How did the United States react and why the Soviet Union exploded its first atomic bomb in 1949?

Race for the Superbomb | Article

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The Soviets called their first atomic test "First Lightning." A train belching black smoke, shipped the bomb components 2,000 miles from Arzamas, the weapons laboratory in Russia to the test site at Semipalatinsk in Kazakhstan. Like the Americans, the Soviets constructed a tower from which to test their weapon. They assembled the device in an adjacent concrete hall which had railway trucks running down its entire length. The bomb components came in one end and the completed device was wheeled out the other end to be hoisted to the top of the tower. 

The Soviets wanted to learn about the effects of nuclear weapons. So in addition to instruments that would measure the size of the shock wave and the intensity of the radiation, they constructed wooden and brick houses, bridges, tunnels and water towers in the vicinity of the tower. They also put caged animals nearby so that they could study the effects of nuclear radiation. 

Igor Kurchatov, the scientific director of the soviet nuclear bomb program who was in charge of the test, arrived at the site in May of 1949. In the weeks leading up to the blast he organized two rehearsals so everyone would know exactly what to do on shot day. The chair of the Special Committee on the atomic bomb, Lavrentii Beria, arrived in the middle of August. He observed the assembly work and reported back to Soviet leader Joseph Stalin. 

At 2 am on August 29, 1949 the assembled bomb was wheeled to the tower. The blast was scheduled for 6 am. Kurchatov and a handful of other scientists gathered in the command post with Beria and his entourage. They left the door open so they could watch the blast go off . They knew that they would have time to close the door because it would take 30 seconds for the shock wave to reach them. Kurchatov gave the order for the detonation. 

An observer from a northern post about nine miles from the blast had one of the best views: "On top of the tower an unbearably bright light blazed up. For a moment or so it dimmed and then with new force began to grow quickly. The white fireball engulfed the tower and the workshop and expanding rapidly, changing color it rushed upwards. The blast wave at the base, sweeping in its path structures, stone houses, machines, rolled like a billow from the center, mixing up stones, logs of wood, pieces of metal and dust into one chaotic mass. The fireball, rising and revolving, turned orange, red. Then dark streaks appeared. Streams of dust, fragments of brick and board were drawn in after it, as into a funnel." 

The relief and euphoria in the room was overwhelming. Kurchatov cried out, "It works! It works!" And Iulii Khariton, the scientific director of Arzamas, remembers Beria hugging him. All of the scientists knew that their own personal fates depended on the success of the bomb. One of them later said that if it had failed they would have all been shot. But besides being thankful for their own lives, many of the scientists felt they had contributed to the Soviet Union's security. Khariton later said, "when we succeeded in solving this problem, we felt relief, even happiness -- for in possessing such a weapon we had removed the possibility of its being used against the USSR with impunity." 

Beria's own joy temporarily dissipated when his suspicions got the better of him. He put a call through to an observer at the north post who had also witnessed an American test in 1946. "Is it the same as the American one?" Beria wanted to know. "It is," the observer assured him. The bomb had in fact yielded 20 kilotons, making it about the same size as Trinity, the first U.S. atomic test. 

Two months later the scientists principally responsible for designing the bomb won honors for their roles on the project. As the story goes, Beria adopted a simple rule in deciding who should get what prize. Those who would have been shot if the bomb had failed, became Heroes of Socialist Labor; those who would have been imprisoned were awarded the less prestigious honor, the Order of Lenin.

"Layer Cake" Test

On August 20, 1953, the Soviet press announced that the USSR had tested a hydrogen bomb. Eight days prior in Kazakhstan, the explosive device “Joe-4” put to the Soviet developed “layer cake” design to the test. The bomb technology received its name due to its alternating layers of a fusion fuel, consisting of lithium-6 deuteride with tritium, and a fusion tamper, uranium. Results of the explosion seemed to indicate the device as more similar to a powerful fission bomb than an actual hydrogen bomb. The test’s explosion yielded the equivalent of 400 kilotons of TNT, making it 30 times larger than the atomic bomb dropped on Hiroshima. It was also small enough to fit in a plane and therefore, unlike “Mike" the American thermonuclear device tested a year earlier, it was not limited and could easily be turned into a deliverable weapon. 

Initial Soviet research into the H-bomb followed closely the path the U.S. scientists were pursuing. The work was conducted by a group in Leningrad led by Iakov Zel'dovich that had been given access to information provided by atomic spy Klaus Fuchs. This included a detailed description of the "classical super" design, physicist Edward Teller's original idea for a super bomb. Zel'dovich's team began calculations on the basis of this information. But in 1948, Igor Kurchatov, director of the Soviet nuclear program, set up a second team to investigate the feasibility of the H-bomb. Its assignment was to check the Zel'dovich group's calculations. 

Andrei Sakharov was a member of this second team. Before long, he had come up with an innovative new scheme. He suggested a "Layer Cake" design, which would consist of alternating layers of hydrogen fuel and uranium. High explosives surrounding the "Layer Cake" would be used to implode and ignite an atomic bomb at the center of the device. The atomic explosion would heat and compress the hydrogen fuel sufficiently to cause a fusion reaction. The fusion reaction in the hydrogen would lead to the emission of high energy neutrons which would in turn create further fissioning in the uranium. 

