Project began modestly in 1939, but grew to employ more than 130,000 people and cost nearly US$2 billion (about $26 billion as of 2013). Over 90% of the cost was for building factories and producing the fissionable materials, with less than 10% for development and production of the weapons. Research and production took place at more than 30 sites across the United States, the United Kingdom and Canada. Two types of atomic bomb were developed during the war. A relatively simplegun-type fission weapon was made using uranium-235, an isotope that makes up only 0.7 percent of natural uranium. Since it is chemically identical to the main isotope, uranium-238, and has almost the same mass, it proved difficult to separate. Three methods were employed for uranium enrichment:electromagnetic, gaseous and thermal. Most of this work was performed atOak Ridge, Tennessee. In parallel with the work on uranium was an effort to produce plutonium. Reactors were constructed at Hanford, Washington, in which uranium was irradiated and transmuted into plutonium. The plutonium was then chemically separated from the uranium. The gun-type design proved impractical to use with plutonium so a more complex implosion-type weapon was developed in a concerted design and construction effort at the project's weapons research and design laboratory in Los Alamos, New Mexico. The Manhattan Project operated under a blanket of tight security, but Sovietatomic spies still penetrated the program. It was also charged with gathering intelligence on the German nuclear energy project. Through Operation Alsos, Manhattan Project personnel served in Europe, sometimes behind enemy lines, where they gathered nuclear materials and rounded up German scientists.

 

The first nuclear device ever detonated was an implosion-type bomb at the Trinity test, conducted at New Mexico's Alamogordo Bombing and Gunnery Range on 16 July 1945. Little Boy, a gun-type weapon, and the implosion-typeFat Man were used in the atomic bombings of Hiroshima and Nagasaki, respectively. In the immediate postwar years the Manhattan Project conducted weapons testing at Bikini Atoll as part of Operation Crossroads, developed new weapons, promoted the development of the network of national laboratories, supported medical research into radiology and laid the foundations for thenuclear navy. It maintained control over American atomic weapons research and production until the formation of the United States Atomic Energy Commission in January 1947.

 

Origins

 

In August 1939, prominent physicists Leó Szilárd and Eugene Wigner drafted the Einstein–Szilárd letter, which warned of the potential development of "extremely powerful bombs of a new type". It urged the United States to take steps to acquire stockpiles of uranium oreand accelerate the research of Enrico Fermi and others into nuclear chain reactions. They had it signed by Albert Einstein and delivered to President Franklin D. Roosevelt. Roosevelt called on Lyman Briggs of the National Bureau of Standards to head the Advisory Committee on Uranium to investigate the issues raised by the letter. Briggs held a meeting on 21 October 1939, which was attended by Szilárd, Wigner and Edward Teller. The committee reported back to Roosevelt in November that uranium "would provide a possible source of bombs with a destructiveness vastly greater than anything now known." Briggs proposed that the National Defense Research Committee (NDRC) spend $167,000 on research into uranium, particularly theuranium-235 isotope, and the recently discovered plutonium.On 28 June 1941, Roosevelt signed Executive Order 8807, which created the Office of Scientific Research and Development (OSRD), with Vannevar Bush as its director. The office was empowered to engage in large engineering projects in addition to research. The NDRC Committee on Uranium became the S-1 Uranium Committee of the OSRD; the word "uranium" was soon dropped for security reasons. In Britain, Otto Frisch and Rudolf Peierls at the University of Birmingham had made a breakthrough investigating the critical mass of uranium-235 in June 1939. Their calculations indicated that it was within an order of magnitude of 10 kilograms (22 lb), which was small enough to be carried by a bomber of the day. Their March 1940 Frisch–Peierls memorandum initiated the British atomic bomb project and its Maud Committee, which unanimously recommended pursuing the development of an atomic bomb. One of its members, the Australian physicist Mark Oliphant, flew to the United States in late August 1941 and discovered that data provided by the Maud Committee had not reached key American physicists. Oliphant then set out to find out why the committee's findings were apparently being ignored. He met with the Uranium Committee, and visited Berkeley, California, where he spoke persuasively to Ernest O. Lawrence. Lawrence was sufficiently impressed to commence his own research into uranium. He in turn spoke to James B. Conant,Arthur Compton and George Pegram. Oliphant's mission was therefore a success; key American physicists were now aware of the potential power of an atomic bomb.At a meeting between President Roosevelt, Vannevar Bush and Vice President Henry A. Wallace on 9 October 1941, the President approved the atomic program. To control it, he created a Top Policy Group consisting of himself—although he never attended a meeting—Wallace, Bush, Conant, Secretary of War Henry L. Stimson and the Chief of Staff of the Army, General George Marshall. Roosevelt chose the Army to run the project rather than the Navy, as the Army had the most experience with management of large-scale construction projects. He also agreed to coordinate the effort with that of the British, and on 11 October he sent a message to Prime Minister Winston Churchill, suggesting that they correspond on atomic matters.

