Nuclear technology has been spreading around the globe for the past half-century. Some countries—like South Africa, Argentina, Libya, and Switzerland—started nuclear-weapons programs, only to cancel them. The International Nuclear Non-Proliferation Treaty recognizes only five “official” nuclear powers: the United States, Russia, China, France, and Great Britain. But there are four more “unofficial” members of the nuclear club who are not signees to that document. Israel developed nuclear weapons in the mid-1960s, and India tested its first atomic bomb in 1974. In 1998 and 2006, respectively, they were followed by two countries that don’t have the best of reputations: Pakistan, which is considered a very weak state, and the unpredictable dictatorship that is North Korea.
Nuclear weapons have continued to spread, gradually but steadily, because of a small, unassuming machine, the centrifuge, which allows even atomic paupers to produce the material needed to build the bomb. In the Islamic Republic of Iran, thousands of centrifuges are currently in operation—ostensibly for the civilian purposes of producing atomic energy.
The story of this dangerous apparatus begins in the final days of World War II. Hitler’s Germany was defeated, and the Soviet Red Army was marching upon the surreal remnants of bombed-out Berlin. The end of the Third Reich was simultaneously the beginning of a new political order. Parts of this transition happened publicly: the capitulation of Nazi Germany, the liberation of the concentration camps, and the division of the defeated enemy into occupation zones. But events that would set the stage for the Cold War were also transpiring away from the public eye. The United States and the Soviet Union had long seen themselves as rivals and were trying to gain advantages—cultural, scientific, and military—in a conflict between opposing systems. Both sides desperately wanted to profit from the know-how of German scientists and military technicians, and they specifically targeted experts with this aim in mind. Particularly coveted were members of the German “Uranium Association”—the researchers who had worked in Hitler’s atomic program.
Disputes remain about how close German scientists got to building an atomic bomb for the Führer, but it is clear that in the early years of World War I, they had a significant lead over their American counterparts. Less than a year after Otto Hahn, Fritz Strassmann, and Lise Meitner discovered atomic fission in 1938, a Hamburg professor named Paul Harteck approached the Nazi War Ministry to discuss with the military leadership the possibility of constructing a nuclear weapon. The country that succeeded in building this doomsday device first, Harteck argued, would enjoy an enormous advantage over its enemies.
The Nazis had ample access to the materials needed to build the bomb. Germany contained huge uranium deposits, and heavy water—a crucial element needed for transforming uranium into weapons-grade plutonium—was being produced in occupied Norway. Yet although the crème de la crème of German physics, including Hahn, Carl Friedrich von Weizsäcker, and Nobel laureate Werner Heisenberg, worked on the Nazi nuclear program, the Third Reich was unable to exploit its advantageous position.
It is impossible to reconstruct precisely why the uranium project failed in Nazi Germany. In all likelihood, a combination of factors, rather than a single reason, explain why Hitler never got the bomb. One popular explanation was that many of Germany’s best scientific minds were Jews who had been expelled from the country and worked for the Allies during the war. Neither did the Nazi leadership do itself any favors by sending a number of researchers to the front, leaving the nuclear project understaffed. Furthermore, Heisenberg, who quickly became the head of the initiative, may or may not have intentionally sabotaged it. When asked by Armaments Minister Albert Speer how much money he needed to build an atomic bomb, Heisenberg asked for only 40,000 thousand Reichsmarks—while the Brookings Institute put the total cost of the U.S. atomic weapons program during World War II at 20 billion dollars. Heisenberg also dampened the enthusiasm of Speer and the military leadership by telling them in the summer of 1942 that the earliest a nuclear weapon would be ready was in three years. That prognosis made investing large amounts of energy in the project seem unattractive. Finally, targeted bombing raids and acts of sabotage by the Allies, for example on a shipment of heavy water that was being transported in Norway, spelled the end of productive nuclear research in Nazi Germany.
