B61-12 Test Unit Image
Sandia National Laboratories technologists Curt Tenorio (left) and Jessie Fowler install instrumentation on a B61-12 test unit for a vibration and shaker-shock test. (Photo by Randy Montoya)

Sandia National Laboratories marked a major milestone when the Nuclear Security Enterprise successfully produced the first completely refurbished bomb for the B61-12 life extension program in November 2021.

“This is the first complete unit built with nuclear and non-nuclear components that has been fully qualified from the ground up,” said David Wiegandt, a Sandia senior manager on the B61-12 program. “The first production unit is the first War Reserve B61-12 built at Pantex that meets all customer requirements and is acceptable for use by the U.S. Air Force.”

More than 5,000 employees have worked on the B61-12 life extension program at Sandia during the last decade. As part of the program, Sandia worked to refurbish, replace or reuse about 50 different components and sub-systems that make up the B61-12.

The B61, a nuclear gravity bomb deployed from U.S. Air Force and North Atlantic Treaty Organization bases, has been in service since 1968. The B61-12 will replace most older modifications of the B61 and have an extended service life of at least 20 years. The life extension program addresses all known age-related concerns found within the nation’s stockpile of B61 weapons, upgrades encryption algorithms, modernizes the safety and use control features of the weapon, and supports compatibility with future aircraft designs.

Sandia, Los Alamos National Laboratory and Boeing are the design agencies responsible for the design and engineering of the B61-12, with Sandia also producing custom electronics. Additional production activities are performed at Kansas City National Security Campus, Y-12 National Security Complex, the Savannah River Site and the Pantex Plant. The refurbished B61 is set to begin full-scale production in May 2022, with completion expected in 2026.

The program began with a concept phase where the team developed various weapon architectures that would meet NNSA and Air Force requirements. After the design was stabilized, the team started to develop and produce all the individual components that go into the weapon, then spent several years integrating those components into systems, and then tested them and made modifications and refinements as necessary. After about three full design cycles, the team reached the final design, said Matt Kerschen, a Sandia manager on the B61-12.

Kerschen described a couple firsts for the program, including integrating a U.S. Air Force supplied Tailkit Assembly that guides the bomb to its target location and implementing a new digital interface between the bomb and the aircraft flying it. Another key part of the program was the development and qualification testing of the bomb. Sandia completed a series of tests determining how the refurbished B61 would handle temperature, shock, vibration, radiation, humidity and more throughout its extended lifetime.

Sandia also coordinated with the Air Force Nuclear Weapons Center to test compatibility between the B61-12 and the different aircraft that will be capable of deploying it, Rich Otten, a Sandia senior manager on the B61-12, said.

“It starts with on-the-ground evaluations of the electrical system to ensure the B61-12 communicates with the aircraft and usually concludes with a flight test at Tonopah Test Range,” Otten said. “We learn a lot from both flight and ground tests. We want to make sure we understand everything before we fly, and a flight test is a final proof that in the combined environments the B61-12 operates as expected.”