The Making of the Atomic Bomb

In addition to his new Met Lab responsibilities Seaborg still coordinated basic scientific studies of uranium and plutonium at Berkeley. At the beginning of June he traveled to California to meet with “the fellows on the third floor of Gilman Hall” and to marry Ernest Lawrence's secretary. On June 6, returning to Chicago through Los Angeles, where Seaborg's parents lived, bride and groom prepared for a quick Nevada wedding. They got off the train in Caliente, Nevada, stored their bags with the telegraph operator at the station and asked directions to the city hall. “But to our vexation we learned there is no city hall here and in order to get our marriage license we would have to go to the county seat, a town called Pioche, some 25 miles to the north.” Providentially the deputy sheriff who served as Caliente's travel adviser and all-around troubleshooter turned out to be a June graduate of the Berkeley chemistry department. He arranged for the professor and his bride, Helen Griggs, to ride to Pioche in a mail truck. “Our witnesses were a janitor whom we recruited and [a] friendly clerk. We returned to Caliente on the mail truck's 4:30 run and checked into the local hotel here for our overnight stay.”

Arriving in Chicago on June 9 Seaborg delivered his wife to the apartment he had rented before he left for California and proceeded immediately to his office. His mail informed him that Edward Teller was joining the Chicago project to work in the theoretical group under Eugene Wigner.

Two days later Robert Oppenheimer turned up in Chicago and dropped by to see Seaborg; they were old friends but “it was more than just a social call.” Gregory Breit, the Wisconsin-based theoretician on the Uranium Committee who had been responsible for fast-neutron studies, had resigned from the bomb project in protest over what he felt were serious violations of security. “I do not believe that secrecy conditions are satisfactory in Dr. Compton's project,” he had written Briggs on May 18. His litany of examples approached paranoia. “Within the Chicago project there are several individuals strongly opposed to secrecy. One of the men, for example, coaxed my secretary there to give him some official reports out of my safe while I was away on a trip… The same individual talks quite freely within the group… I have heard him advocate the principle that all parts of the work are so closely interrelated that it is desirable to discuss them as a whole.” The dangerous individual Breit chose not to name was Enrico Fermi, pushing to make the chain reaction go. Compton had appointed Oppenheimer to replace Breit and Oppenheimer was visiting Seaborg for a briefing on the fast-neutron studies Seaborg was coordinating at Berkeley. Studying fast-neutron reactions, Seaborg notes, was “a prerequisite to the design of an atomic bomb.” Oppenheimer had found a place for himself on the ground floor.

The Washington University cyclotron crew moved the first 300 pounds of uranium nitrate hexahydrate into position around the machine's beryllium target on June 17. The UNH was scheduled for a month's bombardment, 50,000 microampere-hours. Though the chain reaction had not yet been proved and no one had yet seen plutonium, the various Met Lab councils of which Seaborg was a member had already begun debating the design and location of the big 250,000-kilowatt production piles that would create pounds of the strange metal if all went well. Fermi thought plutonium production needed an area a mile wide and two miles long for safety. Compton proposed building piles of increasing power to work up to full-scale production and was considering alternative sites in the Lake Michigan Dunes area and in the Tennessee Valley.

A question that would eventually encompass many other issues, some of them profound, was how to cool the big piles. Early in the organization of the Met Lab Compton had appointed an engineering council to consider such questions; besides an engineer and an industrial chemist the council included Samuel Allison, Fermi, Seaborg, Szilard and John A. Wheeler among its membership. By late June its discussions had progressed to the point of tentative commitment. Helium was one prospective coolant, to be circulated at high pressure inside a sealed steel shell; its zero cross section for neutron absorption was only one of its several advantages. Water was another coolant possibility, the heat-exchange medium most familiar to engineers but corrosive to uranium. An exotic third was bismuth, a metal with a low 520°F melting point that serves as a watchful solid in fuses and automatic fire alarms. Melted to a liquid it would transfer heat far more efficiently than helium or water. Szilard championed a liquid-bismuth cooling system in part because the metal could be circulated through the pile with a scaled-up version of the magnetic pump he and Albert Einstein had invented for refrigerators, a mechanism that had no moving parts to leak or fail.

