Big Science

by Michael Hiltzik

  Through early 1943, the encouraging design experiments at Berkeley, the rapid progress of construction at Oak Ridge, and Ernest’s infectious enthusiasm combined to make electromagnetic separation appear to be the best bet for producing core material for the uranium bomb. Urey’s gaseous diffusion plant at Oak Ridge, designated K-25, was falling far behind schedule: in the spring of 1943, no one yet had any idea what material for a diffusion membrane would best resist the corrosive properties of the malevolent hex, and no one could say how soon an answer might be found. Urey quarreled repeatedly with John Dunning, a Columbia colleague who was a specialist in the process. More seriously, he clashed with Groves. “The problem of where to concentrate Dr. Urey’s energy is still unsolved,” Colonel Nichols scribbled in his notes after a fraught meeting over K-25.

  By contrast, plans for Y-12 kept expanding even as the plant rose from the valley floor. The newest idea percolating through the hallways at the Rad Lab called for a two-stage separation process using a new variety of calutron to further enrich the product of the original racetracks. The originals were to be designated the Alpha racetracks; the new, smaller racetracks, which would have thirty-six tanks arranged in a rectangle, with two ion sources each, were labeled Betas.

  Groves signed off on the new system in March, launching another round of frenetic experimentation in Berkeley. The Betas would process less material but at higher intensities, leaving less flexibility for loss. Some material always spattered over the interior of the Alphas, much of it recoverable through washing and scrubbing, but the partially enriched uranium serving as the Betas’ feedstock was too valuable for even a speck of it to be left behind on the ion sources, electrodes, or vacuum tank walls.

  By late spring, construction was well along on five Alpha racetracks, two Betas, and a host of outbuildings for chemical processing. Lawrence predicted that each Alpha would be capable of producing 300 grams of enriched uranium a month. The first racetrack was to be ready to start producing by September.

  Then this one great step forward was pushed two steps back. The Los Alamos lab, recently established under Oppenheimer’s leadership, tripled to 40 kilograms its estimate of the quantity of U-235 needed for a bomb. Hearing the news in Washington, Conant despaired of obtaining so much bomb material out of Oak Ridge by any method. But Lawrence saw opportunity in the discouraging new figure. Arguing that Y-12 was the most reliable option for meeting the new specifications, he pressed for a major expansion of the plant, encompassing additional Betas and a new, more productive Alpha design. After a test Alpha at Oak Ridge ran successfully for the first time on August 17, Groves approved the Alpha expansion to nine racetracks from five.

  In early November, the first racetrack was being readied for the production phase. But disaster struck when it was energized on November 13, 1943. Nichols would remember the day, his thirty-sixth birthday, without fondness. For the racetrack failed almost instantly. The powerful magnets jolted the fourteen-ton vacuum tanks out of place, which threatened in turn to pull apart the superstructure of pipes, pumps, and cables. Even the tanks that stayed put sprung vacuum leaks, microscopic holes that had to be hunted down one by one and sealed by hand.

  The magnets kept shorting out for reasons the engineers were able to diagnose only after opening one up, when they discovered its cooling oil had been thoroughly contaminated by rust, metal shavings, and sediment. The only option was to ship all the magnets back to the manufacturer, Allis-Chalmers, for cleaning and radical reconditioning. At least a month’s delay was in store.

  The fiasco placed heavy pressure on Lawrence, whose outwardly sunny disposition concealed how close he had been brought to physical collapse by the weight of his responsibilities and the strain of constant traveling. Things only got worse when, in the midst of the frenetic effort to track down the causes of failure, an incensed General Groves arrived on the scene. Groves blamed Lawrence personally for the delay, especially after learning that the Rad Lab had experienced a similar flaw with its cyclotron magnets and therefore should have anticipated the problems. He aimed a stream of “caustic comments” (in Nichols’s surely understated words) at Lawrence, and finally Lawrence broke. He made his way to Chicago for an S-1 meeting at the Met Lab, so tormented by back spasms that he had to be carried into the session in a chair. Immediately afterward, he checked himself into the University of Chicago Hospital and summoned Luis Alvarez from the Met Lab.

