Calutron Operators at the Y-12 Plant

Well, in our last blog we saw how Lawrence reacted to the discovery of nuclear fission; that discovery could give Hitler a weapon of unimaginable power. Lawrence invented a machine, the calutron, that could separate highly fissionable uranium-235 from natural uranium, and a Rad Lab physicist and chemist, McMillan and Seaborg, discovered plutonium. Often acting alone, Lawrence got government officials, especially Vannevar Bush, to start an atomic program to build an atomic bomb before the Nazis could.

To pick up the story, we’ll have to describe how America produced the atomic bomb that ended a world war—the Manhattan Project. A multitude of books have been written, documentaries have been made, and Hollywood movies produced about the Manhattan Project, and they generally center around activities at Los Alamos. It would be daunting to think I had to repeat those stories in order to keep my story going. It turns out the activities at Los Alamos were only a fraction of the Manhattan Project, and activities elsewhere are relatively unknown. Lawrence’s activities were almost entirely outside of Los Alamos, so, there’s hope this will not get boring.

As a West Pointer, and a former combat engineer, I got a kick learning how the Manhattan Project got started. West Point graduates who were engineer officers played key roles—I knew we were good. When looking up Kenneth Nichols in the West Point Register of Graduates, I was curious to see where he fit within his class—the Academy kept explicit records of how each cadet ranked in his class. When you’re a cadet, that’s important stuff! Wasn’t I surprised to see the name George Lincoln one place above Nichols 5^th place. Good old Colonel Lincoln was the head of the Social Sciences Department while I was a cadet! What a small world this is.

I read three or four books to understand operations at the Y-12 Plant in Oak Ridge. That place looked like a debacle, and I wasn’t kidding when I say in my manuscript it would have failed except for Lawrence’s enormous talents as an experimentalist and leader. I chose a photo of the calutron operators at the Y-12 Plant to represent this post—they’re all young women. It turns out the first set of technicians entrusted with the calutrons were young local men, and they failed miserably. (No offense meant to anyone with a male relative who worked at the Y-12 Plant during the war.) For the second set of technicians, management switched to young women. Apparently, they took the opportunity to read the instruction booklets, because they got the calutrons to run, and those young women produced the uranium fuel used at Hiroshima.

Please enjoy reading these highlights from my upcoming book, From Berkeley to Berlin:

Conducting atomic research was one thing; that kind of work was well suited for Lawrence and his Rad Lab. But, producing an atomic bomb was quite different. Bush partnered with a large organization to make an atomic bomb, the US Army. He met with the Army Chief of Staff, General George C. Marshall, and together they agreed to organize a national atomic program. They had little time to spare, for the country had just entered World War II following the attack on Pearl Harbor.

General Marshall acted quickly, and in June 1942, the director of the Syracuse Engineer District of New York, Colonel James C. Marshall, no relation to the Army Chief of Staff, took command of a project to produce an atomic bomb. Colonel Marshall organized his command, which he called the Development of Substitute Materials (DSM) Project. His deputy was a thirty-four-year-old lieutenant colonel named Kenneth D. Nichols, who had studied engineering at European universities before completing a doctorate in hydraulic engineering at Iowa State. 

A West Pointer, Nichols graduated fifth in his class, one academic rank lower than George A. Lincoln, the Rhodes Scholar then serving as General Marshall’s strategic planner. The two classmates, and friends, played pivotal roles in determining the outcome of the war; Nichols as a key player in the atomic bomb project, and Lincoln who laid out the strategic goals of allied forces in the conquest of the Axis Powers. To a later generation of West Point cadets, including myself, Colonel Lincoln was the head of the Department of Social Sciences. He was a consultant to Presidents Kennedy and Johnson, and his department acted as a think tank that provided the nation with forward thinking military officers in her future wars, like General David Petraeus.

First class engineer officers in the Army made up a small, but well connected, social group, and in a coincidence that later touched his career, as a second lieutenant, Nichols joined with First Lieutenant Leslie Groves to survey a route for an inter-ocean canal through the jungles of Nicaragua. Nichols was well suited for his new role in an atomic program. Although he had no background in nuclear physics, with his exceptional engineering education, he became an essential conduit to interpret technical requirements for an atomic device into engineering specifications.

A location was spotted for construction of the uranium isotope separation plants, and once the site was acquired, Nichols would be responsible for organizing its operations. It was along the Clinch River Valley in Tennessee at an area locally known as Oak Ridge. Unfortunately, Colonel Marshall was unwilling to acquire the site until all proposed processes for enriching uranium had proven themselves. (There were three competing processes: Lawrence’s calutron was called the electromagnetic process, Nobel laureate Harold Urey led a gaseous diffusion process, and finally there was a centrifuge process led by a physicist named Jesse Beams.)

With his program growing, Colonel Marshall moved his headquarters from Syracuse to the Manhattan Engineer District, and with the switch of headquarters, he changed his program’s name from the DSM Project to the Manhattan Project. Marshall was a good officer, but he lacked the enthusiasm needed for an important mission. He left much of the work with his deputy Nichols, who managed to do a remarkable job of moving requisitions through the rank conscious Washington bureaucracy. At Bush’s instigation, and to head off a looming crisis, Colonel Marshall was relieved as project manager and replaced by Colonel Leslie R. (Dick) Groves. 

Groves appeared at Bush’s office on September 17, 1942, and formally announced his appointment to direct the Manhattan Project. Within forty-eight hours he acquired Oak Ridge. Two weeks later he contracted the Du Pont Company to build a plutonium production plant in Hanford, Washington.^[ii] After a month of observing Groves, Bush knew that he had the right leader for his atomic program. Groves kept Lieutenant Colonel Nichols as his deputy. Importantly, Groves had to establish a bond with scientists he knew he would have to rely on—he approached Lawrence and they became trusted colleagues and friends.

