The W82 was a low yield tactical nuclear warhead developed by the United States and designed to be used in a 155mm artillery shell (sometimes called the XM785 shell). It was conceived as a more flexible replacement for the W48, the previous generation of 155mm nuclear artillery shell. A previous attempt to replace the W48 with the W74 munition was canceled due to cost.
Originally envisioned as a dual purpose weapon, with interchangeable components to allow the shell to function as either a 'standard' fission explosive, or an "enhanced radiation" device, the warhead was developed at Lawrence Livermore Laboratory starting in 1977. The eventual prototype round had a yield of 2 kilotons in a package 34 inches long and weighing 95 lbs, which included the rocket-assisted portion of the shell. The unit cost of the weapon was estimated at $4 million. Although enhanced radiation devices were considered more effective at blunting an invasion due to the high and persistent radiation that they produce, the more complex design eventually led to the cancellation of the dual purpose W-82-0 program in 1982. Development of a 'standard' weapon, the W-82-1, was restarted in 1986. The program was finally cancelled in 1991 due to the end of the Cold war.