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article number 650
article date 03-23-2017
copyright 2017 by Author else SaltOfAmerica
All Brains Together—First to Develop the Atom Bomb, Part 8: Plutonium Production, Hanford Washington
by William Laurence, Reporter, New York Times

From the 1946 book, Dawn Over Zero.

* * *

THE story of the creation, production, and purification of plutonium must rank as one of the greatest of modern times. In the histories of the future it will mark the beginning of a new chapter in the life of man.

In this achievement he has gone far beyond the dream of the alchemists. Not only has he succeeded in transmuting a base metal into one much more precious than gold; he has created an entirely new element not known to exist under the sun or anywhere else in the cosmos.

Plutonium, element 94, is the child of neptunium, element 93, another man-made element. It is the grandchild of a new isotope of uranium, U.239, which is also artificially produced.

Thus in creating plutonium man took three steps beyond nature.

The process of this elemental creation starts in the atomic pile, in which U.238 is mated with U.235. As often happens in the act of propagation of species, the male element, U.235, is destroyed in the consummation of this marriage of the elements.

By its very act of death the U.235 liberates the fertilizing agent, the neutron, which penetrates the U.238 nucleus. When this happens, the U.238 also goes out of existence, and a new isotope of uranium is born, containing 147, instead of 146, neutrons.

This new isotope has a rather turbulent existence. The nucleus is top-heavy and begins making frantic efforts to restore the balance between protons and neutrons. Soon a negative electron (beta particle) comes flying out.

This negative electric particle is lost by one of the 147 neutrons in the U.239 nucleus. That neutron is thus left with its positive charge deneutralized; that is, it has been converted into a proton.

In other words, the U.239 again has the original quota of 146 neutrons; but instead of 92 protons, it now has 93.

This means that a new element, element 93, has been created out of element 92. Since uranium was named after the planet Uranus, the element beyond uranium was named neptunium, after the planet Neptune.

But the volcanic eruptions started by the neutron do not end here. Neptunium also has a turbulent life. In a short time the process repeats itself. One of its 146 neutrons radiates away a negative particle and becomes transmuted into a proton. This means that the nucleus now has 94 protons and 145 neutrons.

It still has a mass of 239, but it is now an entirely new element, beyond uranium as well as beyond neptunium, a ninety-fourth building block in the cosmic edifice. Following the nomenclature of elements 92 and 93, element 94 was named after the planet Pluto.

The great-grandchild of uranium, named after Uranus, god of the heavens, thus bears the name of the god of death.

Strangely enough, the planets Neptune and Pluto, as well as the two elements named after them, entered the realm of being after they had existed for some time in the realm of ideas. The two planets and the two elements are both outstanding examples of the materialization of intellectual concepts.

Neptune was discovered first by mathematical calculations, based on a disturbance in the motion of Uranus, which enabled the astronomers Adams and Leverrier to predict correctly not only the existence of the unknown planet but also its size and exact position.

Similarly Pluto was discovered following a prediction of its existence by Percival Lowell, also made on the basis of variations in the motion of Uranus.

In the same manner, neptunium and plutonium were discovered as the result of predictions, based on the nuclear reactions of uranium with neutrons.

Atomic pile building under construction at Hanford Engineering Works.

It will be remembered that the whole story of fission came as the direct result of an attempt to create an element beyond uranium. It was another case in which the quest of a passage to the Indies led to the discovery of a new continent. What had been mistakenly believed to be elements 93 and 94, and other elements beyond them, turned out to be fission products of uranium.

Yet the hope of creating a true transuranic element was never given up, and the discovery that U.238 absorbed neutrons without being split made it practically certain on theoretical grounds that, while U.235 underwent fission, U.238 was transmuted into a new element, or elements, by fission-liberated neutrons.

However, in spite of many attempts to discover these hypothetical true transuranic elements, no experimental proof of their actual creation could be found during 1939 and the early months of 1940. The difficulties in the way were enormous.

There was no pure U.238 or U.235. The best experimental method available was to bombard natural uranium with neutrons by means of the cyclotron.

This, of course, led to the fission of the U.235 in the uranium sample and the creation of a host of highly radioactive fission fragments. If in the process some U.238 atoms were transmuted into a transuranic element, the sample was too small to be identified amid the whirlwind of the U.235 fragments.