The engineering council ruled out liquid cooling, Seaborg writes, “because of potential chemical action, danger of leaks and difficulty in transferring heat from oxide… There was general agreement to use helium.”

Eugene Wigner had not been invited onto the council despite his interest in its problems and his thorough knowledge of chemical engineering. Wigner strongly favored water cooling, says Szilard, because “a water cooled system could be built in a much shorter time.” Seaborg corroborates Wigner's continuing desperate concern about a German bomb:

Compton repeated a conversation that ensued between him and Wigner on a possible schedule of the Germans. Like us, they have had three years since the discovery of fission to prepare a bomb. Assuming they know about [pluto-nium], they could run a heavy water pile for two months at 100,000 kw and produce six kilograms of it; thus it would be possible for them to have six bombs by the end of this year [1942]. On the other hand, we don't plan to have bombs in production until the first part of 1944.

Compton encouraged Wigner's group to design a water-cooled pile but ordered up detailed engineering studies only of a system using helium.

The basic issue behind the technical dispute was control, which Szilard at least understood they were systematically signing away to the U.S. government. A meeting on June 27 intensified the conflict. Bush's latest status report to Roosevelt on June 17 had proposed dividing the work of development and ultimate production between the OSRD and the U.S. Army Corps of Engineers, bringing in the Army to build and run the factories as Bush had planned to do all along. Roosevelt initialed Bush's cover letter “OK. FDR.” and returned it immediately. The same day the Chief of Engineers ordered Colonel James C. Marshall of the Syracuse Engineer District, a 1918 West Point graduate with experience building air bases, to report to Washington for duty. Marshall selected the Boston construction engineering corporation of Stone & Webster as principal contractor for the bomb project. To report the reorganization Compton called the June 27 meeting of his group leaders and planning board. Allison, Fermi, Seaborg, Szilard, Teller, Wigner and Zinn attended, among others.

“Compton opened the meeting with a pep talk,” Seaborg remembers, “asking us to go ahead with all vigor possible. He said our aim the past half-year has been to investigate the possibilities of producing an atomic bomb — now we have the responsibility to proceed from the military point of view on the assumption it can be done and we can assume we have a project for the entire duration of the war.” Compton was stealthily working his way to the new arrangements. He emphasized the program's secrecy. “Only about six men in the U.S. Army are permitted to know what is going on,” Seaborg paraphrases him; those privileged few included Secretary of War Henry L. Stimson — heady company for men who had only recently been graduate students or obscure academics — and “two construction experts,” generals whom Compton then named. He described the responsibilities of the “construction experts” and finally broke the news: “It is hoped to have a contractor assume responsibility for the production plant.” A contractor already had.

Compton's announcement had the effect he seems to have feared, Seaborg goes on: “A number of the people present expressed great concern about working for an industrial contractor because of their fear that this would not be a compatible environment in which to work.” They would not have to work for such a contractor, though they would obviously have to work with one, but to make the reorganization palatable Compton hinted at worse that might be yet to come: “There was considerable talk about our being absorbed into the Army [i.e., commissioned as officers] and what the advantages and disadvantages might be. There were vigorous objections from most of the people present.”

The problem would fester all summer and burst through again in the fall. Szilard would define it precisely in a memorandum: “Stated in abstract form, the trouble at Chicago arises out of the fact that the work is organized along somewhat authoritative [sic: authoritarian] rather than democratic lines.” The visionary Hungarian physicist did not believe science could function by fiat. “In 1939,” he had already written Vannevar Bush passionately in late May, before the cooling-system and contractor debates, “the Government of the United States was given a unique opportunity by Providence; this opportunity was lost. Nobody can tell now whether we shall be ready before German bombs wipe out American cities. Such scanty information as we have about work in Germany is not reassuring and all one can say with certainty is that we could move at least twice as fast if our difficulties were eliminated.”