But probably the most important reason for the failure of the German nuclear-weapons program was the fact that the Nazi leadership, and above all Hitler, did not comprehend the destructive potential of an atomic bomb and thus did little to fast-track its development. Nuclear chemist Nikolaus Riehl, a “Uranium Association” insider, would later claim that German scientists had, consciously or not, refused to build the bomb for Hitler, even though they probably had the ability to do so. “A researcher or engineer,” Riehl wrote in his memoirs, “who was driven by scientific curiosity and a love of technical experimentation would have hardly been able to withstand the lure of the uranium project, and the Germans would have gotten much further if they had been pressured to do so and supported in their efforts by the government.” Riehl attributed the relatively “lukewarm” interest of Germany’s rulers to the intellectual primitiveness of Hitler and his henchmen. Riehl writes: “They no doubt could understand things like missiles, which made a lot of noise and whose function was obvious. But they had no real comprehension of unfamiliar abstract concepts like the massive amount of energy that could be released by nuclear fission.” In Riehl’s view, insufficient state support convinced most researchers that “there would be no ultimate breakthrough in the uranium project before Hitler’s downfall, so there was no need to consult their consciences.”
The American scientists who were working on the Manhattan Project received contradictory signals from Germany. After a now-legendary meeting with Heisenberg in Copenhagen in September 1941, Danish physicist Niels Bohr brought a sketch of the German design for an atomic bomb with him to the United States. When his colleague Hans Bethe saw the sketch, he exclaimed: “My God, the Germans are planning to drop a nuclear reactor on London.” J. Robert Oppenheimer, the father of the American bomb, is said to have merely remarked that as a weapon it was extremely “useless.”
The controversial German historian Rainer Karlsch contends that German physicists, including Heisenberg’s great rival Kurt Diebner, continued to work on a nuclear bomb even as the war was drawing to a close. Karlsch maintains that according to a report by Soviet spies, as late as March 1945, a few weeks before Germany’s surrender, a mysterious explosion took place in the central German state of Thuringia. Trees were reportedly uprooted in a radius of 500 to 600 meters, several buildings were destroyed, and a number of POWs were killed. Karlsch concludes that this was the result of a nuclear test. But a search for residual radioactivity at the supposed test site in 2006 came back negative. The German governmental organization that examined the land in question therefore determined that no nuclear-weapons test had ever taken place there. And significantly, after the war, not a single prototype—to say nothing of a functional nuclear weapon—was ever found anywhere in occupied Germany. All that remained of the efforts of the “Uranium Association” was an experimental reactor discovered in a basement in the tiny town of Haigerloch in the south of the country, and it was unlikely that this bit of machinery would ever have been capable of producing plutonium.
The only things of value left behind by the German nuclear program were the members of the “Uranium Association,” and both sides of the Cold War were keen to exploit their know-how. But the efforts to recruit Nazi scientists were often farcically clumsy, as documents from a British special unit reveal. The so-called “T Force” was a mobile unit that moved out ahead of other Western troops and occupied German industrial concerns and research facilities. T Force soldiers abducted any research scientists they discovered and tried to get them to reveal what they knew with a combination of threats and incentives. But the T Force was unable to distinguish between valuable and worthless sorts of knowledge—on one occasion they interrogated a harmless German widow, extracting from her the formula for “4711,” the original eau de cologne. Meanwhile, starting in 1943, the American intelligence services ran a program, code-named the “Alsos,” that explicitly targeted German nuclear research. Whereas the original aim had been to determine the state of the German weapons program, by the end of the war it was charged with capturing Heisenberg and his colleagues and occupying atomic research facilities. On April 23, 1945, a vanguard expedition of the Alsos arrived at the research reactor in Haigerloch, which had been taken by French troops the day before. To keep the reactor from falling into French hands, the Americans immediately decided to dismantle and remove it. But the machinery contained neither uranium nor heavy water. In the end, the intelligence officers persuaded a group of German physicists to reveal where the missing substances had been hidden. The uranium was found buried in a field, the heavy water in the basement of an old mill.
The Alsos succeeded in capturing a number of major German scientists from April to October 1945, and the intelligence program was subsequently terminated. Thanks to their early interest, the Americans were better prepared for this task than were the other Allies. They were also aided by the fact that by the end of the war, most notable German researchers were located in the western half of the country. Scientists who had done atomic research at the Kaiser Wilhelm Institutes in Heidelberg and Berlin were detained in their apartments in Southern German towns, and Heisenberg himself was apprehended at his summer home on Lake Walchen in the Bavarian Alps.
