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Weapons of Mass Destruction (WMD)

W76-0/Mk4 / W76-1/Mk4A

The W76/MK4 Reentry Body deployed on the TRIDENT Strategic Weapon System at one point comprised the bulk of the Nation's Strategic Deterrent and reached its original design life. The cost of producing a new reentry body being prohibitive, continued high confidence in this deterrent had to be preserved through the life extension of critical components in the system. A team at Los Alamos National Laboratory in New Mexico designed the W-76.

The Department of Energy’s National Nuclear Security Administration (DOE/NNSA) celebrated the completion of the Program of Record for the W76-1 Life Extension Program (LEP) 23 January 2019 at the Pantex Plant in Amarillo, Texas. The W76-1 is a refurbished W76-0 warhead, which is a submarine-launched ballistic missile system first introduced into the stockpile for the U.S. Navy in 1978. This LEP has strengthened the safety and security of the United States by extending the warhead’s service life from 20 years to 60 years. “A great deal of teamwork and dedication went into this incredible achievement. People all across our country did their part to make the delivery of this refurbished warhead possible and they did it ahead of schedule and under budget,” said U.S. Secretary of Energy Rick Perry. The LEP has been underway since October 1998 and every one of the Nuclear Security Enterprise’s labs, plants, and sites contributed to this major modernization program.

“The success we’ve achieved on the W76-1 is a testament to our ability across the Nuclear Security Enterprise to deliver on commitments to the Department of Defense, Congress, and the American people,” said Undersecretary for Nuclear Security and NNSA Administrator Lisa E. Gordon- Hagerty. “With this proven path forward, we will continue to make progress on our other modernization programs, including the B61-12, W80-4 and the W88 Alteration 370.”

The W76/Mk4 reentry body assembly (RBA) on Trident I (C4) and Trident II (D5) strategic weapon systems were designed and produced between 1972 and 1987. Meeting its mission required that the W76/Mk4 RBA be deployed well beyond its original service life of 20 years. W76 refurbishment, scheduled to begin in FY'07, was to include re-qualifying the pit, replacing the primary high-explosive, secondary refurbishment, a new arming, fuzing and firing (AF&F) system, and a new gas transfer system.

The removal from strategic service of 4 SSBNs was expected to result in the transfer of over 700 W76 warheads to the inactive stockpile.

To ensure the protection of the public, employees, facilities, and the environment from nuclear explosive accidents, Department of Energy (Department) policy specifies that a team of nuclear explosive safety experts must independently review nuclear explosive operations every five years. This review process is called a Nuclear Explosive Safety (NES) study. Operations for the W76 were suspended twice since 1989 - once for 24 months and then again for 18 months - after the initial NES and revalidation expired. A new NES study was completed in September 2000; however, it did not cover reassembly operations.

In 1993, the Department initiated a process to reduce or eliminate hazards in assembly, disassembly, and testing of nuclear explosives through the reengineering of tooling (testers and equipment) and procedures. Under this process, for example, devices for handling nuclear explosives are to be developed. Such devices will eliminate the majority of manual lifting operations thereby significantly reducing the risk that a weapon will be accidentally dropped. However, the improvement initiative, called Seamless Safety for the 21st Century (SS-21), had only been fully implemented for the W76 disassembly and inspection operation.

Reliable Replacement Warhead

Skeptics argued that the weapon is unreliable and, unlikely to detonate at its design yield. The W-76 is thus a cadidate for replacement by the new Reliable Replacement Warhead.

According to Richard L. Morse, a Los Alamos physicist who directed work on advanced bomb designs, the controversy centers on the weapon's uranium radiation case. In some places it is amazingly thin, said to be "not much thicker than a beer can," though with plastic backing for strength. The case must remain intact for microseconds to reflect the X-Rays that ignite the thermonuclear secondary. If the case even deformed significantly or shattered prematurely, the secondary would not ignite.

The Rayleigh-Taylor instability could perturb the expanding plasma of the hot radiation case, creating ripples that blocked ignition of the thermonuclear fuel. Quite minute variations in the case led to the onset of turbulence, frustrating efforts to eliminate the problem.

