The
Mk/B53 was a high-yield
bunker busterBunker-busting nuclear weapons, also known as earth-penetrating weapons , are a type of nuclear weapon designed to penetrate into soil, rock, or concrete to deliver a nuclear warhead to a target. These weapons would be used to destroy hardened, underground military bunkers buried deep in the ground...
thermonuclear weapon developed by the
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
during the
Cold WarThe Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
. Deployed on
Strategic Air CommandThe Strategic Air Command was both a Major Command of the United States Air Force and a "specified command" of the United States Department of Defense. SAC was the operational establishment in charge of America's land-based strategic bomber aircraft and land-based intercontinental ballistic...
bombers, the B53, with a
yieldThe explosive yield of a nuclear weapon is the amount of energy discharged when a nuclear weapon is detonated, expressed usually in the equivalent mass of trinitrotoluene , either in kilotons or megatons , but sometimes also in terajoules...
of 9 MtonTNT, was the most powerful weapon in the U.S. nuclear arsenal after the last
B41 nuclear bombThe B41 was a thermonuclear weapon deployed by the United States Strategic Air Command in the early 1960s. It was the most powerful nuclear bomb ever developed by the United States with a theoretical maximum yield of 25 megatons...
s were retired in 1976.
The B53 was the basis of the
W-53 warhead carried by the Titan II Missile, which was decommissioned in 1987. Although not in active service for many years before 2010, fifty B53s were retained during that time as part of the "Hedge" portion of the
Enduring StockpileThe "Enduring Stockpile" is the United States's arsenal of nuclear weapons following the end of the Cold War.During the Cold War the United States produced over 70,000 nuclear weapons. By its end the U.S. stockpile was about 23,000 weapons of 26 different types...
until its complete dismantling in 2011. The last B53 was disassembled on October 25, 2011, a year ahead of schedule.
With its retirement, the largest bomb currently in service in the U.S. nuclear arsenal is the
B83The B83 nuclear weapon is a variable yield gravity bomb developed by the United States in the late 1970s, entering service in 1983. With a maximum yield of 1.2 megatons, it is currently the most powerful atomic weapon in the US arsenal...
, with a
maximum yieldVariable yield — or dial-a-yield — is an option available on most modern nuclear weapons. It allows the operator to specify a weapon's yield, or explosive power, allowing a single design to be used in different situations...
of 1.2 MtonTNT. The B53 was replaced in the
bunker-bustingBunker-busting nuclear weapons, also known as earth-penetrating weapons , are a type of nuclear weapon designed to penetrate into soil, rock, or concrete to deliver a nuclear warhead to a target. These weapons would be used to destroy hardened, underground military bunkers buried deep in the ground...
role by a variant of the two-stage
B61 nuclear bombThe B61 nuclear bomb is the primary thermonuclear weapon in the U.S. Enduring Stockpile following the end of the Cold War. It is an intermediate yield strategic and tactical nuclear weapon featuring a two-stage radiation implosion design....
.
History
Development of the weapon began in 1955 by
Los Alamos National LaboratoryLos Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...
, based on the earlier
Mk 21The Mark 21 nuclear bomb was a United States nuclear gravity bomb first produced in 1955. It was based on the TX-21 "Shrimp" prototype that had been detonated during the Castle Bravo test in March 1954...
and
Mk 46The B46 nuclear bomb was a tested but never deployed American high-yield thermonuclear bomb which was designed and tested in the late 1950s. Though originally intended to be a production design, the B46 ended up being only an intermediate prototype which was test fired several times...
weapons. In March 1958 the
Strategic Air CommandThe Strategic Air Command was both a Major Command of the United States Air Force and a "specified command" of the United States Department of Defense. SAC was the operational establishment in charge of America's land-based strategic bomber aircraft and land-based intercontinental ballistic...
issued a request for a new
Class C (less than five tons, megaton-range) bomb to replace the earlier
Mk 41The B41 was a thermonuclear weapon deployed by the United States Strategic Air Command in the early 1960s. It was the most powerful nuclear bomb ever developed by the United States with a theoretical maximum yield of 25 megatons...
. A revised version of the
Mk 46 became the
TX-53 in 1959. The development TX-53 warhead was apparently never tested, although an experimental TX-46 predecessor design was detonated 28 June 1958 as
HardtackOperation Hardtack I was a series of 35 nuclear tests conducted by the United States in 1958 in the Pacific Ocean.Operation Newsreel was a series of three high-altitude nuclear tests conducted as part of Hardtack I. The individual tests in the series were Orange, Teak and Yucca.-Test Blasts:-...
Oak, which detonated at a yield of 8.9
MegatonsTNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...
.