The Soviets were at a great disadvantage when it came to recruiting German chemists and physicists, and to make matters worse for them, the United States dropped the first-ever atomic bomb on Hiroshima on August 6, 1945, demonstrating just how devastating a nuclear weapon could be. Stalin was deeply disturbed. The new weapon threatened to alter the equilibrium of power between the world’s two aspiring superpowers. For a brief moment in history, the U.S. military appeared undefeatable, and the Soviet Union redoubled their efforts to build their own nuclear weapon, which had commenced in 1943. The head of Soviet atomic program, Igor Kurchatov, sent his finest researchers to East Germany to secure uranium and locate any remaining principals of the “Uranium Association.” This operation, directed by State Security General Ivan Serov, was a resounding success, as the Soviets captured Nikolaus Riehl as well as physicist Robert Döpel, Director of the Berlin Kaiser Wilhelm Institute for Physical Chemistry Peter Adolf Thiessen, Nobel laureate Gustav Hertz, and electronics wizard Manfred von Ardenne.
Riehl later recalled that the scientists were treated very politely and that the “professionals” of the Russian State Security Service had been quite friendly:
They gave me advice and sent chocolate, tobacco and other amenities my way. When I was transported to the Soviet Union, a particularly fearsome State Security lieutenant, a real brick wall of a fellow, ran after the car, shook my hand, wished me well and prophesied, “You’ll soon be driving around Moscow in your very own car.”
Once the prominent prisoners of war had arrived in the Soviet capital, they were quartered in the same luxurious villa where the German field marshal Friedrich Paulus and his staff had been kept after they surrendered at Stalingrad. On the dining hall walls, there was still a map upon which soldiers had traced the front lines. Riehl, Ardenne, and some of the others were even taken to the Bolshoi Theater, where Borodin’s Prince Igor was being performed to celebrate the Soviet Union’s victory over Nazi Germany.
The Soviets, of course, expected something in return for the hospitality shown to the captured scientists. That was made abundantly clear to them in a meeting with Lavrentiy Beria, Stalin’s much-feared head of state security and the secret police. Ardenne summarized the tenor of that encounter, saying that Beria had told him, “You are now going to build bombs for us as well.” Ardenne immediately recognized that he was trapped. If the Germans refused to cooperate with the Soviets, they would be sent to a labor camp or executed. If they cooperated, they would become privy to the most sensitive Soviet secrets and would never be allowed to return to Germany. Just moments after the challenge was posed, Ardenne hit upon a bold idea, which he then proposed to Beria and the other state-security operatives. “Building the bombs is the easy part,” he told them. “You can do that yourself.” But the German scientists would agree to produce the material needed to make a nuclear bomb.
In fact, the design of the bombs themselves was so comparatively straightforward that the Americans had not bothered to test a uranium bomb before dropping one on Hiroshima. “Little Boy,” as the first nuclear weapon was nicknamed, contained two masses of uranium that were propelled into each other by a small “cannon shot” of explosives. The collision yielded a critical mass and unleashed a chain reaction of nuclear fission. Every time an atom was split, it emitted two neutrons, which would then split two further atoms, and on and on. In the process, enormous amounts of energy were released, with devastatingly destructive results.
A much more difficult matter than designing the bomb was extracting the fissible components of natural uranium. The key ingredient was the uranium 235 isotope, which made up a mere 0.72 percent of natural uranium. In Europe, at the time of Ardenne and Beria’s meeting, researchers only had vague hypotheses about a process, called uranium isotope separation, that would allow them to produce tiny amounts of weapons-grade uranium. It had taken the United States years of massive industrial labor to collect the few kilograms of highly enriched uranium contained in Little Boy. The diffusion method the United States had used required tremendous amounts of energy and was extremely costly and inefficient. In fact, it was ill suited for a weapons program. Moreover, and even worse from the Soviet perspective, the details of this process were top secret.