  Alvarez was aghast at Lawrence’s appearance. “I had never seen the guy so completely beaten in my life,” he recalled later. “He was just exhausted, he was depressed, he was just in very poor spirits.” Lawrence feared that the failure at Y-12 would destroy the army’s confidence in the entire bomb project, with billions of dollars—indeed, the entire war effort—hanging in the balance. Adding to his misery was his feeling of impotence; for perhaps the first time in his career, he was confronted with an engineering crisis he could not fix himself. The repairs were dependent on the manufacturer’s engineers pulling the magnets apart, flushing the oil lines, and putting them back together properly. “There was nothing he could do but sit there and sweat it out,” Alvarez recalled. Ernest was fighting a chronic sinus infection, his back was aching, and an orthopedic brace that had been made for him fit so poorly it aggravated rather than relieved the pain. Alvarez hung around to “hold his hands for several days,” at which point Ernest staggered home to Berkeley to await the completion of repairs.

  The crisis proved to be temporary. At length, Allis-Chalmers achieved the necessary fixes. The successful launch of the Alpha II array in mid-January 1944 helped dispel Ernest’s gloom. The new calutrons were plagued by their own flaws—electrical failures, cracked insulators, leaky vacuum tanks, a cascade of trivialities that spelled long halts for dismantling and reassembly—but millimeter by millimeter, the engineers and operators mastered the temperamental machines. By the end of February, the Alpha II racetracks had produced 200 grams of material enriched to 12 percent U-235. The volume was disappointing and the enrichment far below what was needed for a bomb core, but it was also far more than any other method had produced. Some of it was shipped to Los Alamos for experimentation, the rest stored as feedstock for the Betas.

  Lawrence, now back on his feet, felt encouraged enough to outline an appeal for yet another expansion of Y-12. He pressed his case in a letter to Conant, reminding him that Y-12 stood alone as validation of the feasibility of the bomb program. “The primary fact now is that the element of gamble in the overall picture no longer exists,” he wrote. “The electromagnetic plant is in successful operation and the experimental developments at Y [that is, Los Alamos] leave no doubt that the production can be used as an overwhelmingly powerful explosive. It is only a question of time.”

  • • •

  In mid-1944, Groves addressed the problem of K-25’s disappointing output by scaling back the gaseous diffusion program. Diffusion worked as a “cascade”—in steps, with each cycle of diffusion incrementally increasing the concentration of U-235 in the feedstock produced by the previous cycles. Groves’s order reduced K-25 to a supplemental source of raw material for the Beta calutrons of Y-12. In connection with the new arrangement, Lawrence received approval for his expanded Alpha II plant, which would supplement the feed from the diffusion process in a final push to produce uranium enriched to weapon-grade.

  There was one last element to the process. Working on a navy contract quietly and virtually single-handedly at the Philadelphia Navy Yard, Lawrence’s former graduate student Philip Abelson had perfected a way of enriching uranium by thermal diffusion. In April 1944, amid persistent doubts that Oak Ridge could supply a bomb core, Groves learned of the work and dispatched a reconnaissance team to Philadelphia. They found Abelson laboring in a forest of one hundred towering cylindrical columns, in which uranium hexafluoride with a high concentration of U-235 was accumulating. Three weeks later, Groves ordered the erection of a 2,100-column thermal diffusion plant at Oak Ridge.

  By January 1
945, the three-headed process was working. The Alpha tanks produced more than 250 grams per day of uranium enriched to 10 percent U-235. The Betas mixed that with the output of K-25 and the thermal columns to turn out 204 grams of uranium per day enriched to 80 percent U-235. This was bomb-grade fuel. At that rate, one bomb core would be produced by July 1, 1945. This core, manufactured largely by a process essentially cobbled together out of the bits and pieces of Ernest Lawrence’s precious cyclotrons, would go into the device known as Little Boy, which detonated above Hiroshima on August 6, 1945.

