EASTMAN AT OAK RIDGE
DURING WORLD WAR II
Howard S. Young
Talk given 11 Sep 2002 by HSY to the
East Tennessee Section of
The American Institute of Chemical Engineers
Tennessee Eastman contributed in two major ways to the abrupt ending of the Second World War. First, it operated the huge Y-12 plant in Oak Ridge to produce the isotope of uranium known as U-235. This material was the explosive for the single atomic bomb that destroyed the center of the Japanese city of Hiroshima on August 6, 1945. This bomb was by far the most powerful weapon that had ever been used in warfare. Eastman did its work as part of the enormous Manhattan Project of the U. S. Army’s Corps of Engineers, that was the largest industrial project in the history of mankind, employing about 500,000 people.
Second, Eastman at Kingsport made Composition B, a machinable mixture of RDX, TNT, and wax that was used as the fast-burning component of the extremely complicated explosive lenses used to cause compression of plutonium and set off the atomic bomb that destroyed the center of the Japanese city of Nagasaki on August 9, 1945.
Let's start the story with research done by Ernest Rutherford in 1898, near the beginning of nuclear physics. Rutherford was a New Zealander who had trained at Cambridge University in England, and had just become a professor of physics at McGill University in Canada. McGill had received a grant from a tobacco magnate to build up its science efforts, and had hired Rutherford as a promising young physicist. Soon after arrival at McGill he found that the energy output in radioactivity from uranium was far greater than in any chemical process. This was the first hard evidence of the enormous latent power within the atom.
At about the same time, Rutherford became intrigued by some odd behavior that he had observed in the radioactivity of thorium compounds. The amount of radioactivity seemed to vary and to be sensitive to currents of air. He came to the conclusion that the thorium was emitting something that was also radioactive and might be a gas. So he got a chemist named Frederick Soddy to work with him, and the two men found that thorium changed to a new form of radium, which was different from the form that the Curies had isolated. This new radium, in turn changed to the gas that we call radon. Rutherford and Soddy had provided the first demonstrations that one element could change to another. For this work they received the Nobel Prize.
Other investigators found another form of radon with a different atomic weight, and within ten years it was Soddy who coined the word "isotope" to describe such forms of the same element. And finally, Rutherford, now back in England, found the proton, a singly charged particle in the nuclei of all atoms, and his student James Chadwick found a particle that he called the neutron to call attention to its lack of electric charge. Then the existence of isotopes of an element could be discussed in the terms we use today.
For uranium, one of the two isotopes that we will talk about has 143 neutrons in its nucleus, and the other has 146. The isotope with the odd number of neutrons will make a bomb, and the one with the even number will not. The chemical properties of the two isotopes are very nearly the same, so chemistry doesn't provide a useful way to get them apart. But the atomic weight of one is 235, and of the other is 238, a difference of 1.3 percent, and it was this mass difference that permitted getting the isotopes apart. Doing that in sufficient quantity for a bomb before the expected end of the war became Eastman’s task.
But in 1932 when the neutron was discovered, no one had any serious thoughts about atomic energy or atomic bombs. There was a lot of speculation though. The "packing effect" and the "packing fraction" curve with hydrogen on one end and uranium on the other were well known. There is a dip in that curve, and as one progresses along it toward the bottom of the dip mass is lost. There is the heart of our story. Our sun gets its enormous energy output by combining four atoms of hydrogen of mass 4.032 into one atom of helium of mass 4.003, for a mass loss of 0.7 %. It is a tiny loss of mass, but remember that Einstein had calculated that its energy equivalent is obtained by multiplying the loss of mass by the enormous velocity of light twice. Conversion of one gram of hydrogen into slightly less than one gram of helium would produce 200,000 kilowatt hours of heat!
Some people said that scientists ought to be able to produce almost free and limitless atomic energy by using the new atomic accelerators to change one kind of atom into another, but in September 1933 Rutherford made headlines in the London papers by quite correctly saying that one wasn’t going to get atomic energy at a reasonable cost by using an accelerator to hurl one atom at another. Accelerators simply cost too much.
The first chapter of Richard Rhodes’ famous book “The Making of the Atomic Bomb” is devoted to telling how Leo Szilard reacted to this headline, and to why he could react as he did. Szilard was a young Jewish escapee from the Nazis who was living in London. Rhodes explains that Szilard was an extremely well-trained physicist, a personal friend of Albert Einstein, and a co-inventor with Einstein on a series of patents on refrigeration systems.
