B61 nuclear bomb

B61
B61 training unit intended for ground crew. It accurately replicates the shape and size of a "live" B61 (together with its safety/arming mechanisms) but contains only inert materials
Type	Nuclear bomb
Service history
Used by	United States
Production history
Designer	Los Alamos National Laboratory
Designed	1963
Manufacturer	Pantex Plant
Produced	1968 (full production)
Number built	3,155
Specifications
Weight	700 pounds (320 kg)
Length	11 feet 8 inches (3.56 m)
Diameter	13 inches (33 cm)
Blast yield	0.3–340 kilotons

The B61 nuclear bomb is one of the primary thermonuclear weapons in the U.S. following the end of the Cold War. It is an intermediate-yield strategic and tactical nuclear weapon featuring a two-stage radiation implosion design.

The B61 is a variable yield bomb (0.3 to 340 kiloton yield in various versions and settings) designed for carriage by high-speed aircraft. It has a streamlined casing capable of withstanding supersonic flight speeds. The weapon is 11 ft 8 in (3.56 m) long, with a diameter of about 13 inches (33 cm). Basic weight is about 700 pounds (320 kg), although the weights of individual weapons may vary depending on version and fuze/retardation configuration.

The B61, known before 1968 as the TX-61, was designed in 1963. It was designed and built by the Los Alamos National Laboratory in New Mexico. It began from a program for a lightweight, streamlined weapon launched in 1961. Production engineering began in 1965, with full production beginning in 1968 following a series of development problems.

Total production of all versions was approximately 3,155, of which approximately 1,925 remain in service as of 2002^[update], and some 1,265 are considered to be operational. The warhead has changed little over the years, although early versions have been upgraded to improve the safety features.

As of late 2013, there were 200 B61 bombs actively in use by the United States. Of these, 180 were deployed with NATO allies in Europe.

Nine versions of the B61 have been produced. Each shares the same "physics package", with different yield options.The newest variant is the B61 Mod 11, deployed in 1997, which is a ground-penetrating bunker buster.