  • • •

  While the refinement and construction of the uranium plants were taking place, Glenn Seaborg ran his own race to perfect a plutonium extraction process. An important breakthrough occurred in a squash court under the west stands of the University of Chicago’s Stagg Field, where Enrico Fermi had erected an atomic pile. On December 2, 1942, he achieved a chain reaction. Arthur Compton was on hand to watch Fermi’s men draw the control rods from a towering pile of graphite blocks within which the uranium was arranged, and to hear the telltale clicks from counters measuring radioactive output from the world’s first controlled atomic reaction. Elated—perhaps in part because he had won his January bet with Lawrence that the chain reaction would be going by the end of that year—Compton called Conant in Cambridge. “Jim,” he said, “you’ll be interested to know that the Italian navigator has just landed in the new world.”

  “Is that so?” Conant replied. “Were the natives friendly?”

  “Everyone landed safe and happy.”

  Seaborg got the news at his office across campus. He recorded the moment in his journal, leavening his relief with the one overriding concern that had lent urgency to the work of all the atomic scientists of those years. “Of course, we have no way of knowing if this is the first time a sustained chain reaction has been achieved,” he wrote. “The Germans may have beaten us to it.”

  On June 1, six months after Fermi’s achievement, Seaborg met with executives of DuPont, which had been cajoled by Groves into contracting to build a pilot plutonium separation plant at Oak Ridge. Their goal was to finalize the plant’s design. Its chain-reacting pile went live at the beginning of November and within six weeks was producing plutonium by the milligram, and soon by the gram. This was shipped back to Chicago for further study by Seaborg’s team, which shortly would abandon its techniques of microchemistry and work with quantities they could see—but which required new safety precautions to protect against breathing or ingesting their “fiendishly toxic” godchild. Meanwhile, DuPont began work on the next stage of the manufacturing cycle: a full-scale production plant located on a bend of the Columbia River in central Washington State, near the little town of Hanford.

  Seaborg was as awestruck by the immensity of the Hanford plant as Lawrence had been on witnessing the transformation of Oak Ridge. It had been four years since he and Emilio Segrè had crossed the Berkeley campus with a bucket of ether infused with microscopic quantities of plutonium and suspended from a long wooden pole. All his work since then had culminated in a factory that could irradiate two hundred tons of uranium at a time to produce a half pound of plutonium every two hundred days. From the slugs of irradiated uranium, fissile plutonium would be extracted at a second plant ten miles away, eventually to be sent on its way to Los Alamos. From that material, the Los Alamos bomb makers would create the device known as Fat Man, the plutonium bomb dropped over Nagasaki three days after the Hiroshima bombing.

  Chapter Fourteen

  * * *

  The Road to Trinity

  The course of the war had outrun work on the bomb, rendering the Allied scientists’ concerns about a Nazi bomb program increasingly irrelevant. The entry of America into the European war, with its stupendous resources, made an Allied victory seem almost inevitable by mid-1943, notwithstanding earlier tactical setbacks in North Africa and the Balkans. The Normandy invasion launched on June 6, 1944, heralded a final Allied push toward Berlin, interrupted chiefly by the six-week winter counterattack by German forces known to Allied military historians as the Ardennes Counteroffensive and in the popular mind as the Battle of the Bulge.

  For the physicists of the atomic bomb program, Germany’s surrender on May 7, 1945, complicated the moral and ethical issues connected with the device they had invented. Those issues had seemed comparatively straightforward while the Allied war effort remained primarily focused on the Nazi regime. The terrifying thought that Adolf Hitler might beat the Allies to exploitation of the atom’s destructive capacity had prompted many eminent scientists, including numerous refugees from Nazi Germany, to participate willingly in the Manhattan Project. In 1942 and 1943, the uncertain course of the war pushed doubts about building and using an atomic bomb to the background. Given the existential threat posed by a German bomb, few harbored any qualms about the Allies using theirs first.