 

Feasibility

Proposals

 

A 1940 meeting at Berkeley with (from left to right) Ernest O. Lawrence, Arthur H. Compton, Vannevar Bush, James B. Conant, Karl T. Compton, and Alfred L. Loomis The S-1 Committee held its first meeting on 18 December 1941 "pervaded by an atmosphere of enthusiasm and urgency" in the wake of the attack on Pearl Harbor and the subsequent declaration of war by the United States on Japan and Germany. Work was proceeding on three different techniques forisotope separation to separate uranium-235 from uranium-238. Lawrence and his team at the University of California, Berkeley, investigated electromagnetic separation, while Eger Murphree and Jesse Wakefield Beams's team looked into gaseous diffusion at Columbia University, and Philip Abelson directed research into thermal diffusion at the Carnegie Institution of Washington and later the Naval Research Laboratory. Murphree was also the head of an unsuccessful separation project using centrifuges. Meanwhile, there were two lines of research into nuclear reactor technology, with Harold Urey continuing research into heavy water at Columbia, while Arthur Compton brought the scientists working under his supervision at Columbia University and Princeton University to the University of Chicago, where he organized the Metallurgical Laboratory in early 1942 to study plutonium and reactors using graphite as a neutron moderator. Briggs, Compton, Lawrence, Murphree and Urey met on 23 May 1942 to finalize the S-1 Committee recommendations, which called for all five technologies to be pursued. This was approved by Bush, Conant and Brigadier General Wilhelm D. Styer, the chief of staff of Major General Brehon B. Somervell's Services of Supply, who had been designated the Army's representative on nuclear matters. Bush and Conant then took the recommendation to the Top Policy Group with a budget proposal for $54 million for construction by the United States Army Corps of Engineers, $31 million for research and development by OSRD and $5 million for contingencies in fiscal year 1943. The Top Policy Group in turn sent it to the President on 17 June 1942 and he approved it by writing "OK FDR" on the document. 

 

Bomb design concepts

 

Different fission bomb assembly methods explored during the July 1942 conference

Compton asked the theoretical physicist J. Robert Oppenheimer of the University of California, Berkeley, to take over research into fast neutron calculations—the key to calculations of critical mass and weapon detonation—from Gregory Breit, who had quit on 18 May 1942 because of concerns over lax operational security. John H. Manley, a physicist at the Metallurgical Laboratory, was assigned to assist Oppenheimer by contacting and coordinating experimental physics groups scattered across the country. Oppenheimer and Robert Serber of the University of Illinois examined the problems of neutron diffusion—how neutrons moved in a nuclear chain reaction—and hydrodynamics—how the explosion produced by a chain reaction might behave. To review this work and the general theory of fission reactions, Oppenheimer convened meetings at the University of Chicago in June and at the University of California, Berkeley, in July 1942 with theoretical physicists Hans Bethe, John Van Vleck, Edward Teller, Emil Konopinski, Robert Serber,Stan Frankel, and Eldred C. Nelson, the latter three former students of Oppenheimer, andexperimental physicists Felix Bloch, Emilio Segrè, John Manley and Edwin McMillan. They tentatively confirmed that a fission bomb was theoretically possible.

 

There were still many unknown factors. The properties of pure uranium-235 were relatively unknown, as were those of plutonium, an element that had only been discovered in February 1941 by Glenn Seaborg and his team. The scientists at the Berkeley conference envisioned creating plutonium in nuclear reactors where uranium-238 atoms absorbed neutrons that had been emitted from fissioning uranium-235 atoms. At this point no reactor had been built, and only tiny quantities of plutonium were available from cyclotrons. Even by December 1943, only two milligrams had been produced. There were many ways of arranging the fissile material into a critical mass. The simplest was shooting a "cylindrical plug" into a sphere of "active material" with a "tamper"—dense material that would focus neutrons inward and keep the reacting mass together to increase its efficiency. They also explored designs involving spheroids, a primitive form of "implosion" suggested by Richard C. Tolman, and the possibility ofautocatalytic methods, which would increase the efficiency of the bomb as it exploded.

 

Considering the idea of the fission bomb theoretically settled—at least until more experimental data was available—the Berkeley conference then turned in a different direction. Edward Teller pushed for discussion of a more powerful bomb: the "super", now usually referred to as a "hydrogen bomb", which would use the explosive force of a detonating fission bomb to ignite a nuclear fusion reaction indeuterium and tritium. Teller proposed scheme after scheme, but Bethe refused each one. The fusion idea was put aside to concentrate on producing fission bombs. Teller also raised the speculative possibility that an atomic bomb might "ignite" the atmosphere because of a hypothetical fusion reaction of nitrogen nuclei. Bethe calculated that it could not happen, and a report co-authored by Teller showed that "no self-propagating chain of nuclear reactions is likely to be started." In Serber's account, Oppenheimer mentioned it to Arthur Compton, who "didn't have enough sense to shut up about it. It somehow got into a document that went to Washington" and was "never laid to rest".

 

Organization

Manhattan District

 

The Chief of Engineers, Major General Eugene Reybold, selected Colonel James C. Marshall to head the Army's part of the project in June 1942. Marshall created a liaison office in Washington, D.C., but established his temporary headquarters on the 18th floor of 270 Broadway in New York, where he could draw on administrative support from the Corps of Engineers' North Atlantic Division. It was close to the Manhattan office of Stone & Webster, the principal project contractor, and to Columbia University. He had permission to draw on his former command, the Syracuse District, for staff, and he started with Lieutenant Colonel Kenneth Nichols, who became his deputy.

 

Manhattan Project Organization Chart, 1 May 1946

 

Because most of his task involved construction, Marshall worked in cooperation with the head of the Corps of Engineers Construction Division, Major General Thomas M. Robbins, and his deputy, Colonel Leslie Groves. Reybold, Somervell and Styer decided to call the project "Development of Substitute Materials", but Groves felt that this would draw attention. Since engineer districts normally carried the name of the city where they were located, Marshall and Groves agreed to name the Army's component of the project the Manhattan District. This became official on 13 August, when Reybold issued the order creating the new district. Informally, it was known as the Manhattan Engineer District, or MED. Unlike other districts, it had no geographic boundaries, and Marshall had the authority of a division engineer. Development of Substitute Materials remained as the official codename of the project as a whole, but was supplanted over time by "Manhattan".

