B83 (nuclear weapon)
B83 gravity bombs have the highest yield of any deployed U.S. nuclear weapon. Called the "modern strategic bomb", it has a yield adjustable between the "low kiloton" range and 1.2 megatons. They are carried aboard B-52 and B-2 bombers, as well as tactical aircraft including the F-16 Fighting Falcon, F-18 Hornet and F-18 Super Hornet, and AV-8 Harrier. A B-2 can carry up to 16 and a B-52 up to 8.
Designed by Lawrence Livermore National Laboratory, 650 were built between 1984 and 1991. The weapon remains in active service; there is some speculation that it might be the last U.S. nuclear gravity bomb since missile delivery may be the standard in the future. Without earth penetration, nuclear weapons may not be able to attack deep facilities — which are in the range of specialized precision guided munitions. The B83 had been considered for the Robust Nuclear Earth Penetrator cancelled by Congress. 9MT B53 bombs remain in storage but are not operational.
The bomb can be dropped at high or low altitude, and has a Kevlar parachute that allows low-altitude delivery from a supersonic aircraft. It was the first U.S. nuclear weapon designed with insensitive high explosive, but it "has LX-10 boosters that should have an impact on the likelihood of detonation in accidents.". The B83 is equipped with a Category D Permissive Action Link.  In addition, it has a fire-resistant pit and enhanced electronic isolation. While it is not ground-penetrating, it has a reinforced steel nose that lets it be dropped at supersonic speed at 45 meter altitude.
- Michael A. Levi, "The Case against New Nuclear Weapons", Issues in Science and Technology
- Safe Handling of Insensitive High Explosive Weapon Subassemblies at the Pantex Plant, Defense Nuclear Facilities Safety Board, September 1999, DNFSB/TECH-24, p. 4-1
- Carey Sublette (November 11, 1997), The B83 (Mk-83) Bomb: High yield strategic thermonuclear bomb
- Ray Kidder (26 July 1991), Report to the Congress: Assessment of the Safety of U.S. Nuclear Weapons and Related Nuclear Test Requirements, Lawrence Livermore National Laboratory, Report UCRL-LR-107454,