Major milestones for the W88

The W88 warhead, which can be launched on missiles from Ohio-class submarines, entered the nuclear weapons stockpile in 1988. Deployed now for more than 30 years, the warhead has been updated to maintain its current state of readiness.

More specifically, the W88 has undergone an alteration (alt), which includes changes to the weapon’s systems, subsystems, or components. An alteration is a limited-scope change that affects the assembly, maintenance, and/or storage of a weapon. An alt may address identified defects and component obsolescence, but it does not change a weapon’s operational capabilities.

The W88’s alteration—officially called the W88 Alt 370—began in 2012 to replace the warhead’s arming, fusing, and firing subsystem and to include safety enhancements, such as a lightning arrestor connector. Sandia National Laboratories and Lockheed Martin were the primary organizations involved in the alt. Los Alamos National Laboratory, which had designed the original warhead in the 1980s, had a minor role.

But then, in 2015, the Nuclear Weapons Council expanded the scope of the alteration and asked Los Alamos—the design agency for the weapon’s nuclear explosive package—to become more involved. The Lab would be responsible for “CHE refresh activities,” which means that the conventional high explosives (CHE) and related components in the weapon’s nuclear explosive package would be replaced.

“The scope added into the ongoing Alt 370 project was significant, and there was no schedule flexibility to accommodate this effort,” says James Owen, associate Laboratory director for Weapons Engineering. “Nevertheless, we were confident that challenging Los Alamos to find innovative ways to accelerate our work—while maintaining the utmost in technical standards, quality, and project management—would result in remarkable success for the W88 and the nation’s deterrent.”

In July 2021, the first production unit (FPU) was delivered. In the FPU phase of the nuclear weapons life cycle, all weapons components have been produced through qualified processes; all the necessary qualification testing, engineering analysis, and physics certification activities have been completed; and the first production unit has been built at the Pantex plant, near Amarillo, Texas. In essence, all the processes required to produce the weapon are qualified and exercised.

In October 2021, the W88 Alt 370 successfully passed the Design Review and Acceptance Group review and is now a standard stockpile item, which means that the updated W88 warhead will gradually replace the older W88 warheads in the stockpile.

“I am extremely proud of the performance of our Los Alamos team; we rose to the challenge of supporting the deterrent by completing a large body of work in nearly record time, which is quite an accomplishment,” says Rob Bishop, who leads the Lab’s Stockpile Modernization group, which was largely responsible for the alteration. “The W88 Alt 370, with the CHE scope, will allow the W88 to continue to be reliable and effectively support the deterrent for future decades.”