Sandia National Laboratories will produce spare components until 2026, which it targets for the final closeout activities, while the National Nuclear Security Administration is now looking at the development and production of the B61-13 bomb.
Sandia National Laboratories announced on Feb. 20, 2025, the conclusion of the production of the B61-12 nuclear gravity bomb, nearly two months after the LPU (Last Production Unit) was produced in Dec. 2024, concluding the B61’s LEP (Life Extension Program). The laboratory will still produce spare components until 2026, the year planned for the final closeout activities.
SNL is the design, engineering and systems integration laboratory for the non-nuclear components in the B61-12’s LEP. It also produces several components to be delivered to the Kansas City National Security Campus and Pantex Plant for full-scale production.
The laboratory’s role was to refurbish, replace or reuse about 50 different components and subsystems that make up the B61-12. The B61-12’s First Production Unit (FPU) was delivered in 2021, with full-rate production starting a year later.
The B61, a nuclear gravity bomb deployed by the U.S. Air Force and North Atlantic Treaty Organization (NATO) forces, has been in service since 1968. The B61-12 will replace most older modifications of the B61, including the B61-3, B61-4, B61-7 and B61-11, and have an extended service life of at least 20 years.
B61-12 system production ends, sustainment begins
Source: Sandia pic.twitter.com/sDuFA0gXFS
— Casillic (@Casillic) February 20, 2025
The LEP addresses ageing and obsolescence issues in the components and parts of the B61 stockpile, including encryption algorithms, safety and use control features, and supports compatibility with future aircraft designs.The production began nearly three years ago and the LEP reported cost was around $9 billion.
As reported by The Aviationist in January, the NNSA (National Nuclear Security Administration) is now looking at the development and production of the B61-13 bomb.
Remanufactured bomb with reused components
The B61-12 is not exactly a new weapon, since it takes the warheads from the older B61-4 (that started production in 1979) and puts them in a new body. This contains advanced guidance, INS (Inertial Navigation System), electronics, a tail assembly by Boeing and two spin-rocket motors.
The low-yield tactical nuclear weapon has four yield options – 0.3, 1.5, 10 and 50 kilotons and an accuracy of roughly 30 meters, according to the Federation of American Scientists (FAS).
The B61-12 has a host of reused, redesigned and remanufactured components, including the Spin Rocket Motor, actuators, pulse battery assemblies, impact sensors, patch antennas, gas transfer system, power supplies, thermal batteries and casings.
Development and testing
An earlier press release from Sandia, announcing the first completely refurbished B61-12 as a part of the LEP in Feb. 2022, gave an insight into the technical processes of the development and testing journey. The program began with a concept phase where the team developed various weapon architectures that would meet the NNSA’s and Air Force’s requirements.
TEST PREP — Ron Maes, at right, and Jeff Meador (both 2155) prepare a B61-12 test assembly that will used to study and understand the behavior and performance of weapon components and systems under a variety of conditions. The work is part of Sandia’s B61 Life Extension Program pic.twitter.com/cdLeMNu5Jp
— Casillic (@Casillic) November 29, 2021
After the initial design was finalized, the team began to develop and produce all the individual components that go into the weapon. Several years were spent integrating those components into systems, with the team testing them and making modifications and refinements as necessary. It took “three full design cycles” for the team to freeze the final design configuration, according to Matt Kerschen, a Sandia manager on the B61-12.
A couple of firsts included integrating the U.S. Air Force-supplied Tail Kit Assembly and installing a new digital interface between the bomb and the user aircraft. Another key part was the qualification testing of the bomb, as Sandia completed a series of tests determining how the refurbished B61 would handle temperature, shock, vibration, radiation, humidity and more throughout its extended lifetime.
B61-12 DEVELOPMENT FLIGHT test just after release from an F-16C. Clearly visible are the spin rocket motor flames, which are part of the arming subsystem.