The controvery began soon after the moratorium on nuclear testing, and work soon focused on an alternative design with a thicker radiation case. By 1995, a joint effort began with the Navy and the nuclear weapons complex. In March 2004, Morse and four critics [three former weaponsn lab employees and one who currently works at Los Alamos] discussed their concerns in a meeting with Los Alamos and federal officials. Lab officials deny there is a problem with the W-76, citing the successful tests of the device at the Nevada Test Site. But the W-76 remains a candidate for redesign.

In mid-2000 Lockheed Martin Space Systems -- Missiles & Space Operations, Sunnyvale, CA, completed a 23-year production run of Mk4 reentry body assembly hardware kits used to house nuclear warheads in the Trident I C4 and Trident II D5 submarine launched ballistic missile arsenal. The Mk4 reentry system, developed jointly in the early 1970's by the Navy Strategic Systems Programs and the Department of Energy (DOE), is specifically designed to house the missile's W76 nuclear warhead. Additionally, it provides thermal protection for the warhead from the harsh reentry environment while ensuring accurate delivery of the payload to its intended target. The first W76/Mk4 reentry body entered the nation's nuclear stockpile in 1979, and today comprises the largest percentage of any strategic weapon in the US nuclear inventory.

Missiles & Space received the first Mk4 production contract in 1976 and full-rate manufacturing began in 1977. Since that time, Missiles & Space has manufactured more than 5,000 Mk4 reentry body assembly kits for the U.S. and U.K. Navies. Each Trident missile carries multiple W76/Mk4 reentry bodies. The W76/Mk4 reentry body is assembled at the DOE PANTEX facility from hardware supplied by Missiles & Space, including the reentry body aeroshell, RF subsystem, nose-tip and complete release assembly.

As of 2000 Department of Defense plans callled for the W76/Mk4 reentry body to support FBM operations until around 2040. To meet this service life requirement, the Navy and DOE planned a life extension program for the W76/Mk4. This program, slated to start early in the decade, was projected to be complete around 2020. To support this effort, Missiles & Space will retain all Mk4 production tooling and most manufacturing capabilities.

W76 Life Extension Program [LEP]

The W76-1 LEP extends the original warhead service life from 20 years (as designed) to 60 years. Completion of production is scheduled for no later than the end of FY 2019. The W76-1 first production unit was completed in September 2008, and the first delivery of warheads to the U.S. Navy took place in FY 2009. The program made all deliveries on schedule and under budget.

In the early 1990s Sandia undertook to design a replacement neutron generator for the W76 nuclear warhead on the Mark 4 reentry body of the Navy's Trident I system. There were several compelling reasons for doing so, including the need to increase the component's design margins, simplify its manufacturability, augment its resistance to new profiles of hostile environments, and increase its life span.

The MC2912 is the Arming, Fusing, and Firing System (AF&F) designed by Sandia and employed on the W76/Mk4 nuclear warhead. The AF&F's safety features ensure the weapon does not detonate in accidental or other unintended scenarios. The Arming and Fuzing (A&F) subsystem is one of the critical components of the W76/MK4 Reentry Body requiring life extension.

Strategic Systems Programs conducted a joint effort with the Department of Energy (DOE), Sandia National Laboratory (SNL) and its contractors to perform Nuclear Weapons Council approved Design Options and Cost Feasibility Study for a life extended W76/MK4 Reentry Body. This study, in accordance with Dr. Gansler's Acquisition Reform Initiatives, had the primary objective of defining a design approach to achieve the best value for this very critical project. A subsystem IPT was formed to trade-off design concepts, develop selected design options and prepare program plans including detailed cost estimates for a life extended A&F subsystem.

Historically, performance and nuclear safety have had priority over cost in developing and producing reentry bodies. This has fostered a "cultural mindset" in favor of performance achievement that is entrenched in the nuclear community. This effort is the first of its kind to make cost subservient only to nuclear safety. The objective was to apply innovation for cost reduction and to arrive at a "best value" program where performance/cost tradeoffs with associated risks were well understood. Fostering a cultural change was paramount to this effort.

The cost for the development of the A&F subsystem will be reduced by 60%. The production unit cost met the 25% goal. The total development and production potential cost avoidance resulting from this program as contrasted with previous equivalent programs is up to $750,000,000. This large cost avoidance is made possible by the tenets of Acquisition Reform and by the introduction of cultural changes accepting cost as a program driver. These approaches enabled critical design trade-offs attaining the objective of defining an affordable A&F sub-system, thereby contributing to the preservation of the TRIDENT System as the primary National Strategic Deterrent.


