Teller and Ulam Develop the First Hydrogen Bomb

Date 1951-1952

Inspired by the work of Ulam and others, Teller proposed a workable concept that led to the construction of a thermonuclear device called the hydrogen bomb, the most powerful bomb ever exploded.

Also known as H-bomb; superbomb

Locale Los Alamos, New Mexico; Marshall Islands, Micronesia

Key Figures

• Edward Teller (1908-2003), Hungarian-born American theoretical physicist
• Stanislaw Ulam (1909-1984), Polish-born American mathematician

Summary of Event

A few months before the 1942 creation of the Manhattan Project , the United States-led effort to build an atomic (fission) bomb, Enrico Fermi suggested to Edward Teller that such a bomb could release more of the energy that binds atomic nuclei together by heating a mass of the hydrogen isotope deuterium and igniting the fusion of hydrogen into helium. These were also the thermonuclear reactions in stars, making them shine and radiate heat, that Hans Bethe, George Gamow, and Teller had been studying in the United States since 1934. Initially, Teller dismissed Fermi’s idea, but later in 1942, in collaboration with Emil Konopinski, he concluded that a hydrogen bomb, or superbomb, could be made.

German scientists were working on an atomic bomb, and with Teller’s advocacy, the superbomb received serious consideration within the Manhattan Project. To increase the probability of success for the concept then championed by Teller, Konopinski suggested that the rare heavy isotope of hydrogen—tritium—should be added also as fusion fuel. An atomic bomb had not yet been produced, and in 1944 the Los Alamos Laboratory governing board concluded that Teller’s proposed superbomb would require more tritium than could be available for some time. J. Robert Oppenheimer , then director at Los Alamos, stated that after World War II, the United States should make every effort to determine the practical feasibility of a hydrogen bomb. In the meantime, Teller worked less on the atomic bomb, devoting his time to investigating the superbomb.

With the war over and the atomic bomb a proven reality, Teller returned to Los Alamos in 1946 to chair a secret conference on the superbomb attended by, among other Manhattan Project veterans, Stanislaw Ulam and Klaus Emil Julius Fuchs. Supporting the investigation of Teller’s concept, the conferees requested a more complete mathematical analysis of his own admittedly crude calculations on the hydrodynamics of the fusion reactions. In 1947, Teller believed that these calculations might take years. Two years later, however, for Teller, with his parents in a Hungary that was now within the folds of the Iron Curtain, and for his supporters, the Soviet Union’s explosion of an atomic bomb meant that America’s Cold War adversary was hard at work on its own superbomb. Even when new calculations cast further doubt on his designs, Teller began a vigorous campaign for a crash development of the superbomb, or H-bomb.

For several reasons, Oppenheimer and the General Advisory Committee (GAC) of the Atomic Energy Commission (AEC) in 1949 did not endorse Teller’s urgent demands. The GAC did not find evidence to support a high probability of success in Teller’s design to warrant massive expenditures at that time. Also, the GAC was certain that with modest funding and existing facilities, the addition of fusion components to an atomic bomb would boost efficiency by several orders of magnitude, producing yields of about 200,000 tons of TNT (trinitrotoluene). Any weapon with a greater explosive yield than that, the GAC observed, could only be used to commit genocide. Teller, however, was gaining important political and military support. For him, it was a moral imperative of the United States to be the first nation to develop such a weapon.

In 1950, the same year that Fuchs admitted passing information to the Soviet Union about U.S. nuclear weapons programs, the Korean War broke out, and President Harry S. Truman decided to approve an all-out effort to build the H-bomb. The basic design under consideration remained Teller’s classic superbomb, one that consisted of liquid deuterium and tritium configured within an atomic device. During that year and into the spring of 1951, however, Ulam, Cornelius J. Everett, Fermi, Frederick de Hoffman, and the ENIAC computer had disproved the workability of Teller’s design. That some other design might work, however, remained a possibility.

Scientists did not doubt that fusion reactions could be induced by the explosion of an atomic bomb. The basic problem was simple and formidable; how could fusion fuel be heated and compressed long enough to achieve significant thermonuclear burning before the expansion of the fireball from the atomic explosion blew the assembly apart? During these difficult months, the collaboration of these individuals and others, and verification provided by ENIAC, moved them closer to a practical solution of building a workable H-bomb. As a group, however, their recollections and contemporary documentation revealed that they were hoping to discover that an H-bomb could not be built by any nation. Early in 1951, however, a major part of the ultimate solution came from Ulam, who proposed using the energy from an exploding atomic bomb to induce significant thermonuclear reactions in adjacent fusion fuel components.