 

Marshall later conceded that "I had never never heard of atomic fission but I did know that you could not build much of a plant, much less four of them for $90 million." A single TNT plant that Nichols had recently built in Pennsylvania had cost $128 million. Nor were they impressed with estimates to the nearest order of magnitude, which Groves compared with telling a caterer to prepare for between ten and a thousand guests. A survey team from Stone & Webster had already scouted a site for the production plants. The War Production Board recommended sites around Knoxville, Tennessee, an isolated area where the Tennessee Valley Authority could supply ample electric power and the rivers could provide cooling water for the reactors. After examining several sites, the survey team selected one near Elza, Tennessee. Conant advised that it be acquired at once and Styer agreed but Marshall temporized, awaiting the results of Conant's reactor experiments before taking action. Of the prospective processes, only Lawrence's electromagnetic separation appeared sufficiently advanced for construction to commence.

 

Marshall and Nichols began assembling the resources they would need. The first step was to obtain a high priority rating for the project. The top ratings were AA-1 through AA-4 in descending order, although there was also a special AAA rating reserved for emergencies. Ratings AA-1 and AA-2 were for essential weapons and equipment, so Colonel Lucius D. Clay, the deputy chief of staff at Services and Supply for requirements and resources, felt that the highest rating he could assign was AA-3, although he was willing to provide a AAA rating on request for critical materials if the need arose. Nichols and Marshall were disappointed; AA-3 was the same priority as Nichols' TNT plant in Pennsylvania.

 

Military Policy Committee

J. Robert Oppenheimer and Leslie Groves at remains of the Trinity test in September 1945. The white overshoes prevent fallout from sticking to the soles of their shoes.

Bush became dissatisfied with Colonel Marshall's failure to get the project moving forward expeditiously, specifically the failure to acquire the Tennessee site, the low priority allocated to the project by the Army and the location of his headquarters in New York City. Bush felt that more aggressive leadership was required, and spoke to Harvey Bundy and Generals Marshall, Somervell and Styer about his concerns. He wanted the project placed under a senior policy committee, with a prestigious officer, preferably Styer, as overall director. Somervell and Styer selected Groves for the post, informing him on 17 September of this decision, and that General Marshall ordered that he be promoted to brigadier general, as it was felt that the title "general" would hold more sway with the academic scientists working on the Manhattan Project. Groves' orders placed him directly under Somervell rather than Reybold, with Colonel Marshall now answerable to Groves. Groves established his headquarters in Washington, D.C., on the fifth floor of the New War Department Building, where Colonel Marshall had his liaison office. He assumed command of the Manhattan Project on 23 September. Later that day, he attended a meeting called by Stimson, which established a Military Policy Committee, responsible to the Top Policy Group, consisting of Bush (with Conant as an alternate), Styer andRear Admiral William R. Purnell. Tolman and Conant were later appointed as Groves' scientific advisers. On 19 September Groves went to Donald Nelson, the chairman of the War Production Board, and asked for broad authority to issue a AAA rating whenever it was required. Nelson initially balked but quickly caved in when Groves threatened to go to the President.[45] Groves promised not to use the AAA rating unless it was necessary. It soon transpired that for the routine requirements of the project the AAA rating was too high but the AA-3 rating was too low. After a long campaign, Groves finally received AA-1 authority on 1 July 1944. One of Groves' early problems was to find a director for Project Y, the group that would design and build the bomb. The obvious choice was one of the three laboratory heads, Urey, Lawrence or Compton, but they could not be spared. Compton recommended Oppenheimer, who was already intimately familiar with the bomb design concepts. However, Oppenheimer had little administrative experience, and, unlike Urey, Lawrence or Compton, had not won a Nobel Prize, which many scientists felt that the head of such an important laboratory should have. There were also concerns about Oppenheimer's security status, as many of his associates were communists, including his brother, Frank Oppenheimer; his wife, Kitty; and his girlfriend, Jean Tatlock. A long conversation on a train in October 1942 convinced Groves and Nichols that Oppenheimer thoroughly understood the issues involved in setting up a laboratory in a remote area and should be appointed as its director. Groves personally waived the security requirements and issued Oppenheimer a clearance on 20 July 1943.

 

Collaboration with the United Kingdom

The British and Americans exchanged nuclear information but did not initially combine their efforts. Britain rebuffed attempts by Bush and Conant in 1941 to strengthen cooperation with its own project, codenamed Tube Alloys, because it was reluctant to share its technological lead and help the United States develop its own atomic bomb. An American scientist who brought a personal letter from Roosevelt to Churchill offering to pay for all research and development in an Anglo-American project was poorly treated, and Churchill did not reply to the letter. The United States as a result decided as early as April 1942 that its offer was rejected, and that it should proceed alone.The United Kingdom did not have the manpower or resources of the United States and despite its early and promising start, Tube Alloys soon fell behind its American counterpart.On 30 July 1942, Sir John Anderson, the minister responsible for Tube Alloys, advised Churchill that: "We must face the fact that ... [our] pioneering work ... is a dwindling asset and that, unless we capitalise it quickly, we shall be outstripped. We now have a real contribution to make to a 'merger.' Soon we shall have little or none." That month Churchill and Roosevelt made an informal, unwritten agreement for atomic collaboration.