The W76 program at Sandia continued to exceed performance expectations in FY98. Through continuous process improvement efforts the Product Realization Team saved $200,000, decreased cycle time by 20 percent, had 19 consecutive successful Quality Assurance Inspection Procedure (QAIP) submittals to DOE, gained sufficient trust of DOE to eliminate the QAIP requirement from one level of the conversion process, and decreased the budget by 17 percent.


In 1999 the MC4380 Neutron Generator and its MC4378 Timer, MC4705 Voltage Bar, MC4148 Rod, MC4437 Current Stack, and MC4277 Neutron Tube were qualified for use in the Navy's W76 weapon system. This culminated a multi-year development effort which included the transfer of production capability from the Pinellas Plant to Sandia. This is the first weaponized neutron generator to employ a focused ion-beam neutron tube for higher reliability, the first produced at Sandia, and the first Sandia component with radiation hardness requirements to be qualified without underground testing.

Neutron generator subassemblies from retired weapons and other sources have been examined for reapplication to the W76/Mk4 and W78 systems. Enough assets have been identified that need minor modifications to meet near-term needs for the W78, and to reduce stress on the production facility during startup of the MC4380 neutron generator production. These units have resulted in more than $55 million of cost savings for DOE.

Neutron generators present unique challenges for design engineers. The physics of these devices are complex: they function as miniature linear accelerators, to produce deuterium-tritium reactions in order to generate neutrons. Consequently, their design parameters are sensitive to minute variations. They must be designed for ruggedness against severe environments such as acceleration, vibration, high voltage, radiation, and mechanical impulse. In the past, NNSA had always relied on an iterative design process involving numerous physical tests and whatever modeling tools were practical at the time.

Neutron generators also present tough challenges for production engineers. These devices necessarily contain exotic materials that require special fabrication processes, and they must be manufactured for high reliability over many years. Processes such as brazing, welding, plating, metallizing, material deposition, and encapsulation must be performed to very high DOE quality-control standards.

The neutron generator recertification program for the W76/Mark 4 benefited in concrete ways from DOE's investment in supercomputing and advanced design and production technologies. Sandia's production facility began delivering the new MC4380 neutron generators in October 1999. The ASCI and ADaPT initiatives, together with supporting research activities, have provided outstanding capabilities to perform this stockpile responsibility with greater confidence.

The W76/Mk4 Enhanced Fidelity Instrumented-A unit collects structural dynamics response data and investigate in-flight body dynamics. The unit was conceptualized, designed, built, qualified, and delivered in 24 months for a Navy flight test. The design includes modular telemetry in the physics package volume, and the highest data rate and battery energy density of any joint test assembly. The project involved Sandia, Los Alamos National Laboratory, Pantex, DOE/AL, Lockheed Martin, and the Navy.

The first W76 Enhanced Fidelity Instrumented-A (EFI-A) Reentry Body (RB) and Type 2G High Fidelity Flight Test Unit were successfully flown in February 1999. Sandia was the project integrator for development, building, and qualification of the flight test units. The EFI-A experiment provided valuable data using a newly designed, state-of-the-art telemetry system. The data has increased our understanding of the missile/RB interactions, internal RB shock/vibration environments, and RB dynamic behavior. The EFI-A was the first W76 flight test body to collect first-stage ignition data.

A life extension study was conducted during 1999 for the W76/Mk4 Reentry Body Assembly by Sandia, Los Alamos, DOE, Navy Strategic Systems Programs, US Strategic Command, Lockheed Martin Missiles and Space, and ITT Industries. The study identified design options, production and certification plans, and cost estimates. Sandia's conceptual design for the replacement Arming, Fuzing, and Firing (AF&F) subsystem was expected to come close to meeting the important goal of costing one-quarter of the W88/Mk5 AF&F cost.

1999 Weapon Safety Specification (WSS) Review

In 1999 the Defense Nuclear Facilities Safety Board (Board) recently reviewed the Weapon Safety Specification (WSS) for the W76. The WSS plays an important role in safe nuclear weapons operations at the Pantex Plant as defined by the DOE Albuquerque Field Office in Appendix 56XB, Development and Production Manual: to ensure that lessons learned from surveillance program data and relevant as-built information are properly incorporated in the Seamless Safety for the 21st Century (SS-21) process at the Pantex Plant, and to provide essential information for the safety basis documentation.

