Nuclear physics research efforts in the United States were not entirely asleep before 1939. Although research expenditures for fundamental sci­ence were chronically short by today’s standards, there was never a short­age of curiosity and a need to push physics into unknown territory. An

area where the United States made bold progress during the Great Depres­sion years was in particle acceleration. Charged subatomic particles, such as protons or electrons, can be accelerated electrically from rest energy up to great speeds, simulating radioactive decay products blasting free of nuclei but on a larger scale. The availability of a large flux of energetic charged particles made it possible to do element transmutation or nuclear disintegration on a scale order of magnitude bigger than had been accom­plished using radioactive sources. Using a large enough accelerator, mea­surable quantities of isotopes could be manufactured in a laboratory, or enhanced resolution in nuclear probing was available. This class of machine came to be known as the atom smasher. The master of atom smasher design was Ernest Lawrence, of the University of California.

Ernest Lawrence (1901-58) was unique in the field of Nobel Prize­winning physics, in that his entire education was in the United States, without the degree from Europe that was considered necessary at the time. He started his college work at the University of South Dakota, transferred to the University of Minnesota, and received his bachelor’s degree in 1922. He earned a master’s in physics in 1923 and went to Yale University in Connecticut for a Ph. D. in physics in 1925. His most important contribu­tions to nuclear research and development were two-fold. He invented the cyclotron atom smasher and the calutron large-scale isotope separator. He won the Nobel Prize in physics in 1939 for his work with the cyclotron.

Lawrence built his first cyclotron in 1929 at the University of Califor­nia, Berkeley, using available materials. He called it his “proton merry — go-round” because it constrained charged particles to spin around in a tight spiral under a magnetic field as they gained power. The machine cost about $25 to build, the equivalent of about $313 today, and it was only five inches (13 cm) around, but it proved his point. Although the concept of the cyclotron probably occurred several places at about the same time, Lawrence dug in and built one. Leo Szilard patented a cyclo­tron in Europe, but it takes more than a patent to break up nuclei. In 1934, Lawrence obtained a patent for the cyclotron, and by 1936 he had taken over the Civil Engineering Testing Laboratory, renamed it the Radiation Laboratory, and filled it with a 37-inch (94-cm) cyclotron capable of accel­erating alpha particles to 16 MeV. He used it to create the first artificial element, technetium, a substance that is in the middle of the periodic table but does not exist in the crust of the Earth.

In 1939, Lawrence completed his 60-inch (150-cm) cyclotron, just in time to participate in the pivotal year in nuclear physics. It was a colossal

Ernest Lawrence’s 60-inch (152-cm) cyclotron at the University of California, Berkeley. Lawrence was awarded a Nobel Prize for his work with cyclotrons and later developed a magnetic isotope separator used in the atomic bomb project. (Lawrence Berkeley National Laboratory)

machine, with a magnet weighing 220 tons (200 metric tons), and it would be used to discover carbon-14, neptunium, and plutonium. Lawrences calutron was an industrial version of the magnetic mass spectrometer invented at the Cavendish Lab in Great Britain in 1918. It would be a criti­cal component of the atomic bomb development project that would soon consume the United States.

When World War II started in Europe, the United States had all it needed to develop nuclear weapons and power systems. Available were many of the best scientists of Europe, an amazing array of homegrown physicists graduating from or teaching in universities, an industrial infra­structure capable of building anything that could be assembled by man­kind, and a warehouse in New York filled with uranium ore. All that was needed was the spark to start the fire. In the next chapter, the spark and the beginning of the resulting conflagration are revealed.

Maria “Manya” Sklodowska (1867-1934) was born in Warsaw, then a part of Poland under the occupation of the Russian Empire. As a child she was encouraged to seek a higher education by her mother, a math teacher, and her father, a physics teacher, and eventually she was able to attend the Floating University, an illegal night school in Warsaw. Working as a tutor and as a governess for children of wealthy families while studying math­ematics and chemistry, Manya was eventually able to gain acceptance to the prestigious Sorbonne. In 1891, she moved to Paris and changed her name to Marie, to fit into the French culture, as she applied herself dili­gently to her studies in math and physics.

By 1894, Marie had performed pioneering research on magnetism and steel, and she was the laboratory chief at the Municipal School of Indus­trial Physics and Chemistry in Paris, where she shared laboratory space with a like-minded scientist named Pierre Curie (1859-1906). In July 1895, the two scientists were married, and Marie Sklodowska became Marie Curie. The research work of Marie and Pierre Curie was performed in a barely adequate structure in Paris, fondly referred to as “the miserable old shed,” with minimum funding, and yet they were able to steer the course of atomic science and be awarded three Nobel Prizes between them. Marie was the first person to win Nobel recognition in two different sciences, physics and chemistry. The 1903 Nobel Prize in physics was shared by Marie, Pierre, and Marie’s doctoral thesis adviser, Henri Becquerel.

In 1896, Becquerel’s newly discovered rays were considered interesting by the scientific community, but much more attention was focused on Wilhelm Roentgen’s X-rays. Marie found the neglected rays from ura­nium interesting, and she used a new technique to detect and quantify them. A precision electrometer had been invented 15 years earlier by her husband, Pierre, and his brother, Jacques. She used it to measure the ion­ization effect in air caused by the passage of Becquerel rays. Using this novel equipment setup, she was able to confirm Becquerel’s observations that the radiation from uranium is constant, regardless of whether the uranium was solid or pulverized, pure or in a compound, wet or dry, or

exposed to light or heat. Minerals having the highest concentration of uranium seemed to emit the most radiation. She then went farther than Becquerel, suggesting a hypothesis that the rays were a result of some property of the very structure of the uranium atoms.