Szilard knew full well that accelerators to produce atomic energy would cost too much. After all, he had filed a patent application on the cyclotron accelerator three months before Ernest Lawrence first thought of it. So Szilard turned his fertile mind to ways to get atomic energy without such devices. What he thought on that fateful day in 1933 was that he could get atomic energy and bombs by using a neutral particle that required no accelerator to interact with an atom. He could use Chadwick’s neutron.
Szilard thought of using an element that would pick up a neutron and cause some process that would release a great amount of energy and two neutrons. He would arrange the element so that loss of neutrons from its surface would be minimized, which meant that he would arrange it in a sphere, in which one has the least surface area for a given amount of material. If a small sphere still lost too many of the neutrons, he might, for example, double its diameter. Its volume and amount of the element would go up eight-fold, but its surface area, through which neutrons could be lost, would go up only four-fold. Somewhere up such a series of steps the chain reaction he wanted would be self-sustaining. In other words, the number of neutrons would climb the familiar series 1, 2, 4, 8, 16, 32 and on up, and he could have a source of power or a bomb.
A practical way to make such a bomb would be to prepare two masses of such an element, each one of less than the critical mass, and thus too small to sustain a chain reaction, and to bring them together extremely quickly and at the same time provide a source of neutrons. That’s a pretty good description of a crude version of the Hiroshima bomb.
Of course in 1933 Szilard didn’t know what element to use. He just filed a patent application and waited for some one to find the element for him. His plan was that when it was found, he would amend his patent application.
It was six years, 1939, before Szilard knew what element might work. The clue came from the work in Germany of the physicist Lise Meitner. She and the chemists Otto Hahn and Fritz Strassman had been working on the absorption of neutrons by the element uranium. They expected to find bigger elements than uranium. But their results didn’t match their expectation. (The process they expected can happen, and that is the way plutonium is made from uranium, but they didn't find that out.) The two chemists finally realized that the results showed that uranium atoms, which have 92 protons, were splitting into much smaller atoms, such as barium, which has only 56 protons. No one had anticipated this result, not even Rutherford. At first no one would believe it. But the chemists were right. The uranium atom was splitting. We say it was undergoing fission. And this new nuclear reaction was producing much energy.
When the discovery of Meitner, Hahn and Strassman was announced, there was widespread recognition that if two or more neutrons were being released after one neutron entered a uranium atom, an atomic bomb might be made. Very quickly the great Danish physicist Niels Bohr reasoned from theory that it was the 235 form of uranium that was undergoing fission, and not the much more abundant 238 form.
The packing fraction curve has only a small slope on the uranium end, and only one tenth of one percent of the mass of those atoms undergoing fission was converted to energy. In the Nagasaki bomb only about one gram of matter was converted to energy. But the energy from conversion of one gram of matter is equal to the energy released by the explosion of 18,000,000,000 grams of TNT. That’s 20,000 tons of TNT. Just for fun I calculated how many big cars it would take, bumper to bumper, to weigh 20,000 tons. Well, at 2 tons per car it takes 10,000 cars. At 17 feet per car, that is 170,000 feet, or 32 miles of cars!
If a fission device could be made small enough to be carried by a bomber, that one airplane could carry as much explosive energy as 5,000 of the bombers then on the drawing boards.
Looking at these numbers again, at one tenth of one percent loss of mass it takes only 1,000 grams, or 2.2 pounds, of fissioning uranium, to result in one gram of its mass being converted to energy. If a uranium-235 bomb were only three percent efficient, one would still need only about 75 pounds of uranium-235 to destroy a small city with one blast.
So, the two great questions that were before the physicists of the world were: did the fission process produce two or more neutrons? And if so, could practical means be found to isolate U-235? After all, it makes up only 0.7 percent of natural uranium. That's one atom out of every 140.
It was Leo Szilard, now in New York and using a laboratory at Columbia University, and a neutron source made from radium that he rented from a hospital and a block of beryllium that he got from England, who showed that about two neutrons were produced for each one absorbed by uranium, so that indeed a chain reaction would be possible. That night, he recalled later, there was very little doubt in his mind that the world was headed for grief.
Szilard set out to beat the Nazis to the bomb so they could not use it to dominate the world. After much deliberation and consultation with others, he prepared a letter to President Roosevelt for Einstein's signature. By then, Germany had invaded Poland, and Great Britain and France were at war with Germany, and Roosevelt agreed to at least limited initial support of Szilard's proposal for research. He appointed an advisory committee on uranium to report directly to himself.