Ardenne’s promise to solve the problem of uranium isotope separation was a risky gambit. He suspected that the outcome would be very unpleasant if he and his team failed in their endeavor, which initially seemed to have more to do with alchemy than science. The Soviets debated Ardenne’s proposal for half an hour before accepting it. Years later, at an official state reception, Soviet Premier Nikita Khrushchev took Ardenne to one side and congratulated him for how cleverly he had managed to wriggle out of the noose around his neck.
The Germans were then taken to Sinop, a picturesque little village around two kilometers from the Black Sea resort town of Sukhumi. There, a hotel complex had been hastily converted into a research institute and equipped with various bits of scientific hardware looted from German chemistry and physics laboratories. Anything further the researchers felt they needed was requisitioned from Soviet industrial facilities, although the scientists were no doubt warned of the dire consequences that would follow, should their experiments turn out to be a waste of time and resources.
Nonetheless, despite enormous efforts on all sides, the uranium project did not get off to an auspicious start. The key to success, Ardenne immediately realized, would not be technology, but a team of scientific minds capable of achieving the impossible. Frantically, Ardenne started searching POW camps for gifted chemists, physicists, and engineers, and Soviet authorities provided him with lists of specialists whom they had captured. Anyone who seemed interesting was whisked away to the sunny climes of the Georgian resort. Ardenne could not have suspected how lucky he would be. One of the two men who would prove crucial to the project just happened to be alive and well in a Soviet POW camp—and that by accident.
Max Steenbeck was the former director of the Siemens-Reiniger electrical and medical technology plant in Berlin. His groundbreaking research had earned him the nickname “the pope of plasma.” As the Red Army advanced on the German capital, Steenbeck had defended the installation as a voluntary militiaman. Upon being captured by the Soviets, he swallowed a cyanide pill, but the poison had no effect. A friend who was also a chemist speculated that the digestive liquids in Steenbeck’s stomach were abnormally basic and thus neutralized the effect of cyanide, which is an acid. The more probable explanation, though, is that the pill was a mere placebo.
After a forced march to the province of Posen, the unsuccessful suicide was interned in a POW camp. Steenbeck, a sensitive man who was used to enjoying the amenities of social status, had severe difficulty adjusting to the conditions of Soviet imprisonment. After a few weeks, his skin was covered with sores, and he was suffering from fever and persistent diarrhea. The only relief the seriously ill chemist was given was a straw sack as a blanket and a daily glass of milk. A short time after miraculously escaping death, Steenbeck was again very close to it. His condition was no doubt too poor for him to appreciate what was happening when Soviet officers appeared and took him away from his barracks in October 1945. In his memoirs, he recalled being “far too apathetic for any sensations,” as he was led through the gate and the surrounding barbed wire, “a moment all of us had envisioned with hope and fear.” Steenbeck still didn’t comprehend the situation when he was taken to the camp commandant’s office: “Nothing at all moved me, not even the fact that there was a table set before me with tasty things, no idea what they were—all I can remember is a glass of vodka. In my lethargy, I didn’t think it was real. Everything seemed like a dream … When I woke up the following day, I was lying in a real bed with fresh linens, all alone in a large room. I didn’t really know why this should be the case.” Steenbeck had been saved because his name was on Ardenne’s list, although the “plasma pope” had no way of suspecting that at the time.
As soon as the Soviets had gotten Steenbeck back on his feet, he was taken to the Black Sea. The situation there was the opposite of the wretched life in the POW camp. The researchers under Ardenne may have been prisoners who had to obey instructions from Soviet authorities, but the Germans in Sukhumi scarcely noticed that their liberty was curtailed. The living conditions were nearly ideal, much better than those enjoyed by average Soviet citizens or people back at home in war-ravaged occupied Germany.
Sukhumi, today the capital of Abkhazia, is located at the foot of the Caucasus Mountains, and its broad beachfront promenade, which, sadly, was destroyed in the Georgian civil war of the 1990s, attested to the city’s glamorous past. It was Beria’s birthplace and, in Soviet days, a flourishing port known as “the white city on the sea.” Sukhumi was part fishing village and part Soviet pomp, a pastoral spa town with Communist grandezza, a mixture that had an undeniable sultry charm. Stalin’s security service resided under palm trees that were hundreds of years old. Next door, people could bathe in sulfur waters and stroll along the promenade. The authorities had built gigantic apartment buildings for the working-class elites, and on every floor of these Orwellian structures there was guaranteed to be a government spy. On weekends, deserving Soviet citizens would pour in and get rousingly drunk on the beach or take a romantic hike in the Caucasus that also usually ended in an alcoholic bender. Life in Sukhumi was as decadent as possible within the constraints of Stalinist dictatorship.