In essence, the function of the WSS is to identify hazards inherent in the weapon itself, and to provide a summary of the analyses concerning mechanical, electrical, thermal, and chemical insults to a nuclear weapon. This information is drawn from design drawings, baseline process flows, use control reports, criticality reports, intrinsic radiation reports, and past surveillance data that are pertinent to safety. The as-built information provided in the WSS should pertain to the characteristic design features, safety attributes, and hazards for a nuclear weapon or family of similar nuclear weapons. In addition, skills and knowledge drawn from individuals involved with initial production, surveillance operations, system modification operations, and disassembly operations are also key features of an adequate WSS. The document is intended as a tool to facilitate interactions with the Pantex contractor during the development of the authorization basis. The WSSs are also to be reviewed and updated (if needed) annually. The design agencies are the principal authors of the WSS.

While the WSS provided extensive information about design characteristics related to nuclear safety to ensure enhanced nuclear detonation safety (ENDS) for the W76 in the ultimate user configuration, it did not organize this information in a manner that facilitates hazard analysis of Pantex activities involving partially assembled and disassembled systems. Potential weapon response information for thermal, kinetic energy, electrical, and chemical insults cannot readily be derived from the WSS. Thus, Pantex hazard analysts must rely on the design agencies for information on material response for many hazard-inducing environments. Providing such information for the four basic categories of insults at various stages of assembly/disassembly could enhance the efficiency of hazards analyses at the Pantex Plant.

The WSS provides a great deal of information on the properties of the high explosives used in the W76, as well as the performance characteristics of many of its subsystems. The WSS also raises issues that are the result of uncertainties due to modeling capabilities and fundamental data. Examples included in the WSS are issues relating to aging of high explosives, thermal insults, and one-point safety. A path forward for resolving uncertainties is provided for some cases, but not universally. The significance of these uncertainties should be presented in the WSS.

Overall, the WSS provides extensive technical information on the characteristics of materials and components used in the W76. There is archival data relevant to the W76 system, such as pit hydriding issues and associated safety concerns. It appears, however, that the most recent surveillance information is not included in this revision of the WSS, dated November 9, 1998. For example, a Surveillance Finding Investigation (SFI) opened in February 1998 is not mentioned; in fact, the most recent SFIs included in the report were opened in 1995.


The Nuclear Weapons Council (NWC) approved the Block 1 refurbishment plan for the W76 in March 2000. The Block 1 refurbishment of the warhead (about one quarter of all W76 warheads) focused on the high explosive, detonators, organic materials, cables and addition of a new Acorn gas transfer system. The Block 1 refurbishment also added a new arming firing and fusing (AF&F) system. The FPU of Block 1 was planned to be available by the end of FY 2007, and Block 1 production is planned for completion in FY 2012. During the Block 1 production, a decision will be made to either continue Block 1 retrofits on the entire W76 stockpile, change to a Block 2 retrofit that could include other options, or stop the retrofit altogether. The Block 2 effort, if approved by the NWC, would continue from FY 2012 to FY 2022 to refurbish the remaining W76 warheads.

The US Navy W76-0/Mk4 Joint Test Assembly (JTA) redesign achieved First Production Unit status in August 2001, following a successful development flight test in February 2000. The redesign replaced sunset technology components in the existing 20-year-old JTA, which is used to test the continued conformance of a denuclearized version of the War Reserve (WR) warhead. The new JTA collects significantly more state-of-health and critical performance data from onboard the Reentry Body (RB), as part of the core surveillance program.

Aging concerns, the non-availability of replacement components used in original designs, and a desire to modernize nuclear safety features requires a refurbishment of the W76/Mk4 RBA for it to meet the extended service life. This should be accomplished in a planned, methodological manner to prevent possible weapon downtime and the total consumption of the National Nuclear Security Agency (NNSA) nuclear weapons complex capacity that could occur if a critical problem were identified. The US Navy Strategic Systems Programs (SSP) requested and the Nuclear Weapons Council Standing and Safety Committee (NWCSSC) approved a joint Department of Defense (DOD)/DOE Phase 6.2/6.2A Study, which was initiated on 19 October 1998. The study was conducted under the W76/Mk4 Project Officers Group (POG). The results of the study were briefed by the W76/Mk4 POG to the NWCSSC on 8 December 1999 and to the Nuclear Weapons Council (NWC) on 13 March 2000.

