by Steve Olson
Workers generally followed safety procedures, but not always. “We did a lot of foolish things,” said one chemist who worked at Hanford during the war. “We took risks to get results rather than spend days and weeks designing equipment so that you could do everything without getting very close or taking any risks. . . . We felt a tremendous pressure. We believed the Germans likewise were doing this. And we had to beat the Germans because if they got there first they would win the war.”
EVEN AS THE T PLANT began to produce plutonium at the beginning of 1945, another major construction project was nearing completion. Groves and Matthias had always thought of the Hanford camp as temporary. It would accommodate the rowdy construction workers for a few years and then be abandoned. But the people who would be overseeing and operating the production plants—the construction managers, scientists and engineers, DuPont executives, plant operators, security officers—needed a place to live. The nearby towns of Kennewick and Pasco were too far away, too provincial, and too accessible to house the high-level employees of a secret facility. Groves needed a town that would attract people to the middle of a desert, keep them there, and isolate them so that no one else knew what they were doing.
At four o’clock in the morning on March 2, 1943, the renowned Spokane architect Gustav Pehrson received a phone call. A committee had recommended that Pehrson bid on a big project going up about 150 miles southwest of Spokane. “Impossible,” he said, and hung up. When the phone rang again, it was Matthias on the line and his tone was different: “You will meet Lieutenant Colonel Kadlec at 2:00 p.m. tomorrow in Pasco.” Pehrson inspected the site the next day, and two weeks later his bid was accepted. He and his firm were to provide plans for a completely new town to be built atop the small farming community of Richland—streets, houses, dormitories, parks, commercial buildings, and infrastructure. The purpose of the town was shrouded in mystery, but it would have to house thousands of people. Pehrson’s initial designs were due in a week.
Over the course of several conversations with DuPont officials, Pehrson developed his ideas, despite not knowing exactly what the residents of his new town would be doing. The designer of some of Spokane’s most distinguished downtown buildings, the Swedish-born Pehrson envisioned a town of comfortable houses on large lots set back from gracefully curving streets. He designated his two dozen or so house designs by letters of the alphabet. Even today, people in Richland will say that they live in a B house—an 882-square-foot single-story duplex with two bedrooms and a half basement—or an L house—a 1,536-square-foot two-story structure with four bedrooms and bathrooms upstairs and downstairs. Pehrson designed the houses with large plate glass windows so occupants could look out at the neighborhood and the endless desert sky. He gave them modern appliances and good ventilation to stay cool in the scorching summers. The houses would be surrounded by trees and shrubs for privacy and shade. Residential streets fed into a commercial core of shops and public facilities, as in traditional American small towns. Originally, the types of houses were supposed to be entirely mixed so that all neighborhoods had people at different income levels. But as the plans evolved, sites for the larger and nicer houses tended to move toward the Columbia River while the smaller houses and duplexes clustered in the dusty plains beyond.
When Groves got his first look at the designs, he exploded. These were supposed to be residences for wartime employees, not comfortable middle-class homes. To Groves, it looked as if DuPont was using federal funds to build a luxury resort in the middle of the desert. How would that look when Groves appeared before congressional committees after the war to explain how he’d spent the public’s money? He immediately started making cutbacks, so that the houses in Richland looked simpler, more like the houses he had grown up in. He took out the picture windows and elaborate molding. He scratched the men’s clothing store and funeral parlor from the commercial center. He even renamed the planned hotel the “transient quarters,” since “hotel” sounded too extravagant to him.
DuPont and Pehrson fought back. They pointed to “the necessity for maintaining high morale among workers transplanted to what will probably seem a strange country,” as Pehrson put it in his November 1943 plans, which “cannot be achieved by crowding skilled and veteran workers into inadequate dwellings.” Grudgingly, Groves gave way, at least on a few points. Houses could have three or four bedrooms, not the one or two Groves preferred. The commercial center could contain more businesses than he wanted.
Over the next 18 months, DuPont’s contractors built more than 4,000 houses using Pehrson’s designs. The result was an odd combination of government town, company town, and detention center. The government provided everything—furniture, light bulbs, electricity, a lawn mower. Yet residents quickly adopted the language and imagery of the West, emphasizing their own volition and independence. “Hanford workers were living at the frontier,” historians John Findlay and Bruce Hevly have observed. “They and their families had left the smoky industry of the East behind and moved West into a nuclear-powered new day.”
Richland was something new on the American landscape. The majority of the people living there were blue-collar workers. They manufactured fuel elements, adjusted controls on the reactors, or tested the intermediate products of the separation plants. Yet they were able to fashion new lives for themselves, far from the ones they had left behind. Five years before Abraham Levitt and his two sons, using construction techniques adopted from the navy, built Levittown on Long Island, the nation’s first mass-produced suburb rose on a dusty, windswept plain in south-central Washington State.