 

The opportunity for an equal partnership no longer existed, however, as shown in August 1942 when the British unsuccessfully demanded substantial control over the project while paying none of the costs. By 1943 the roles of the two countries had reversed from late 1941; in January Conant notified the British that they would no longer receive atomic information except in certain areas. While the British were shocked by the abrogation of the Churchill-Roosevelt agreement, head of the Canadian National Research Council C. J. Mackenzie was less surprised, writing "I can't help feeling that the United Kingdom group [over]emphasizes the importance of their contribution as compared with the Americans."As Conant and Bush told the British, the order came "from the top". The British bargaining position had worsened; the American scientists had decided that the United States no longer needed outside help, and they and others on the bomb policy committee wanted to prevent Britain from being able to build a postwar atomic weapon. The committee supported, and Roosevelt agreed to, restricting the flow of information to what Britain could use during the war—especially not bomb design—even if doing so slowed down the American project. By early 1943 the British stopped sending research and scientists to America, and as a result the Americans stopped all information sharing. The British considered ending the supply of Canadian uranium and heavy water to force the Americans to again share, but Canada needed American supplies to produce them.They investigated the possibility of an independent nuclear program, but determined that it could not be ready in time to affect the outcome of the war in Europe.

 

By March 1943 Conant decided that British help would benefit some areas of the project. James Chadwick and one or two other British scientists were important enough that the bomb design team at Los Alamos needed them, despite the risk of revealing weapon design secrets. In August 1943 Churchill and Roosevelt negotiated the Quebec Agreement, which resulted in a resumption of cooperation between scientists working on the same problem. Britain, however, agreed to restrictions on data on the building of large-scale production plants necessary for the bomb. The subsequent Hyde Park Agreement in September 1944 extended this cooperation to the postwar period. The Quebec Agreement established the Combined Policy Committee to coordinate the efforts of the United States, United Kingdom and Canada. Stimson, Bush and Conant served as the American members of the Combined Policy Committee, Field Marshal Sir John Dill and Colonel J. J. Llewellin were the British members, and C. D. Howe was the Canadian member. Llewellin returned to the United Kingdom at the end of 1943 and was replaced on the committee by Sir Ronald Ian Campbell, who in turn was replaced by the British Ambassador to the United States, Lord Halifax, in early 1945. Sir John Dill died in Washington, D.C., in November 1944 and was replaced both as Chief of the British Joint Staff Mission and as a member of the Combined Policy Committee by Field Marshal Sir Henry Maitland Wilson.

 

When cooperation resumed after the Quebec agreement, the Americans' progress and expenditures amazed the British. The United States had already spent more than $1 billion ($13,400,000,000 today ), while in 1943 the United Kingdom had spent about £0.5 million. Chadwick thus pressed for British involvement in the Manhattan Project to the fullest extent and abandon any hopes of a British project during the war. With Churchill's backing, he attempted to ensure that every request from Groves for assistance was honored. The British Mission that arrived in the United States in December 1943 included Niels Bohr, Otto Frisch, Klaus Fuchs, Rudolf Peierls and Ernest Titterton. More scientists arrived in early 1944. While those assigned to gaseous diffusion left by the fall of 1944, the 35 working with Lawrence at Berkeley were assigned to existing laboratory groups and stayed until the end of the war. The 19 sent to Los Alamos also joined existing groups, primarily related to implosion and bomb assembly, but not the plutonium-related ones.Part of the Quebec Agreement specified that nuclear weapons would not be used against another country without mutual consent. In June 1945 Wilson agreed that the use of nuclear weapons against Japan would be recorded as a decision of the Combined Policy Committee.

 

The Combined Policy Committee created the Combined Development Trust in June 1944, with Groves as its chairman, to procure uranium and thorium ores on international markets. The Belgian Congo and Canada held much of the world's uranium outside Eastern Europe, and the Belgian government in exile was in London. Britain agreed to give the United States most of the Belgian ore, as it could not use most of the supply without restricted American research. In 1944, the trust purchased 3,440,000 pounds (1,560,000 kg) of uranium oxide ore from companies operating mines in the Belgian Congo. In order to avoid briefing US Secretary of the Treasury Henry Morgenthau Jr. on the project, a special account not subject to the usual auditing and controls was used to hold Trust monies. Between 1944 and the time he resigned from the Trust in 1947, Groves deposited a total of $37.5 million into the Trust's account.

 

Groves appreciated the early British atomic research and the British scientists' contributions to the Manhattan Project, but stated that the United States would have succeeded without them. Whether or not he was correct, the British wartime participation was crucial to the success of the United Kingdom's independent nuclear weapons program after the war when the McMahon Act of 1946 temporarily ended American nuclear cooperation.

 

Project sites

 

- Oak Ridge 

- Los Alamos 

 - Argonne 

- Hanford 

- Canadian sites 

- Heavy water sites 

 

Uranium

- Ore

- Isotope separation 

   ^Centrifuges

   ^Electromagnetic separation

   ^Gaseous diffusion

   ^Thermal diffusion

- Gun-type weapon design

 

-Plutonium

  ^X-10 Graphite Reactor

  ^Hanford reactors

   ^Separation process

  ^Weapon design

  ^Trinity

 

Secrecy

Censorship

 

A billboard encouraging secrecy among Oak Ridge workers

Voluntary censorship of atomic information began before the Manhattan Project. After the start of the European war in 1939 American scientists began avoiding publishing military-related research, and in 1940 scientific journals began asking the National Academy of Sciences to clear articles. William L. Laurence of The New York Times, who wrote an article for The Saturday Evening Post in September 1940 on atomic fission, later learned that government officials asked librarians nationwide in 1943 to withdraw the issue.