This arrangement of materials became known as the Teller-Ulam configuration, that is, the physical separation of the A-bomb primary from the secondary’s fusion fuel; all H-bombs are cylindrical, with an atomic device at one end and the other components filling the remaining space. In Teller’s unexpected approach, energy from the exploding primary could be transported by X rays at near-light speed, thus affecting the secondary before the arrival of the explosion. De Hoffman’s work verified and enriched the new concept.

Now, moderated X rays from the primary would in the secondary irradiate a reactive plastic medium surrounding concentric and generally cylindrical layers of fusion and fission fuel. Instantly, the plastic becomes a hot plasma that compresses and heats an inner layer of fusion fuel, which in turn compresses a central core of fissile plutonium to supercriticality. Thus compressed and bombarded by fusion-produced, high-energy neutrons, the fission element expands rapidly in chain reaction from the inside out, further compressing and heating the surrounding fusion fuel, resulting in the liberation of more energy and fast neutrons that induce fission in a fuel casing-tamper made of normally stable uranium 238.

The device to test Teller’s new concept weighed more than 60 tons with its equipment to refrigerate the hydrogen isotopes. Like all the H-bomb prototypes, concepts were given workable forms by the Los Alamos Laboratory, with which Teller was no longer affiliated. During Operation Ivy, the bomb was tested at Elugelab Island in Eniwetok Atoll on November 1, 1952. Exceeding the expectations of all concerned and vaporizing the island, the explosion equaled 10.4 million tons of TNT, or about seven hundred times greater than the atomic bomb used on Hiroshima in 1945. An emergency capability version of this device weighing about 20 tons was prepared for delivery by specially modified Air Force B-36 bombers.

In development at Los Alamos before the 1952 test was a device weighing only about 4 tons, a “dry bomb” that did not require cryogenic equipment or liquid fusion fuel; when sufficiently compressed and heated in its molded-powder form, the new fusion fuel component, lithium-6 deutride, instantly produces tritium. This concept was tested during Operation Castle at Bikini Atoll in 1954 and produced a yield of 15 million tons of TNT, the largest-ever nuclear explosion by the United States. Not until 1956, in Operation Cherokee-Redwing, did the United States explode an H-bomb dropped from an aircraft, an Air Force B-52 bomber.

Significance

The successful explosion of a Teller-inspired thermonuclear device in 1952 gave impetus to an ongoing global nuclear arms race. Teller was not alone in believing that the world could produce many nuclear and thermonuclear-capable nation-states and that some would threaten the United States.

During these early years of military and ideological confrontation with the Soviet Union, Teller advocated and received in 1952 a second nuclear weapons facility, the Lawrence-Livermore National Laboratory in California. For many years within the scientific community there existed disagreement over weapons development and the role that such weapons should play in national defense policymaking. Prior to the identification of Teller’s name with the H-bomb, it had been Oppenheimer, Los Alamos, and the A-bomb receiving attention. Oppenheimer and others on technical and moral grounds had initially opposed building the H-bomb, seeking instead an international moratorium on its development. For many years in the future, the expression of such concerns within the weapons community would not be tolerated.

With anticommunist activity and legislation reaching a peak, Oppenheimer’s loyalty was questioned. During Oppenheimer’s security clearance hearing held by the AEC in 1954, Teller’s testimony against his former superior at Los Alamos and consistent critic of his early H-bomb designs proved decisive. President Dwight D. Eisenhower endorsed the AEC findings, and Oppenheimer’s security clearance for work in classified nuclear areas was withdrawn. Teller became the scientific adviser in the nuclear affairs of the nation to presidents, from Eisenhower to Ronald Reagan. The widespread blast and fallout effects of H-bombs assured the mutual destruction of combatants. Teller knew that the availability of H-bombs encouraged but did not guarantee the deterrence of use.

A long-standing schism developed within the U.S. scientific community between the supporters of Teller or Oppenheimer and the combatants over the issue of nuclear test ban treaties. Teller consistently advised against U.S. participation with the Soviet Union in a moratorium on nuclear weapons testing. Largely based on Teller’s advocacy of retaining the prerogative to test underground, the United States rejected a total moratorium in favor of the 1963 Limited Test Ban Treaty.