Study ground rules included the following:

  • Modernize nuclear detonation safety features (to Mk5-like interface)
  • Consider W76/Mk4 on Trident II (D5) only
  • Current W76/Mk4 Military Characteristics (MCs) and Stockpile-To-Sequence (STS) were baseline
  • Plan for a one-time refurbishment process (DOD and NNSA)
  • Plan for total stockpile quantities reflected in the current Long Range Planning Assessment (LRPA)
  • Production duration goal of 10 years or less
  • Goal for a post-refurbishment life extension of 30 years

Emphasis was placed on meeting performance requirements over the extended life and minimizing the cost of necessary refurbishment.

The drivers for refurbishment are fourfold:

  1. The W76/Mk4 is the most critical element of our nation's strategic deterrent and cannot be allowed to be degraded by a serious aging problem;
  2. The W76/Mk4 Dual Revalidation Program has shown that even though components are aging gracefully, there are some negative changes;
  3. The Stockpile Surveillance Program cannot predict failures; rather, it only detects them when they appear and when it may be too late to prevent degradation; and
  4. The Navy has expressed the desire to retain an average system age of no more than 30 years, compatible with life extension of the Trident Weapon system.

The POG-recommended refurbishment option meets the life extension requirements for the W76/Mk4, while enhancing surety and providing increased targeting flexibility and effectiveness. Careful examination of technical, certification, and compatibility issues have identified no unacceptable program risks. DOD and NNSA costs have been identified to the degree appropriate for this phase of the program. Based on these factors, the POG recommended refurbishment of the W76/Mk4 beginning on 1 April 2000.

The Nuclear Weapons Council initiation of the W76 Life Extension Project was the culmination of a multiyear effort to assess the warhead state-of-health, develop refurbishment options, and generate management processes and plans to meet aggressive requirements. The conceptual design incorporates new performance options and challenges Sandia to implement technical innovation and employ new modeling and simulation tools. Key to winning authorization was our systematic scrutiny of requirements and design options, our plan to reuse selected components, incorporate high-grade commercial electronic parts, streamline production and qualification processes, and rigorously manage risk.

Working with counterparts at the Kansas City plant Sandia designed and built two versions of prototype firing sets for the W76 Arming, Fuzing, and Firing life extension program. Through the use of simulation and rapid prototyping tools and techniques, Sandia was able to go from paper designs to hardware, demonstrating form, fit and function in less than a year. In addition, these tools allowed Sandia to evaluate and solve a variety of design and manufacturing issues before the prototypes were fabricated.

The W76 SLEP down-select for Phase 6.3 for the Navy Mk4A weapon systems occurred in July 2000. A 12300 independent Weapon Assessment Team reviewed the warhead candidates for quality, reliability, nuclear safety, stockpile surveillance, and security/use control attributes and effectiveness. The Weapon Assessment Team confirmed the Preferred Option candidate, recommended by Div. 2000, as a viable design that enhanced reliability over the extended lifetime and afforded nuclear safety and significant use control enhancements to the present baseline W76 design. The selection of the Baseline Option was made with idea of a block upgrade approach, where the surety advantages of the Preferred option could be incorporated at a later date.

On September 22, 2000, the W76-0/Mk4 became the first enduring stockpile weapon to complete the DOE Seamless Safety Process for Disassembly & Inspection operations at the Pantex plant in Amarillo. The project included development of new tooling, new procedures, a Weapon Safety Specification, a Hazards Analysis, and hazards controls. DOE authorization for W76 operations makes it possible to conduct weapon surveillance assessments at Pantex, which provide essential information about weapon reliability and state-of-health.

The most detailed structural dynamic model validation experiments ever performed on a nuclear weapon system were completed during 2000 on the W76/Mk4 Reentry Body (RB). These experiments successfully identified modes of vibration as high as 1,000 Hz for the RB and each major subassembly. The test series discovered significant unit to unit variability for frequencies above 1,000 Hz. Data gathered from multi-level shock and vibration inputs will be critical to the validation of high fidelity models that mimic the nonlinear behavior of real weapon structures.