 

The Manhattan Project operated under tight security lest its discovery induce Axis powers, especially Germany, to accelerate their own nuclear projects or undertake covert operations against the project.The government's Office of Censorship, by contrast, relied on the press to comply with a voluntary code of conduct it published, and the project at first avoided notifying the office. By early 1943 newspapers began publishing reports of large construction in Tennessee and Washington based on public records, and the office began discussing with the project how to maintain secrecy. In June the Office of Censorship asked newspapers and broadcasters to avoid discussing "atom smashing, atomic energy, atomic fission, atomic splitting, or any of their equivalents. The use for military purposes of radium or radioactive materials, heavy water, high voltage discharge equipment, cyclotrons." The office also asked to avoid discussion of "polonium, uranium, ytterbium, hafnium, protactinium, radium, rhenium, thorium, deuterium"; only uranium was sensitive, but was listed with other elements to hide its importance.

 

Soviet spies

Main article: Atomic spies

The prospect of sabotage was always present, and sometimes suspected when there were equipment failures. While there were some problems believed to be the result of careless or disgruntled employees, there were no confirmed instances of Axis-instigated sabotage. However, on 10 March 1945, a Japanese fire balloon struck a power line, and the resulting power surge caused the three reactors at Hanford to be temporarily shut down. With so many people involved, security was a difficult task. A special Counter Intelligence Corps detachment was formed to handle the project's security issues. By 1943, it was clear that the Soviet Union was attempting to penetrate the project. Lieutenant Colonel Boris T. Pash, the head of the Counter Intelligence Branch of the Western Defense Command, investigated suspected Soviet espionage at the Radiation Laboratory in Berkeley. Oppenheimer informed Pash that he had been approached by a fellow professor at Berkeley, Haakon Chevalier, about passing information to the Soviet Union.

 

The most successful Soviet spy was Klaus Fuchs, a member of the British Mission who played an important part at Los Alamos.The 1950 revelation of Fuchs' espionage activities damaged the United States' nuclear cooperation with Britain and Canada. Subsequently, other instances of espionage were uncovered, leading to the arrest of Harry Gold, David Greenglass and Ethel and Julius Rosenberg. Other spies like George Koval and Theodore Hall remained unknown for decades. The value of the espionage is difficult to quantify, as the principal constraint on the Soviet atomic bomb project was a shortage of uranium ore. The consensus is that espionage saved the Soviets one or two years of effort.

 

Foreign intelligence

Main article: Operation Alsos

In addition to developing the atomic bomb, the Manhattan Project was charged with gathering intelligence on the German nuclear energy project. It was believed that the Japanese atomic program was not far advanced because Japan had little access to uranium ore, but it was initially feared that Germany was very close to developing its own weapons. At the instigation of the Manhattan Project, abombing and sabotage campaign was carried out against heavy water plants in German-occupied Norway.[235] A small mission was created, jointly staffed by the Office of Naval Intelligence, OSRD, the Manhattan Project, and Army Intelligence (G-2), to investigate enemy scientific developments. It was not restricted to those involving nuclear weapons.[236] The Chief of Army Intelligence, Major General George V. Strong, appointed Boris Pash to command the unit,[237] which was codenamed "Alsos", a Greek word meaning "grove".[238]

 

 

Allied soldiers dismantle the German experimental nuclear reactor at Haigerloch.

The Alsos Mission to Italy questioned staff of the physics laboratory at theUniversity of Rome following the capture of the city in June 1944. Meanwhile Pash formed a combined British and American Alsos mission in London under the command of Captain Horace K. Calvert to participate inOperation Overlord. Groves considered the risk that the Germans might attempt to disrupt the Normandy landings with radioactive poisons was sufficient to warn General Dwight D. Eisenhower and send an officer to brief his chief of staff, Lieutenant General Walter Bedell Smith.

 

Under the codename Operation Peppermint, special equipment was prepared andChemical Warfare Service teams were trained in its use.

 

Following in the wake of the advancing Allied armies, Pash and Calvert interviewed Frédéric Joliot-Curie about the activities of German scientists. They spoke to officials at Union Minière du Haut Katanga about uranium shipments to Germany. They tracked down 68 tons of ore in Belgium and 30 tons in France. The interrogation of German prisoners indicated that uranium and thorium were being processed in Oranienburg, 20 miles north of Berlin, so Groves arranged for it to be bombed on 15 March 1945.

 

An Alsos team went to Stassfurt in the Soviet Occupation Zone and retrieved 11 tons of ore from WIFO.[244] In April 1945, Pash, in command of a composite force known as T-Force, conducted Operation Harborage, a sweep behind enemy lines of the cities ofHechingen, Bisingen and Haigerloch that were the heart of the German nuclear effort. T-Force captured the nuclear laboratories, documents, equipment and supplies, including heavy water and 1.5 tons of metallic uranium.

 

Alsos teams rounded up German scientists including Kurt Diebner, Otto Hahn, Walther Gerlach, Werner Heisenberg and Carl Friedrich von Weizsäcker, who were taken to England where they were interned at Farm Hall, a bugged house in Godmanchester. After the bombs were detonated in Japan, the Germans were forced to confront the fact that the Allies had done what they could not.

