The Mk4B protects a submarine-launched ballistic missile warhead during its return through Earth’s atmosphere. The program will convert every W76-1/Mk4A and W76-2/Mk4A unit in the stockpile to the newer Mk4B configuration.
“Sandia is providing leadership in system integration and is the design agency for the NNSA’s non-nuclear components in the Mk4B,” said Todd Simmermacher, a Sandia National Laboratories manager in nuclear deterrence. “We make sure all the requirements are met and that the system is qualified.”
Sandia is working with Los Alamos National Laboratory and Lockheed Martin Space, which are also design agencies for the program. NNSA and the Navy used established processes at the Kansas City National Security Campus, Pantex Plant and Lockheed Martin Space to deliver components early.
“NNSA is making good on our commitment to accelerate production for the nation’s nuclear deterrent and delivering the first W76 Mk4B to the Navy ahead of schedule,” NNSA Administrator Brandon Williams said. “As a former nuclear submarine officer, I have a special appreciation for the sea leg of our triad, which is essential to our assured second-strike capability.”
“Enhancing the reliability of the W76’s reentry body will help ensure the reliability of the deterrent and strengthen America’s national security more broadly,” Williams said. The milestone supports U.S. military requirements for maintaining the sea-based element of the nuclear triad.
“Once a unit is converted to a Mk4B, it is ready to head back to the stockpile and serve as part of the nuclear deterrent,” Simmermacher said. “It requires a Labs-wide effort and partnership across the enterprise to deliver this product.”