This was the surreal environment in which Steenbeck suddenly found himself. He’d been informed before his arrival that he was to help build a Soviet atomic bomb, and faced with no alternative, he’d agreed. Ardenne immediately made him a departmental director, and he was given a chauffeur-driven car and an expansive room with a park-front view. From the foyer of the villa, an open-air staircase flanked by lions carved in sandstone led out into the greenery. Photos from the 1940s and ’50s give a good impression of how the Germans lived in Sukhumi: they show studies with bookshelves up to the ceiling, polished hardwood floors, and friendly-looking men smoking pipes on the veranda. The bosses resided in gleaming white villas, the engineers and laborers in purpose-built, rustic wooden houses. A brook ran through the middle of the research center, contributing to the “Riviera in the Caucasus” atmosphere described by one of the researchers:
Wild vines with sweet grapes cover the trees amidst the subtropical vegetation and along the brook over the grounds. Plums and other edible fruits grew there too, for anyone who wished to pick them. Mandarin oranges were cultivated on the surrounding estates, and you could buy 20-kilogram crates of them for a cheap price.
The only disturbances in this paradise were “the unbelievably loud and sleep-inhibiting concert of frogs and fish” in the brook.
In March 1946, a late arrival and the second key figure in the Soviet uranium project joined the Black Sea group. The Austrian engineer Gernot Zippe had the sort of practical mindset that perfectly complemented Steenbeck’s extraordinary conceptual abilities. Zippe had amply demonstrated his technical acumen during World War II. He had helped develop the first German radar tracking system, and later he had experimented with new, ultra-fast airplane propellers at the Luftwaffe’s research center in Prague. A fellow POW suggested that the Soviets take a closer look at this multifaceted technician.
In contrast to Steenbeck, who eventually became a committed socialist and later served as a member of the State Research Council in Communist East Germany, Zippe was no great admirer of Marx and Engels. In fact he freely admitted his abiding admiration for the Führer. In his memoirs he wrote:
On account of my education and my experience of the Engelbert Dollfuss and Kurt Schussnigg dictatorships in Austria, and notwithstanding our defeat in the war, I avowed that I was a passionate follower of Adolf Hitler … Of course, there were things I, and not only I, found out “afterward.” For example, we were shown films of the horrors of the concentration camps, of which I previously had no knowledge. But the fact was that I had been able to experience the unbelievable mood of optimism accompanied by a series of great social triumphs.
Zippe and Steenbeck not only differed radically in their political views; they were also two very different sorts of men. Whereas the Austrian was reserved and introverted, Steenbeck was considered an arrogant know-it-all. Even in his own book Crisis and Renewal, he described himself as egocentric. Yet despite these differences in outlook and temperament, the two men quickly formed the most efficient team within the Sukhumi uranium project. The key to their success was mutual respect. Steenbeck, who was nominally Zippe’s boss, appreciated the latter’s pragmatic intelligence and left him to his own devices. Zippe, for his part, acknowledged Steenbeck’s visionary energy and spirit. That is not to say that their collaboration was without some rough patches. Significantly, Steenbeck hardly mentions the Austrian in his autobiography. Zippe’s memoirs, by contrast, contain a number of critical asides aimed at Steenbeck. The brilliant theoretician, Zippe wrote, “often had his head so far in the clouds that you would think he believed that nature necessarily had to follow his calculations, whereas the opposite, in my opinion, is the case.” Zippe claimed that he often had to bring Steenbeck “back down from his lofty dreams to the terra firma of natural laws and constraints.”