 

Bombing of Hiroshima and Nagasaki

Main article: Atomic bombings of Hiroshima and Nagasaki

 

Preparations

Starting in November 1943, the Army Air Forces Materiel Command at Wright Field, Ohio, began Silverplate, the codename modification of B-29s to carry the bombs. Test drops were carried out at Muroc Army Air Field, California, and the Naval Ordnance Test Station at Inyokern, California.[248] Groves met with the Chief of United States Army Air Forces (USAAF), General Henry H. Arnold, in March 1944 to discuss the delivery of the finished bombs to their targets. The only Allied aircraft capable of carrying the 17-foot (5.2 m) long Thin Man or the 59-inch (150 cm) wide Fat Man was the British Avro Lancaster, but using a British aircraft would have caused difficulties with maintenance. Groves hoped that the American Boeing B-29 Superfortress could be modified to carry Thin Man by joining its two bomb bays together.Arnold promised that no effort would be spared to modify B-29s to do the job, and designated Major General Oliver P. Echols as the USAAF liaison to the Manhattan Project. In turn, Echols named Colonel Roscoe C. Wilson as his alternate, and Wilson became Manhattan Project's main USAAF contact.[249] President Roosevelt instructed Groves that if the atomic bombs were ready before the war with Germany ended, he should be ready to drop them on Germany.

 

Silverplate B-29 Straight Flush. The tail code of the 444th Bombardment Group is painted on for security reasons.

The 509th Composite Group was activated on 17 December 1944 at Wendover Army Air Field, Utah, under the command of Colonel Paul W. Tibbets. This base, close to the border with Nevada, was codenamed "Kingman" or "W-47". Training was conducted at Wendover and at Batista Army Airfield, Cuba, where the 393d Bombardment Squadron practiced long-distance flights over water, and dropping dummy pumpkin bombs. A special unit known as Alberta was formed at Los Alamos under Captain William S. Parsons as part of the Manhattan Project to assist in preparing and delivering the bombs. Commander Frederick L. Ashworth from Alberta met with Fleet AdmiralChester W. Nimitz on Guam in February 1945 to inform him of the project. While he was there, Ashworth selected North Field on the Pacific Island Tinianas a base for the 509th Composite Group, and reserved space for the group and its buildings. The group deployed there in July 1945.[253] Farrell arrived at Tinian on 30 July as the Manhattan Project representative.

 

Most of the components for Little Boy left San Francisco on the cruiserUSS Indianapolis on 16 July and arrived on Tinian on 26 July. Four days later the ship was sunk by a Japanese submarine. The remaining components, which included six uranium-235 rings, were delivered by three C-54 Skymasters of the 509th Group's 320th Troop Carrier Squadron.

 

Two Fat Man assemblies travelled to Tinian in specially modified 509th Composite Group B-29s. The first plutonium core went in a special C-54.

 

A joint targeting committee of the Manhattan District and USAAF was established to determine which cities in Japan should be targets, and recommended Kokura, Hiroshima, Niigata and Kyoto. At this point, Secretary of War Henry L. Stimsonintervened, announcing that he would be making the targeting decision, and that he would not authorize the bombing of Kyoto on the grounds of its historical and religious significance. Groves therefore asked Arnold to remove Kyoto not just from the list of nuclear targets, but from targets for conventional bombing as well. One of Kyoto's substitutes was Nagasaki.

 

Bombings

In May 1945, the Interim Committee was created to advise on wartime and postwar use of nuclear energy. The committee was chaired by Stimson, with James F. Byrnes, a former US Senator soon to be Secretary of State, as President Harry S. Truman's personal representative; Ralph A. Bard, the Under Secretary of the Navy; William L. Clayton, the Assistant Secretary of State; Vannevar Bush; Karl T. Compton; James B. Conant; and George L. Harrison, an assistant to Stimson and president of New York Life Insurance Company. The Interim Committee in turn established a scientific panel consisting of Arthur Compton, Fermi, Lawrence and Oppenheimer to advise it on scientific issues. In its presentation to the Interim Committee, the scientific panel offered its opinion not just on the likely physical effects of an atomic bomb, but on its probable military and political impact. At the Potsdam Conference in Germany, Truman was informed that the Trinity test had been successful. He told Joseph Stalin, the leader of the Soviet Union, that the US had a new superweapon, without giving any details. This was the first communication to the Soviet Union about the bomb, but Stalin already knew about it from spies. With the authorization to use the bomb against Japan already given, no alternatives were considered after the Japanese rejection of the Potsdam Declaration.

 

Little Boy explodes over Hiroshima, Japan, 6 August 1945 (left);Fat Man explodes over Nagasaki, Japan, 9 August 1945 (right).

 

On 6 August 1945, the 393d Bombardment Squadron B-29 Enola Gay, piloted and commanded by Tibbets, lifted off with Parsons on board as weaponeer, and Little Boy in its bomb bay. Hiroshima, an important army depot and port of embarkation, was the primary target of the mission, with Kokura and Nagasaki as alternatives. With Farrell's permission, Parsons completed the bomb assembly in the air to minimize the risks during takeoff. The bomb detonated at an altitude of 1,750 feet (530 m) with a blast that was later estimated to be the equivalent of 13 kilotons of TNT. An area of approximately 4.7 square miles (12 km2) was destroyed. Japanese officials determined that 69% of Hiroshima's buildings were destroyed and another 6–7% damaged. About 70,000 to 80,000 people, or some 30% of the population of Hiroshima, were killed immediately, and another 70,000 injured.

 

On the morning of 9 August 1945, the B-29 Bockscar, piloted by the 393d Bombardment Squadron's commander, Major Charles W. Sweeney, lifted off with a Fat Man on board. This time, Ashworth served as weaponeer and Kokura was the primary target. Sweeney took off with the weapon already armed but with the electrical safety plugs still engaged. When they reached Kokura, they found cloud cover had obscured the city, prohibiting the visual attack required by orders. After three runs over the city, and with fuel running low, they headed for the secondary target, Nagasaki. Ashworth decided that a radar approach would be used if the target was obscured, but a last-minute break in the clouds over Nagasaki allowed a visual approach as ordered. The Fat Man was dropped over the city's industrial valley midway between the Mitsubishi Steel and Arms Works in the south and the Mitsubishi-Urakami Ordnance Works in the north. The resulting explosion had a blast yield equivalent to 21 kilotons of TNT, roughly the same as the Trinity blast, but was confined to the Urakami Valley, and a major portion of the city was protected by the intervening hills. About 44% of the city was destroyed; 35,000 people were killed and 60,000 injured.