During the 1980’s, Teller, among others, convinced President Reagan to embrace the Strategic Defense Initiative (SDI). Teller argued that SDI components, such as the space-based Excalibur, a nuclear bomb-powered X-ray laser antiwarhead weapon proposed by the Lawrence-Livermore National Laboratory, would make thermonuclear war not so much unimaginable as theoretically impossible.

Teller’s hawkish views provoked dislike from the Left, but he also earned numerous awards, including the Ablert Einstein Award, the National Medal of Science, and the Presidential Medal of Freedom, the latter presented by President George W. Bush less than two months before Teller’s death on September 9, 2003.

Bibliography

Bethe, Hans. “Comments on the History of the H-Bomb, 1954.” In The American Atom: A Documentary History of Nuclear Policies from the Discovery of Fission to the Present, 1939-1984, edited by Robert C. Williams and Philip L. Cantelon. Philadelphia: University of Pennsylvania Press, 1984. Nobel laureate Bethe provides a critical eyewitness assessment of Teller’s role in the H-bomb program, describes Teller’s early designs and why they would not work, and declares Ulam’s work essential. Argues that Teller’s direction of the program was itself an inhibiting factor and defends the technical skepticism of Oppenheimer and the GAC in 1949.

Goodchild, Peter. Edward Teller: The Real Dr. Strangelove. Cambridge, Mass.: Harvard University Press, 2004. A good work of history that examines the scientific legacy of the “father of the H-bomb.” Much of the work is based on interviews with Teller and on archival material.

Kelly, Cynthia C., ed. Oppenheimer and the Manhattan Project: Insights into J. Robert Oppenheimer, “Father of the Atomic Bomb.” Hackensack, N.J.: World Scientific, 2006. A concise but comprehensive history of Oppenheimer’s scientific legacy. Bibliography, index.

‗‗‗‗‗‗‗. Remembering the Manhattan Project: Perspectives on the Making of the Atomic Bomb and Its Legacy. Hackensack, N.J.: World Scientific, 2004. A report on the proceedings of the 2002 Atomic Heritage Foundation’s Symposium on the Manhattan Project, held in Washington, D.C. Bibliography, index.

Kevles, Daniel J. The Physicists: The History of a Scientific Community in Modern America. New York: Alfred A. Knopf, 1977. A valuable study for understanding the changing twentieth century relationships between academic and industrial science, and the military. Extensive bibliography.

Morland, Howard. The Secret That Exploded. New York: Random House, 1981. Based on information in the public domain, Morland conjectured the secret of the Teller-Ulam configuration. In 1979, the federal government sued his employer, The Progressive magazine, to prevent publication of his diagrams. To avoid further revelations, the government conceded the case; in 1979, the article and more accurate diagrams were published. Includes diagrams of H-bomb schemata, photographs of facilities, processes of fabrication, and H-bombs.

Rhodes, Richard. Dark Sun: The Making of the Hydrogen Bomb. New York: Simon & Schuster, 1995. Still the best of the many books released to coincide with the fiftieth anniversary of the first atomic explosion. Authoritative, extensively documented, and highly readable.

‗‗‗‗‗‗‗. The Making of the Atomic Bomb. New York: Simon & Schuster, 1986. The discussion of the H-bomb in this Pulitzer Prize-winning book draws on and confirms the claims and observations of Bethe, Ulam, York, Morland, and others. Exhaustive bibliography and diagrams and photographs of nuclear bombs and the original emergency-capability thermonuclear bomb.

Teller, Edward. “The Hydrogen Bomb: The Work of Many People.” In Better a Shield than a Sword: Perspectives on Defense and Technology. 1955. Reprint. New York: Free Press, 1987. Teller’s recollection of H-bomb development. He acknowledges his indebtedness to many others but does not grant Ulam major status in the solution of the H-bomb problem.

Ulam, Stanislaw. “Thermonuclear Devices.” In Perspectives in Modern Physics: Essays in Honor of Hans A. Bethe, edited by R. E. Marshak. New York: Interscience, 1966. Adds credibility to the belief that while an H-bomb was theoretically possible, Teller had no practicable idea of how to realize it until the spring of 1951. As other sources confirm, Ulam’s contributions were more than architectural.

York, Herbert F. The Advisors: Oppenheimer, Teller, and the Superbomb. 1976. Stanford, Calif.: Stanford University Press, 1989. York, the first director of the Lawrence-Livermore National Laboratory, corroborates the accounts of others. York believed Ulam’s contributions were critical and discusses the emergence of Teller as the authority on nuclear matters. Extensive bibliography.