The
Mk 53 entered production in 1962 and was built through June 1965. About 340 bombs were built. It entered service aboard
B-47 StratojetThe Boeing Model 450 B-47 Stratojet was a long-range, six-engined, jet-powered medium bomber built to fly at high subsonic speeds and at high altitudes. It was primarily designed to drop nuclear bombs on the Soviet Union...
,
B-52G StratofortressThe Boeing B-52 Stratofortress is a long-range, subsonic, jet-powered strategic bomber operated by the United States Air Force since the 1950s. The B-52 was designed and built by Boeing, who have continued to provide maintainence and upgrades to the aircraft in service...
, and
B-58 HustlerThe Convair B-58 Hustler was the first operational supersonic jet bomber capable of Mach 2 flight. The aircraft was designed by Convair engineer Robert H. Widmer and developed for the United States Air Force for service in the Strategic Air Command during the 1960s...
bomber aircraft in the mid-1960s. From 1968 it was redesignated
B53.
Some early versions of the bomb were dismantled beginning in 1967. About 50 bomb and 54
TitanTitan was a family of U.S. expendable rockets used between 1959 and 2005. A total of 368 rockets of this family were launched, including all the Project Gemini manned flights of the mid-1960s...
warhead versions were in service through 1980. After a W-53-equipped Titan II missile exploded in Arkansas, the remaining Titan warheads were retired. The B53 was intended to be retired in the 1980s, but 50 units remained in the active stockpile until the deployment of the B61-11 in 1997. At that point the obsolete B53s were slated for immediate disassembly; however, the process of disassembling the units was greatly hampered by safety concerns as well as a lack of resources. In 2010 authorization was given to disassemble the 50 bombs at the
PantexThe Pantex plant is America's only nuclear weapons assembly and disassembly facility and is charged with maintaining the safety, security and reliability of the nation’s nuclear weapons stockpile. The facility is located on a 16,000 acre site 17 miles northeast of Amarillo, in Carson County,...
plant in Texas. The process of dismantling the last remaining B53 bomb in the stockpile commenced on October 25, 2011 and was completed soon afterwards.
Specifications
The B53 was 12 in 6 in (3.81 m) long with a diameter of 50 inches (1.27 m). It weighed 8850 pounds (4,014.3 kg), including the 800 to 900 lb (362.9 to 408.2 kg)
parachuteA parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon...
system and the honeycomb aluminum
nose coneThe term nose cone is used to refer to the forwardmost section of a rocket, guided missile or aircraft. The cone is shaped to offer minimum aerodynamic resistance...
to enable the bomb to survive
laydown deliveryLaydown delivery is a mode of deploying a free-fall nuclear weapon in which the bomb's fall is slowed by parachute so that it actually lands on the ground before detonating. Laydown delivery requires that the weapon's case be reinforced so that it can survive the impact, and generally involves a...
. It had five parachutes: one 5 feet (1.52 m)
pilot chuteA pilot chute is a small auxiliary parachute used to deploy the main or reserve parachute. The pilot chute is connected to the deployment bag containing the parachute by a bridle. On modern skydiving rigs three types of pilot chutes can be found:...
, one 16 feet (4.88 m) extractor chute, and three 48 feet (14.63 m) main chutes. Chute deployment depends on delivery mode, with the main chutes used only for laydown delivery. For free-fall delivery, the entire system was jettisoned.
The warhead of the B53 used oralloy (highly enriched
uraniumUranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
) instead of
plutoniumPlutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...
for fission, with a mix of
lithiumLithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
-6
deuterideDeuterium, also called heavy hydrogen, is one of two stable isotopes of hydrogen. It has a natural abundance in Earth's oceans of about one atom in of hydrogen . Deuterium accounts for approximately 0.0156% of all naturally occurring hydrogen in Earth's oceans, while the most common isotope ...
fuel for fusion. The
explosive lensAn explosive lens—as used, for example, in nuclear weapons—is a highly specialized explosive charge, a special type of a shaped charge. In general, it is a device composed of several explosive charges that are shaped in such a way as to change the shape of the detonation wave passing through it,...
comprised a mixture of
RDXRDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It was developed as an explosive which was more powerful than TNT, and it saw wide use in WWII. RDX is also known as cyclonite, hexogen , and T4...
and
TNT, which was not
insensitiveInsensitive munitions are munitions that are chemically stable enough to withstand mechanical shocks, fire, and impact by shrapnel, but that can still explode as intended to destroy their targets.-Description:...
. Two variants were made: the
B53-Y1, a "dirty" weapon using a U-238-encased secondary, and the
B53-Y2 "clean" version with a non-fissile (
leadLead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
or
tungstenTungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...
) secondary casing. Explosive yield was approximately nine
megatonsTNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...
.