In 1898, Marie found another element that emitted Becquerel rays. It was thorium, and she was becoming convinced that it was an atomic property and not some external cosmic-ray influence. By this time, Pierre was so intrigued by Maries findings that he dropped his own investiga­tions into crystals and joined her in studying pitchblende and chalcolite, which were uranium ores. She had found something interesting: Pitch­blende, from which uranium was extracted, was more radioactive than was pure uranium. There was apparently something mixed in with the uranium.

By chemically processing tons of pitchblende, the Curies were able to identify two new radioactive elements existing in the same mineral with uranium. The first element discovered Marie named polonium, in honor of her native Poland. The second she named radium, for its aggressive radioactivity. With tremendous difficulty, Marie and Pierre managed to refine the radium down to a pure metal, in sub-gram quantities. It was an interesting material. It would glow blue in the darkened laboratory, but the power and the danger in that blue glow were only suspected.

The war was over, but only in theory. The armed forces of Japan were expecting an invasion of the home islands, and they were prepared to repel such intrusion with the lives of every human being who could walk and swing a stick. The Japanese diplomatic corps was counting on a last-minute alliance with the Soviet Union, which would hopefully stop an American ground invasion. On July 28, 1945, the Japanese prime minister Admiral Baron Kantaro Suzuki publicly announced that Japan would ignore the latest peace plan from the Allies, the Potsdam Procla­mation, and continue to fight. On August 2, the new president of the United States, Harry S. Truman (1884-1972), weighing the pros and cons of using this new type of weapon, gave the order to drop the bombs on Japan.

The 509th Composite Group of the 313th Bombardment Wing of the U. S. Army Air Force had trained and prepared to drop the atomic bombs. The personnel and aircraft were assigned to the air base on Tinian Island in the Pacific Ocean. Special air-conditioned buildings were erected for assembling and testing the bombs, and loading pits were sunken into the pavement off the runway for gently lifting the heavy devices into waiting aircraft. A new custom-fitted B-29 four-engine bomber, named the Enola Gay for its pilot’s mother, took off in the early morning of August 6 carry­ing the uranium bomb, “Little Boy,” number L-11.

The target was Hiroshima, the seventh largest city in Japan with a pop­ulation of about 350,000. It had been spared the bombings of most other industrial cities in Japan, and it was hoped that its complete destruction by a single device would convince the government of Japan of the futility of resistance. Dropping an atomic bomb on Tokyo, the largest city, would have been pointless. All the buildings had long since been burned to the ground or knocked over by a relentless conventional bombing campaign, and an atomic bomb explosion would have made no difference.

The bombing run was perfect and by the textbook, with clear weather, no enemy fighter planes, and no antiaircraft fire. At 9:15:17 a. m. Hiro­shima time, “Little Boy” was released from an altitude of 31,000 feet (9,500 m). Exactly 44.4 seconds later, it exploded 1,968 feet (600 m) above the

center of the city, and Hiroshima was lost to Japan by a device that had never been tested. Casualties were impossible to count, but are thought to be more than 83,000 people.

The government of Japan was oddly silent about this event. It would take a few days for the enormity of it to sink in. Bomber command sent another B-29, “Bock’s Car,” with a plutonium-fueled implosion bomb on August 9. The target was the undisturbed city of Kokura, home to 110,000 people and the site of a major army arsenal. Fortunately for Kokura, it was clouded over that day, and the bomber moved to the secondary target, Nagasaki. It had 212,000 people and a large Mitsubishi armaments plant.

At 10:58 a. m. Nagasaki time, “Fat Man” dropped, almost directly over a soccer field, and Nagasaki went up in a mushroom-shaped cloud. Six days later, at noon Japan standard time, the people of the Empire of the Rising Sun for the first time in history heard the voice of their emperor, Hirohito (1901-89), over the radio via a phonograph record, made two days before. This unprecedented “Jewel Voice Broadcast” carried a carefully prepared message, beginning as:

TO THE SUBJECTS OF JAPAN

After examining Japan’s current situation and condition, I have decided to take extraordinary measures. I have ordered our government to inform the governments of the United States, Great Britain, China, and the Soviet Union that Japan will accept the provisions of the joint declaration.

The speech went on to admit that “the war has not progressed entirely as we have wished,” and it mentions that “the enemy now possesses a new and terrible weapon.” The war with Japan was finally over.

James Chadwick (1891-1974), son of a businessman from Cheshire, England, applied to the University of Manchester at age 16. He planned to major in mathematics, but as he stood in the queue for his entrance inter­view he realized too late that he was in the wrong line. He was too embar­rassed to admit it and wound up in physics. His first year was miserable, as the physics classes were big and noisy, but when he heard a lecture by Ernest Rutherford he was converted to physics. He graduated in 1911 with a bachelor’s degree in physics and went on to Cambridge, where he earned

a master of science degree in physics in 1913. From there, he was awarded a scholarship to engage in nuclear research with Hans Geiger (1882-1945) at the University of Berlin, a valuable opportunity

Caught in Germany at the beginning of World War I, Chadwick was kept in a prisoner of war camp for nonmilitary aliens for the duration of the war. Released at the end of the war, he was hired by Rutherford to resume his research at the Cavendish Laboratory. His assignment was to look for the neutron, Rutherford’s theoretical particle, and it would be a long search. He started by studying what others in the field were doing. They were bombarding light elements with alpha particles to see what would happen.