By 2002 the life extension of the Navy's W76 system was proceeding on schedule toward a first production unit in 2007 with an estimated initial operational capability of April 2008. Evaluation of the condition and life expectancy of the materials in the nuclear explosive package is being addressed. The warhead refurbishment will extend the lifetime of this system for thirty years.

In 2002 the W76-1/Mk4A Life Extension Program successfully completed its second year of development engineering, achieving several significant milestones:

  • Numerous reviews, including the Customer Requirements Review, and the Arming, Fuzing, and Firing Subsystem and Joint Test Assembly Conceptual Design Reviews.
  • Completion of two reentry body Model Validation Tests and our first Joint Ground Test in support of structural and thermal model validation and environmental specification.
  • Delivery of our first flight test bodies in support of the Demonstration and Shakedown Operation Navy flight test in FY03.

The MC4380A Neutron Generator was designed and qualified for the W76-0/Mk4 Trident warheads to provide additional margin in radiation environments. This intensive two-year project successfully supported the stockpile needs without the benefit of underground tests. The effort began in August 2000 and was completed in April 2002, followed by completion of the first production unit in May 2002 and delivery of the first units to the Navy and the UK in the summer of 2002.

The W76-1 Arming and Fuzing Subsystem (AFS) integrates radar, flight computer, and diagnostics in a single compact assembly. The design met aggressive cost goals through use of commercial off- the-shelf parts, innovative packaging, and automated production processes. The AFS is part of the W76-1 Arming, Fuzing, and Firing system, and tested in the Navy FCET-30 flight test. The project team delivered the first two AFS flight test units on schedule.

Sandia has responsibility for the integrated arming, fuzing, and firing (AF&F) system of the W76-1/Mark-4A life extension program. Science-based design tools will permit performing the redesign of this complicated and critical assembly at lower cost and with higher quality than was previously possible. The redesigned unit will combine advanced fuzing options, modern nuclear safety improvements, and enhanced reliability. Moreover, NNSA incorporated surveillance features into the unit so that its "state of health" can be assessed in the field with minimal intrusion.

Qualification of the new W76-1/Mark-4A AF&F will involve both testing and simulation using tools provided by science-based stockpile stewardship. NNSA must conduct a variety of environmental tests in the laboratory to evaluate the unit's performance under various normal and abnormal conditions. Sandia will perform system flight-tests with de-nuclearized payloads to achieve flight environment conditions that cannot be simulated in the laboratory. Radiation tests using aboveground simulators will provide radiation effects testing for most spectra of concern. Parameters derived from all these categories of tests will be incorporated into computational models that can calculate system performance over a broader and more intense range of conditions.


BY mid-2003 the Y-12 National Security Complex was implementing actions necessary to begin refurbishment of W76 warheads in the US weapons stockpile. The refurbishment project will keep Y-12 busy for the foreseeable future, with delivery of the first production unit planned for 2007. Refurbishing the W76 will require Y-12 to upgrade or restart some processes and equipment shut down at the end of the Cold War. Together, Y-12 and the design agencies were identifying and resolving any age-related issues with the W76. Key remaining questions concerned reusing or remanufacturing certain components.

A W76 Life Extension Program could use some of the technologies and equipment provided for other Life Extension Programs as well as those technologies being developed and deployed by Campaigns to meet National Nuclear Security Administration stockpile support mission requirements. One of these technologies is the Casting Advisor system for predicting how much material is needed to ensure that a cast blank contains the minimum material to make a specified partensuring the part is in the blank.



The W76 Life Extension Program will extend the life of the W76 for an additional 30 years with the FPU in FY 2007. R&D activities include qualification and certification activities ensuring refurbished warheads meet all required military characteristics and Stockpile Management efforts will include work on the nuclear explosive package; the Arming,Fuzing,and Firing system;gas transfer system; and associated cables, elastomers, valves, pads,foam supports,tapered tapes,telemetries,and miscellaneous parts.

In FY 2005, R&D efforts completed engineering design of the nuclear explosive package primary subsystem components; conduct the final design and independent peer reviews; and design-flight test bodies for the follow-on commander-in-chief evaluation test (FCET-34). Stockpile Management efforts will ramp up activities in qualification system engineering; procure commercial off-the-shelf parts and associated production materials; design and fabricate tools and gauges; and, conduct process prove-in of production activities for major components including flight tests bodies.