  Japan presented an entirely different case, at least to the scientists. Japan’s technological capabilities appeared to be far inferior to those of Germany, and the Japanese regime’s threat to the world of a much more limited order. Although only a handful of the Manhattan Project scientists were fully aware of the state of progress on the bomb—chiefly those working on the device itself at Los Alamos and those with high-level clearance, such as Ernest Lawrence—the experts at the program’s far-flung laboratories perceived that a successful conclusion to their work was drawing near. This sharpened the feelings in the physics community and among the program’s civilian leadership that discussions about the deployment of the bomb and postwar management of its technology should be urgently stepped up.

  Leo Szilard felt deeply the difficulty of balancing the imperative to build the bomb with humanitarian concerns about its use. The refugee Hungarian physicist had placed the very notion of atomic weaponry on the federal government’s radar in 1939, when he prompted Albert Einstein to alert Franklin Roosevelt to the military potential of nuclear fission. Szilard’s views on the program he midwifed had traveled a tortuous path. For four dispiriting years, he had hectored government officials to place the program on the fast track. Yet by May 1945, he was urging those same officials that the best hope for averting a postwar nuclear arms race lay in “not using the bomb against Japan, keeping it secret, and letting the Russians think that our work on it had not succeeded.” After the German surrender, he brought one more argument to the table: using the bomb on Japan would fatally compromise America’s moral and humanitarian standing, undermining any efforts to create a workable international control regime. Yet the hour was getting late. The planned test of the plutonium bomb over the sands of Alamogordo, New Mexico, an event known as Trinity, was nigh; deployment of the bomb in war could be only a few weeks further off.

  Discussions about the control of nuclear arms and use of the bomb on Japan had been going on since 1943. The center of debate over postwar planning, as well as of opposition to dropping the bomb, was the Metallurgical Laboratory—the Met Lab—headed by Arthur Compton at the University of Chicago, where Glenn Seaborg had successfully separated plutonium. There were several explanations for the Met Lab’s prominence in the debate. One was that its direct work on the bomb had been completed by early 1944, for as soon as Seaborg and his colleagues perfected the separation process in Chicago, large-scale plutonium production using atomic piles was moved to Hanford. The Met Lab scientists therefore had the time and leisure to ponder the greater implications of nuclear weaponry and its control. Then there was the presence at the lab of James Franck, a German physicist of unassailable reputation who had devoted a great deal of careful thought to the social and political implications of atomic energy. These conditions did not exist at the other important research centers within the Manhattan Project universe: Los Alamos remained frantically busy through the Trinity test and up to the bombings, and Berkeley marched to the tune set by one man, Ernest Lawrence, whose hostility to the distractions of “politics” was crystal clear—though he himself would soon be drawn into exactly
the sort of discussions he abhorred hearing in his own laboratory.

  Sharpening the tenor of the discussions in Chicago were signals that the government was considering shutting down the Met Lab. In July 1944, General Groves told Arthur Compton to plan a personnel cutback of as much as 75 percent by September 1. The prospect dismayed the staff. Having been immersed in the development of the atom’s destructive potential, they were hoping to shift as a team into work on the generation of electricity and other such peacetime aspects of the embryonic science. As Franck would observe later, they were uneasy that the government’s interest in atomic energy might begin and end with its effectiveness as a weapon. The fear was that if the bomb failed, government support for all other work in the field would cease, and research into the atom’s benefits to society would go fallow. On the other hand, if the bomb succeeded, the demand for fundamental research on atomic energy would only increase, though it would be likely focused on more and better weapons. But whether the future of nuclear technology lay in war or peace, dispersing an effective team of experienced researchers and leaving them without financial support would be a foolhardy course for the government.

  Compton managed to bring these concerns before Groves and his civilian counterparts, Vannevar Bush and James Conant. He proposed several long-range projects to carry the Met Lab through 1945, among them supporting Hanford and Los Alamos with research and development assistance, and launching research into new technologies such as advanced nuclear reactors and applications of radiation for industry, medicine, and the military. Compton also moved quietly to establish the University of Chicago as a postwar center of nuclear research by trying to lure Fermi from Columbia University with a professor’s chair at the university and the directorship of the Manhattan Project’s Argonne National Laboratory west of Chicago. His attempted poaching of Fermi succeeded only in provoking an outraged protest by Columbia to Bush, who forbade the move.