The alpha particle, as discovered and named by Rutherford, is an extremely heavy particle of great energy. It consists of two protons and two neutrons stuck together, and it is literally the nucleus of a helium atom. In the 1920s, it was only known to be heavy and positively charged. Hit a light element, such as boron or aluminum, with an alpha particle and the nucleus disintegrates, throwing off a burst of gamma rays and proton debris. Oddly, beryllium emitted a rash of gamma rays 10 times that of other elements bombarded with alphas, and there was no proton debris from a supposed nuclear destruction. No one knew why.

Irene Joliot-Curie (1879-1956) and her husband, Frederic Joliot-Curie (1900-58), had reported detecting protons being knocked out of a sheet of paraffin by the gamma rays produced by the alpha-beryllium experi­ment. Chadwick was highly skeptical of the French findings. He believed their observations of the radiation were correct, but their explanation was questionable. They were saying that gamma rays from the beryllium were knocking protons out of solid wax. It was true that gamma rays of suf­ficient energy could deflect electrons, but protons are 1,836 times heavier than electrons. Saying that gamma rays were tossing protons into the ion chamber was like saying that a dump truck could be knocked into the oncoming lane by hitting it with a well-thrown baseball. Chadwick set up his own version of the Joliot-Curie experiment.

The protons were indeed knocked into the detector in Chadwick’s setup. The only thing that could exchange momentum with a stationary proton and send it flying at high speed into the ion chamber would be a particle of the same weight, hitting it hard. There were no protons coming out of the beryllium, or they would have shown up in the ion chamber. Chad­wick proposed a logical explanation. The particles coming out of the beryl­lium were neutrons. The neutrons made no impression on the radiation

RHODIA

(Stan

LAMBEF*

The toolbox of James Chadwick (1891-1974), ca. 1932, which he used to discover the neutron. These are silver and aluminum foils of various thicknesses used as barriers to assess the strength of radiation, which he kept in a cigarette box. (© SSPL/lmage Works)

detection apparatus simply because they were electrically neutral particles, but by hitting the paraffin a secondary effect could be seen, as the protons recoiled from billiard-ball collisions with the flying, invisible particles.

On February 17, 1932, after getting very little sleep over the previous week of intense work, James Chadwick published an announcement in the science journal Nature titled “Possible Existence of a Neutron,” and the productive era of nuclear physics began.

In late 1939, with a world war already ignited in Europe, there was suffi­cient high-level theory to indicate that explosives using the binding energy of atomic nuclei were possible. Weapons based on nuclear energy princi­ples had a frightening potential, with the most concern being that the opposing side would develop them first.

While solid theories made such devices seem possible, there were many details of implementation to be worked out. There were experi­ments to be run and data to be collected, and after that a massive indus­trial conversion would be necessary, going from small-scale laboratory setups to large-scale production. It was nothing that any individual, any organization, or any consortium of companies had the resources to make happen. There was too much risk of failure, even if the expense and effort were feasible. It was a problem of governmental scale, and not just any government could handle it. In this chapter, the process of awakening the U. S. government to engagement in this massive scientific research and development is examined.

The working weapon theory was that a runaway chain reaction of fis­sions could be started, but to this point no such action had been observed. It would take a large, pure sample of U-235 to perform an experiment, and the problem of purifying a rare isotope of uranium in mined ore was enormous. It would be a large waste of effort if it turned out that a chain reaction was not possible. This chapter reveals the important step of first

proving the chain reaction concept using naturally occurring concentra­tions of the fissile uranium isotope, creating a controlled, nonexplosive form of nuclear energy release.

By 1899, scientific studies had established that matter is divided into char­acteristic atoms and that electrically charged components of these atoms can be ripped off and sent flying through a vacuum. These tiny, invisible components, later to be named electrons, behave as predicted by the mathematical models formulated by Maxwell and Faraday. The flight of an electron through the vacuum deflects in a predictable trajectory by an imposed magnetic or electrical field. Furthermore, Maxwell and his groundbreaking set of equations had predicted that a changing magnetic field causes an electrical field and that a changing electrical field causes a magnetic field. Strike a high-voltage spark across two electrodes and the burst of an electrical field will cause a magnetic field, which causes another electrical field, which causes another magnetic field, and so on, as a wave of electrical and magnetic fields radiates through space at the speed of light, alternating between electricity and magnetism at a frequency that is proportional to its energy of creation.

The gradual discovery and confirmation of this electromagnetic wave phenomenon would prove monumental, as it became evident that light itself was a manifestation of this wave effect. A wave of lesser energy would be exploited for radio communications, and waves of greater energy would be used as X-rays for medical diagnosis. These interesting scientific discoveries would spin off into successful commercial products in the new century, but the scientists would continue to push open the

door of discovery, ever curious concerning the nature of matter and find­ing that solving a puzzle of the natural world simply uncovered more puzzles. Scientists in Germany and France found that there were other ways to derive radiation without direct application of the Maxwell equa­tions. Some heavy elements, such as uranium and the newly discovered polonium and radium, would dismantle themselves on the atomic level, emitting even more powerful forms of radiation.

With the end of World War II, the furious push for nuclear development came to a sudden halt. The scientists, engineers, and technicians were tired, and as a group they experienced the depression that can come from the completion of a huge task and the unique dread of having built unusu­ally ferocious weapons. Many workers at Los Alamos, having performed their duty, returned immediately to their lives in academia or industry. Some lingered. Robert Oppenheimer, director of the lab, remained a year and then resigned to return to the Institute for Advanced Studies at Princeton and to become chairman of the general advisory committee for nuclear project funding and laboratory construction. Enrico Fermi, inventor of the nuclear reactor, went back to teach at the University of Chicago.