It was the theoretician Steenbeck who hit upon a new method of producing uranium 235. The idea was to construct a special centrifuge to isolate minute quantities of weapons-grade material from natural uranium. Steenbeck was hoping to exploit the fact that in its gaseous form, uranium 235 is a tiny bit lighter than the rest of the radioactive metal. When uranium hexafluoride was run through a centrifuge, uranium 235 would be concentrated in the middle. The principle was the same as with an everyday washing machine: clean water weighs less than dirty water and thus remains in the middle of the drum. In a washing machine the drum needs to revolve fifteen times a second to produce this effect. Steenbeck calculated that in order to be capable of separating uranium 235 from other isotopes, the drum of the centrifuge would have to revolve a dizzying, supersonic 90,000 times a minute. That presented an almost insoluble dilemma since speeds of that sort would rip apart any normal drum, no matter how solidly it was constructed. No one in 1946 knew how to build the type of centrifuge the project required. Nonetheless, Steenbeck’s plan seemed to be the only viable option. A second research group in Sukhumi, which had been experimenting with diffusion methods, had made little progress, and a third procedure that Steenbeck had initially favored had proven utterly impracticable.
Meanwhile, the researchers’ Soviet masters were increasing the pressure to succeed. Many of the scientists would later recall that Beria kept a list of names in his safe, detailing which researchers would be sent to labor camps and which executed in the event that the bomb project failed.
So Steenbeck and Zippe got down to work. Wherever they looked, all they saw were seemingly insurmountable obstacles. The first issue was one of material. As soon as the centrifuge drums reached a critical velocity, they bent out of shape and eventually disintegrated. No metal could withstand that sort of strain. Zippe and Steenbeck began experimenting with rubber tubing, but it developed what they called “vibration bellies” and burst. Experiments were also carried out with glass and brass—with perilous results. The cylinders invariably broke into countless splinters that would go flying through the laboratory. Zippe considered asking for a suit of knight’s armor to wear for protection. “It was only down to a huge amount of luck,” he later wrote, “that there was no serious accident during the first phase of experimentation.” The Germans working on other parts of the project could only shake their heads every time there was an explosion in the centrifuge laboratory. Steenbeck later acknowledged that his group was considered “crazy.” Their experiments were made even more dangerous because Zippe and Steenbeck filled their prototypes with uranium hexafluoride, which occurs as sparkling crystals in an airless void but is transformed at the slightest contact with water into a potent acid. Any contamination with water meant that the liquid would eat through the centrifuge drum, even if it was made of the strongest glass. Moreover, the unpredictability factor was dramatically increased by the fact that Zippe’s Russian laboratory assistant habitually drank a full measuring cup of 192-proof alcohol before starting every shift. Safety precautions at Sukhumi ranged from lax to nonexistent. On one occasion, an explosion in another laboratory blinded one of Zippe and Steenbeck’s colleagues. He was taken away by his assistants and never seen again.
Nonetheless, despite all the obstacles, Zippe and Steenbeck were making progress. They came up with the idea of using coupling links to prevent metal drums from breaking apart due to eccentric motion at critical velocities. Meanwhile, Steenbeck constructed an electric motor capable of rotating the drum at the necessary speed. Initial results were encouraging, yet there was still a decisive hurdle to be overcome: friction. Whenever two bodies rub against each other, heat is generated. In the case of a centrifuge spinning at supersonic speeds, the result was an extraordinary amount of heat that destroyed the machine. Even when the mechanical parts barely touched one another, friction with the surrounding air was enough to cause irreparable damage.
To relax and clear his head, Zippe went on extensive tours through the mountains. The captive scientists enjoyed four weeks of holiday, the division heads, six. Zippe would drive a Jeep through the Caucasian highlands, accompanied by a guard who also served as an interpreter. On a hike around Lake Riza, at an elevation of 3,200 meters, Zippe looked down upon fields of snow and plateaus upon which horses were galloping. Time was gliding by. At a time when the first regular POWs were being allowed to return to Germany, the scientists labored on in their golden cage on the Black Sea. Days turned into months, and months into years.
