(In July 1943, when the Red Army pushed the Wehrmacht back across the Ukraine west to the Dnieper River, liberating Kharkov, Kirill Sinelnikov had immediately returned to his laboratories there and gone to work restoring the electrostatic generators so that he could begin measuring cross sections; that operation took the name Laboratory No. 1. Sinelnikov's English wife Eddie described the destruction her husband found in Kharkov in a December letter home: “Kira has been on an official visit to Kharkov and the Institute. He says in places you might think the streets had not been destroyed. The outline is the same, but when you walk down a street you find
it is only the shell of the buildings that remain… He found an absolutely
empty and dirty flat. Our beautiful Steinway [piano] lying on the road near the garage having been used by the Germans as a platform for washing lorries… We shall have to begin again from the beginning.”)
That summer of 1943, the seventy-five-ton magnet of the Leningrad cyclotron arrived in Moscow (brought, remarkably, through the German blockade) and construction began in the basement of the laboratory at the Silver Woods site on what would be the most powerful particle accelerator in Europe — and a way of making a few micrograms of plutonium, work which Kurchatov assigned to his chemist brother Boris.
Sometime in spring 1943, Moscow Center passed Igor Kurchatov the first flood of espionage material from the United States. An unidentified person with access to the files of the reference committee of the Washington- based National Research Council that controlled publication of any research that had military significance — Morris Cohen's physicist friend, whose code name according to Yatzkov was “Perseus,” or some other unidentified American spy — had either copied or summarized the contents of 286 classified scientific papers filed with the committee in lieu of publication.
Kurchatov completed his review of this extensive secret literature by early summer 1943. On July 3 he sent Pervukhin his analysis of 237 works he deemed relevant. Their content covered a full range, as a Russian historian notes:
Of 237 analyzed works, twenty-nine were devoted to the separation of isotopes by [gaseous] diffusion, which Kurchatov believes to be the main method under development in the USA, eighteen to centrifuge separation, four to electromagnetic separation, six to thermal diffusion, five to general problems of isotope separation, ten to the design of a U235 bomb (his analysis of these works takes relatively much space). Thirty-two works concern uranium-heavy-water piles, twenty-nine concern uranium-graphite piles, fourteen concern transuranics (plutonium and neptunium), three concern the [rare] uranium isotopes U232 and U233, thirty concern general issues in the neutron physics of nuclear fission, fifly-five relate to the chemistry of uranium (production of metallic U, oxide, hexafluoride used for diffusion separation and other substances, including metallorganic substances with uranium) and three works concern the physiological action of uranium.
Kurchatov wrote in his July 3 report that the twenty-nine works that concerned the development of a uranium-fueled, graphite-moderated nuclear reactor constituted “the main results of American work on a uranium- graphite pile.” By then he had decided that the Soviet Union should also take that route to achieving a controlled chain reaction in uranium; clearly his decision had been significantly influenced by the espionage information he had seen.
The twenty-nine summaries or abstracts gave “only a brief presentation of the general results of research,” however, and did not include “important technical details” (which implies that the American espionage agent who assembled the collection was a secretary or a clerk operating within the National Research Council rather than a physicist, who would have realized that abstracts were inadequate). The fact that the summaries concerned technical problems such as “temperature of the walls of cooling tubes, diffusion of fission products in uranium under high temperatures, etc.,” that were “characteristic of a technical project rather than an abstract physical scheme” gave further evidence of “the seriousness of the attempts the American scientists are making to realize a uranium- graphite pile in the nearest future.” Kurchatov asked for more information: “It is extremely important to receive detailed technical material on this problem from America.”
The reports on nuclear reactor development in the United States that Kurchatov was reviewing were a full year out of date. In fact, CP-1 had operated successfully at the University of Chicago beginning in December 1942;[9] its successor, CP-2, had been assembled and was operating with shielding at a site in the Argonne Forest outside Chicago; a vast tract of land had been purchased near Hanford, Washington, where industrial-scale reactors for plutonium production then being designed would be built; a one- thousand-kilowatt air-cooled reactor that would produce gram quantities of plutonium was under construction at Oak Ridge, Tennessee; and distilleries were going up in the United States and Canada that were planned to produce three tons of heavy water per month by October 1943 for a heavy-water-moderated reactor to be assembled at Argonne. Either the espionage documents in Kurchatov's hands had been passed at least a year before he saw them, which is unlikely (why would the NKVD have allowed him to review equally sensitive British files but withheld this cornucopia of American information from him during the previous several months when he and his team were formulating their first plans?); or they reflected some abrupt cutoff of information. A cutoff is probable. Morris Cohen had been drafted into the US Army in the summer of 1942, breaking the espionage connection with his contact or contacts until Yatzkov reestablished it with Lona Cohen several months later. Morris Cohen's contact may not have been able to pass the information he or she had collected until after reconnecting with Lona. Alternatively or additionally, whoever was supplying the Soviets with information may have lost access to the files.
Kurchatov next reviewed fourteen works that contained “detailed information on the physical properties of elements 93 [neptunium] and 94 [plutonium].” The cross section for fission of 94239 by slow neutrons, for example, had been reported in a classified May 29,1941, paper by Berkeley physicists and chemists J. W. Kennedy, Glenn Seaborg, Emilio Segre and A. C. Wahl to be even larger than that of U235. Kurchatov wanted to see a further classified work by Seaborg and Segre, for which he seems to have had at least a reference, “devoted to fission of 94 — element eka-osmium — by fast neutrons.” Kurchatov explained:
In its response to the action of neutrons, this element is similar to U235, for which the action of fast neutrons hasn't yet been explored. Thus Sea-borg's data on eka-osmium 94239 is of interest for the problem of realizing a U235 bomb. That's why we consider it especially important to receive the results of this work of Seaborg and Segre.
The Soviet project director noted that all this work showed that the United States was involved in a major effort to build an atomic bomb. It also showed, he wrote, that Soviet research was being conducted “(although of course not in sufficient volume)” along the same lines as American research with two exceptions — a uranium- heavy-water pile and electromagnetic separation of uranium isotopes — for which work in the Soviet Union had not yet been started.
“I think that we ought to begin working in both of these directions,” Kurchatov concluded, “and the first of them demands the most serious attention.” A heavy-water pile would be more difficult to build than a graphite pile, he pointed out, because they would have to organize heavy-water production on a scale of tons. But it would resolve a serious problem-, the Soviet project's lack of uranium. The realization of a heavy-water pile, Kurchatov revealed, “would demand not 50, but 1–2 tons of uranium, the amount we have at hand in 1943, while it remains unclear when our country will accumulate a stock of uranium of as much as 50 tons.”
“It was… the results of earlier research by the Soviet scientists themselves,” writes Yuli Khariton of himself and his colleagues, “that put them in a strong starting position when they embarked on a solution to the atomic problem.” By the summer of 1943, an open flood of espionage from England and the United States had added significantly to that base. But even if the Soviets could have caught up with the Anglo-Americans technically, they could not yet have built a bomb; they lacked the necessary raw materials, and had not yet begun to develop the vast industrial enterprise they would need to process them.
4
A Russian Connection