 

Groves expected to have another atomic bomb ready for use on 19 August, with three more in September and a further three in October. Two more Fat Man assemblies were readied. The third core was scheduled to leave Kirtland Field for Tinian on 12 August. Robert Bacher was packaging it at the Ice House at Los Alamos when he received word. However, when the Japanese initiated surrender negotiations, Groves ordered the shipments suspended. On 11 August, Groves phoned Warren with orders to organize a survey team to report on the damage and radioactivity at Hiroshima and Nagasaki. A party equipped with portable Geiger counters arrived in Hiroshima on 8 September headed by Farrell and Warren, with Japanese Rear Admiral Masao Tsuzuki, who acted as a translator. They remained in Hiroshima until 14 September and then surveyed Nagasaki from 19 September to 8 October. This and other scientific missions to Japan would provide valuable scientific and historical data.

 

The necessity of the bombings of Hiroshima and Nagasaki became a subject of controversy among historians. Some questioned whether an "atomic diplomacy" would not have attained the same goals and disputed whether the bombings or the Soviet declaration of war on Japan was decisive.David H. Frisch recounts that alternative proposals such as a technical demonstration of an atomic explosion to the Japanese were circulated among scientists but in the end were not carefully analyzed. The Franck Report was the most notable effort pushing for a demonstration but was turned down by the Interim Committee's scientific panel. The Szilárd petition, drafted in July 1945 and signed by dozens of scientists working on the Manhattan Project, was a late attempt at warning President Harry S. Truman about his responsibility in using such weapons.

 

After the war

 

Presentation of the Army–Navy "E" Award at Los Alamos on 16 October 1945. Standing, left to right: J. Robert Oppenheimer, unidentified, unidentified, Kenneth Nichols,Leslie Groves, Robert Gordon Sproul, William Sterling Parsons.

A 1945 Life article estimated that "[p]robably no more than a few dozen men in the entire country knew the full meaning of the Manhattan Project, and perhaps only a thousand others even were aware that work on atoms was involved." The magazine wrote that the more than 100,000 others employed with the project "worked like moles in the dark". Warned that disclosing the project's secrets was punishable by 10 years in prison or a $10,000 ($129,000 today[1]) fine, they saw enormous quantities of raw materials enter factories with nothing coming out, and monitored "dials and switches while behind thick concrete walls mysterious reactions took place" without knowing the purpose of their jobs. The result amazed them as much as the rest of the world; newspapers in Oak Ridge announcing the Hiroshima bomb sold for $1 ($13 today[1]).

 

In anticipation of the bombings, Groves had Henry DeWolf Smyth prepare a history for public consumption. The Atomic Energy for Military Purposes, better known as the "Smyth Report", was released to the public on 12 August 1945.Groves and Nichols presented Army–Navy "E" Awards to key contractors, whose involvement had hitherto been secret. Over 20 awards of the Presidential Medal for Merit were made to key contractors and scientists, including Bush and Oppenheimer. Military personnel received the Legion of Merit, including the commander of the Women's Army Corpsdetachment, Captain Arlene G. Scheidenhelm.

 

At Hanford, plutonium production fell off as Reactors B, D and F wore out, "poisoned" by fission products and swelling of the graphite moderator known as the Wigner effect. The swelling damaged the charging tubes where the uranium was irradiated to produce plutonium, rendering them unusable. In order to maintain the supply of polonium for the urchin initiators, production was curtailed and the oldest unit, B pile, was closed down so at least one reactor would be available in the future. Research continued, with DuPont and the Metallurgical Laboratory developing a redox solvent extraction process as an alternative plutonium extraction technique to thebismuth phosphate process, which left unspent uranium in a state from which it could not easily be recovered.

 

Bomb engineering was carried out by the Z Division, named for its director, Dr. Jerrold R. Zacharias from Los Alamos. Z Division was initially located at Wendover Field but moved to Oxnard Field, New Mexico, in September 1945 to be closer to Los Alamos. This marked the beginning of Sandia Base. Nearby Kirtland Field was used as a B-29 base for aircraft compatibility and drop tests. By October, all the staff and facilities at Wendover had been transferred to Sandia.As reservist officers were demobilized, they were replaced by about fifty hand-picked regular officers.

 

Nichols recommended that S-50 and the Alpha tracks at Y-12 be closed down. This was done in September. Although performing better than ever,[285] the Alpha tracks could not compete with K-25 and the new K-27, which had commenced operation in January 1946. In December, the Y-12 plant was closed, thereby cutting the Tennessee Eastman payroll from 8,600 to 1,500 and saving $2 million a month.

 

President Harry S. Truman signs the Atomic Energy Act of 1946 establishing the United States Atomic Energy Commission.

 

Nowhere was demobilization more of a problem than at Los Alamos, where there was an exodus of talent. Much remained to be done. The bombs used on Hiroshima and Nagasaki were like laboratory pieces; work would be required to make them simpler, safer and more reliable. Implosion methods needed to be developed for uranium in place of the wasteful gun method, and composite uranium-plutonium cores were needed now that plutonium was in short supply because of the problems with the reactors. However, uncertainty about the future of the laboratory made it hard to induce people to stay. Oppenheimer returned to his job at the University of California and Groves appointed Norris Bradbury as an interim replacement. In fact, Bradbury would remain in the post for the next 25 years. Groves attempted to combat the dissatisfaction caused by the lack of amenities with a construction program that included an improved water supply, three hundred houses, and recreation facilities.