Then, on August 29, 1949, things changed abruptly. At 7:00 a.m. that day, the Soviet Union successfully tested its first atomic bomb—without the help of the Sukhumi centrifuge-makers. Kurchatov had simply bypassed the problem of producing uranium 235 by using another fissionable substance, plutonium. Plutonium naturally occurs only in the minutest quantities, but it can be created in nuclear reactors from the energy released when uranium 238 is bombarded with neutrons. The fuel needed to run the reactors is a lower grade of uranium 235, enriched only by a factor of 4 to 5 percent, compared with the 80 to 90 percent needed for an atomic bomb.
Thanks to a few well-placed spies within the American atomic-weapons program, Kurchatov had succeeded in overcoming the two major barriers to building a plutonium bomb. First of all, producing plutonium was a painstaking process, and the Soviets were forced to master the techniques of running huge reactors. Second, it was far more difficult to detonate a plutonium bomb than a uranium one. The forces working upon the radioactive material had to be absolutely regular in order to achieve an explosive chain reaction. The solution was to surround a plutonium ball with highly volatile conventional explosives, which were then detonated with an extremely complicated mechanism. That caused the plutonium to implode, triggering a critical mass like the one that resulted in the two halves of uranium 235 in the cannon-detonation procedure. The result, which Kurchatov witnessed with his own eyes, was a gigantic, multicolored fireball that rose into the sky over Semipalatinsk, Kazakhstan.
The test represented a historical watershed for the world as a whole and for the United States in particular. Mutual mistrust between the superpowers intensified, and it was clear that the Cold War had the potential of turning into a direct, global military battle inflamed by the destructive power of atomic fission. The West focused even more on what was happening at Sukhumi and the other Soviet nuclear research facilities. The Soviets had mastered the laborious techniques needed to make a plutonium bomb, but would they be able to build a uranium one? When Steenbeck’s wife was granted permission to join her husband in Sukhumi, she was contacted by a member of the British secret service, MI6, who asked her to smuggle sensitive information back to the West inside her lipstick case. She politely refused. But the incident, together with an extensive CIA report, shows that Western intelligence agencies knew at least the outlines of what was going on in Steenbeck and Zippe’s laboratory.
In the end, the centrifuge-makers achieved several breakthroughs. To avoid the problem of excessive heat from friction, Zippe mounted his centrifuge much like a top on a tiny needle. The drum was held in place vertically with strong magnetic rings, which meant it did not need to be mounted in conventional fashion. The furious revolving cylinder did not even make contact with air, since the interior of the machine was a vacuum. In this way, a centrifuge could attain the necessary revolutions without being subjected to destructive friction.
The Soviet repaid the researchers for their help by giving them various state decorations and then released them from captivity in the early summer of 1956. Zippe and Steenbeck’s records were confiscated, and even a notebook of sheet music was taken away from them because it seemed suspicious. On July 28, Zippe travelled back home to Austria via Moscow and Budapest. He didn’t have a single note in his luggage, but his head was full of valuable information. As soon as they could, Zippe and Steenbeck took out a joint patent on their uranium centrifuge. Zippe subsequently arranged with the CIA to be brought to the United States, where he handed over detailed plans for the device he had envisioned in Sukhumi to dumbfounded American officials.
The advantages of the procedure Zippe proposed for enriching uranium were obvious. Centrifuges were reliable and energy-efficient. One no longer needed reactors to produce weapons-grade material. By using a sufficient number of centrifuges, employed one after another in so-called “cascades,” it was possible to enrich a large quantity of uranium 235 in a short time. It was far less complicated to design a uranium bomb than a plutonium one, and the costs of a nuclear-weapons program oriented in this way were seductively low. It is no accident that atomic weapons produced in part by Zippe’s centrifuges became known as the “poor man’s bombs.” Last but not least, a bomb-building program that employed centrifuges was relatively easy to conceal from prying eyes—a fact that would become ever more significant with the passing of decades.
Most of the advantages of the centrifuge-built bomb also applied to the enrichment of uranium for civilian purposes, such as producing fuel for nuclear power plants. Zippe exploited this fact and went to work for the nuclear energy industry, joining the Degussa company in Frankfurt in the 1960s and later moving to the German-Dutch-British consortium Urenco. As part of the contracts he signed, the companies had to pledge that they would only apply his and Steenbeck’s research to civilian purposes and would take every precaution to ensure it was not misused. Nonetheless, Zippe would have been hard pressed to answer, had he been asked, how a multinational corporation like Urenco, with hundreds of employees scattered in several locations around the world, could have possibly guaranteed it would safeguard the secrets of his centrifuges.
