Tsar Bomba

AN602
The Tsar Bomba mushroom cloud
Type	Thermonuclear weapon
Place of origin	Soviet Union
Production history
Number built	1 (plus one mock bomb)
Specifications
Weight	27,000 kilograms (60,000 lb)
Length	8 metres (26 ft)
Diameter	2.1 metres (6.9 ft)
Blast yield	50 megatons of TNT (210 PJ)

Tsar Bomba (Russian: Царь-бомба), is the nickname for the AN602 hydrogen bomb — the largest, most powerful nuclear weapon ever detonated.

Developed by the Soviet Union, the bomb was originally designed to have a yield of about 100 megatons of TNT (420 PJ); however, the bomb yield was reduced to 50 megatons—one quarter of the estimated yield of the 1883 eruption of Krakatoa—in order to reduce nuclear fallout. This attempt was successful, as it was one of the cleanest hydrogen bombs ever detonated. Only one bomb of this type was ever built and it was tested on October 30, 1961, in the Novaya Zemlya archipelago.^[1]

The remaining bomb casings are located at the Russian Atomic Weapon Museum, Sarov (Arzamas-16), and the Museum of Nuclear Weapons, All-Russian Research Institute of Technical Physics, Snezhinsk (Chelyabinsk-70). Neither of these casings has the same antenna configuration as the actual device that was tested.

The Tsar Bomba is attributed with many names in literature: Project number – Project 7000; Product code – Product code 202 (Izdeliye 202); Article designations – RDS-220 (РДС-220), RDS-202 (РДС-202), RN202 (PH202), AN602 (AH602); Codename – Vanya; Nicknames – Big Ivan, Tsar Bomba. The term "Tsar Bomba" was coined in an analogy with two other massive Russian objects: the Tsar Kolokol, the world's largest bell, and the Tsar Pushka, the world's largest howitzer. Although the bomb was so named by Western sources, the name is now used in Russia as well.

Design

Site of the detonation

A Tsar Bomba-type casing on display at Sarov

The Tsar Bomba was a three-stage Teller–Ulam design hydrogen bomb with a yield of 50 megatons (Mt).^[2] This is equivalent to 1,400 times the combined power of the two nuclear explosives used in World War II (Little Boy (13-18 kilotons) and Fat Man (21 kilotons), the bombs that destroyed Hiroshima and Nagasaki).^[3], or 10 times the combined power of all the explosives used in WWII. A three-stage H-bomb uses a fission bomb primary to compress a thermonuclear secondary, as in most H-bombs, and then uses energy from the resulting explosion to compress a much larger additional thermonuclear stage. However, there is evidence that the Tsar Bomba had a number of third stages rather than a single very large one.^[4]

The initial three-stage design was capable of approximately 100 Mt, but would have caused too much radioactive fallout. To limit fallout, the third stage and possibly the second stage had a lead tamper instead of a uranium-238 fusion tamper (which greatly amplifies the reaction by fissioning uranium atoms with fast neutrons from fusion reaction). This eliminated fast fission by the fusion-stage neutrons, so that approximately 97% of the total energy resulted from fusion alone (as such, it was one of the "cleanest" nuclear bombs ever created, generating a very low amount of fallout relative to its yield). There was a strong incentive for this modification since most of the fallout from a test of the bomb would fall on populated Soviet territory.^[4][5]

The components were designed by a team of physicists headed by Academician Julii Borisovich Khariton and including Andrei Sakharov, Victor Adamsky, Yuri Babayev, Yuri Smirnov, and Yuri Trutnev. Shortly after the Tsar Bomba was detonated, Sakharov began speaking out against nuclear weapons, which culminated in his becoming a dissident.^[1][5]

The test

The Tsar Bomba's fireball, measuring 8 kilometres (5.0 mi) in diameter, is said to have touched the ground and nearly reached the altitude of the deploying Tu-95 bomber.

The Tsar Bomba was flown to its test site by a specially modified Tu-95V release plane, flown by Major Andrei Durnovtsev. Taking off from an airfield in the Kola peninsula, the release plane was accompanied by a Tu-16 observer plane that took air samples and filmed the test. Both aircraft were painted with a special reflective white paint to limit heat damage.

The bomb, weighing 27 tons, was so large (8 metres (26 ft) long by 2 metres (6.6 ft) in diameter) that the Tu-95V had to have its bomb bay doors and fuselage fuel tanks removed. The bomb was attached to an 800 kilogram fall-retardation parachute, which gave the release and observer planes time to fly about 45 kilometres (28 mi) from ground zero.