The work of Roosevelt’s advisory committee gained urgency when it was learned that the Kaiser Wilhelm Institute at the University of Berlin had been taken over by the German army for research on uranium. When France surrendered to Germany, Roosevelt established a more powerful committee, the National Defense Research Committee, under the chairmanship of Vannevar Bush, head of the Carnegie Institute and former Dean of Engineering at MIT. Roosevelt arranged for the Uranium Committee to be one of its subcommittees.
Under this new sponsorship, an urgent research program on separation of the uranium isotopes was established. The British had been experimenting with molecular diffusion, in which molecules containing uranium were forced through a barrier. To a quite small extent those molecules containing 235 would go through the barrier faster than molecules containing 238. So a tiny enrichment of 235 would occur each time the molecules were forced through a barrier. This technique was developed into the process that Union Carbide operated in Oak Ridge in the enormous K-25 and K-27 plants. The uranium compound used was the hexafluoride.
In this country, Ernest Lawrence at the University of California at Berkeley had proposed separating the forms of uranium in a mass spectrograph derived from his Nobel Prize-winning cyclotron. Lawrence was one of the great drivers of the project to get an atomic bomb, and his technique was developed into the process that Tennessee Eastman operated in Oak Ridge.
The chemist James Conant, President of Harvard University, became Bush’s deputy for atomic matters. By March of 1942 Conant concluded that both the diffusion and the cyclotron methods were ready for pilot plants. Because of the pressures of war, the pilot plants were never built, and the processes were scaled up directly from the research laboratories into the two giant manufacturing plants at Oak Ridge.
To direct the engineering and construction effort, the Army Corps of Engineers was directed to create a new engineer district. It was called the Manhattan District simply because its first head worked in that part of New York City. But matters still didn’t move quickly enough to suit Bush. He discussed his frustration with the general in charge of the Army Services of Supply, Brehon Somervell, who proposed that the entire responsibility for the project be turned over to the Corps of Engineers, which was under his command. Bush agreed, and in September 1942, Somervell selected Leslie R. Groves as head of the Manhattan Project. Groves was deputy chief of construction for the U. S. Army, and had just finished building the Pentagon. He had studied engineering at M. I. T., and had been graduated fourth in his class at West Point. With his appointment things began to move.
Typical of Groves, on the first day after he was appointed he broke an administrative logjam and sent his deputy to New York City to buy 1,250 tons of extraordinarily rich uranium ore that the Belgians had shipped to the U. S. after both British and French scientists had warned them to keep it from the Germans. So, he had raw material with which to work. On the next day he bluffed the civilian head of the War Production Board into assigning first priority to the Manhattan Project. And on that same day he approved a directive, which had been stalled, for the acquisition of 52,000 acres of land along the Clinch River in eastern Tennessee.
On Christmas Eve 1942 Mr. James C. White, General Manager of Tennessee Eastman Corporation, received a phone call from California. It was from General Groves. He told Mr. White that the Army wanted Tennessee Eastman to operate another plant for military purposes. A number of years later Mr. White said "We got into Oak Ridge primarily because we had done such an outstanding job on the RDX project. General Groves had selected Dupont and Union Carbide to operate other parts of the Manhattan Project and he was looking for someone to operate the electromagnetic plant. He called me to see if we would be interested in taking on the job. I told him we were already stretched too thin." (End of quote) TEC had only about 6,500 employees, and of these about 2,200 were on military leave.
Nevertheless, Mr. White called Mr. Wilcox in Rochester. He agreed that TEC could not do anything more. But White had told the General that Mr. Hargraves or Dr. Chapman at the very top of the company might have a different view of what TEC should take on. After Groves called these top officers of Eastman Kodak, Wilcox and White were sent to meet with the General. Quoting Mr. White again, “he convinced us there was a real job to do. We asked him what the job was. He wouldn’t tell us, not until he got us signed up and everybody cleared. I said that it would help us if he would tell us about the size of the job and the kind of people that would be needed. He said it could not possibly get to be more than 2,500 people. He thought it would be about 1,500. They would be quite high-class people, quite a few would be college graduates, the rest would be skilled operators. You can see how wrong he was. We had over 24,000 people before it was over. Anyway we ended up with the job. The process was being developed at the University of California under the direction of E. O. Lawrence, developer of the cyclotron. They were making the prototypes of the equipment out there. They were enormous things made of copper. They had to be made very accurately, and we had hundreds of them and replacements to make. It was an experimental plant blown up to enormous size.” (End of quotes from Mr. White).