Role
It was intended as a
bunker busterA bunker buster is a bomb designed to penetrate hardened targets or targets buried deep underground.-Germany:Röchling shells were bunker-busting artillery shells, developed by German engineer August Cönders, based on the theory of increasing sectional density to improve penetration.They were tested...
weapon, using a surface blast after laydown deployment to transmit a
shock waveA shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...
through the earth to collapse its target. Attacks against the Soviet deep underground leadership shelters in the
ChekhovChekhov is a town and the administrative center of Chekhovsky District of Moscow Oblast, Russia. Before 1954, it was named Lopasnya , after the Lopasnya River. Population: 56,000 ....
/Sharapovo area south of Moscow envisaged multiple B53/W53 exploding at ground level. It has since been supplanted in such roles by the earth-penetrating
B61 Mod 11The B61 nuclear bomb is the primary thermonuclear weapon in the U.S. Enduring Stockpile following the end of the Cold War. It is an intermediate yield strategic and tactical nuclear weapon featuring a two-stage radiation implosion design....
, a bomb that penetrates the surface to deliver much more of its explosive energy into the ground, and therefore needs a much smaller yield to produce the same effects.
The B53 was intended to be retired in the 1980s, but 50 units remained in the active stockpile until the deployment of the B61-11 in 1997. At that point the obsolete B53s were slated for immediate disassembly; however, the process of disassembling the units was greatly hampered by safety concerns as well as a lack of resources. The last remaining B53 bomb began the disassembly processes on Tuesday, 25 October 2011 at the Energy Department’s Pantex Plant.
W53
The
W53 warhead of the Titan II ICBM used the same physics package as the B53, without the air drop-specific components like the parachute system, reducing its mass to 8140 lb (3,692.2 kg). With a yield of 9
MegatonsTNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...
, it was the highest yield warhead ever deployed on a US missile. About 65 W53 warheads were constructed between December 1962 and December 1963.
On September 19, 1980 a fuel leak caused a Titan II to explode within its silo in
ArkansasArkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...
, throwing the W53 warhead some distance away. Due to the safety measures built into the weapon, it did not explode or release any radioactive material. 52 active missiles were deployed in silos prior to the beginning of the retirement program in October 1982. With the retirement of the Titan fleet, disassembly of the W53 warheads was completed by about 1988.
Effects
Assuming a detonation at optimum height, a 9 megaton blast would result in a fireball with an approximate 4 kilometre diameter. The radiated heat would be sufficient to cause lethal
burnsA burn is a type of injury to flesh caused by heat, electricity, chemicals, light, radiation or friction. Most burns affect only the skin . Rarely, deeper tissues, such as muscle, bone, and blood vessels can also be injured...
to any unprotected person within a 28.7 kilometres (17.8 mi) radius (995 square mile). Blast effects would be sufficient to collapse most residential and industrial structures within a 14.9 km (9.3 mi) radius (300 square mile); within 5.7 kilometres (3.5 mi) virtually all above-ground structures would be destroyed and blast effects would inflict near 100% fatalities. Within 4.7 km (2.9 mi) a 500 rem dose of
ionizing radiationIonizing radiation is radiation composed of particles that individually have sufficient energy to remove an electron from an atom or molecule. This ionization produces free radicals, which are atoms or molecules containing unpaired electrons...
would be received by the average person, sufficient to cause a 50% to 90% casualty rate independent of thermal or blast effects at this distance.
Artifacts
- B53 on display in the free introduction exhibit room at the Atomic Testing Museum
The Atomic Testing Museum in Las Vegas, Nevada, documents the history of nuclear testing at the Nevada Test Site in the desert north of Las Vegas.-Founding:The museum opened in March 2005...
, Las Vegas, NevadaLas Vegas is the most populous city in the U.S. state of Nevada and is also the county seat of Clark County, Nevada. Las Vegas is an internationally renowned major resort city for gambling, shopping, and fine dining. The city bills itself as The Entertainment Capital of the World, and is famous...
- B53 on display at the Wings Over the Rockies Air and Space Museum
The Wings Over the Rockies Air and Space Museum is located on the former grounds of Lowry Air Force Base in Denver, Colorado. The museum, which opened in 1994, is housed in the Hangar #1 built in 1939. The museum preserves the history of Lowry AFB's operations from 1938 to 1994 in its...
, Denver, ColoradoColorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
- Mark 53 casing is on display in the Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
Gallery at the National Museum of the United States Air ForceThe National Museum of the United States Air Force is the official museum of the United States Air Force located at Wright-Patterson Air Force Base northeast of Dayton, Ohio. The NMUSAF is the world's largest and oldest military aviation museum with more than 360 aircraft and missiles on display...
in Dayton, OhioDayton is the 6th largest city in the U.S. state of Ohio and the county seat of Montgomery County, the fifth most populous county in the state. The population was 141,527 at the 2010 census. The Dayton Metropolitan Statistical Area had a population of 841,502 in the 2010 census...
.
External links