Dark Sun: The Making Of The Hydrogen Bomb

note, “but there was still some hope that a loophole was possible. The cross sections were not very reliable and we felt that we had to dig through the material.”

Believing that a nuclear reactor as well as a bomb would require increasing the U235 content of natural uranium, Kurchatov's group examined various methods of uranium enrichment. Gaseous diffusion — pumping a gaseous form of uranium against a porous barrier through which the lighter U235 isotope would diffuse faster than the heavier U238, selectively enriching the product — the physicists discounted as impractical. Instead they recommended separating U235 from U238 in gaseous form in a high-speed centrifuge, a method Khariton had studied in detail in 1937 but one for which the technology had not yet been developed.

These early discussions caught the attention of Leonid Kvasnikov, the head of the science and technology department of the state security organization, the People's Commissariat of Internal Affairs, known by its Russian initials NKVD. The NKVD, which had orchestrated the Great Terror (which then swallowed up some 28,000 of its own), had been headed since 1938 by Stalin's brutally efficient fellow Georgian Lavrenti Pavlovich Beria. It maintained a network of spies throughout the world run by NKVD rezidents stationed in Soviet consulates and embassies. One important field of rezi-dency work was industrial espionage — stealing industrial processes and formulas to save the Soviet Union the expense of licensing these technologies legitimately from their developers. The American industrial chemist Harry Gold, who began a long career of espionage for the Soviet Union in 1935, mentions among such information “the various industrial solvents used in the manufacture of lacquers and varnishes…, such specialized products as ethyl chloride (used as a local anesthetic) and in particular, absolute (100 %) alcohol (used to blend, i.e., ‘extend,’ motor fuels).” These commonplace products, Gold understood, “would be a tremendous boon to a country [that was] back in the 18th century, industrially speaking (in spite of some localized advances).” They “could go toward making the harsh life of those who lived in the Soviet Union a little more bearable.”

Early in 1940, Kvasnikov alerted the rezidency network to collect information on uranium research. According to Georgi Flerov, the early focus of Soviet concern was on German more than on Anglo-American work, just as it was in England and America:

It seemed to us that if someone could make a nuclear bomb, it would be neither Americans, English or French but Germans. The Germans had brilliant chemistry; they had technology for the production of metallic uranium; they were involved in experiments on the centrifugal separation of uranium isotopes. And, finally, the Germans possessed heavy water and reserves of uranium. Our first impression was that Germans were capable of making the thing. It was obvious what the consequences would be if they succeeded.

Espionage, then, accompanied the Soviet development of nuclear energy from its earliest days.

In the spring of 1940, George Vernadsky, who taught history at Yale University, sent his father, V. I. Vernadski, an article about atomic energy published in the New York Times. Vernadski wrote a letter to the Soviet Academy of Sciences about the article, following which the academy created a Special Committee for the Problem of Uranium. Khlopin, who had succeeded Vernadski as director of the State Radium Institute, was appointed to head the Uranium Committee, which also included Vernadski, Ioffe, the distinguished geologist A. Y. Fersman, Kapitza, Kurchatov and Khariton as well as a number of senior Soviet scientists. The committee was directed to prepare a scientific research program and assign it to the necessary institutes, to oversee the development of methods of isotope separation and to organize efforts toward achieving a controlled chain reaction — that is, building a nuclear reactor. The decree that established the committee also ordered the construction, completion or improvement of no fewer than three Soviet cyclotrons, two already at hand in Leningrad and one to be built in Moscow; set up a fund for the acquisition of uranium metal, which Soviet industry at that time did not have the technology to produce; and appointed Fersman to lead an expedition into Central Asia to prospect for uranium. (“Uranium has acquired significance as a source of atomic energy,” Vernadski wrote a colleague in July. “With us uranium is a scarce metal; we extract radium from deep brine [pumped from oil wells], and any quantity can be obtained. There is no uranium in these waters.”)

Kurchatov was disappointed with the committee's plan, which the Academy of Sciences approved in October 1940. He believed it to be unduly conservative. Despite the expectation that uranium would have to be enriched, he wanted to move directly to building a nuclear reactor. At the Fifth All-Union Conference on Nuclear Physics in Moscow in late November, he analyzed fission studies published throughout the world to demonstrate that a controlled chain reaction was possible and listed the equipment and materials he would need. Asked if a uranium bomb could be built, he said confidently that it could and estimated that a bomb program would cost about as much as the largest hydroelectric plant that had been built in the Soviet Union up to that time — an estimate low by several orders of magnitude, but comparable to one Rudolf Peierls and Austrian emigre physicist Otto Robert Frisch had prepared in England eight months earlier for the British government. In any case, as Frisch commented later, the cost of a plant for separating U235 “would be insignificant compared with the cost of the war.”

Golovin was an excited eyewitness to the November debate:

The situation… during Kurchatov's talk was rather dramatic. The workshop took place at the Communist Academy on Volkhonka Street, in a large hall with an amphitheater overcrowded by numerous participants. In the course of the presentation the excitement of the audience kept growing and by the end of it the general feeling was that we were on the eve of a great event. When Kurchatov finished his talk, and, together with the chairman of the meeting, Khlopin, went to the adjacent room from the rostrum, Ioffe, Semenov, [A. I.] Leipunski, Khariton and others started to move there one after the other. Meanwhile, the discussion over Kurchatov's talk was continued in the hall… The break was delayed. Instead of the ordinary five or ten minutes between talks, the chairman, Khlopin, didn't return even in twenty minutes… A noisy discussion was taking place [in the adjacent room].

The Great Terror had taught its survivors wary circumspection. In the fifteen months since the beginning of the Second World War on September 1, 1939, Germany had overrun Europe. To buy time, Stalin had concluded a nonaggression pact with Hitler, but the Soviet Union was gearing up for the war with Germany that Stalin understood was coming; in May 1941 he would tell his inner circle, “The conflict is inevitable, perhaps in May next year.” The Soviet leadership had made clear its suspicion of “impractical” science, and Stalin had ordered the scientists in no uncertain terms to roll up their sleeves and get down to practical work. Nor had Khariton and Zeldovich's calculations encouraged optimism in an older generation still suspicious of the new physics. Surprisingly, even Ioffe was skeptical. He was not a nuclear physicist, and after the discovery of fission he had taken a long view of its potential, predicting that “if the mastering of rocket technology is a matter of the next fifty years, then the utilization of nuclear energy is a matter of the next century.” All these factors would have influenced the noisy discussion going on in the adjacent room at the Communist Academy. Golovin:

A quarter of an hour later, Khlopin returned to the rostrum and declared that he had come to the conclusion that it was too early to ask the government for large grants since the war was going on in Europe and the money was needed for other purposes. He said that it was necessary to work a year more and then make the decision whether there would be some grounds to involve the government… The audience was disappointed.

The development of a capacity to build atomic bombs required a massive commitment of government funds, funds that would have to be diverted from the conventional prosecution of the war. If atomic bombs could be built in time they would be decisive, in which case no belligerent could afford not to pursue them. But making that judgment depended critically on how much scientists trusted their governments and how much governments trusted their scientists.

Trust would not be a defining issue later, after the secret, the one and only secret — that the weapon worked — became known. This first time around, however, it was crucial, as the Russian physicist Victor Adamsky emphasizes in a discussion of why Nazi Germany never developed an atomic bomb:

The tension [between scientists and their governments] stemmed from the fact that there existed no a priori certainty of the possibility of creating an atomic bomb, and merely for clarification of the matter it was necessary to get through an interim stage: to create a device (the nuclear reactor) in order to perform a controlled chain reaction instead of the explosive kind. But the implementation of this stage requires