by Craig Nelson
At the last minute in getting the family ready to head west, Enrico was called away to oversee the final building of his next-generation piles in Hanford, Washington, so Laura and the children had to go on without him. But when they arrived at Lamy in August 1944, Laura hadn’t been told of her alias, “Mrs. Farmer,” and so kept telling the WAC driver sent to meet them that, though she wasn’t as important as this Mrs. Farmer, maybe she could get a ride in the car since the VIP hadn’t shown up.
When Enrico then arrived in September, he and Laura turned down the school faculty cottage that had been set aside for them to take an ordinary apartment, to make a statement about the castes forming in the mesa. Physicist Bob Wilson’s wife, Jane: “Below her, she had Rudolf and Gennia Peierls. They were very good friends, but Mrs. Peierls had a very loud and piercing voice, and her voice came wafting up through the floorboards—her laughter, too. Actually, the first time I met Laura, she was with Gennia Peierls, they were good friends, and I noted in my diary that every time Gennia spoke (and Gennia was a person of many words) Laura visibly shuddered. . . . I was somewhat surprised, having known Enrico off and on for quite a while, to find, after this ebullient, extroverted man, this very serious, shy, reticent woman. I think Enrico prided himself on being matter-of-fact and pragmatic, and Laura was unabashedly idealistic. . . . [She would say,] ‘We wanted to become genuine Americans.’ I don’t think her American dream was the Mercedes in the garage or the mansion in the suburbs; it really was the Jeffersonian ideal. . . . In Italy, this lady had been blessed with two maids; she had been raised in a wealthy household where the maids did the housework, her mother picked out her clothes, and she didn’t know anything about money. Even when she married Enrico, on a salary of $90 a month, she had a maid. Then here she was at Los Alamos, with amenities few and far between, which Chadwick had characterized as ‘pigging it,’ and we had famous water shortages always, incredible dust, and limited supplies. As for maids, she was lucky to have an Indian maid a couple hours, several times a week. Even under those circumstances, she had one dinner party after another, with good food, and really, it was remarkable. I think she liked it.”
Mici Teller took Enrico Fermi for his first ride on a horse, and “he told the horse in a firm voice, ‘I am the boss.’ It worked.”
Emilio Segrè: “I required a special small laboratory for measuring spontaneous fission, the like of which I have never seen before or since. It was in a log cabin that had been occupied by a ranger and was located in a secluded valley a few miles from Los Alamos. It could be reached only by a Jeep trail that passed through fields of purple and yellow asters and the canyon whose walls were marked with Indian carvings. On this trail we once found a large rattlesnake. The cabin laboratory, in a grove protected by huge broadleaf trees, occupied one of the most picturesque settings one could dream of. Fermi was very fond of the site and visited us there several times.”
The great secret that made America the leader in nuclear warfare and gave it an atomic monopoly for many years took place far, far away from the glories of New Mexico. Though the scientists and engineers of that desert paradise engineered the method of uranium and plutonium bombs and ensured their place in history, America’s real nuclear breakthrough was taking place in Godzilla-size buildings in the hollows of Tennessee and the inland gulches of Washington State. Not every nation in the world has an atomic stockpile because, though it is simple enough to make a bomb, it is not so easy to fashion weapons-grade fissile fuel in the form of plutonium or highly enriched uranium (HEU)—the isotope U-235. That was America’s great “atomic secret”—the secret that kept others from developing their own nuclear arsenals—the making of plutonium from reactors and enriched uranium by separating U-235 from U-238, using the 2 percent difference of their weights.
Jim Conant was told he needed to pick between three methods of isolating U-235 (gas, electromagnetic, or centrifuge), or of building a nuclear reactor to generate plutonium. He chose all four, the U-235 done at Oak Ridge, Tennessee, and the plutonium at Oak Ridge, in the Chicago suburb of Argonne, and at Hanford, Washington.
Fermi’s squash-court reactor, now called Chicago Pile-1, was dismantled and reassembled at Red Gate Woods in February 1943—the spot in the Argonne Forest twenty-five miles southwest of Chicago where it was supposed to have been built in the first place. Now known as Chicago Pile-2, it was still overseen by Fermi and produced plutonium for Los Alamos. After the war, her descendants at Argonne would be the research vessels for modern-day reactors and the power plants of nuclear submarines.