Having already built a prototype calutron in Berkeley, Lawrence transferred the physicists who had developed it to Oak Ridge to help install calutrons there. Each calutron required an electro-magnet that weighed 330 tons and used hundreds of feet of wiring, but copper wiring was critically short—the Y-12 Plant would require 552 calutrons. Nichols came up with an idea. He ordered 14,700 tons of silver, an excellent conductor that could replace the copper wiring, to be transported from the national silver repository at West Point, New York, and delivered to the Y-12 Plant. While negotiating with the Treasury Department, Nichols said he would need between five and ten tons of silver immediately. The Treasury Department official responded to Nichols’ request icily: “Colonel, in the Treasury we do not speak of tons of silver, our unit is the Troy ounce.”^[iii]

Once the calutrons were emplaced, many of the Rad Lab physicists returned to Berkeley, but the electromagnets still needed much care and attention: they shorted out, and components quit working. That wasn’t the only problem: uranium vapor deposits gathered on the inside of conduit walls and operators recruited from nearby towns proved to be inadequate to keep the machines operational. The calutron project looked like a disaster. Lawrence ordered the calutrons torn apart and reassembled in time for a second trial at the end of 1943, and he reassigned several hundred scientists and technicians from the Rad Lab to work at Oak Ridge. Once operations were running smoothly, the plant was turned over to a new set of local crews, which mostly consisted of young women fresh out of high school, dressed in blue jumpers. They proved to be up to the task at hand. The calutron operators were the young women portrayed in Janet Beard’s book The Atomic City Girls.

The trust given to Lawrence and his calutrons paid off. The technical difficulties facing the program were horrendous. It was only through Lawrence’s perseverance and skill that operations at Y-12 succeeded. In the end, it was the Y-12 plant that provided the highly enriched uranium used to make the bomb dropped over Hiroshima. 

* * *

To set up a wartime plutonium production line to fuel an atomic bomb required more resources than McMillan and Seaborg could provide. Help came from a world-renowned physicist and Italian expatriate—Enrico Fermi. He was among the elite of Italian physicists, but he was disenchanted with the Italian government. It began with the rise of Fascism and the Italian invasion of Ethiopia. He worried about the safety of his family, for the Italian dictator Mussolini had entered into a political alliance with Nazi Germany’s Hitler. Like Germany, the Italian government passed laws aimed at Jewish citizens, denying them rights granted to other Italian citizens. 

Fermi’s wife, Laura, the daughter of an Italian naval officer, was Jewish. The couple realized the coming danger, reluctantly decided they had to leave the country, and did it secretly. (Laura’s father was later imprisoned in Auschwitz.) They would use the Nobel Prize money to immigrate to America, where Fermi had an offer to join the faculty of Columbia University in New York City. Fermi and his family departed Fascist Italy in a train, crossed through Nazi Germany, and arrived in Sweden in time for the Nobel award ceremonies. When the pomp and circumstance ended, he and his family boarded an ocean liner for New York. As the Fermi’s entered New York harbor and glanced at the Statue of Liberty, Laura stood by her husband and heard him say they were about to start the “American branch of the Fermi family.”

Within months of his arrival at Columbia University, Fermi delved into research on nuclear fission. He built what is called a nuclear pile, which is a lattice of uranium fuel rods encased within a large rectangular pile of graphite blocks. The graphite is needed to moderate, or slow down, neutrons because, as Fermi had discovered, neutrons interact much more readily when they are slowed down. Fermi’s nuclear pile at Columbia was eight feet square at the base and eleven feet high, but it was a subcritical reactor, it could not sustain a chain reaction—once started, nuclear reactions slowed down.

To produce needed quantities of plutonium, the Manhattan Project would need a critical reactor—a nuclear pile that could run indefinitely. Bush had placed Arthur Compton, a Nobel laureate and an extraordinary experimentalist, in charge of the plutonium project. Compton had Fermi build a critical pile near the Metallurgical Laboratory in Chicago, Illinois. 

Compton had just faced a labor dispute in October 1941 that delayed construction of Fermi’s nuclear pile, scheduled to be built at a site in the Argonne Preserve. To stay on schedule, the pile needed a temporary facility elsewhere—but where?^[Compton kept things going by locating it in a squash court under the stands of the University of Chicago’s football stadium. He did not confer with Bush on his decision; he dared not. He would bear full responsibility if anything went wrong. He had just agreed to build a critical nuclear pile in a structure that was adjacent to one of the densest population areas in America. Nobel laureate Eugene Wigner observed that Compton was a world-class experimentalist who knew how to evaluate risks; he was showing his mettle in handling a critical situation that did not allow for mistakes.

Enrico Fermi in a laboratory

 Some doubted the project would work—DuPont engineers released a report suggesting a critical nuclear pile could not be built. Word of that reached Washington, DC, and Compton repeatedly had to reassure Bush that Fermi knew what he was doing. By mid-morning, December 2, 1941, one week before the attack on Pearl Harbor, Fermi raised the control rods of his nuclear pile in an excruciatingly slow process to increase the flux of neutrons until he achieved criticality. Finally, at 3:20 PM, counters indicated a sustained chain reaction was occurring. A short time later, after the release of a few watts of power, Fermi shut down the pile.

Within a month, Glenn Seaborg, still with the Rad Lab, invented a chemical process to extract plutonium from the spent nuclear fuel in a pile (reactor). Thereafter nuclear piles in Hanford, Washington, were built to produce plutonium in quantity. It would be the reactors in Hanford that provided the nuclear fuel for the atomic bomb dropped on Nagasaki.