Richland gave its residents incomes and access to amenities that they never could have achieved before the war, but they paid for their privileges. They were under continual surveillance and were severely limited in what they could say or do. Employees underwent background investigations, fingerprinting, and regular vehicle searches. Security officers known as Groves’s creeps listened to conversations, tapped phone calls, edited outgoing mail, and conducted investigations. To catch anyone who might be giving away secrets, agents posed as hotel clerks, tourists, electricians, painters, and even gamblers. Forty-four documented cases of “un-Americanisms” involved such infractions as possessing a two-way radio or criticizing President Roosevelt. If a spouse or child created a disturbance, an employee could lose a security clearance, and spreading rumors warranted an immediate reprimand or termination. Today, people are used to government and large corporations having access to large amounts of personal information. In Richland and the other cities built and run by the Manhattan Project during World War II, this surveillance society was something new.
Chapter 12
IMPLOSION
ON FEBRUARY 2, 1945, FRANKLIN MATTHIAS GOT INTO A CAR IN Richland carrying a square wooden box. He drove past the Horse Heaven Hills, through the spectacular windswept gorge that carries the Columbia River through the Cascade Mountains, and into the city of Portland. There he boarded the West Coast passenger train for Los Angeles, the box and a suitcase at his side.
At Los Angeles Union Station, he met a security officer from the Manhattan Project’s Los Alamos laboratory. “Do you have a locked compartment to go back to Los Alamos?” he asked, nodding at the box.
“No, I couldn’t get a bedroom,” answered the officer. “I have an upper berth.”
“Do you have any idea what we have here?” Matthias barked. “You better highball it down and get yourself a locked compartment.”
“What do you mean?”
“I mean that it cost $350 million to make it. If you don’t get it to Los Alamos intact, you’re going to be in a hell of a lot of trouble.”
THE NEXT MORNING, the first shipment of Hanford plutonium arrived at Los Alamos. By this time, all three of the Manhattan Project’s major sites were running around the clock. At Hanford, the reactors and separation plants were churning out product. At Oak Ridge, gigantic factories nestled amidst the Tennessee hills were separating uranium-235 from uranium ore
. And at Los Alamos, scientists and engineers under the direction of Robert Oppenheimer—Seaborg’s colleague at Berkeley, whom Groves had chosen to run the lab—were designing weapons that would produce the most powerful explosions ever created by humans. But Los Alamos was also in the midst of the Manhattan Project’s greatest crisis, and the reason for that crisis was plutonium.
The initial shipment of plutonium from Hanford in February 1945 was not the first batch of plutonium to arrive at the laboratory. The previous year, Seaborg’s Berkeley colleague Emilio Segré, whom Oppenheimer had recruited to Los Alamos, had received a couriered shipment of plutonium from the pilot reactor in Tennessee. Immediately, he tested it to see whether it was going to cause a problem that he and Seaborg had been worrying about for months. The results of the test were disastrous. The entire approach to making an atomic bomb with plutonium would have to change.
Physicists had come up with a relatively simple design for an atomic bomb not long after the discovery of fission. It hinged on a concept known as critical mass. A free neutron moving inside a mass of either uranium-235 or plutonium-239 can do one of two things. It can strike the nucleus of another atom, in which case that atom is likely to fission. Or it can escape from the sides of the mass and fly away without causing another fission.
In a small mass of plutonium, a neutron is more likely to escape than it is to hit another atom, because the sides of the mass are always nearby. But that changes as a piece of plutonium gets larger. At a certain mass, known as the critical mass, a neutron is more likely to hit another plutonium atom than to leak into space. At that point, the chain reaction begins to grow exponentially, releasing immense quantities of energy.
But even with a critical mass of plutonium, not all the plutonium atoms will fission. A plutonium atom takes about a billionth of a second to split and release neutrons, and in a critical mass of plutonium these neutrons take a few more billionths of a second to find and split other plutonium atoms. As a result, the chain reaction occurs very quickly—an atomic bomb releases all the energy it’s going to release in less than a millionth of a second. But before all the atoms in a critical mass can split, the energy released by fission blows the bomb apart. When that happens, the neutrons from a fissioning atom can no longer find other plutonium atoms to split. In the plutonium bombs designed at Los Alamos, only about one-seventh of the plutonium atoms split before the bomb blew itself apart and the chain reaction ceased.
The concept of critical mass suggested a basic bomb design. A cannon barrel would have two pieces of uranium-235 or plutonium-239, both smaller than a critical mass, at either end. One piece would be shaped like a stack of washers, forming a cylinder with a hole in it. The other piece would be a cylindrical post just small enough to fit inside the hole. A conventional explosive would send the hollow cylinder hurtling down the cannon’s barrel. As the hollow cylinder settled around the solid cylinder, like a ring slipping onto a stubby finger, the combination of the two pieces would form a critical mass and explode.
But the designers were always aware of a potential complication. When the hollow cylinder began to slip over the solid cylinder, the two pieces would form a critical mass before they were fully joined. A spare neutron anywhere in this assembling mass would almost instantaneously set off a chain reaction. As a result, the bomb would blow itself apart well before the two masses had completely merged. The result would be what the designers called a fizzle—a premature detonation far less powerful than the explosion they were seeking.