Source: Sandia pic.twitter.com/UZfI8W5Zva
— Casillic (@Casillic) July 7, 2019
The next several years saw laboratory and ground tests with full-scale bombs being subjected to a barrage of environments and physical handling.
One such test included the B61-12’s nose assembly fired from a Sandia National Laboratories’ Davis gun into an 8 foot deep pool, sending a 2,000 pound (907 kg) reaction mass flying away from the other end. Another trial was a Forward Ballistic Impact test on a rail mounted high-speed test track.
“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,” Rich Otten, a Sandia senior manager said in the release. “We learn a lot from both flight and ground tests…to (ensure) 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,” Otten added.
B61-12 nose assembly fired from Sandia National Laboratories’ Davis gun splashes water from an 8-foot-deep pool as a 2,000-pound reaction mass sails into the air from the other end of the gun in a successful impact test! Note the reaction mass flies away
01/28/2015 pic.twitter.com/KkFgYD1O25
— Casillic (@Casillic) March 27, 2022
Sandia also coordinated with the Air Force Nuclear Weapons Center to test compatibility between the B61-12 and the different user aircraft. Images available show the B61-12 being dropped from an F-16C in Jul. 2019 and an F-35A in Nov. 2020.
An F-35A flying at supersonic speed carried out a drop-test of the new B61-12 guided nuclear bomb. The first in a series of tests to certify the F-35A to be capable of delivering the B61-12. https://t.co/mM3yNVeGBE Some 480 B61-12s will arm US and NATO aircraft. pic.twitter.com/CzMAj8BO4p
— Hans Kristensen (also on Bluesky) (@nukestrat) November 23, 2020
Future
Scott Klenke, a Sandia senior manager overseeing stockpile sustainment, added that work will however continue with recurring “surveillance activities” on the B61-12, including randomly selecting units, disassembling them at the Pantex Plant and testing components at Sandia’s Weapons Evaluation Testing Laboratory.
Some units will also be used to support surveillance flight tests, laboratory and flight activities, with the collected testing data going into the system’s annual assessment report. This report precedes the Labs director’s letter “asserting the safety, reliability and performance of weapons in the stockpile.”
“These surveillance and assessment activities continue until retirement and until the last unit is dismantled,” Klenke said.
B61-12 Forward Ballistic Impact
Source: Sandia pic.twitter.com/Sm1LRsy6oq
— Casillic (@Casillic) November 10, 2023
User aircraft
The original B61-4 has been certified to be operated by nearly all strike aircraft in the U.S. Air Force and U.S. Navy inventory, including the B-2 Spirit, B-52 Stratofortress, F-16 Fighting Falcon, F/A-18 Hornet, the B-1B (which no longer has a nuclear role), and the since retired A-6 Intruder, A-4 Skyhawk, and F-111. The F-16s and the German and Italian Panavia Tornado are also certified to carry the B61 for various NATO partner nations.
A few nice shots of B61-12 with tail kit
Source: Sandia pic.twitter.com/FBSZz4INvJ
— Casillic (@Casillic) December 10, 2022
In 2020, the F-15E Strike Eagle became the first aircraft certified to carry the B61-12. The F-35A Lightning II, the B-2 Spirit, the F-16 Fighting Falcon and the German Air Force Panavia Tornado followed soon after. The NNSA had also said that the B61-12 would be integrated on the Italian Air Force’s Panavia Tornado and the U.S. Air Force’s incoming B-21 stealth bomber.
Nice close up of F35 with B61-12 Thermonuclear Gravity Bomb inside weapons bay!
Source: Sandia pic.twitter.com/AMPCPXorrD
— Casillic (@Casillic) March 26, 2022
The new B61-13 is however meant to be used by the Raider only. An October 2024 report from the National Nuclear Security Administration said that the First Production Unit (FPU) of the B61-13 is scheduled for FY 2026, with completion planned for FY2028. The development of the new variant was first announced in 2023.