The Hanford Works in Washington State kept turning out plutonium by the ton, and the gaseous diffusion plant at Oak Ridge, Tennessee, now running at full capacity, started producing bomb-grade U-235, even though there were no plans to build another uranium bomb. The Fat Man design was improved, and a few MK III plutonium implosion devices were assembled, in case of renewed global hostilities. Although building an electrical power plant using the vast wealth of knowledge and experi­mental data gained during the war seemed a logical idea, it was an idea for the future, and there was no immediate push to civilize the weapons work or to move on to public service applications. In comparison to the

effort of building a nuclear-based power plant, a bomb seemed simple. “Little Boy,” after all, had exactly one moving part, and it had cost $1.8 billion to build it. A nuclear plant would have turbines, pumps, and valves of all descriptions, electrical controls and monitors, and it would have to be taken apart to refuel it. The machinery would have to be safe enough to run in populated areas without disruptive accidental radiation releases. It was easier to build a nuclear device that would spread radiation than to build a nuclear device that would not spread radiation.

This atmosphere and attitude of not rushing into anything lasted only briefly, and soon there was a push for nuclear power and even a com­petition among the United States, the Soviet Union, Canada, and Great Britain to tame the wartime technology, and all would eventually claim to have built the first nuclear power plant. The four countries would have different approaches to similar goals, and it is interesting to see the results of the race for atomic power.

THE BUILDING OF THE NAUTILUS2

Of all the possible applications for nuclear power that tantalized scientists in the early days of development, from nuclear spaceship propulsion to heating an Antarctic station, the most sensible, immediate application was to power a submarine. Submarines in World War II were only mar­ginally capable of submerging for a few hours, operating slowly on batter­ies or near the surface on diesel engines sucking air through a snorkel sticking above the water. A submarine desperately needed a power source that would require no air and expel no exhaust. With such an engine, a submarine could operate indefinitely under water, and all the military advantages of submersion, stealth, speed, and safety could be used to full advantage. The navy, after an initial recoil from such radically new con­cepts in 1939, had begun to see the obvious advantages of nuclear power in 1940, but the army’s bomb program took supreme priority and command of nuclear matters and confiscated the navy’s thermal-column uranium enrichment facility for use at Oak Ridge.

At the end of the war, the U. S. Navy had 1,000 ships sitting idle, qui­etly rusting away at anchor. The world had just finished a long and costly crisis, and there were other needs to be met. Europe and Japan were in ashes and would need to be rebuilt; Great Britain was starving; and returning soldiers in the United States were jobless. There was also the inconvenient problem of uranium stockpiles. The United States had none to speak of. All the uranium in stock had been bought from Canada and from Belgian companies operating in the Congo, or had been seized in Germany from mines in Czechoslovakia. There was no clear source of uranium for the United States without dealing with touchy international situations. All uranium stocks were frozen, dedicated to future atomic bomb production.

Captain Hyman Rickover (1900-86) of the U. S. Navy was among the first to push for the development of a nuclear-powered submarine. Rickover was ambitious, creative, and tireless. He was also controversial, iron-fisted, and impatient with normal naval channels as a way of doing things. He was a master of the vituperative report, and he drove men and machines to the breaking point. He was famous, in naval circles, as a man who could “get the job done,” and he believed that the shortest path was a straight line, even if it cut through several admirals. He had been assigned to a post at Oak Ridge to study nuclear topics, and the concept of a nuclear submarine stuck him as an idea whose time had come. He formed a group of like-minded men at the Oak Ridge Laboratory, “The Naval Group,” composed of himself, Lieutenant-Colonel James H. Dunford, Lieutenant — Colonel Miles A. Gilbey, Lieutenant-Colonel Lou Roddis, and Lieutenant Ray Dick. It would require an enormous, seemingly superhuman effort, but this determined group would convince the navy, the Atomic Energy Commission (AEC), Westinghouse, General Electric, the Congress, and the general nuclear physics community that a nuclear submarine should and would be constructed, and it should be a priority project.

The technical problems were small compared to bureaucratic prob­lems, but they were still formidable, and the solution of these problems would affect all future application of nuclear power. At the time, in 1946, a nuclear reactor, or “pile,” was assumed to be built using blocks of graphite. Graphite is a fine neutron moderator, having a very small neutron cap­ture probability, and low-grade “natural” uranium can be used as fuel. Graphite is a solid and will neither boil away nor leak. A problem with a traditional graphite pile is that it is huge. The graphite power reactors at the Hanford Works fit in buildings the size of gymnasiums. A submarine, on the other hand, is a slender steel tube, designed to move through water. A graphite pile would simply not fit in even a large submarine, which was only 28 feet (8.5 m) in diameter. The reactor would have to be a completely different design and could not be a modification of a research reactor or a plutonium production facility. An alternate type of moderator material, allowing a small reactor core, would have to be found and proven.

The army, as owner of all the Manhattan Project facilities and every piece of nuclear material and researched knowledge, took a progressive move in April 1946. The Oak Ridge Laboratory was run by the Monsanto Company and the postwar director of the lab was Dr. Farrington Daniels (1889-1972), professor of chemistry at the University of Wisconsin. Dan­iels proposed that Monsanto, working for the army, build a demonstration industrial pile at Oak Ridge as a prototype civilian nuclear power plant. It became known as the Daniels Pile, and work began immediately, to be completed within 18 months.