In one corner at Columbia, Harold Urey (Enrico and Laura’s Leonia neighbor) and a team of chemists combined natural uranium with fluorine to produce a uranium gas—uranium hexafluoride—which they centrifuged to separate out the U-235. Months of trials determined that making this centrifuge process work at an industrial level would mean fifty thousand one-meter-rotor machines operating continuously at state-of-the-art speeds to produce a kilo a day. That plan was abandoned; the technology has since so evolved that Urey-style centrifuges are now the most common method of producing HEU; but at the same time that one Urey-Columbia team was working on centrifuges, another was developing diffusion, which used membrane-fine filters to separate the lighter U-235 from 238. It worked, but barely, as the uranium hexafluoride needed to be diffused again and again to produce even a tiny amount of isotope—through thousands of membranes, known as cascades, requiring plants of hundreds of acres in size, with bicycles and cars driven inside to get from pipe to pipe.
Starting around the year 1900, an Elza, Tennessee, prophet named John Hendrix proselytized to his neighbors that the Bear Creek Valley—their four little hamlets of tobacco, corn, and coal in the Cumberland Mountains by the Clinch River forty miles west of Knoxville—“someday will be filled with great buildings and factories, and they will help toward winning the greatest war that ever will be.” When in 1942 FDR held a secret meeting with congressional leaders to discuss the Manhattan Project’s finances, he asked them to put aside petty local concerns to ensure victory. Senate Appropriations chair and senior senator from Tennessee Kenneth McKellar replied, “Mr. President, I agree that the future of our civilization may depend on the success of this project. Where in Tennessee are we going to build it?” Soon after, the Army Corps of Engineers requisitioned all fifty-nine thousand acres of Bear Creek Valley, with a court order for three thousand to vacate their homes. Groves built at Oak Ridge, Tennessee, the world’s biggest building, the U-shaped K-25, finished in the last months of 1943, which cost $500 million and employed twelve thousand to diffuse fissile uranium with the Urey cascade method. Physicist James Mahaffey rhapsodized, “The sight of the inside of the K-25 building, with its clean and orderly maze of gleaming nickel plumbing [the hexafluoride would immediately corrode any other metal] seeming to extend forever and disappearing into the haze at semi-infinite distance, was beautiful.” After the war, the sealant developed for the cascades’ pumps appeared in American home kitchens, where it was known as Teflon.
At Berkeley, chemist Glenn Seaborg had tried various techniques to extract plutonium from uranium, getting a yield of 250 parts per million, or two tons producing an amount the size of a penny. Testing this required microchemistry, where under 30x power microscopes, capillary straw pipettes became test tubes and a single quartz fiber with a platinum-foil tray was a weighing scale. Next, about twelve miles from K-25, rose the $427 million Y-12 Plant, where thirteen thousand workers ran Lawrence’s Alpha calutrons: 3,000-to-10,000-ton, 250-foot-long magnets across ninety-six vacuum tanks in five merry-go-rounds to separate uranium-235. His next-generation Beta calutrons had twenty-five hundred tanks, eighty-five thousand vacuum tubes, were the lengths of four football fields, and employed twenty-five thousand.
Building his magnets required five thousand tons of copper, which in wartime couldn’t even be gotten by Leslie Groves, but a substitute was discovered—silver. When Undersecretary of the Treasury Daniel W. Bell was asked for six tho
usand tons of silver bullion, he erupted, “You may think of silver in tons, but the Treasury will always think of silver in troy ounces!” Eventually, 14,700 tons were needed, costing Groves $300 million. A pickling plant had to be built on-site for cleaning the pipes.
By bending the path of speeding uranium ions, the lighter 235s would pull slightly ahead of the 238s in the proton merry-go-rounds and splat against a target in a slightly different location. This low-production method, with less than 5 percent of the distilled 235 hitting the sweet spot, required constant monitoring of the magnetic pulse to correct for the wavering voltages of the factory’s power supply. At first the calutrons were run by Berkeley scientists to work out the bugs; then they were turned over to local women sitting on stools, most of whom were high school dropouts. The two teams had a race . . . and the women won. The management believed it was because they were “trained like soldiers not to reason why,” while “the scientists could not refrain from time-consuming investigation of the cause of even minor fluctuations of the dials.”
