The W78 is an American
thermonuclear warhead
A thermonuclear weapon, fusion weapon or hydrogen bomb (H-bomb) is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a lowe ...
with an estimated yield of , deployed on the
LGM-30G Minuteman III intercontinental ballistic missile
An intercontinental ballistic missile (ICBM) is a ballistic missile with a range (aeronautics), range greater than , primarily designed for nuclear weapons delivery (delivering one or more Thermonuclear weapon, thermonuclear warheads). Conven ...
(ICBM) and housed in the Mark 12A
reentry vehicle
Atmospheric entry (sometimes listed as Vimpact or Ventry) is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. Atmospheric entry may be ''uncontrolled entr ...
. Minuteman III initially carried the older
W62 warhead with a yield of , but starting in December 1979 and ending in February 1982, some W62 were replaced with the W78. It is publicly estimated that 1083 warheads were manufactured.
History
The W78 was designed at
Los Alamos National Laboratory
Los Alamos National Laboratory (often shortened as Los Alamos and LANL) is one of the sixteen research and development Laboratory, laboratories of the United States Department of Energy National Laboratories, United States Department of Energy ...
(LANL) starting in 1974. It is thought that the warhead has never been tested at full yield, with the weapon producing a "disappointing" yield shortly before the 1976
Threshold Test Ban Treaty came into force, leading to a redesign of the weapon that was not complete before the treaty came into force. This led to a dispute between LANL and
Lawrence Livermore National Laboratory
Lawrence Livermore National Laboratory (LLNL) is a Federally funded research and development centers, federally funded research and development center in Livermore, California, United States. Originally established in 1952, the laboratory now i ...
who estimated the weapon's yield below that of LANL. The dispute was resolved by a panel led by former LLNL director
John Foster who found in favor of LANL's yield estimate.
[
The final W62 warhead was not removed from service until March 2010.]
Design
Dimensions of the W78 are unknown, but it fits within the Mark 12A reentry vehicle
Atmospheric entry (sometimes listed as Vimpact or Ventry) is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. Atmospheric entry may be ''uncontrolled entr ...
which is conically shaped. The RV is in diameter at its base and long, and total warhead and reentry vehicle weight is estimated to be .[
The H1224A and H1501A-1 containers have an inner diameter of 50.8 cm. Here is a diagram showing that the diameter of the reentry vehicle is no more than 50.8 cm.][
]
See also
* List of nuclear weapons
This is a list of nuclear weapons listed according to country of origin, and then by type within the states. The United States, Russia, China and India are known to possess a nuclear triad, being capable to deliver nuclear weapons by land, sea a ...
References
External links
W78 Warhead page
at nuclearweaponarchive.org
{{United States nuclear devices
Nuclear warheads of the United States
Military equipment introduced in the 1970s