Rickover’s group watched the Daniels Pile initiative spiral out of con­trol quickly and lose progress. Learning from this observation, the navy team decided to begin anew, designing their naval reactor backward. Instead of starting with the design of the uranium core, they began with the propeller shaft on the submarine. To move a submarine hull underwa­ter faster than a destroyer could run, they needed 10 megawatts of high — temperature steam directed into twin, multistage turbines, turning the two propellers. Another requirement for this reactor was unique: It would be enclosed in a metal tube with a crew of sailors, and they must be able to stay in the tube for an unlimited time without being subjected to harmful radiation. No radioactive substance, such as fuel, fission products, radio­active gases, or contaminated coolant could have the slightest leak into the submarine. This was a difficult proposition. Nobody had been killed by the big power reactors at Hanford, so far, but when one was running at full power no one could be near it. Moreover, the reactor had to have an inherently safe character.

The leakage of water from the primary cooling system, such as that caused by the failure of a pump or a valve, would result in a loss of moder­ator. The dual purpose of the water in the reactor, as both moderator and coolant, meant that losing water was losing moderator. With the modera­tor gone or reduced in volume, the fission process could not continue. The reactor shuts down and cannot be restarted, and this is considered a safe condition for a nuclear system with broken hardware. This was not neces­sarily a characteristic of the big graphite reactors. Lose the water coolant through a pipe rupture or boil-off and the reactor would go supercritical because the graphite alone was a better neutron moderator than graphite with water running through it.

As an additional requirement, the reactor had to be able to run for years at full speed without refueling, unlike the graphite piles. Using nat­ural uranium, the fuel in a graphite reactor had to be almost constantly replenished, pushing new fuel in one side of the pile with spent fuel falling out the other side of the pile, on a weekly basis.

Working in reverse, the submarine design continued from the turbines to the steam generator, with sizes and weights determined by the volume and pressure of steam needed to provide the specified power. The steam generator, or boiler, needed a source of heat. The source of heat was the combination coolant and moderator for the reactor core.

Instead of assuming that there would be no uranium fuel, Rickover assumed that there would be plenty of fuel. The United States is a big, wide country, and there had yet to be a comprehensive survey of avail­able uranium deposits. Given unlimited uranium reserves, a submarine could run on enriched fuel, made 50 percent U-235 in the diffusion plant at Oak Ridge. Given the high concentration of fissile U-235, graphite or any other high-efficiency moderator was not necessary. Ordinary or “light” water would be sufficient. The neutron slowing-down distance for the hydrogen in ordinary water is unusually short, so the core could be very small, the size of a garbage can. Water was well understood, easily pumped and managed, transparent, and liquid under pressure, regardless of the temperature. Liquid water under pressure, pumped in a tight loop through a reactor core, is both the coolant and the moderator. Lose cool­ant through mishap, and the reactor shuts down, because moderator is lost. Any fission-products or broken fuel are confined to this tight, inner loop of water, so everything on the other end of the power plant, from the steam generator to the turbines and the condenser, is isolated and free of potential radiation contamination.

One thing that Rickover had learned from his service on creaky, prewar undersea vessels was how not to design a submarine, and his plan, now named Nautilus after the craft in Jules Verne’s Twenty Thousand Leagues Under the Sea, would be safe and solid. The reactor plant would be inher­ently foolproof, free from possible criticality excursions, with far more strength than was necessary in all important components. Every piece of technical equipment on Rickover’s submarine would be built to shock and vibration specifications, with verification through physical testing.

Official approval for his submarine project in the navy would require the highest official approval, and Rickover decided to shorten the tedious chain of command, writing a letter directly to Fleet Admiral Chester Nimitz (1885-1966), decorated hero of World War II, former commander in chief of the Pacific Ocean areas, now chief of naval operations, and the navy’s principal expert on submarines. Writing a letter to Nimitz was

hardly a trivial matter, and even though directly addressed it still required approval and rewriting all up the line, from Rickovers captain level up to fleet admiral level. It took Rickover two months to build the letter and send it through official channels. Finally, on December 5, 1947, the letter reached Admiral Nimitz.

Nimitz was fascinated by the details of the proposed project. He signed the letter immediately, approving the program to build a nuclear-powered submarine. Still, much work was needed to persuade both the navy and the AEC that Nautilus should be built, but on May 1,1948, the concept had full approval. On August 2, Rickover formed the nuclear power division of the Bureau of Ships and re-collected his naval group from Oak Ridge. The Westinghouse Corporation was chosen to design a most critical part of the system, the steam generator, under an $830,000 contract.

Technical problems in Nautilus were interesting and numerous, and their solutions would forever guide the nuclear power industry. An exam­ple was the production of zirconium. It was found early on that zirconium was ideal for internal structures of a submarine reactor. It could with­stand high temperatures and did not absorb neutrons. Unfortunately, it was a rare material, more precious than platinum. They would need a lot of it for one reactor. A metallurgist broke the news of its cost to Rickover. It would be more than $1,000 per gram.

“My God,” Rickover said, “$1,000 a gram is $450,000 a pound. A half a million dollars a pound! . . . What’s the problem?”

The problem, explained the metallurgist, was that all the zirconium in the United States could be put in a shoe box.

“Well, we’ve got to step this thing up,” replied Rickover. “From now on you call me Mr. Zirconium, because I am going to get this stuff produced by the ton.”

