Spy's Role in Soviet H-Bomb Now Discounted
New York Times: January 3, 1990

Nuclear experts have concluded that the Soviet Union learned almost nothing of how to make the hydrogen bomb from the atom spy Klaus Fuchs and may have instead deduced the crucial secret by analyzing radioactive fallout from American nuclear blasts.

The experts now believe Dr. Fuchs, a British citizen, passed along hydrogen bomb data that he did not know were seriously flawed. These experts, in their historical revision, attribute much of the faulty data to early work by Dr. Edward Teller and also diminish his role in the invention of the weapon.

Two of three critical ideas for the invention grew out of the work of Dr. Stanislaw M. Ulam, a mathematician who played a major role at the Los Alamos laboratory in New Mexico, experts now believe. Dr. Teller, a physicist at Los Alamos who is often called the "father" of the hydrogen bomb, added a third idea that insured the invention's success.

'Worse Than Worthless'

The major revision in the history of the hydrogen bomb is the work of various scholars, largely working independently of one another. Daniel Hirsch and William G. Mathews, nuclear experts, write about Dr. Fuchs and the fallout question in the January issue of The Bulletin of the Atomic Scientists. Thomas B. Cochran and Robert S. Norris, authors of The Nuclear Weapons Databook, and Chuck Hansen, author of U.S. Nuclear Weapons: The Secret History, deal with the genesis of the hydrogen bomb.

The scholars are civilian experts whose books and articles are the basis for much of the public's knowledge of nuclear weapons.

"It is now clear that the 'secrets' regarding the H-bomb known to Fuchs were worse than worthless," Dr. Hirsch and Dr. Mathews write in The Bulletin.

A hydrogen bomb fuses light atoms, usually isotopes of hydrogen, to release energy stored in the atomic nucleus. Hydrogen bombs are generally more powerful than atomic bombs, which split heavy atoms to liberate nuclear energy in a process known as fission. Fusion is more efficient than fission. Scientists who tried to achieve fusion in the 1940's and early 1950's thus called their hypothetical bomb "the Super."

Dr. Fuchs, a physicist who worked on the Manhattan Project to develop the atomic bomb during World War II, is often credited with giving the Soviets the secret of the hydrogen bomb. He definitely tried, passing along early hydrogen bomb speculations. Dr. Fuchs's confession in January 1950 to the British authorities that he had worked for the Soviet Union and passed along atomic and hydrogen bomb secrets influenced President Harry S. Truman's decision in March 1950 to try to speed the development of the hydrogen bomb.

The world's first hydrogen bomb, the size of a small building, was detonated by the United States on Nov. 1, 1952, on the Pacific island of Elugelab. The island, a mile in diameter, disappeared. The bomb's power was about 700 times greater than the atomic bomb dropped on Hiroshima. The Soviets detonated their first full-scale hydrogen bomb in 1955.

Today, the vast majority of the weapons in the world's nuclear arsenals are hydrogen bombs, most far more powerful than the early atomic bombs.

New Material Released

The new history of the development of the hydrogen bomb got a boost when Dr. Hirsch, then director of the nuclear policy program at the University of California at Santa Cruz, obtained under the Freedom of Information Act a declassified version of a top-secret technical history of the hydrogen bomb program written by the physicist Hans Bethe in 1952. Though extensively censored, it contained hints that set Dr. Hirsch and other scholars racing through the literature and interviewing physicists who remembered details of the development of the hydrogen bomb.

The article in The Bulletin details errors and incomplete calculations that bedeviled the nation's hydrogen bomb program in its early days, most of them by Dr. Teller and his colleagues at Los Alamos.

Dr. Fuchs left the American weapons program in 1946, and, therefore, had access only to faulty hydrogen bomb ideas before the breakthrough. The information he passed to the Soviet Union, The Bulletin article says, amounted to little more than a series of false assumptions and sketchy calculations that plagued the American hydrogen bomb effort from 1942 to 1950. Dr. Fuchs died in East Germany in January 1988.

'Signature in the Fallout Debris'

The secret may actually have been revealed, Dr. Hirsch and Dr. Mathews write, by "a telltale signature in the fallout debris" from the first American test of the breakthrough idea on Elugelab. The ratio of atomic isotopes in the debris hinted that the fusion fuel had undergone "enormous compression," the secret to the bomb.

Dr. Hirsch and Dr. Mathews say in their article that the British discovered the hydrogen bomb secret by analyzing fallout from a Soviet hydrogen bomb blast. And they speculate that the Soviets learned the secret from the Americans in the same way.