Calutron operator Theodore Rockwell: “If you walked along the wooden catwalk over the magnet, you could feel the tug of the magnetic field on the nails in your shoes. It was like walking through glue. People who worked on the calutrons would take their watch into the watchmaker and discover that it was all smashed inside. The magnetic field had grabbed the steel parts and yanked them out by the roots. . . . One time they were bringing a big steel plate in and got too close to the magnetic field. The plate pinned some poor guy like a butterfly against the magnetic field. So the guys ran over to the boss and said, ‘Shut down the magnet! Shut down the magnet! We got to get that guy off.’ And the boss replied, ‘I’ve been told the war is killing three hundred people an hour. If we shut down the magnet, it will take days to get restabilized and get production back up again, and that’s hundreds of lives. I’m not going to do that. You’re going to have to pry him off with two-by-fours.’ Which is what they did. Luckily he wasn’t badly hurt, but that showed what our priorities were.”
By the start of 1944, Urey’s membrane cascades were still corroding viciously. The Naval Research Lab’s Phil Abelson told Groves about their work with thermal diffusion, which had been pioneered by the omnipresent yet underappreciated fission codiscoverer and U-235 cocalculator, Otto Robert Frisch, and Groves decided to try that method as well. Construction of S-50, a thermal-diffusion plant, started on June 24, 1944, with twenty-one racks of 2,142 forty-eight-foot-tall columns housing three concentric tubes ferrying 545°F steam on the outside, cool water on the inside, and uranium hexafluoride in the middle—the lighter 235 floated up with the rising heat, while the heavier 238 settled down at the colder bottom.
By March 1945, Oppenheimer understood that feeding the various outputs into each other dramatically increased the yield, so the thermal-diffusion output was sent to be gaseously diffused, and those results were in turn racetracked in the calutron merry-go-rounds. The final product was 89 percent enriched—good enough to power the Bomb. Yet, by the summer of 1944, even with this massive effort, the calutrons were producing only enough U-235 to make a single explosive. Because they had so little HEU and the uranium gun bomb was so simple in design, Oppenheimer decided it could be dropped on the enemy without even being tested.
The third Oak Ridge plant, the $12 million pilot nuclear reactor X-10, employed 1,513 people and was built ten miles from Y-12. It was known as the Black Barn and joined Chicago Pile-2 in creating plutonium-239 for the implosion bomb. The Oak Ridge reactor was modified from Fermi’s Chicago pile by using channels for replacing exhausted uranium rods with fresh fuel—the depleted uranium used to make armor-penetrating bullets—and pressurized helium as a coolant. Coolant was a topic sure to cause an argument, with Fermi insisting on air, Szilard wanting liquid bismuth (as he and Einstein had used in their refrigerator patent), and Wigner believing in ordinary water from the river. In time, Szilard’s technique would be used with breeder reactors, and Wigner’s with standard burners.
With Fermi in attendance, X-10 went critical on November 4, 1943. One of its engineers, Arthur Rupp, had not believed in Wigner’s calculations of what would happen, yet the results almost exactly matched the Hungarian’s predictions. “I knew then,” Rupp said, “the atomic bomb was going to work!” X-10 would, for the implosion bomb, produce 326.4 grams of plutonium, and Eugene Wigner would become Oak Ridge’s “patron saint.”
Though the army was fully against it for security reasons, Emilio Segrè insisted on touring Oak Ridge to make sure it was operating properly. He found that the Tennessee reactor employees thought they could use a small amount of water to contain the extract, having no idea the water would then become lethally radiant. They also didn’t realize that storing fuel in adjacent rooms against a shared wall could start a chain reaction. Segrè was horrified, and Oppenheimer sent in Richard Feynman to do a follow-up inspection. Feynman was told by his boss that, if the army refused to listen to the physicist, he should say, “Los Alamos cannot accept the responsibility for the Oak Ridge plant.” That suitably alarmed the army bureaucrats, and the physicists’ recommendations were followed.
