The term “life extension program (LEP)” means a program to repair/replace components of nuclear weapons to ensure the ability to meet military requirements. By extending the "life," or time that a weapon can safely and reliably remain in the stockpile without having to be replaced or removed, National Nuclear Security Administration (NNSA) is able to maintain a credible nuclear deterrent without producing new weapons or conducting new underground nuclear tests.
Underlying the LEP planning process, NNSA remains committed to supporting the President’s nuclear agenda as articulated in the 2010 Nuclear Posture Review . LEP activities will support the goal to reduce both the number of warhead types and the stockpile size by formulating options for interoperable (i.e., common or adaptable) warheads that could be flexibly deployed across different delivery platforms.
Additionally, a well-planned and well-executed stockpile life extension strategy will result in improved safety and security while also enabling the Department of Defense to build a deployment and hedgestrategy consistent with the Administration’s agenda to establish a smaller, yet still effective, deterrent.
Each facility in NNSA's nuclear weapons complex contributes to the life extension process. The majority of the physical work on the warhead and bombs is carried out at the NNSA Production Office which contains the Pantex Plant  and Y-12 National Security Complex . The Pantex Plant does assembly and disassembly of the warheads and bombs while the Y-12 National Security Complex manufactures, assembles, and disassembles certain key components. The Kansas City Plant’s  main mission is to manufacture and procure key non-nuclear components. The design laboratories – Los Alamos , Lawrence Livermore  and Sandia National Laboratories  - assess the health of the current stockpile, design the components and systems for the life extension program warheads and bombs, and certify the life extended models when they enter the stockpile. The Nevada National Security Site  provides facilities and expertise for experiments used to assess the health of the current stockpile systems and to evaluate proposed component designs for life extension programs. The Savannah River Site  provides tritium gas, an essential and limited life material used in modern warheads.
NNSA must develop individual life extension programs by using science-based research for each weapon type and develop specific solutions to extend the lifetime of each particular weapon because each is unique. Over time, the components of nuclear warheads deteriorate, even when kept in storage. LEPs will address known aging issues in weapon systems, and each LEP will study the options for increasing the safety, security and reliability of weapons on a case-by-case basis.
Life extension efforts are intended to extend the lifetime of a weapon for an additional 20 to 30 years. The current planning scenario envisions that the useful lifetimes of the W76, B61, and the W88 will have been extended through major LEP efforts by 2031. The Phase 6.X process  should be used when life extension activity is planned for a weapon already in the stockpile.
In summary, the current LEP and alteration plans endorsed by the Nuclear Weapons Council include the following:
- W76-1 LEP
- Extend the life of the Submarine Launched Ballistic Missile (SLBM) W76 warhead for an additional 30 years by refurbishing various components.
- Complete production no later than the end of fiscal year (FY) 2019
- W88 Alt 370
- Replacing the arming, fuzing, and firing system in the W88 SLBM warhead.
- Complete development to support a first production unit no later than December 2019
- B61-12 LEP
- Consolidation of multiple B61 mods and replacement of aging components.
- Complete a first production unit no later than March 2020
- W78/W88-1 LEP
- Extend the life of the Air Force’s W78 warhead, including the possibility of using the resulting warhead on SLBMs to reduce the number of warhead types.
- Complete a first production unit no earlier than 2030