The transuranic elements were once again plaguing the nuclear chemists and physicists, this time by their absence instead of their presence. Whereas before there had been too many of them to be accounted for legitimately, they had now managed to hide themselves completely in the atomic jungle.

From bewildering realities they had changed into elemental ghosts.

As has often happened before in the history of scientific discovery, the first glimpse of the ghost came by chance, but it was the sort of chance that, in the words of Pasteur, “favors the prepared mind.”

For many months Dr. McMilIan and Dr. Abelson had been methodically investigating the fission products of U.235. By means of a technique developed by Dr. Abelson for identifying radioactive substances by their characteristic X-rays, with which he had come very close to the discovery of fission, they had set out to classify the various ingredients in the brew of the fission caldron.

At the same time they were not unmindful of the possibility that the mixture might also yield at least one of the elusive transuranium elements.

And sure enough, one day in the spring of 1940 they noticed a newcomer. Unlike the fission products, which recoiled with tremendous energy, this stranger kept apart from them, displaying very little kinetic energy as compared with the others.

This indicated at once that it was not a product of fission of U.235, but more likely a new radioactive isotope of uranium, which, not having been split, did not possess the great energy imparted by the broken-up U.235 nucleus to its fragments.

Radioactive elements can be used as tracers. Even amounts so minute that they cannot be seen can be detected through their radioactivity. By using various reagents and precipitants, it can be determined which of these carries the radioactive substance along with it, and this, in turn, provides information on the chemical properties of the unknown radioactive substance.

Building an atomic pile at Hanford works.

With such methods Drs. McMillan and Abelson were able to determine, by May 1940, that the unknown radioactive substance was element 93, born through the emission of an electron by U.239, which in turn had been produced by the capture of a neutron by U.238.

In their published report, which appeared on June 1, 1940, they also described a method for separating neptunium from the other known elements, based on the chemical properties revealed through tracer quantities of the new element. The report further pointed out that, since neptunium had been observed to emit an electron, “element 94 was certainly present in the neptunium decay product.”

They were unable, however, to demonstrate the presence of element 94, since it was present in amounts too minute for detection even by radioactivity.

Before they could proceed with this work, Dr. McMillan was called away to work on microwave radar at the newly formed radiation laboratory at the Massachusetts Institute of Technology, Cambridge, Massachusetts, while Dr. Abelson, who had completed his work for his Ph.D., left to take a position with the Carnegie Institution of Washington.

Dr. Glenn T. Seaborg, of the University of California chemistry department, wrote to Dr. McMillan and Dr. Abelson for permission to carry on the work in search of element 94. They not only granted Dr. Seaborg’s request, but also turned over to him all their unpublished data and ideas.

By December 20, 1940, Dr. Seaborg, in collaboration with Dr. Joseph W. Kennedy and Arthur C. Wahl (at that time a graduate student in chemistry), and with the co-operation of Dr. McMillan through correspondence, succeeded in producing a new substance by the bombardment of uranium with the nuclei of heavy hydrogen (deuterons) fired by the cyclotron.

However, at that time the new substance could only be partially identified as element 94.

While this work was in progress in California, a conference of far-reaching import was held at Columbia University on December 15, 1940, between Drs. Fermi, Lawrence, and Emilio Segrè, of the University of California, a former associate of Fermi in Rome.

Fermi was at that time already at work on a chain-reacting pile, and he strongly suspected even at that early date that in such a pile the U.238 would be transmuted into plutonium.

The implications of this hypothesis were enormous, for it was practically certain that plutonium would have the same fissionable properties as U.235 and would have the tremendous advantage of being separable by chemical means.

In a word, it would mean that fissionable material could be produced in the quantities necessary for atomic bombs.

The work of McMillan and Abelson in creating neptunium, and particularly their observation that it emitted electrons and thus was most likely transmuted into element 94, furnished the first experimental proof that the hypothesis was correct.

Only one more step was necessary to make the evidence conclusive—to make actual observations of the transmutation. This would require performing the McMillan-Abelson experiments on a much larger scale, so that a sufficient amount of element 94 (it had not yet been named) would be produced.