Another talented young physicist Vitalii Ginzburg's came up with what Sakharov called the "Second Idea." Initially Sakharov suggested that the hydrogen fuel should consist of a mixture of deuterium and tritium, both of which are isotopes of hydrogen. Ginzburg suggested using lithium deuteride instead, a compound of lithium and deuterium, which has the advantage of being a solid at room temperature. In addition, it would produce tritium during the course of the explosion. Kurchatov understood immediately that Ginzburg's idea was a breakthrough and he arranged to have lithium deuteride produced on an industrial scale. 

The first test of the "Layer Cake" took place on August 12, 1953. Four days earlier, one of the Soviet leaders, Georgii Malenkov announced to the Supreme Soviet that the U.S. no longer had a monopoly in hydrogen weapons. The scientists, who were already at the test site heard the speech on the radio. And in his memoirs, Sakharov noted that Malenkov's announcement would have "raised the tension if we had not already been keyed up to the maximum." 

Just a few days before the detonation, the scientists realized that fallout from the blast might seriously injure people living in the surrounding area. At the last minute, the military commander organized an evacuation; some of those removed from their homes couldn't return for 18 months. 

Kurchatov was in charge of the test and gave the order for the countdown. A witness gave this account of the blast: "The earth trembled beneath us, and our faces were struck, like the lash of a whip, by the dull, strong sound of the rolling explosion. From the jolt of the shock wave it was difficult to stand on one's feet. A cloud of dust rose to a height of eight kilometers (five miles). The top of the atomic mushroom reached a height of twelve kilometers (seven and a half miles), while the diameter of the dust of the cloud column was approximately six kilometers (almost four miles). For those who observed the explosion from the west, day was replaced by night."

Soviet Two Stage Weapon Test 

In the spring of 1954, three years after U.S. scientists Edward Teller and Stanislaw Ulam came up with a solution for building a superbomb, their Soviet counterparts hit upon the same idea: radiation implosion. According to physicist Andrei Sakharov, several scientists came up with the answer at the same time. And they all recognized that this was the way to build a weapon of virtually unlimited explosive force. Almost immediately the team abandoned Sakharov's "Layer Cake" design which they had been working on for several years. 

A test of the new design was scheduled for November 20, 1955. By early October the device had been loaded onto a military train and sent the 2,000 miles from the weapons lab in Russia to the test site in Kazakhstan. In an effort to minimize the fallout from the blast, the bomb was to be dropped from a plane and detonated at an altitude sufficiently high to ensure that dust would not be drawn up into the radioactive cloud. To reduce the risk that the bomber would be ignited by the heat of the blast, it was painted with white reflective paint. 

The first attempt to carry out the mission was aborted at the very last moment. The plane had already taken off carrying its deadly cargo. As it approached ground zero, a low cloud unexpectedly obscured the crew's view of the test site. Igor Kurchatov, the scientific director of the Soviet nuclear program, called off the test. The airfield had iced over while the bomber was in the air and Kurchatov worried that a crash might cause the bomb to explode. Sakharov was ordered to the command post, where he stated in writing that an accidental detonation of the device was extremely unlikely. The runway was cleared and the plane landed safely. 

The test went ahead two days later. Sakharov watched the blast from a post about 45 miles away. He described it in his memoirs. "I saw a blinding yellow-white sphere swiftly expand, turn orange in a fraction of a second, then turn bright red and touch the horizon, flattening out at its base... Shock waves crisscrossed the sky, emitting sporadic milky-white cones and adding to the mushroom image. I felt heat like that from an open furnace on my face--and this was in freezing weather, tens of miles from ground zero." 

Following the success of the test, news of two accidents immediately dampened the scientists' exuberant mood. A trench had collapsed under the force of the explosion killing a young soldier. And in a nearby town a two-year-old girl was killed when the shock wave demolished a rudimentary bomb shelter. Seeing the unbelievable destruction caused by the blast and hearing about the two deaths made Sakharov reflect more deeply on his responsibility in creating weapons of mass destruction than he ever had before. "I experienced a range of contradictory sentiments, perhaps chief among them a fear that this newly released force could slip out of control and lead to unimaginable disasters." 

An incident at a banquet to celebrate the event heightened his foreboding. Sakharov made the first toast. In his memoirs he remembers saying: "May all our devices explode as successfully as today's, but always over test sites and never over cities." The military director of the test, Marshall Mitrofan Nedelin, responded with a joke that challenged the role of scientists in the Soviet Union.

The point of Nedelin's story was clear to Sakharov. The scientists' job was to create the weapons, not to decide how to use them; that was up to the Party leaders and military hierarchy. More than 20 years later he wrote: "Of course, I knew this already--I wasn't that naive. But understanding something in an abstract way is different from feeling it with your whole being, like the reality of life and death. The ideas and emotions kindled at that moment have not diminished to this day, and they completely altered my thinking."