The National Nuclear Security Administration said Monday it has wrapped up production of critical non-nuclear systems required to upgrade the W76 warhead.

The Department of Energy’s (DoE) semiautonomous stockpile steward said the milestone involves the W76’s Arming Fuzing Subsystem: a single assembly that includes “the weapon’s radar, programmer, and timer.” The NNSA did not say exactly when it hit this production milestone.

Cutaway of W76 warhead and Mk-4 reentry vehicle. Image: Los Alamos National Lab
Cutaway of W76 warhead and Mk-4 reentry vehicle. Image: Los Alamos National Lab

The W76-1 is a warhead for the U.S. Navy’s submarine-launched ballistic missile, the Trident II D5. The warhead was first put into service in 1978 with a 20-year design life. The DoE in 2000 approved the current life extension program, which aims to extend the warhead’s useful life to 60 years. The NNSA delivered the first refurbished W76 warhead to the Navy in 2009.

While the Trump administration in May requested a small increase for the W76 life extension program — about $225 million for fiscal 2018, or $1.25 million more than the 2017 appropriation — spending on the program is trending down, according to DoE.

In 2016, the NNSA received almost $245 million for the W76-1 life extension. Included in that was $20 million to procure W76-1 parts and components for the Kansas City National Security Complex, which specializes in manufacturing the non-nuclear parts of U.S. nuclear weapons.

The Los Alamos and Sandia national laboratories designed the original W-76 warhead. Much of the hands-on work for the warhead’s life extension is done at the Pantex Plant in Texas: the NNSA’s main warhead assembly-and-disassembly hub. The Y-12 National Security Complex on the Oak Ridge Reservation in Tennessee, with its uranium enrichment and refinement capabilities, also contributes.

The W76 life extension program is slated to finish in 2019 and will not add any new “military capabilities” to the warhead, according to the NNSA.