Updated weapons head to sea

Los Alamos National Laboratory, together with partners across the nuclear security complex, has completed the last production unit (LPU) of the W88 Alteration (Alt) 370, a multiyear program to modernize the W88 nuclear warhead carried onboard Ohio-class ballistic missile submarines. 

The W88 first entered the U.S. nuclear stockpile in 1988. In 2012 the alteration effort began to replace the warhead’s arming, fuzing, and firing subsystem and to add safety enhancements, including a lightning-arrestor connector. Sandia National Laboratories and Lockheed Martin led the initial update efforts, while Los Alamos—designer of the original 1980s-era warhead—played a limited role.

That role expanded in 2015, when the Nuclear Weapons Council broadened the scope of the alteration and tasked Los Alamos with refreshing the conventional high explosives and related components within the weapon’s nuclear explosive package.

The program reached a major milestone in July 2021, when the first production unit of the W88 Alt 370 was assembled at the Pantex Plant in Amarillo, Texas, and delivered into the stockpile. Four years later, the final unit has now been completed. Achieving this milestone required close collaboration among program managers and technical experts from Los Alamos, Sandia, Pantex, the Y-12 National Security Complex, and the Kansas City National Security Campus, who worked collectively on design, development, qualification, and component production.

“Reaching LPU for the W88 Alt 370 is a landmark accomplishment for this Laboratory and the entire complex,” says Anita Carrasco Griego, Weapons Systems division leader. “This program was unlike any other as it was defined by an extraordinary level of reacceptance work, much of it entirely new to us, and carried out under demanding constraints. Our teams met every challenge head-on. Hundreds of people across the complex worked with remarkable tenacity and professionalism to ensure this vital deterrent system was delivered successfully and on schedule. This accomplishment reflects the very best of our Laboratory: innovation under pressure, rigor in the face of the unknown, and unwavering commitment to national security.” ★