This, in substance, was the subject of the conference that day at Columbia University. It led to the momentous decision to push the work on 94 as vigorously as possible. It was further realized that, in order to reproduce conditions that would prevail in the pile, it would be necessary to use neutrons, instead of deuterons, as the particles for bombarding uranium.

On March 1, 1941 Drs. Seaborg, Segrè, Kennedy, and Lawrence proceeded to bombard about one kilogram of uranium with neutrons. It was the largest amount of any substance ever subjected to bombardment by the cyclotron. For six days and nights this terrific bombardment against the citadel of the uranium nucleus was carried on.

On March 6 they succeeded. As in the McMillan Abelson experiments, the uranium had been transmuted into neptunium. And, beautiful to behold, they found that the neptunium had in turn, by the emission of an electron, been metamorphosed into a new element.

The newcomer announced his arrival by a shower of alpha particles, telltale radiations that theory had predicted as characteristic of element 94, plutonium.

Construction of Hanford facility.

Man had produced the first made-to-order element in history, but the great test was yet to come. By March 28 about one half of a microgram of plutonium 239 had been produced. This the scientists proceeded to bombard the plutonium 239 with slow neutrons to determine whether it was subject to fission in the same degree as U.235.

On that day a tense group stood around the oscilloscope. They saw the ionization pulses in the atomic thermometer rise to the same peaks produced by the fission of U.235.

The news traveled quickly to the Uranium Committee in Washington. It reached the physics laboratory at Columbia University.

It gave the Atomic Bomb Project, at that time still tentative, a new impetus and a new direction.

* * *

Work then proceeded vigorously on the production of further amounts of plutonium. To increase the yield it became highly desirable to procure some metallic uranium, practically non-existent at that time. On consult in Professor Gilbert N. Lewis, it was learned that some fourteen years before, one of his students, a native of Sweden, had prepared a fairly large sample of metallic uranium of a high degree of purity.

No one knew what had become of the uranium or of the student. Through the Swedish Legation it was learned that he had returned to Sweden. An urgent cable was sent to him asking the whereabouts of the precious metal.

Came back the reply: “In Professor Lewis’s desk.” It had been there for fourteen years.

As the result of the discovery of neptunium and plutonium, Drs. Seaborg and M. L. Perlman made a search for these elements in pitchblende and found evidence of the existence of plutonium to the extent of about one part to 100,000 billion parts of pitchblende by weight. They ascribe this amount present in the ore as being due to the continuous absorption by U.238 of an appreciable fraction of the neutrons that are continually emitted during the spontaneous fission of uranium.

This indicates that plutonium is also being constantly created in nature, the only known example of creation still going on.

When the building of plutonium-producing piles was under consideration in 1942, some of the scientists feared that it might take too long to work out the chemical procedures for its separation. Dr. Seaborg, however, felt confident that it could be done in a reasonable time.

Since no more than microgram amounts could be made by the cyclotron, Seaborg and his associates started work on the ultramicro scale.

The first plutonium in the form of a compound was isolated on August 18, 1942, by Drs. B. B. Cunningham and L. B. Werner, and a number of further compounds were made a month later.

On the basis of these “bits of nothing” they proceeded to design a huge chemical plant to scale, the microgram amounts serving as a pilot plant for actual operations some ten billion times greater in scope.

To do so they had to use a host of other chemicals in exact proportions, in quantities of micrograms and fractions of micrograms, within a limit of accuracy of three percent. (A human breath weighs about 70,000 micrograms.)

To achieve this unheard-of accuracy in weighing, an ultramicro balance of an extremely high sensitivity was designed and built by P. L. Kirk and R. D. Craig of the University of California. This balance could weigh amounts as small as a microgram with an accuracy of three per cent, and could actually weigh a mass as small as 0.03 micrograms.

Work continued on approximately this scale of operation until about January 1944, at which time milligram amounts of plutonium became available. There soon followed experiments on the gram and then on the ten-gram scale. Following these the scale became substantially larger.

Construction of a Hanford Works facility for the chemical extraction process of Plutonium.

On the basis of these ultramicro-scale procedures a large pilot plant was built at the Clinton Engineer Works, where the chemistry for concentrating and purifying plutonium was further developed under the direction of Professor Warren Johnson, of the University of Chicago, and Major Oswald H. Greager, formerly of the du Pont Company.