 

Two Fat Man–type detonations were conducted at Bikini Atoll in July 1946 as part of Operation Crossroads to investigate the effect of nuclear weapons on warships.[287] Able was detonated on 1 July 1946. The more spectacular Baker was detonated underwater on 25 July 1946.

 

In the face of the destructiveness of the new weapons and in anticipation of the nuclear arms race several project members including Bohr, Bush and Conant expressed the view that it was necessary to reach agreement on international control of nuclear research and atomic weapons. The Baruch Plan, unveiled in a speech to the newly formed United Nations Atomic Energy Commission (UNAEC) in June 1946, proposed the establishment of an international atomic development authority, but was not adopted.

 

Following a domestic debate over the permanent management of the nuclear program, the United States Atomic Energy Commission (AEC) was created by the Atomic Energy Act of 1946 to take over the functions and assets of the Manhattan Project. It established civilian control over atomic development, and separated the development, production and control of atomic weapons from the military. Military aspects were taken over by the Armed Forces Special Weapons Project (AFSWP).[290] Although the Manhattan Project ceased to exist on 31 December 1946, the Manhattan District would remain until it too was abolished on 15 August 1947.

 

Cost

 

Manhattan Project costs through 31 December 1945

                                                 SiteCost (1945 USD)          Cost (2013 USD)

Oak Ridge                                   $1,188,352,000                  $15.3 billion

Hanford                                         $390,124,000                    $5.04 billion

Special operating materials             $103,369,000                    $1.33 billion

Los Alamos                                      $74,055,000                    $956 million

Research and development                $69,681,000                    $900 million

Government overhead                        $37,255,000                   $481 million

Heavy water plants                            $26,768,000                   $346 million

 

Total                                         $1,889,604,000                $24.4 billion

 

The project expenditure through 1 October 1945 was $1.845 billion, equivalent to less than nine days of wartime spending, and was $2.191 billion when the AEC assumed control on 1 January 1947. Total allocation was $2.4 billion. Over 90% of the cost was for building plants and producing the fissionable materials, and less than 10% for development and production of the weapons.

 

A total of four weapons (the Trinity gadget, Little Boy, Fat Man, and an unused bomb) were produced by the end of 1945, making the average cost per bomb around $500 million in 1945 dollars. By comparison, the project's total cost by the end of 1945 was about 90% of the total spent on the production of US small arms (not including ammunition) and 34% of the total spent on US tanks during the same period.

 

Legacy

See also: Nuclear weapons in popular culture

The political and cultural impacts of the development of nuclear weapons were profound and far-reaching. William Laurence of the New York Times, the first to use the phrase "Atomic Age", became the official correspondent for the Manhattan Project in spring 1945. In 1943 and 1944 he unsuccessfully attempted to persuade the Office of Censorship to permit writing about the explosive potential of uranium, and government officials felt that he had earned the right to report on the biggest secret of the war. Laurence witnessed both the Trinity test and the bombing of Nagasaki and wrote the official press releases prepared for them. He went on to write a series of articles extolling the virtues of the new weapon. His reporting before and after the bombings helped to spur public awareness of the potential of nuclear technology and motivated its development in the United States and the Soviet Union.

 

The wartime Manhattan Project left a legacy in the form of the network of national laboratories: the Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, Oak Ridge National Laboratory, Argonne National Laboratory and Ames Laboratory. Two more were established by Groves soon after the war, the Brookhaven National Laboratory at Upton, New York, and the Sandia National Laboratories at Albuquerque, New Mexico. Groves allocated $72 million to them for research activities in fiscal year 1946–1947. They would be in the vanguard of the kind of large-scale research that Alvin Weinberg, the director of the Oak Ridge National Laboratory, would call Big Science.

 

The Naval Research Laboratory had long been interested in the prospect of using nuclear power for warship propulsion, and sought to create its own nuclear project. In May 1946, Nimitz, now Chief of Naval Operations, decided that the Navy should instead work with the Manhattan Project. A group of naval officers were assigned to Oak Ridge, the most senior of whom was Captain Hyman G. Rickover, who became assistant director there. They immersed themselves in the study of nuclear energy, laying the foundations for a nuclear-powered navy.[300] A similar group of Air Force personnel arrived at Oak Ridge in September 1946 with the aim of developing nuclear aircraft. Their Nuclear Energy for the Propulsion of Aircraft (NEPA) project ran into formidable technical difficulties, and was ultimately cancelled.

 

The ability of the new reactors to create radioactive isotopes in previously unheard-of quantities sparked a revolution in nuclear medicinein the immediate postwar years. Starting in mid-1946, Oak Ridge began distributing radioisotopes to hospitals and universities. Most of the orders were for iodine-131 and phosphorus-32, which were used in the diagnosis and treatment of cancer. In addition to medicine, isotopes were also used in biological, industrial and agricultural research.

 

On handing over control to the Atomic Energy Commission, Groves bid farewell to the people who had worked on the Manhattan Project:

Five years ago, the idea of Atomic Power was only a dream. You have made that dream a reality. You have seized upon the most nebulous of ideas and translated them into actualities. You have built cities where none were known before. You have constructed industrial plants of a magnitude and to a precision heretofore deemed impossible. You built the weapon which ended the War and thereby saved countless American lives. With regard to peacetime applications, you have raised the curtain on vistas of a new world.

 

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