And so he did. By 1952, zirconium was being mined, milled, and pro­duced in quantity and at low price, by Westinghouse. Asked by a congres­sional committee how in the world they managed to get the machinery and the expertise to make zirconium so quickly, the Westinghouse rep­resentative replied, “Rickover made us get it.” The zirconium exercise almost made the procurement of hafnium, a rare metal resistant to high temperature and perfect for the Nautilus control rods, seem simple.

With technical issues resolved, the first submarine reactor was built in 1952 by Westinghouse and the Electric Boat Company of Groton, Con­necticut, but it was nowhere near the ocean. It was built in a simulated ocean, a spherical building 18 stories tall, 225 feet (69 m) in diameter, filled with seawater and named the “Hortonsphere.” Located in the wilds of Idaho, near the town of Arco at the AEC’s Desert Test Station, the con­struction was a tightly held military secret. Those of little faith believed that an experimental reactor should be built where it could explode harm­lessly, and Rickover believed that it should be proven in a simulated sub­marine hull, completely under water.

The development of Rickover’s submarine reactor would have a pro­found effect on future nuclear power plant design in the United States. As the state of nuclear power production stands today, most of the reactors in the United States and in the world are based on the equipment in Hyman Rickover’s submarine, the Nautilus. The choice of moderator and coolant, reactor tank configuration, piping, safety systems, controls and monitors, exotic materials used, and even operator training are all directly con­nected to the navy’s first nuclear submarine program. The result is com­pact machinery, overbuilt for stamina, expensive, highly reliable, and safe to operate. The nuclear power program for the United States and most of the world was thus designed in reverse, starting with a highly specialized system, built to fit in a small space, with price being no object and using enriched uranium fuel, instead of first building a plant spread out over many acres, using readily available machinery and materials and the most inexpensive form of fuel. There would be other designs, but for better or

worse, this is the system that Rickover gave the nuclear industry. The navy reactor is known as the pressurized water reactor, or the PWR. It is the most licensed, copied, and stolen reactor plant design in the world.

The keel of the Nautilus, hull number SSN-571, was laid on June 14, 1952, at the shipyard in Groton, Connecticut. The president of the United States, Harry S. Truman, was present, as were the secretaries and chiefs of the armed forces, the governor of Connecticut, the chairman of the AEC, lesser officials of all types, and Hyman G. Rickover. The radical new vessel was launched into the Thames River on January 21,1954. It took 10 months to install the nuclear power equipment, and at 11:00 a. m. on Janu­ary 17,1955, she put to sea under Captain Eugene R Wilkinson (1918- ).

The age when uranium fission would be used for something other than explosives had begun.

News of Chadwicks discovery traveled quickly, from England to Den­mark to France to Germany, as experimentalists and theorists alike turned their rapt attention to the new particle and its interactions with the

nucleus. To those working in theoretical quantum mechanics, the pres­ence of a neutral particle in the nucleus made perfect sense. They had modeled the outer electron cloud as fixed stations of energy levels. As electrons were induced to jump from one level to another, the acceleration of the negative charge caused electromagnetic radiation in the form of light. The protons in the nucleus were obviously bound together by some strong force. It had to be stronger than the electromagnetic force that caused like charges to repel each other. They called it simply the strong nuclear force, and it has to depend on the neutrons. Alone, the protons lack enough force to hold themselves together.

The protons and neutrons making up the nucleus have their own abstract orbitals, as if they were swirling around in the tight, limited space at the center of the atom. Each orbital station in the nuclear orbit structure has an energy associated with it. The forces holding the nucleus together are millions of times more powerful than the forces holding electrons in orbit. Disturb the nuclear structure by knocking out a neutron, for example, and the nucleus has to reconfigure itself, with protons and neutrons jockeying for position and changing orbits. The severe change of energy status of a proton, with its positive electrical charge, causes a powerful electromag­netic pulse to radiate from the nucleus, in accordance with Maxwell’s equa­tions. Quantum mechanics thus explained the presence of gamma rays, the penetrating photon radiation produced in the beryllium experiment.

On Tuesday morning, September 12, 1933, Leo Szilard (1898-1964), a brilliant physicist from Hungary, happened to be in London, loung­ing in the lobby of the Imperial Hotel and reading the Times newspaper. The headlines were all about nuclear science. “BREAKING DOWN THE ATOM,” “TRANSFORMATION OF ELEMENTS,” “THE NEUTRON,” and halfway down the second column, a summary of a speech by Ernest Rutherford, “HOPE OF TRANSFORMING ANY ATOM.” There was a scientific meeting going on involving all the top scientists in England, and Szilard was acutely aware that he had not been invited. He started reading about Rutherford’s speech:

What, Lord Rutherford asked in conclusion, were the prospects 20 or 30 years ahead? . . . We might in these processes obtain very much more energy than the protons supplied, but on the average we could not expect to obtain energy in this way. It was a very poor and inefficient way of producing energy, and anyone who looked for a source of power in the transformation of the atoms was talking moonshine.

Rutherford was saying that nuclear power on an industrial scale is impractical and not worth thinking about. Szilard found such pronounce­ments bothersome. He tossed away the paper and wandered out onto the street, where he could think while walking. He was so put off by a scientist of such large reputation saying that something could not be done without having tried it, he tried to think of a counterargument.

He stopped at a traffic light on Southampton Row, at Russell Square, across from the British Museum in Bloomsbury. The light turned green, and just as he stepped off the curb to cross the street an idea flashed through his mind. Neutrons have no charge and are not constrained by the shielding effects of the electron or the proton. A neutron is free to hit the nucleus head on, if it is so directed. If an extra neutron wandered

into and was absorbed by an already heavily laden nucleus, such as in one of the heavier elements, it could render it unstable. The unstable nucleus would then vibrate itself apart, rending into two nuclei. These two nuclei would almost surely weigh less together than the original large nucleus, and the weight deficit would express as pure energy.