Construction of Y-12, the electromagnetic separation plant that Eastman operated, was started by Stone and Webster of Boston in February 1943. But Eastman was more than just the operator of the Y-12 plant. Imagine writing the procedures for such an operation and recruiting and training the thousands of operators who had never been in a production plant before. Because of secrecy considerations no one explained to the operators what their control knobs and switches did or what their instruments measured, and the operators were not allowed to ask. The importance of secrecy about even the smallest operation was stressed to all. Even the engineers and scientists when talking among themselves never used the word uranium. I never heard it used there, and I was in the research laboratory that carried out the last chemistry in the Y-12 process and sent the first product to Los Alamos, before the production department was ready to run. The British had given us a good code name: “tubealloy.” So Y-12's product was called tubealloy tetrafluoride.
Operators were drawn from a distance of as much as a hundred miles. For the day shift, buses would pick them up starting at 3:30 in the morning and deliver them to a Y-12 gate at 6:45. Most were girls. Some had no electricity in their homes. To turn them into operators, Eastman carried out one of the largest civilian training programs ever undertaken. Each of the thousands of operators went through several weeks of on-site training.
The Y-12 plant is a huge complex. More than 250 buildings of various sizes occupy an area of several square miles. Some of the buildings housed the largest magnets ever built--weighing more than 10,000 tons each.
During the war copper was in extremely tight supply, and early in the project a major problem was where the material to make the coils for the magnets was going to come from. To the physicists, the answer was obvious: use the government’s coinage silver. After all, silver is a better conductor than copper, and it was not being used. It was just sitting in storage in the government’s vaults. Well, Y-12 got it, just as it got anything else it needed. A total of 395 million troy ounces of silver--thousands of tons of silver--went into the magnets in Y-12. The silver would be worth about 2 billion dollars today. At the end of the project, recovery of the silver was greater than 99.96%.
Feedstock for the mass spectrographs in Y-12 was uranium tetrachloride. The process for making it was worked out at Brown University by Professor Charles A. Kraus. The coproduct was the war gas phosgene, and sometimes a rupture disk blew and the gas spewed out of the Research building on Brown’s campus, leading to a convenient and never-denied cover story that Kraus was working on new war gases. I went to Oak Ridge because I was Kraus' student.
The chemical engineer Dr. George Akin was sent from Rochester to the University of California to learn the processes for recovery and recycle of the uranium from the mass spectrographs. For a while then he alternated his time between Stone and Webster and Rochester as construction plans were completed. By October 1943 the chemical plant up to the final product was pretty well defined, and most of the Eastman employees on the project moved to Oak Ridge.
George Akin has said that as you can imagine, a huge plant built with such urgency and with so little information had many bugs. Changes were required in almost every part of the process. New equipment had to be installed. It was soon discovered, for example, that the uranium ions struck the collecting receivers with such energy that they penetrated the metal to the extent that they could not be fully recovered by the acid washes that had been provided. It took only a few weeks to set up a line to electroplate the receivers with copper, which would dissolve in the acid wash and release the embedded uranium. The second stage receivers, which collected bomb-grade uranium-235, were ultimately made of carbon, which could be burned to recover all of the uranium. Shop facilities had to be set up to make 250 of these receivers each day.
Dr. Alan Bell, later Assistant Director of Eastman’s Research Laboratories in Kingsport, ran the production department to make the uranium tetrachloride. Dr. James McNally, who later headed Eastman’s research in Kingsport, ran the entire Y-12 production. Dr. Fred Conklin, who became plant manager at Tennessee Eastman after the war, had the same position in Y-12.
After the first separation, the product was again converted to uranium tetrachloride and put through a second set of mass spectrographs. That highly enriched U-235 was converted to uranium oxide and then to the tetrafluoride. At Los Alamos it was converted to the metal.
Simply put, for the war effort Y-12 produced about 75 pounds of uranium-235, for one bomb, at a cost of about 5 billion year-2000 dollars.
