Big Ivan, The Tsar Bomba (“King of Bombs”)

The World's Largest Nuclear Weapon

The device offically designated RDS-220, known to its designers as Big Ivan, and nicknamed in the west Tsar Bomba (and referred to as the Big Bomb by Sakharov in his Memoirs [Sakharov 1990]) was the largest nuclear weapon ever constructed or detonated.

 This three stage weapon was actually a 100 megaton bomb design, but the uranium fusion stage tamper of the tertiary (and possibly the secondary) stage(s) was replaced by one(s) made of lead.

This reduced the yield by 50% by eliminating the fast fissioning of the uranium tamper by the fusion neutrons, and eliminated 97% of the fallout (1.5 megatons of fission, instead of about 51.5 Mt), yet still proved the full yield design.

 The result was the "cleanest" weapon ever tested with 97% of the energy coming from fusion reactions. The effect of this bomb at full yield on global fallout would have been tremendous. It would have increased the world's total fission fallout since the invention of the atomic bomb by 25%.
The nickname Tsar Bomba is a reference to a famous Russian tradition for making gigantic artifacts for show. The world's largest bell (the Tsar Kolokol) and cannon (the Tsar Pushka) are on display at the Kremlin [Kalinin 1994; pg. 33].
 Having come to power by overthowing and assassinating the last royal family of Russia, the Soviet leadership would never have countenanced such a royalist name, but this designation has become popular in Russia since the collapse of the Soviet Union.
The entire 1961 test series in which it was conducted, the creation of the Tsar Bomba was the result of political calculation by the Soviet leadership, especially of Premier Nikita Khrushchev.
 A de facto moratorium had existed between the U.S., USSR and UK since the conclusion of the last U.S. and Soviet test series in 1958, and two years of discussion had been conducted regarding formal limitations on nuclear testing.
 But the Cold War continued at high pitch, with the occasional reductions in tension being only partial and transitory phenomena.
Many high-stakes cards remained to be played by the Soviets - the erection of the Berlin Wall and the deployment of missiles to Cuba being notable examples.
The decision to break the moratorium with a "testing spectacular" that coincided with the Twenty Second Congress of the Communist Party of the Soviet Union was a move cast in the same mold.
The Soviet weapons scientists had spent the three years since the last test series in 1958 developing new concepts and refining old ones, but they had not been preparing for a new test series per se until Khrushchev called a meeting with the "atomic scientists" - the leaders of the weapons program - on 10 July 1961.
There was no discussion of whether more tests were necessary or desirable, which Sakharov, the senior weapon designer, very much doubted.
 Khrushchev simply began the meeting with a speech declaring that tests would resume in the fall to 'show the imperialists what we could do', a decision that came as a surprise to the scientists present.
Khrushchev specifically cited as the primary motivation a political rather than a technical justification - his view that the international situation was deteriorating [Sakharov 1990, pg. 215]. From there on until the end of the test series it was an all-out effort to ready as many designs, concepts, and devices for testing as possible.

 
The test was conducted by air dropping the bomb from a specially modified Tu-95N "Bear A" strategic bomber piloted by mission commander Major Andrei E. Durnovtsev.

 
 It was released at 10,500 meters, and made a parachute retarded descent to 4000 meters in 188 seconds before detonation. By that time the release bomber was already in the safe zone about 45 km away.

 
 The drop area was over land at the Mityushikha Bay test site, on the west coast of Novaya Zemlya Island, above test field D-2, near Cape Sukhoy Nos. [Podvig et al 2001; pp. 466, 498], [Khalturin et al 2005]. Durnovtsev was immediately promoted to lieutenant colonel and made Hero of the Soviet Union. The Tu-95 was accompanied by a Tu-16 "Badger" airborne laboratory to observe and record the test. The time of the test is given by [Adamsky and Smirnov 1998] as 11:32 AM Moscow Time; it is listed in [Podvig et al 2001; pg. 498] as occurring at 06:33 Moscow Decree time.
The test location was about 55 km north of the Severny settlement and 250 km north of the headquarters at Belushya, from where it was observed by the State Commission.
 The bomb design team and the test supervisors, headed by Major General Nikolai Pavlov, Chairman of the State Commission, monitored the test at the airfield near Olenya station on the Kola Peninsula 1000 km away/
 Observers were also at many other locations. Among these were Soviet Minister of Medium Machine Building Efim Slavsky and Marshal of the Soviet Union Kirill Moskalenko, deputies to the 22nd Congress of the CPSU then in session, who had arrived by plane on the day of the test to observe the explosion.
They observed the test aboard an Il-14 "crate" at a distance of several hundred kilometers from ground zero. Sakharov himself stayed by the phone, presumably at Arzamas-16, waiting for a call from Maj. Gen. Pavlov.

The effects were spectacular. Despite the very substantial burst height of 4,000 m (13,000 ft) the vast fireball reached down to the Earth, and swelled upward to nearly the height of the release plane.
The blast pressure below the burst point was 300 PSI, six times the peak pressure experienced at Hiroshima. The flash of light was so bright that it was visible at a distance of 1,000 kilometers, despite cloudy skies. One participant in the test saw a bright flash through dark goggles and felt the effects of a thermal pulse even at a distance of 270 km. One cameraman recalled:

The clouds beneath the aircraft and in the distance were lit up by the powerful flash. The sea of light spread under the hatch and even clouds began to glow and became transparent. At that moment, our aircraft emerged from between two cloud layers and down below in the gap a huge bright orange ball was emerging. The ball was powerful and arrogant like Jupiter. Slowly and silently it crept upwards.... Having broken through the thick layer of clouds it kept growing. It seemed to suck the whole earth into it. The spectacle was fantastic, unreal, supernatural.

Another observer, farther away, described what he witnessed as:

... a powerful white flash over the horizon and after a long period of time he heard a remote, indistinct and heavy blow, as if the earth has been killed!

A shock wave in air was observed at Dickson settlement at 700 km; windowpanes were partially broken to distances of 900 km. All buildings in Severny (both wooden and brick), at a distance of 55 km, were completely destroyed.

In districts hundreds of kilometers from ground zero, wooden houses were destroyed, and stone ones lost their roofs, windows and doors; and radio communications were interrupted for almost one hour. The atmospheric disturbance generated by the explosion orbited the earth three times.

 

 A gigantic mushroom cloud rose as high as 64 kilometers (210,000 ft).

Despite being exploded in the atmosphere, it generated substantial seismic signals. According to a bulletin of the U.S. Geological Survey it had seismic magnitude mb = 5.0 to 5.25. The blast wave was detected circling the world.[Khalturin et al 2005]

Some time after the explosion, photographs were taken of ground zero. "The ground surface of the island has been levelled, swept and licked so that it looks like a skating rink," a witness reported.

 "The same goes for rocks. The snow has melted and their sides and edges are shiny. There is not a trace of unevenness in the ground.... Everything in this area has been swept clean, scoured, melted and blown away

To watch the film of the drop and the explosion, go to the links below:

https://www.youtube.com/watch?v=LxD44HO8dNQ