Hostile shock testing of the W76-1 was completed at Sandia's Light Initiated High Explosives (LIHE) facility. Lateral and aft shock impulse tests of the W76-1/MK4A system were conducted to simulate exo-atmospheric cold X-ray-induced blow-off impulse during a hostile encounter. Structural dynamics response data obtained from the tests was used for model validation of the Salinas structural dynamics computational model. This was the first weapon system qualification test completed at the recently renovated LIHE facility since it was mothballed in 1992.

Sandia's Power Sources Group 2520 submitted a new thermal battery for the W76-1 Lifetime Extension Program on schedule and within budget. This is the first new thermal battery designed by Sandia in nearly two decades. The design incorporates new electrochemistry using an advanced cobalt disulfide cathode material and a low-melting-point ternary-salt electrolyte in order to meet tightly constrained, multiple voltage requirements over an extended performance period. Final development and production activities were completed in less than two years, including recovery from a late-stage supplier change.

As part of Phase 6.4 Production Engineering efforts, the W76-1/Mk4A Lifetime Extension Program matured the design definition and achieved successful component producibility reviews. System and arming, fuzing, and firing (AF&F) qualification activities included successful testing as well as significant progress in modeling and simulation of system performance in normal, abnormal, and hostile environments. The project flew four test bodies on FCET-35, the submarine-launched ballistic missile Follow-On Commander's Evaluation Test. These major milestones are critical to the overall W76-1 project and helped to build significant confidence.


The W76-1 and the W80 SS-21 programs, high-visibility activities for NNSA and key elements for W76-1 production and W80 disassembly & inspection, were led by Sandia Centers 2100 and 8200, respectively. Sandia Surety Assessment Center 12300 generated weapon response data for the assembly and disassembly operations of the W76-1 and W80 by teaming with Los Alamos and Lawrence Livermore national labs as well as Sandia organizations. This data enabled Pantex to complete hazard analysis reports that were reviewed by several complex-wide teams before final authorizations were granted.

The W76-1/Mk4A Arming Fuzing Subsystem (AFS) met all product qualification requirements and the first production unit was delivered on schedule, below cost, and with outstanding performance and quality. The effort was the result of years of work by dozens of people at both Sandia and the Kansas City Plant. The AFS team received an NNSA Defense Programs Award of Excellence. In addition, the team was recognized by the US Navy for meeting and exceeding cost targets.

In May 2007 BWXT completed a contractor readiness assessment (CRA) that evaluated whether it was prepared to commence W76-1 SS-21 assembly operations at Pantex. The CRA team identified 20 pre-start findings, 2 post-start findings, and 13 observations. In particular, the review team identified several procedure related issues including numerous errors, steps that could not be performed as written, and inadequate flowdown of requirements into the procedures. The team also noted that production technicians did not always execute the procedures as written. The report included a rather candid discussion of the issues that made this CRA more difficult to conduct, and less successful than usual. Specifically, the CRA team noted that the documented safety analysis had not been approved prior to the start of the review, which was a contributing factor to several of the findings. The mandated 14 June 2007 authorization date for W76-1 operations is in jeopardy as a result.

In August 2007, NNSA decided that B&W would fabricate and disassemble several W76-1 prototype units during FY2008 to exercise the assembly and disassembly processes - the prototype units are also intended to be used for retrofit evaluation system test (REST) surveillance activities. In Octobe 2007 B&W completed the first W76-1 prototype build (FPB). Subsequent prototype build operations had been waiting for the W76-1 disassembly and inspection (D&I) process to be reviewed and authorized. In early December 2007, B&W completed its readiness assessment to determine if it is prepared to startup SS-21 W76-1 D&I operations. The review team identified 8 pre-start findings, 4 post-start findings, and 9 observations. The pre-start findings included a couple minor procedure errors, a few procedure configuration management issues, and two tools that did not function as designed.


In January 2015, the W76-1 LEP passed the halfway point in the total number of refurbished warheads scheduled for delivery to the U.S. Navy according to the current program of record. In FY 2015, KCNSC resumed full-rate production and requalification of most W76-1 components, following relocation of activities from the Kansas City Plant to the new KCNSC. One remaining component is on schedule to complete requalification activities in FY 2016.

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Page last modified: 05-02-2020 08:34:13 ZULU