The need for uranium enrichment grew exponentially with the burgeoning of nuclear power in Europe, and that put Urenco under enormous pressure to deliver sufficient amounts of reactor fuel. To meet the rapidly rising demand, the company passed a number of responsibilities on to subsidiaries and partner companies, including the Dutch consultancy firm Fysisch Dynamisch Onderzoekslaboratorium (FDO). In 1973, Urenco managers complained about metallurgic problems in their uranium centrifuges, and FDO sent a young man named Abdul Qadeer Khan to deal with the problem. He was a Pakistani engineer. The professor who supervised his dissertation later described him as “a nice guy,” and he was married to an equally intelligent and attractive South African woman. Khan was a moderate Muslim who made no secret about his patriotism toward his home country. The life he led in the Netherlands was unremarkable. He and his family lived in a terrace house in the Amsterdam suburb of Zwanenburg, and like many other people, the Khans enjoyed going to the seaside or making trips to the Ardennes on the weekends. No one noticed that Khan had lied when he applied for his job and falsely claimed that his wife Hedrina “Hennie” Khan was a Dutch citizen. During his time at Urenco, Khan had free access to the large centrifuge halls that the company maintained in the town of Almelo. A colleague named Fritz Werman later recalled that Khan often took blueprints back home with him, in violation of the strict confidentiality rules of his employer. In addition, Hennie, who like her husband was multilingual, translated sensitive Urenco documents from Dutch to English.
The rest of the story is widely known. A.Q. Khan was a Pakistani spy. When he returned to his homeland, he provided Pakistani officials with blueprints of uranium centrifuges and lists of companies that supplied Urenco with parts. A number of European companies, including FDO, had no qualms about earning huge profits assisting Pakistan’s atomic program. FDO supplied nuclear know-how and centrifuge components, even though the employees of the company surely must have known what their former colleague Khan intended to do with them. Germany was the biggest supplier of trade-restricted material. The CES Kalthof company in Freiburg even sent Khan an entire enrichment facility, declaring it to customs authorities as a “toothpaste factory.”
Pakistan carried out its maiden nuclear test on May 28, 1998. But that was just the first in a series of alarming developments. In the meantime, Khan was doing booming business with Zippe’s centrifuges, whose secrets he passed on to North Korea, Libya, and Iran, among others. Everywhere around the world, dictators hoped they could acquire this useful and potentially deadly technology. At the same time, further sensitive information was leaking out of the Urenco consortium. Even Saddam Hussein was able to exploit German connections to procure uranium centrifuges. The brand name was still clearly visible when they were later discovered after the First Gulf War. And Khan’s representatives negotiated for months with al-Qaeda after the terrorist group decided to pursue its own nuclear program.
The absolute low point, thus far, in this story came shortly after September 11, 2001, when then–head of the CIA George Tenet met with George W. Bush to inform the president that al-Qaeda had smuggled a functional atomic weapon into New York City and were planning to detonate it. It turned out that the CIA based its warning on false information from an agent codenamed “Dragonfly,” but the incident provided a taste of the sorts of things the world can expert if centrifuge technology is allowed to proliferate. For example, the SILEX process (the Separation of Isotopes by Laser Excitation) has recently been advanced by a number of private companies and raises the possibility of a new era of proliferation. First developed in the 1990s by private Australian researchers, the process produces enriched uranium using lasers and is far more effective than traditional centrifuge enrichment and potentially even easier to conceal. In 2010, the Iranian regime claimed to possess technical knowledge of the process. German nuclear weapons expert Hans Rühle warned in 2012 that “laser uranium enrichment is so attractive that it will be implemented—and Iran could become the test case.”
Gernot Zippe always pointed out that his invention could be used to both the benefit and the detriment of humanity. It was like a kitchen knife, he told the BBC four years before his death in 2008. The analogy was simple: “With a kitchen knife you can peel a potato or kill your neighbor.”