Before this pilot plant was completed, however, work began on three huge separation plants at the Hanford Engineer Works. These plants, rectangular structures 800 feet long, are the most remarkable chemical factories ever conceived or designed.

In these plants enormous quantities of materials are made to go through complicated chemical processes with no human eye ever seeing what actually goes on except through an intricate series of dials and panels that enable the operators to maintain perfect control of every single operation at all times.

Each operation is performed in a remote cell behind thick walls, and when it is completed the treated material invisibly moves on to the next cell, until at the end of a series of such passages the miracle of modern alchemy emerges, ready for the next stage on its ultimate journey.

The remote-control operation was made necessary because the plutonium comes associated with the fission products of U.235, which emit an amount of radiation that would be lethal to any life in its vicinity.

Hanford Engineer Works is located in Benton County, in the south-central portion of the state of Washington, between the Yakima Range and the Columbia River. It lies on the undulating tableland containing for the most part a desolate region of gray sand, gray-green sagebrush, and dried watercourses.

The region is drained by the Columbia River, east of the Cascades, where the Rattlesnake Hills, Saddle Mountains, and Yakima Range form the inland extremities of that system and constitute a plant barricade to the south, north, and west. The nearest community of any size is Yakima, some forty miles westward, which has a normal population of about 30,000.

The manufacturing area lies entirely on the south, or right, bank of the Columbia River, which bounds it to the north and northwest. The manufacturing reservation is nearly level, broken prominently only by Cable Mountain, an outcropping of basalt that underlies the entire site, usually at a considerable depth. The overburden consists of a poorly cemented shale and sandstone stratum known as the Ellensburg Formation, above which are deposits of sand and gravel, chiefly alluvial.

The area owned or controlled through lease amounts to approximately 631 square miles. Of this total, 230 square miles are owned by the Government. The manufacturing reservation contains 195 square miles. The remaining area is accounted for by the purchase of power and irrigation properties and rights, and by the acquisition of Richland Village, to the south of the manufacturing area, as a site for the housing development and the administration center.

Leased property is either on a basis of no occupancy or controlled occupancy as warranted by considerations of safety and security. For the protection of employees and the public generally, monitor stations are strategically located in the operating and service areas, and outside the limits of land owned and leased.

The manufacturing area is divided into three huge sections, and each of these three is subdivided into subsections covering miles of ground.
• One of the three main areas contains the three great chain-reacting piles for the production of plutonium.
• The second area contains the three chemical plants where the plutonium is separated and concentrated.
• The third area is where the raw material for the plutonium piles is prepared.

The three piles are located on the south bank of the Columbia River at the northern extremity of the manufacturing reservation. Each of the piles is bounded by some 4.1 miles of fence, overlooked by guard towers located, at most, 2,000 feet apart. Within the fence lie some 685 acres of land, 4.25 miles of broad-gauge track, and 6.75 miles of roads.

The three plants are completely self-contained. Each is about seven to eight miles distant from the next one. The nearest to Richland Village is thirty miles away.

Hanford Works plant.

The construction of the Hanford Engineer Works presented innumerable and unprecedented problems, which stemmed from several basic requirements established by research and development, engineering design, and policy.

The principal factors that created these problems were:
• the magnitude of the project;
• the distances between the several manufacturing plants to be constructed;
• the isolated location of the site;
• the time element, which demanded that construction proceed without awaiting completion of engineering design;
• the unusually high quality of construction required in many instances; and
• the extreme and rigid requirements of military secrecy.

The magnitude of the work of construction is indicated by the following general items selected at random:
• Excavation amounted to 25,000,000 cubic yards of earth, a quantity approximately one fourth of the earth moved in the construction of the Fort Peck Dam, the largest earth dam ever constructed.
• A total of 40,000 carloads of material were received on the site, equivalent to a train 333 miles long.
• More than 780,000 cubic yards of concrete were placed, an amount approximately equal to 390 miles of concrete highway twenty feet wide and six inches thick.
• Excluding railroad rail and special steels, about 40,000 tons of steel were used in building construction.
• Approximately 160,000,000 board feet of lumber were required, equivalent to the yield from 135 acres of the best timberland.
• About 1,500,000 concrete blocks and 750,000 cement bricks were used in plant construction;
• More than 11,000 poles were required for the electric power and lighting systems;
• More than 8,500 pieces of construction equipment were used.
• Approximately 345 miles of permanent plant roads were constructed on the site.