"Although the United States built the H-bomb in part because of claims that Fuchs gave the Soviets the secrets, he could only have given the Soviets erroneous assumptions and incomplete calcuations of Teller's Los Alamos group," Dr. Hirsch and Dr. Mathews write.

The article quotes Dr. Bethe as saying he believes the Soviets got the hydrogen bomb secret from fallout. "I can't prove it," he is quoted as saying. Dr. Bethe also suggested that Andrei D. Sakharov, often credited with inventing the Soviet hydrogen bomb, knows the truth but "is not going to tell us." Dr. Sakharov died in December.

Dr. Hirsch said in an interview that Dr. Sakharov was once asked about the fallout question and denied that it told the Soviets how to build the bomb. But he did say the Soviets took great interest in it.

The revision of the hydrogen bomb's history also addresses the question of who should get credit for its invention. The issue has long been disputed, its resolution hampered by layers of Government secrecy.

From the start, Dr. Teller has received most of the credit, and sometimes the blame. Newsweek magazine in 1954 hailed him as the "mystery man" behind the bomb. The 1954 book, The Hydrogen Bomb, by James Shepley and Clay Blair Jr., devoted an admiring chapter to Dr. Teller and made one minor reference to Dr. Ulam.

Dr. Teller himself has waffled on the issue of recognition. In a 1955 essay in Science magazine, he credited Dr. Ulam with an "imaginative suggestion." But he also refused to share a Government patent with Dr. Ulam on the hydrogen bomb idea. In his 1962 book, The Legacy of Hiroshima, Dr. Teller made no reference to Dr. Ulam's positive role in developing the bomb.

Role of Dr. Ulam

Dr. Ulam's role has long been unclear. The official history of the Atomic Energy Commission, Atomic Shield, published in 1969, shed little light. Dr. Ulam, who died in 1984, claimed some credit for the achievement but never described his role in detail. Dr. Teller is alive today and nearing his 82nd birthday. Through a spokesman at his office in the Hoover Institution in California, Dr. Teller declined to comment on the revised history of the bomb.

Scholars also say they have uncovered the major steps in the genesis of the hydrogen bomb. Before the breakthrough, scientists believed they simply needed the heat of an exploding atomic bomb to ignite the hydrogen bomb. But the concept failed. Instead, Dr. Ulam proposed a method to make the fuel burn by means of compression.

This breakthrough started in December 1950 when Dr. Ulam proposed a new atomic bomb design that used mechanical shock to compress a second atomic bomb core and make it explode; the purpose was to use fissionable materials more efficiently.

Then, in February 1951, Dr. Ulam took the idea to Dr. Teller, who was unsuccessfully trying to invent a hydrogen bomb. Dr. Ulam suggested that his two-stage idea be applied to making a hydrogen bomb. Mechanical shock from an atomic bomb, Dr. Ulam proposed, could be focused by a special structure to compress the fusion fuel and promote its rapid burning.

These were two of the critical ideas behind the hydrogen bomb: compressing the fuel and arranging the atomic bomb trigger and hydrogen bomb fuel in a special way to achieve it.

Dr. Teller then added a third. He suggested that radiation from the bomb, rather than mechanical shock, be the basis for compressing the fusion fuel. On March 9, 1951, the two men wrote a report in which they presented both alternatives. Dr. Teller's elaboration of the idea became the basis for the success of the nation's hydrogen bomb program.

The new history is given by Dr. Cochran and Dr. Norris in a revision of Encyclopedia Britannica due out in February.

The revision is confirmed in a new biography, Edward Teller, by Stanley B. Blumberg and Louis G. Panos, to be issued in February by Charles Scribner's Sons.

After suffering a heart attack in 1979, Dr. Teller dictated a statement on the genesis of the hydrogen bomb. The new book, written with Dr. Teller's cooperation, quotes that document for the first time. It states that Dr. Ulam came to Dr. Teller in February 1951 with the idea for the hydrogen bomb involving compression and a new arrangement of the components.

"I have a way to make the Super," Dr. Teller recalled Dr. Ulam as saying. Remarkably, the book says, Dr. Teller still belittles Dr. Ulam's role. "Ulam triggered nothing," Dr. Teller is quoted as saying. The reason for this coolness, the book reports, is that Dr. Teller felt Dr. Ulam denigrated the chances of the hydrogen bomb's success even after the breakthrough idea.

John H. Nuckolls, director of the Lawrence Livermore National Laboratory in California and a close colleague of Dr. Teller's, said he felt Dr. Teller was still the weapon's primary inventor by virtue of the many ideas he contributed and his long and vigorous support for its development.