The Oak Ridge reactor was a proving ground for a much bigger operation. The small towns of Hanford, White Bluffs, and Richland in the dry sheep and vineyard inlands of Washington State were evacuated so that fifty-one thousand people—forty-seven thousand of them men—living in a city of barracks and the largest trailer park in history, could build seven nuclear power plants requiring twenty-five thousand gallons a minute of cooling Columbia River water on a half million acres to be known as Hanford Engineer Works. Their bakery made twenty thousand pies a day, and their auditorium seated five thousand for movie nights; the other entertainment was sitting on blankets on the dusty streets, playing cards, gambling, and fighting, the last stopped by security with fire hoses. The work was finished in eighteen months, and their camp was destroyed.
Those going to Hanford imagined it would be like the Washington State of postcards—snow-peaked mountains, crystal mountain streams, great camping, hunting, and fishing. Instead, they arrived at the Columbia Basin desert of sand dunes, saw grass, tumbleweeds, and pygmy rabbits, next to a barren lava plateau—the Scablands. One ordnance émigré from Denver said, “It was so darned bleak. If I’d had the price of a ticket, I wouldn’t have stayed.” The darned bleak was accompanied by dust storms so ferocious they were known as “termination winds” because so many employees gave up and resigned after suffering through one.
On September 13, 1944, Leona Marshall, Crawford Greenewalt, and Enrico Fermi climbed a twelve-story ladder to survey the two-thirds-finished Hanford site, where Fermi would insert the first uranium slug into the first of the three plutonium-generating reactors. It ran perfectly for twelve hours, then the chain faltered and died. The next morning it was back chain-reacting, but twelve hours later it died all over again. Princeton’s John Wheeler theorized that a by-product in the chain was absorbing neutrons, and this turned out to be xenon gas. Wheeler advised DuPont to add more uranium channels, and they tried amending Wigner’s 1,500 with an additional 504. This kept the xenon from overwhelming the uranium, and the plutonium was now generated on schedule.
Hanford operations manager Walter Simon: “Fermi was very discreet about disagreements. He was a very pleasant person. His mind raced all the time. For instance, if there was a little time to kill while they were loading the reactor, he would do equations in his head, with someone next to him with a calculator. You know, multiply 999 by 62 and divide this by that, and he did that for amusement. His mind raced so much the only way he could relax was to walk on the desert. They would try to take him to a movie, and he would sit there, and in five minutes he would have the whole plot figured out.”
One evening, Sam Allison, Arthur Compton, and Enrico Fermi were taking the train to Hanford, a ride that seemed to go on for a purgatorial eternity. To pass the dead hours, Compton said, “Enrico, when I was in the Andes Mountains on my cosmic-ra
y trips, I noticed that at very high altitudes my watch did not keep good time. I thought about this considerably and finally came to an explanation which satisfied me. Let’s hear you discourse on the subject.” Enrico took out his slide rule, a piece of paper, and a pencil and, within a few minutes, had totted up the formula for the interactions of air pressure on a watch balance wheel’s inertia, quickly producing a figure that matched the dissatisfactions of high-elevation timekeeping. Allison said he would never forget Compton’s amazed look.
Shortly after that first Hanford reactor began to be tested early in 1944, a balloon appeared in the sky. It was one of thousands carrying incendiary bombs sent by Japan to incinerate the American West. Though some of these fire balloons did cause forest fires in Northern California, Oregon, and Washington, this one struck the electric line carrying power to the reactor building and shut it down.
By February 4, 1945, Hanford, Oak Ridge, and Chicago reached their target monthly yield of twenty-one kilos of the flourlike yellow-green plutonium oxide, and a few months later, Oak Ridge began sending its HEU to Los Alamos. When Oak Ridge’s U-235 was first unwrapped after reaching the mesa, it was a silvery metal. Contact with the air turned it dawn-sky blue, deepening to cobalt, and then purple. Like the warm, silvery puppy that was plutonium, and the blue-green thrill that was radium, the U-235 also seemed to be, in some way, alive.
Groves now knew that everything was working as he’d hoped and prayed, and that by the end of the year, they would have enough fissile core for eighteen bombs. That is, if the implosion bomb worked at all.