Furthermore, suppose the destruction of the nucleus includes a sin­gle neutron scattered out of the debris. That neutron could then bounce around until it hit another overloaded nucleus, and it would cause another nuclear breakdown. Some neutrons would fail to cause subsequent break­downs, just because there was only a finite probability of one hitting an adjacent nucleus. What if, instead of one free neutron from the break­down, there were two? If there were as many as two individual neutrons in the breakdown debris, then the process could be self-sustaining. It would be a chain reaction, in which energy was released by nuclear disintegra­tions in quantities millions of times greater than any chemical reaction.

By the time he reached the other side of the street, Szilard had outlined the nuclear power process. If such an element exists that will tear apart under neutron bombardment and will release free neutrons in excess of one per disintegration, then Lord Rutherford was wrong. Nuclear power on an industrial scale would be possible. He spent the rest of the day thinking of exploring the solar system and beyond with nuclear-powered rockets and of building weapons based on the severely concentrated energy of nuclear reactions. In 1934, his patent application for a nuclear power reactor was not granted, but the application document was assigned to the British Admiralty for security reasons. Leo Szilard would live to see his daydreams realized.

By 1939, the United States had acquired a large group of expatriate Euro­pean scientists, each associated with a university and engaged in research. All were unusually busy in the fast-breaking world of nuclear physics, exchanging papers, sharing experimental results, absorbing unsubstanti­ated rumors from Germany, and generally conspiring to somehow involve the government of their adopted country in large-scale nuclear research. It was not an easy quest, and there would be obstacles. In 1939, the U. S. military establishment was hardly the innovative powerhouse that it would later become, and a plea by a group of heavily accented theoreti­cians was unlikely to move mountains even if it promised a quick victory over potential enemies. The United States was not at war, and it intended to remain in that posture as long as possible.

Still, it was an effort that had to be made, as the European group became seriously concerned that the German Third Reich would develop nuclear weaponry. Leo Szilard was particularly shrill in his activities, and at Columbia University he was doing what he could with limited research resources to find sustainable fission in uranium. Being naturally persuasive, Szilard was able to borrow 500 pounds of black, dirty uranium oxide from the Eldorado Radium Corporation at Great Bear Lake in the Northwest Territories of Canada. Experiments showed him the value of crystalline carbon as a neutron moderator, and he managed to persuade the National Carbon Company of New York to make him some high — purity synthetic graphite. This specially made material was uncontami­nated by the traces of boron that made most industrial graphite unusable for nuclear work. Even Szilard’s impressive skills at scrounging materials were far short of what was necessary, but he used his talents to persuade Enrico Fermi to stop in at the Navy Department on Constitution Avenue in Washington, D. C., on March 17, 1939, and talk to somebody about the urgent need and the great potential of nuclear power. The undersecretary of the navy was unavailable, but an appointment was made to see the technical assistant to the chief of naval operations, Admiral Stanford C. Hooper (1884-1955), the “Father of Naval Radio,” and convince him of

the importance of nuclear fission. This would be the first contact between scientists pursuing nuclear fission and the U. S. government.

The meeting did not go well. Although it was attended by an impres­sive audience of naval officers, men from the Bureau of Ordnance, and two scientists from the Naval Research Laboratory, Fermi’s hourlong lec­ture on nuclear physics went over their heads. They seemed interested in a power source that required no oxygen, as they were thinking of subma­rine propulsion, but Fermi was too vague and unwilling to speculate. The navy was receptive to being included in announcements of success but not in participation. On July 10, Szilard got the formal letter, thanking the scientists for the interesting presentation but denying any funding.

Helping and encouraging Szilard in his sales efforts were two fellow Hungarians, Eugene Wigner and Edward Teller. Wigner was born in Budapest, Hungary, and in 1921 he became best friends with Leo Szi­lard at the Technische Hochschule in Berlin, Germany. In the 1920s, he became deeply involved in quantum mechanics research and in 1929 was recruited by Princeton University, in New Jersey. Fellow scientists called him the “Silent Genius,” and his work in nuclear reactor theory would be foundational.

Edward Teller was also born in Budapest, and as a child of 11 years he developed a powerful aversion to both fascist and communist govern­ments. As a Hungarian nuclear physicist working in Germany in 1933, it was almost inevitable that he would wind up in the United States working on the atomic bomb program of World War II. He would be of immense value to the further development of nuclear weapons following the war. His strong political views and an insistence on making weapons large enough to evaporate an entire Pacific island would make him perhaps the most controversial scientist in the country.

Fermi gave up early and went back to his laboratory research, but the Hungarian team thought it was worth trying again. Thinking that they should try to approach this problem from an entirely different angle, they decided to draft a letter to Queen Elizabeth of Belgium. The rumors were that the Germans were buying uranium ore stockpiles from the rich lode of pitchblende in the Belgian Congo in equatorial Africa. The right word to the queen might persuade her to discourage her countrymen from ura­nium commerce with the Third Reich, and stopping German research was as important as starting research in the United States. Unfortunately, none of them knew the queen of Belgium, but they knew someone who did. Albert Einstein had met her in 1929, and they were in regular com-

munication. Einstein was a world-famous scientist, who had left his native Germany for a position at Princeton’s Institute for Advanced Study. It was his lofty theories of mass and energy that gave credence to this hypotheti­cal nuclear weapon.