The Tsar Bomba detonated at 11:32 on October 30, 1961 over the Mityushikha Bay nuclear testing range (Sukhoy Nos Zone C), north of the Arctic Circle on Novaya Zemlya Island in the Arctic Sea. The bomb was dropped from an altitude of 10.5 kilometres (6.5 mi); it was designed to detonate at a height of 4 kilometres (2.5 mi) over the land surface (4.2 kilometres (2.6 mi) over sea level) by barometric sensors.^[1][4][5]

The original, November 1961 A.E.C. estimate of the yield was 55-60 Mt, but since 1991 all Russian sources have stated its yield as 50 Mt. Khrushchev warned in a filmed speech to the Communist Parliament of the existence of a 100 Mt bomb (technically the design was capable of this yield). The fireball touched the ground, reached nearly as high as the altitude of the release plane and was seen and felt almost 1,000 kilometres (620 mi) from ground zero. The heat from the explosion could have caused third-degree burns 100 km (62 miles) away from ground zero. The subsequent mushroom cloud was about 64 kilometres (40 mi) high (nearly seven times the height of Mount Everest), which meant that the cloud was well inside the Mesosphere when it peaked. The base of the cloud was 40 kilometres (25 mi) wide. The explosion could be seen and felt in Finland. Atmospheric focusing caused blast damage up to 1,000 kilometres (620 mi) away. The seismic shock created by the detonation was measurable even on its third passage around the Earth.^[6] Its seismic body wave magnitude was about 5 to 5.25.^[7] The energy yield was around 7.1 on the Richter scale but, since the bomb was detonated in air rather than underground, most of the energy was not converted to seismic waves. The TNT equivalent of the 50 MT test could be represented by: a cube of TNT 1025 feet on a side; or, a train of 666,000 boxcars over 6300 miles long, each 50 foot car carrying 75 tons of TNT.

Since 50 Mt is 2.1×10¹⁷ joules, the average power produced during the entire fission-fusion process, lasting around 39 nanoseconds, was about 5.4×10²⁴ watts or 5.4 yottawatts (5.4 septillion watts). This is equivalent to approximately 1.4% of the power output of the Sun.^[8]

The Tsar Bomba is the single most physically powerful device ever utilized by humanity. Its size and weight precluded a successful delivery in case of a real war.^[9] By contrast, the largest weapon ever produced by the United States, the now-decommissioned B41, had a predicted maximum yield of 25 Mt, and the largest nuclear device ever tested by the US (Castle Bravo) yielded 15 Mt (this was due to an unexpected runaway lithium-7 reaction; the design yield was approximately 5 Mt). The largest weapons deployed by the Soviet Union were also around 25 Mt, as in the SS-18 Mod. 2 ICBM warheads.

Analysis

Comparative fireball radii for a selection of nuclear weapons, including the Tsar Bomba. Full blast effects extend many times beyond the radii of the fireballs themselves.

Zone of total destruction of the Tsar Bomba (as an example - over a map of Paris): red circle = total destruction (radius 35 kilometers), yellow circle = fireball (radius 3.5 kilometers).

The weight and size of the Tsar Bomba limited the range and speed of the specially modified bomber carrying it and ruled out its delivery by an ICBM (although on December 24, 1962, a 50 Mt ICBM warhead developed by Chelyabinsk-70 was detonated at 24.2 Mt to reduce fallout).^[10] In terms of physical destructiveness, much of its high yield was inefficiently radiated upwards into space. It has been estimated that detonating the original 100 Mt design would have released fallout amounting to about 25 percent of all fallout emitted since the invention of nuclear weapons.^[11] Hence, the Tsar Bomba was an impractically powerful weapon. It was decided that such a test blast would create too great a risk of nuclear fallout and a near certainty that the release plane would be unable to reach safety before detonation.^[12]

The Tsar Bomba was the culmination of a series of high-yield thermonuclear weapons designed by the USSR and USA during the 1950s (examples include the Mark-17^[13] and B41). Such bombs were designed because:

• The nuclear bombs of the day were large and heavy, regardless of yield, and could only be delivered by strategic bombers. Hence yield was subject to dramatic economies of scale;
• It was feared that many bombers would fail to reach their targets because their size and low speed made detection and interception easy. Hence maximizing the firepower carried by any single bomber was considered vital;
• Prior to satellite intelligence, each side lacked precise knowledge of the location of the other's military and industrial facilities;
• A bomb dropped without benefit of advanced inertial navigation systems could easily miss its intended target. Parachute retardation would only worsen the bomb's accuracy.

Thus certain bombs were designed to destroy an entire large city even if dropped five to ten kilometres from its centre. This objective meant that yield and effectiveness were positively correlated, at least up to a point. However, the advent of ICBMs accurate to 500 metres or better made such a design philosophy obsolete. Subsequent nuclear weapon design in the 1960s and 1970s focused primarily on increased accuracy, miniaturization, and safety. The standard practice for many years has been to employ multiple smaller warheads (MIRVs) to "carpet" an area. This results in greater ground damage.

Documentary

Footage from a Soviet documentary about the bomb is featured in Trinity and Beyond: The Atomic Bomb Movie (Visual Concept Entertainment, 1995), where it is referred to as the Russian monster bomb.^[14] The movie incorrectly states that the Tsar Bomba project broke the moratorium on nuclear tests. Soviets restarted their tests two months before Tsar Bomba, and there was no de jure moratorium in place at the time (the U.S. had already announced that it considered itself free to resume testing without further notice).^[15]

See also

• Soviet atomic bomb project
• Father of all bombs

References

External links

• Tsar Bomba at Carey Sublette's NuclearWeaponArchive.org
• Video of the Tsar Bomba delivery, blast and cloud at Sonicbomb.com
• Tsar Bomb - The biggest bomb ever
• Google Maps