The necessity for separating the several areas from each other and from inhabited localities by relatively great distances imposed abnormal problems for the transportation of men and materials. These distances are emphasized by the fact that 340,000,000 passenger-miles of bus transportation were furnished during the construction phase of the work.

The isolation of the site from any existing centers of population presented serious problems with respect to many phases of construction. These were related primarily to the procurement, transportation, housing, feeding, health, morale, and retention of a maximum total construction force of about 45,000 persons, a total reached in June 1944.

The urgent need for putting the plant in operation at the earliest possible date made it necessary in a number of instances to proceed with construction before basic research had been fully developed. Steps had to be taken that, in the words of Professor Smyth, “no engineer or scientist in his right mind would consider in peacetime,” and could be justified even in wartime only by the “possibility of achieving tremendously important results.”

There is as much difference between the first chain-reacting pile at Chicago and the giant plutonium piles at the Hanford Engineer Works as there is between a toy popgun and a battery of the most powerful modern artillery. Essentially they are both latticeworks of graphite and uranium, in which a chain reaction perpetuates itself through the liberation of neutrons by the fission of U.235 in unseparated uranium, and the slowing down of the neutrons in the graphite. But, by comparison, the first is a crude shack alongside the Empire State Building.

The actual size and power of the Hanford piles cannot be given. Nevertheless, some relative data may prove

Before building the piles at Hanford a small, experimental pile was constructed at the Clinton Engineer Works to serve as a pilot plant. As it turned out, the Hanford piles were designed along different engineering lines, but for purposes of comparison the Clinton pile is much closer to the ones at Hanford than to the Chicago prototype.

Originally designed to operate at a power of a 1,000 kilowatts, which corresponds to the splitting of less than one milligram of U.235 per day, the Clinton pile reached a power level of 1,800 kilowatts in May 1944. This Clinton pile was thus 9,000 times more powerful than the Chicago pile. Yet it is a mere pygmy alongside any of the Hanford giants.

The construction of these mammoth atomic piles required the solution of many problems of a type and a scale never encountered before. The first problem, of course, was to design a practical plant that would produce plutonium in sufficient quantities for atomic bombs.

Constructing a building to house an atomic pile at Hanford Works, Washington.

This end could not be achieved by merely scaling up the Chicago model, as it would have taken five million of these to produce just one kilogram a day. Hence the design had to be of a radically different nature, not merely larger in size.

A pile in which large quantities of U.235 are being split generates radiations equivalent to those of tons of radium. Hence the piles had to be surrounded by concrete walls several feet thick.

Since these radiations are greater by far than anything ever encountered before, they created one of the greatest health problems ever faced. To meet the challenge, a staff of several hundred of the country’s leading radiologists, under the direction of Colonel Warren and Dr. R. S. Stone, was organized to carry out pioneer studies in this unknown field and to devise new methods for the effective protection of all personnel.

The greater the power at which the pile is operated, the greater is the energy liberated in the form of heat. This heat is equivalent to that of burning 3,000,000 kilograms of coal per kilogram of U.235 used up in fission, and if not efficiently carried off, it might vaporize the pile and lead to the greatest of catastrophes.

The cooling problem was one of the most difficult that faced the designers of the pile. It had at first been decided to use helium as the coolant. For various reasons it was finally decided to use water.

This created enormous engineering problems. To carry off the amounts of heat generated in the pile would require the circulation of a quantity of water large enough to supply a fair-sized city. Furthermore, since this water would become hot, it in turn would have to be cooled before it was returned to the Columbia River, as otherwise it might raise the temperature of the river to a point incompatible with fish life.

If it was decided that the water could go through the system only once, a huge retention basin would have to be designed so as to allow the radioactivity induced in the water to die down before the water could be returned to the Columbia river.

The decision to use water as the coolant also opened up another serious problem. To load and unload the pile, the uranium is shaped in the form of cylinders, which are inserted in channels passing through the graphite.

When enough plutonium has accumulated in the cylinders, they are pushed out by remote control into a deep water basin in the rear of the pile, whence they are transferred to the chemical separation plant.