The solution to this problem was to make sure that the two masses did not contain any free neutrons until they were fully joined. That required paying attention to something called spontaneous fission. Uranium-235 and plutonium-239 are so close to the edge of stability that they sometimes fission all by themselves, without being hit by a neutron. When they do, they release their usual two or three neutrons. If they were to do this within a critical mass, the neutrons would start a chain reaction. That would be a calamity if it happened in a gun-type bomb when the two pieces were partly but not fully joined. The result would be a relatively small explosion that would destroy the bomb without having much of an effect.
The bomb designers were confident that spontaneous fission would not be a problem for uranium-235. Its rate of spontaneous fission is so low that a fission would be very unlikely to occur during the fraction of a second while the two pieces of material were joining. The same was true of plutonium-239. Its rate of spontaneous fission is greater than that of uranium-235 but not enough to cause a fizzle.
Seaborg and Segré were worried about something else. What if plutonium-239, after being created in a reactor, were to absorb another neutron and become plutonium-240? The former Berkeley colleagues had reason to believe that plutonium-240 would have a much higher spontaneous fission rate than plutonium-239. Furthermore, there would be no practical way to remove the plutonium-240 from the plutonium-239. If nuclear reactors inevitably ended up producing significant quantities of the heavier isotope, the entire plutonium production project could be a bust.
That’s what Segré was testing when he got his first batch of plutonium from Oak Ridge. He and Seaborg had been right to worry. The plutonium contained way too much plutonium-240 for the gun-type design to work. And if the gun design wouldn’t work, the hundreds of millions of dollars being spent at Hanford would be wasted.
But not all was lost. By then the bomb designers in Los Alamos knew about another way to create a critical mass of plutonium, a better way. What if explosives could be set off around a subcritical sphere of plutonium so that it was suddenly compressed? Because of the sphere’s increased density, neutrons from a fissioning atom would need to travel less distance to find another atom to fission. As a result, neutrons would be less likely to escape from the sphere before fissioning another atom. The compression would happen so quickly that neutrons from plutonium-240 probably would not have time to generate a fizzle before the full nuclear explosion occurred. The idea, known as implosion, might be a way to salvage the use of plutonium in atomic bombs.
A small research group at Los Alamos had been working on the concept even before the plutonium-240 crisis. But implosion seemed so technically difficult that it remained on the fringes of the laboratory’s efforts. The problem is that explosions don’t work that way. If you throw a pebble in a pond, it generates waves that travel outward in a circular pattern. Implosion requires the opposite: a spherical wave traveling inward. How can you turn an explosion outside-in?
In 1944 the spontaneous fission problem gave the bomb designers no choice. They had to develop implosion to get plutonium to work in a bomb. Oppenheimer responded by almost completely reorganizing the Los Alamos laboratory. By that fall, hundreds of scientists, engineers, and technicians were working on implosion. The canyons around Los Alamos resounded with exploding charges as researchers tried to figure out how to direct an explosion inward rather than outward.
The critical breakthrough was the idea of using shaped explosives. Using commercial candy-making machines, the bomb designers created explosives of different sizes, shapes, and compositions. They then put these explosive lenses together in spherical configurations designed to focus the force of an explosion inward. When detonators on the outside of the sphere simultaneously ignited the explosives, a shock wave traveling inward was bent by the shape of the explosives and the speed with which they burned. The goal was to create a converging wave that would compress a small sphere of plutonium at the bomb’s core, like squeezing a snowball in your fist.
But getting the idea to work was fiendishly difficult. No theory satisfactorily explained the forces generated by shaped charges. Instead, the Los Alamos scientists had to experiment. They devised ingenious techniques to observe what was going on during test explosions. They also used some of the world’s first electronic computers to approximate the answers to equations that they could not solve by hand. When voids formed in the test explosives while they were being cast, the researchers
carefully drilled through the explosives using dental tools and filled the holes with small amounts of explosive melted in a steam-heated pot. When asked about the safety of this procedure, the leader of the implosion team, George Kistiakowsky, said, “You don’t worry about it. If fifty pounds of explosive goes [off] in your lap, you have no worries.”
The invention of implosion at Los Alamos required a host of other innovative technologies. Detonators on the outside of the explosives had to fire at exactly the same time to generate a smooth shock wave. A device known as an initiator, placed at the very center of the bomb, had to release neutrons into the imploding core at the precise instant when they were needed to trigger a chain reaction.
Gradually the Los Alamos researchers made progress. Images of test explosions showed that implosion was becoming more symmetric and powerful. The metallurgists at Los Alamos figured out how to alloy and cast plutonium so that implosion would squeeze the material uniformly. By the end of February 1945, Oppenheimer was optimistic enough to say, “Now we have our bomb.”
The development of implosion altered the course of world history. An implosion bomb requires much less nuclear material than a gun-type bomb. The bomb dropped on Hiroshima, which was nicknamed Little Boy for the long thin cannon barrel it contained, used about 140 pounds of uranium from the isotope separation facilities in Oak Ridge, Tennessee. The bomb dropped on Nagasaki, nicknamed Fat Man because of the spherical explosives it contained, used just over 13 pounds of plutonium—less than one-tenth as much material. In fact, if spontaneous fission had not been a problem and implosion had never been developed, Hanford would not have been able to produce enough plutonium for a gun-type bomb by the summer of 1945.