During the war, K-25, the gigantic gaseous diffusion plant at Oak Ridge, began to provide partially enriched uranium-235 to Y-12. As a result, the production by Y-12 of highly enriched uranium-235 rose in proportion to the enrichment K-25 had done. After enough months of the slow buildup of enriched uranium in the final diffusion stages of K-25, Y-12 could be shut down, and that is what happened after the war. Only under great time pressure would any government operate the relatively fast but extraordinarily expensive Y-12-type electromagnetic separation plant. Jumping ahead for a moment, there were news reports that after the occupation of Japan, MacArthur’s people dumped Japan’s experimental electromagnetic separation unit into Tokyo Bay. The German effort was equally puny. In more recent times, Saddam Hussein was found to have built two Y-12s, but we kept him from operating them.
At Los Alamos, part of our uranium-235 was converted into the bullet for the gun in the famous Little Boy bomb. The other part of our uranium-235 was converted into a cored-out sphere, which was placed at the muzzle end of the gun. The gun assembly was about six feet long and in bomb form weighed about 10,000 pounds. One reason that it was so heavy was that each piece of uranium had on it a large piece of dense metal to serve as a reflector for neutrons, and to hold the exploding mass together for a fraction of a second while the chain reaction built up. There was an assured source of neutrons to start the chain reaction. One moiety of the neutron source was beryllium, and the other was polonium, a strong alpha particle emitter. The two parts of the initiator came together to release neutrons when the two parts of uranium came together after the gun was fired inside the bomb.
Late in the war we at last had an airplane that could carry such a big bomb, the B-29. On the morning of August 6, 1945, the bomb was dropped from 31,000 feet over Hiroshima, the headquarters city for the Japanese Second Army. At 1,850 feet the gun fired, the bullet sped into the hole in the sphere, the initiator released neutrons, and the sphere exploded. About 2 pounds of the about 75 pounds of uranium-235 in the bomb underwent fission, and less than one gram of matter turned into energy. It was less than the weight of one raisin in breakfast cereal, but in TNT equivalents, the yield of the bomb was about 12,000 tons. It would have taken 2,000 B-29s to carry enough ordinary bombs to have a similar effect.
In Hiroshima, about 80,000 people were killed. By the end of the year another 60,000 had died from delayed effects. Some 48,000 buildings were destroyed totally.
Incredibly, there was no response from the Japanese government. General George Marshall was surprised and shocked that the Japanese did not immediately sue for peace. But today, people believe that there was simply no communication from Hiroshima for a day, and maybe for longer.
So, absent any response from the Japanese government, on August 9th a much more complicated bomb, a plutonium bomb, was dropped on Nagasaki, the town where the torpedoes used at Pearl Harbor had been made.
The physics of the chain reaction in plutonium had presented the scientists one of the hardest problems in the entire Manhattan Project. This chain reaction was so fast that use of a gun bomb would have been an unacceptable gamble. The bomb might blow itself apart before much chain reaction had occurred. The solution was to create a spherical shock wave that would compress a sphere of plutonium and initiator fast enough to permit a chain reaction to proceed much further than it would in a gun-type bomb.
This was a bigger bomb, probably equal to 22,000 tons of TNT, but steep hills confined the explosion, and by the end of the year only half as many people had died as at Hiroshima. This bomb also had a connection to Eastman, for the firing mechanism that squeezed the sphere uniformly, and was one of the great secrets of the war, contained many pieces of carefully machined Composition B. It is still made for these bombs, and for the enormously larger hydrogen bombs, only one of which would be needed to destroy the largest city on earth. The largest hydrogen bomb ever exploded was more than 1000 times as big as the Nagasaki bomb.
After Nagasaki, President Truman gave orders to stop any atomic bombing, but he did not stop other bombing. There was at least one huge raid after Nagasaki, in which several thousand more Japanese were killed by six thousand more tons of ordinary explosives and incendiaries before the emperor accepted our surrender terms.
Afterwards, Harry Truman said: “On May 2nd, when Germany surrendered I sent a message to Japan urging them to surrender too, but I was not too surprised when they refused. We still had not decided to use the bomb, but when the final plans for invading Japan were presented with the estimate that we would lose 250,000 to 500,000 men (to say nothing of the Japanese losses) I could not bear the thought. On July 26 I sent a final ultimatum (the Potsdam Declaration) to Japan. It called for the unconditional surrender of all Japanese armed forces. The alternative for Japan would be prompt and utter destruction. No answer was received. That led to my decision to use the bomb. I couldn’t worry about what history would say about my morality. I made the only decision I knew how to make. I did what I thought was right.”