Since the heat develops in the uranium, the water would have to circulate in contact with it through the channels in the graphite. The indications were that the uranium would react chemically with the water, probably to the point of disintegrating the uranium cylinders.

Hence it became necessary to seal the uranium in a protective can made of a material that had to meet a number of stringent requirements:
• it must not absorb too many neutrons;
• it had to transmit heat from the uranium to the water;
• it had to protect uranium from water corrosion;
• it had to withstand the terrific heat;
• it had to have a high resistance against the radiations; and
• it had to keep fission products out of the water.

The failure of a single can might result in putting an entire pile out of operation.

The problem of the can proved to be one of the most difficult to solve. Professor Smyth reports that on his periodic visits to Chicago, where the problem was being studied along with the other problems relating to the pile, “he could roughly estimate the state of the canning problem by the atmosphere of gloom or joy he found around the laboratory.”

Aluminum had been decided on as the material best suited for the purpose, but several very troublesome problems still remained. It proved very difficult to get a uniform, heat-conducting bond between the aluminum and the uranium. Nor was it found possible to effect a gas-tight closure for the can. The final solution did not come until October 1944, after the first Hanford pile had begun operations.

Another problem involved the radioactive gases developed as fission products in the pile. High stacks were built to carry them off, but since the behavior of these gases is dependent on the weather, meteorological studies were made over a period of many months to determine whether the stack gases would be likely to spread radioactive fission products in dangerous concentrations.

The studies, made at both Clinton and Hanford, led to the working out of specifications for the operation of the stacks.

The energy from the piles is heating the Columbia River, but the actual rise in temperature is so small that no effect was to be expected on fish life. A series of elaborate experiments confirmed this expectation.

Water pumping station, Hanford Works.

The Hanford piles are the first atomic power plants built on earth, atomic boilers generating enormous amounts of atomic energy in the form of heat.

In these boilers atoms by the trillions are ripped asunder and new elements are constantly being created. Many of these, fission products distinct from plutonium, have great potential value in biology, medicine, and industry.

Thus the atomic pile is actually a three-in-one plant:
• It creates large quantities of plutonium.
• It produces a host of valuable new radioactive elements.
• It liberates a vast amount of atomic energy, which today goes to heat the Columbia, but promises more utilitarian applications for tomorrow.

To behold these atomic power plants standing in their primeval majesty is one of the most terrifying and awe-inspiring spectacles on earth today.

There is not a sign, not the slightest hint, that within these huge man-made blocks titanic cosmic fires are raging such as had never raged on earth in its present form. One stands before them as though beholding the realization of a vision such as Michelangelo might have had of a world yet to be, as indescribable as the Grand Canyon of Arizona, Beethoven’s Ninth Symphony, or the presence “whose dwelling is the light of setting suns.”

In these Promethean structures, which may well stand as eternal monuments to the spirit of man challenging nature, mighty cosmic forces are at work such as had never been let loose on this planet in the million years of man’s existence on its surface, and probably never in the two billion years of the earth’s being.

Here, for the first time in history, man stands in the presence of the very act of elemental creation of matter. Here in the great silences—for the plants operate in a stillness where even the beating of one’s heart can be heard—new elements are being born, a phenomenon that, as far as man knows, has not happened since Genesis.

This development no doubt will rank in the future story of mankind as a definite landmark, signalizing a new cultural age, the Age of Atomics, or of Nucleonics, as some scientists prefer to designate it.

For this there is no parallel. All the great ages—the Iron Age, the Bronze Age, the ages of steam and electricity, each of which revolutionized conditions of living—arrived imperceptibly, and man did not become aware of them until their effects were fully felt.

This marks the first time in the history of man’s struggle to bend the forces of nature to his will that he is actually present at the birth of a new era on this planet, with full awareness of its titanic potentialities for good or evil.

One is reassured on seeing the most remarkable system of automatic controls, and controls of controls, devised to keep this man-made Titan from breaking his bonds. Left without control for even a few seconds, the giant would run wild.

Enormous as the mass is, its mechanisms and controls are adjusted with the fineness of the most delicate jeweled watch, and they respond with the sensitiveness of a fine Stradivarius. The slightest deviation from normal behavior, and the automatic controls go into operation. They can stop the Titan in his tracks almost instantly.

Hanford Works employees buy War Bonds from a portable facility.
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