The W91 was an American thermonuclear warhead intended for use on the SRAM-T

AGM-131 SRAM II

The SRAM II was a nuclear air-to-surface missile intended as a replacement for the AGM-69 SRAM, but it was cancelled by President George H.W...

 variant of the AGM-131 SRAM II

AGM-131 SRAM II

The SRAM II was a nuclear air-to-surface missile intended as a replacement for the AGM-69 SRAM, but it was cancelled by President George H.W...

 air to ground missile.

What was to become the W91 design entered into a Phase 2 design competition between the various nuclear weapons laboratories in November 1988. Further development details are somewhat unclear, but a Los Alamos National Laboratory

Los Alamos National Laboratory

Los 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...

 design won the competition.

The design that emerged was a 310 pound, selectable 10 or 100 kiloton yield nuclear weapon. Other physical characteristics have not been well described in public documents. The design has been described as being named the "New Mexico 1" code name, and as using TATB

TATB

TATB, or triaminotrinitrobenzene, is an aromatic explosive, based on the basic six-carbon benzene ring structure with three nitro functional groups and three amine groups attached, alternating around the ring....

 based insensitive plastic bonded explosive and a fire resistant nuclear fissile material core or pit.

The design was cancelled in September 1991 along with the SRAM T missile, prior to production of any units, though some test devices may have been manufactured.

Notably, the W91 was the last new US nuclear weapon design to reach the point of receiving a model number designation (entering Phase 3 development status).

External links

• University of California 1989 nuclear weapons labs status report
• Allbombs.html at the Nuclear Weapon Archive at nuclearweaponarchive.org