By Kenneth W. Ford
World Scientific. 221 pp. Paperback, $24
In 1945, after the German defeat, the American armies in Europe dropped everything and shipped home. Several million Soviet troops remained deployed. Such an imbalance of forces in war-ravaged Europe might have threatened the West as the Cold War opened, but the U.S. monopoly on atomic weapons seemed to counter it. If the West couldn’t save Eastern Europe from Moscow’s domination, its bombs could at least prevent a Soviet march to the Atlantic.
When the Soviet Union tested its first atomic bomb in 1949, it upset that balance of forces: It now had both troops on the ground in Europe and atomic weapons. A panicky secret debate began within the U.S. government about how to respond.
By then the United States had tested atomic bombs of double the first weapons’ yield and was beginning to manufacture them in quantity. The government’s panel of scientific advisers recommended answering the new Soviet challenge by increasing that production. Other scientists, however, most zealously the Hungarian American theoretical physicist Edward Teller, argued for a crash program to develop a new monopoly — the hydrogen bomb — even though no one yet knew how to build one. Worse, breeding the nuclear materials for Teller’s untested hydrogen-bomb design, the Super, would use up reactor capacity needed for plutonium production, at the rate of 75 plutonium-fueled atomic bombs foregone for each Super — with no guarantee that the Super design would even work.
The U.S. military sided with Teller. President Harry Truman in any case had already made up his mind. On Jan. 31, 1950, he announced that the United States would pursue the Super, alerting the Soviet Union that the nation intended to trust its security to an immensely destructive new weapon it didn’t know how to build. Now Teller and his colleagues would have to deliver.
Nuclear physicist Kenneth W. Ford has published this genial memoir after a long negotiation with the Department of Energy. The DOE wanted about 10 percent of the book redacted, claiming that the information was secret. Ford refused after he found public references to every bomb detail he describes. I encountered nothing unfamiliar anywhere throughout. Perhaps the DOE should check its secrets with Google.
Raised in Kentucky, and educated at Exeter and Harvard, Ford joined the H-bomb effort in 1950 at age 24 while he was a graduate student at Princeton. His first task, he writes, was to run the numbers to see whether an exploding atomic bomb could heat a volume of hydrogen of a special kind, deuterium, hot enough to start a thermonuclear fusion reaction with a corresponding release of energy. (Unlike the fission reaction in an atomic bomb, which stops as the bomb’s core of uranium or plutonium heats up and expands, the fusion reaction in an H-bomb proceeds much like a fire; its yield depends primarily on how much hydrogen fuel is packed into its casing.) The conclusion of all these painstaking calculations, by Ford and others, was that Teller’s Super wouldn’t work. Teller was crushed.
A breakthrough came in February 1951, when the Polish mathematician Stanislaw Ulam, a colleague of Teller’s at the Los Alamos National Laboratory in northern New Mexico, thought of a new arrangement. Ulam had previously conjured a new way to squeeze more yield from atomic bombs. He had seen that they could be arranged in a chain so that the blast from one bomb would squeeze the next bomb to critical mass, which in turn would squeeze the next one and so on, like a string of firecrackers. That January he realized that an atomic bomb, a “primary,” could similarly squeeze and heat a physically separate container of deuterium, a “secondary,” dense enough and hot enough to sustain thermonuclear burning: Such “staging,” as the arrangement came to be called, looked like the answer they had all been searching for.
Ulam took the idea to Teller, who resisted it at first, then embraced it and added a sophisticated improvement: Instead of using the blast from the primary to compress the deuterium, they should use the 50-million-degree X-rays that came off the atomic fireball first, at the speed of light. “At ordinary temperature,” Ford writes, “radiation is like the pixie dust that was visible only to Tinker Bell and her band of fairies. At the temperatures characteristic of nuclear explosions, radiation is ‘stuff,’ full of enormous energy and capable of pushing like a giant piston.” With this Teller-Ulam arrangement, bombs could be made with yields in the millions of tons of TNT-equivalent, rather than the mere thousands of tons possible with fission in a single bomb.
Teller spent the rest of his life progressively erasing Ulam from the story of that 1951 breakthrough. Ford reviews it carefully, as someone who was there at the time and worked with both men. He concludes that Ulam did indeed contribute the idea of staging, while Teller piggybacked on that idea but improved it by adding radiation compression. More to the point, as Ford notes, the ensuing design and construction of the first multi-stage hydrogen bomb, Mike I, was a collaborative effort among several divisions of scientists and engineers at Los Alamos, not the work of one man.
A Los Alamos team fired Mike I on the small island of Elugelab in the Marshall Islands on Nov. 1, 1952. At 82 tons, it was a beast, a polished steel cylinder seven feet in diameter and 20 feet tall before its firestarter, a powerful atomic bomb, was bolted onto the top like a Brobdingnagian match head. Light pipes for diagnostics sticking out of one side of the cylinder made it look as if titans had attacked it with giant darts. Its internal structure included the largest uranium casting ever made, lined meticulously with insulating gold leaf by a security-cleared Santa Fe sign-painter. The uranium casting surrounded a multi-layered Thermos bottle holding liquid deuterium (for easier calculation; later and lighter “dry” bombs used a compound of the light metal lithium, lithium deuteride, which bred its own tritium en passant).
When Mike was fired, X-rays from its atomic bomb flowed down a cylindrical channel around the uranium casting filled with polyethylene, turning the plastic into a hot gas that pushed against the uranium while the X-rays heated it until its surface blew off like a rocket exhaust, squeezing the inner bottle of deuterium to great density and heating the mass in turn to the millions of degrees necessary to force the deuterium to fuse. So a fission bomb started a fusion bomb exploding, which in turn set off the uranium in the surrounding casting: fission-fusion-fission, a three-stage process that yielded 10.4 megatons of explosive force and vaporized Elugelab. “Altogether quite a maelstrom,” Ford comments dryly. The resulting mile-wide crater, 164 feet deep, is an outdoor aquarium today, a haven for Pacific fish.
Ford hardly comments on the larger moral questions of building weapons of immense mass destruction. “After the successful Mike shot,” he writes, “which produced in me that odd combination of euphoria and dread that other nuclear weaponeers have no doubt experienced, I holed up in my small office [at Princeton] and got to work on my doctoral dissertation research.” For the rest of his career he taught physics.
He admits to some naivete as a young man about America’s virtue, feelings that changed with the Vietnam War, as they did for many. In the summer of 1968, working on unclassified research at Los Alamos, he announced at an antiwar meeting that he was giving up weapons work. He hadn’t been asked to do any since the late 1950s, he’s frank enough to add, but he hoped that his announcement would encourage others to reassess their participation.
The right number of nuclear weapons in the world, he concludes, is zero. He’s realistic about when that millennium might arrive. “Perhaps in your lifetime, young reader,” he judges. “Not in mine.” So young men see visions, such as they are, and old men dream dreams.