Wigner and Szilard made an appointment to see Einstein and then drove to his summer home on Nassau Point in Long Island, New York, on Sunday, July 16. Szilard had never learned to drive, so Wigner controlled the car as they strategized and plotted all the way there, carrying a draft of the letter. Einstein was all for the letter, but he hesitated to burden the queen of Belgium with the problem of sales with Germany. He coun — terproposed a note to the Belgian ambassador, and Wigner, having an inkling of knowledge of diplomatic protocol, suggested a cover letter to the State Department. They worked all day on several drafts. When Szi­lard got home, he found a message from a Dr. Alexander Sachs.

Alexander Sachs (1893-1973) of the Lehman Corporation was an economist, a banker, and a personal friend of the president of the United States, Franklin D. Roosevelt. He had learned of Szilard’s letter mission from a mutual friend, and he had a suggestion for improvement. The let­ter should be rewritten as a mandate for the United States, and it must be delivered directly to the president. Szilard eagerly went to work on a new draft, and he made another appointment with Einstein.

Wigner had gone to California for a vacation, but Szilard recruited Teller to drive to Long Island in his trusty 1935 Plymouth on Sunday, July 30. After careful rewriting and editing, the three scientists had crafted a longer, two-page version. It begins with the following:

Sir:

Some recent work by E. Fermi and L. Szilard, which has been commu­nicated to me in a manuscript, leads me to expect that the element ura­nium may be turned into a new and important source of energy in the immediate future. Certain aspects of the situation which has arisen seem to call for watchfulness and, if necessary, quick action on the part of the Administration. . . .

The letter continues, advising that a nuclear chain reaction can possibly be used to generate vast amounts of energy and for extremely powerful bombs. Further suggested is governmental funding of research, under an appointed administrator, coordinating university-based work with indus­trial laboratories, and the letter ends with a hint that Germany may

In 1898, Ernest Rutherford (1871-1937), a scientifically talented young man from New Zealand, studied the radiations emitted from the elements ura­nium and thorium. Working at the Cavendish Laboratory of the Univer­sity of Cambridge, he found two distinct types of radiation, and he named them. The first seemed to have little range. It was easily stopped by air or by thin barriers of almost anything solid, and he named it alpha radiation. The second type had greater range in air and was better at penetrating shields. Rutherford named it beta radiation. A few months later, Paul Vil — lard (1860-1934), working in the chemistry department at the hcole Nor — male in Paris, identified a third, even more penetrating radiation type emitting from uranium. In keeping with Rutherford’s newly established naming convention, he called it gamma radiation.

In 1898, when he was 27 years old, Rutherford moved to Canada to become professor of physics at McGill University in Montreal. Here he had a new, well-equipped physics laboratory, generous funding, and a learned colleague in chemistry named Frederick Soddy (1877-1956). Almost immediately upon arrival, Rutherford presented Soddy with a puzzle: There was some sort of gas emanating from radioactive thorium. What might it be? A chemical analysis was in order.

Soddy analyzed the sample and found that the gas had no chemical characteristics whatsoever. There was only one conclusion possible, that the gas was an inert chemical such as argon. Odd as it seemed, the ele­ment thorium was apparently transmuting itself into argon gas, slowly but steadily. This discovery of the spontaneous disintegration of radioactive elements was a major discovery, and Rutherford and Soddy immediately investigated the known radioactive elements to discover what was hap­pening. By literally counting the number of radioactive particles emit­ted from a sample during a given time, they found that each radioactive

substance was decaying exponentially, at a characteristic rate, or that the source of the radiation would drop by half in a predictable passage of time. Soddy named the characteristic time half-life, meaning the time required for the radioactivity to decrease by half. For a given sample of a radioactive substance, the radiation level would drop by half in one half — life. In another half-life, what was left of the radioactivity would drop by another half, and so on, forever. The radioactivity would never technically disappear, but it would drop by halves in a predictable time period.

Rutherford suspected that beta rays were, in fact, a naturally occurring form of cathode rays being generated by many of his colleagues using elec­trically stimulated vacuum tubes. He was correct, and he demonstrated it using magnetic and electrostatic fields to bend beta rays in a vacuum tube. Instead of using high-voltage electricity between electrodes in the tube, he simply put a sample of uranium at one end. He also suspected that alpha rays were actually helium atoms stripped of their electrons, and he was able to test that theory in a most elegant way at the University of Man­chester in England in 1908.

Rutherfords proof of the nature of alpha rays was stunning for its sim­plicity and almost artistic style. He had a glassblower make him a tube with walls thin enough for alpha rays to penetrate. The tube was evacu-

ated, filled with radon gas (a known alpha-ray emitter), and sealed off at the end. This tube was then put inside another, larger tube with thick walls, which was pumped down and flame-sealed at the end. Rutherford used a light spectrometer to detect anything in the vacuum between the tubes. There was nothing there. He waited a few days and tried again. The space between the tubes had become filled with helium. Therefore, the alpha rays were actually positively charged helium ions, broken free of the much heavier radon and thrown through the thin glass of the inner tube. The name of the radiation was adjusted, from alpha rays to alpha particles, and Rutherford noted that this demonstration explained why helium is found trapped in the crystalline spaces in thorium and uranium ores. He announced the triumphant finding to the audience in Stockholm as he accepted his Nobel Prize in chemistry. Soddy had been almost right about his analysis of the mysterious decay product of thorium. It was not argon. It was another inert gas, helium.