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Nuclear Weapons: NNSA Should Further Develop Cost, Schedule, and Risk Information for the W87-1 Warhead Program

GAO-20-703 Published: Sep 09, 2020. Publicly Released: Sep 23, 2020.
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Fast Facts

The National Nuclear Security Administration plans to replace the W78—an older type of nuclear warhead used in intercontinental ballistic missiles—with the W87-1, starting in 2030. But it's unclear if NNSA can produce enough of the W87-1's fissile cores in time to meet its planned production schedule.

NNSA estimated that the new warhead could cost up to $14.8 billion, which could make it the most expensive program of this type to date. Upcoming design decisions for the weapon could affect cost. But the agency didn't have formal plans to assess the costs and benefits of these decisions.

Our recommendations address these and other concerns.

U.S. Air Force missile maintainers working on an intercontinental ballistic missile

overhead view of ballistic missile silo

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What GAO Found

The National Nuclear Security Administration (NNSA) did not consider cost estimates in early major design decisions for the W87-1 warhead because it was not required to do so, but NNSA has since changed its guidance to require that cost be considered, according to a May 2019 NNSA review of program documentation. The design decisions that remain for features that would achieve either minimum or enhanced requirements for the W87-1 could affect cost, according to NNSA officials (see table). We found, however, that NNSA did not yet have study plans for assessing the costs and benefits of the remaining decisions consistent with best practices as detailed in NNSA's analysis of alternatives business procedure. NNSA does not require and only recommends that programs such as the W87-1 follow these best practices. By directing the W87-1 program and future weapons programs to follow best practices for design studies, or to justify and document deviations, NNSA would have better assurance that design studies apply consistent, reliable, and objective approaches.

NNSA Cost Estimates for W87-1 Warhead Design Variations That Meet Minimum and Enhanced Requirements, as of December 2018 (Dollars in billions)

W87-1 design variations

Cost estimate rangea

Design includes features that meet minimum safety and security


7.7 - 13.3

Design includes enhanced safety and security features

8.6 - 14.8

Difference between the above estimate ranges

0.9 - 1.5

Source: National Nuclear Security Administration (NNSA) documentation | GAO-20-703

aThe cost ranges reflect low and high estimates for a single design variation. The ranges represent technical and production risk and uncertainty.

It is not clear that NNSA will be able to produce sufficient numbers of pits—the fissile cores of the primary—to meet the W87-1 warhead's planned production schedule. Recent NNSA and independent studies have cast doubt on NNSA's ability to ready its two planned pit production facilities in time. If one facility is not ready to produce pits in the early 2030s, for example, NNSA would likely produce fewer weapons than planned, according to GAO's analysis of NNSA plans.

We were unable to fully assess the extent to which the two pit production facilities will be ready to produce pits for the W87-1 because NNSA's plutonium program—which is managing the facility readiness efforts—has not yet completed an integrated schedule for the overall pit production effort. An integrated schedule is important, according to best practices, because it integrates the planned work, resources, and budget. An NNSA official stated that the program was building a schedule, but could not provide documentation that it would meet best practices. A schedule consistent with best practices would provide NNSA with better assurance that it will have adequate pits to meet planned W87-1 production.

This is a public version of a classified report that GAO issued in February 2020. Information that NNSA or DOD deemed classified or sensitive has been omitted.

Why GAO Did This Study

The Department of Defense (DOD) and NNSA restarted a program in fiscal year 2019 to replace the capabilities of the aging W78 nuclear warhead with the W87-1. NNSA made key design decisions for this weapon from 2010 until the program was paused in 2014. NNSA estimated in December 2018 that the W87-1 would cost $8.6 billion to $14.8 billion, which could make it the most expensive warhead modernization program to date. NNSA plans to newly manufacture the entire warhead, including the two major nuclear components, called the primary and secondary, using facilities it is modernizing or repurposing.

You asked us to examine plans for the W87-1 warhead. This report examines, among other things, the extent to which NNSA (1) considered cost estimates in prior design decisions for the W87-1 and the potential effects of remaining design decisions on program cost, and (2) will be able to produce sufficient numbers of key nuclear components to meet W87-1 production needs. GAO reviewed NNSA documentation on prior and remaining design decisions and preliminary cost estimates, reviewed warhead and component production schedules, and interviewed NNSA and DOD officials.


GAO is making four recommendations, including that NNSA require programs such as the W87-1 to follow analysis of alternatives best practices when studying design options and that the plutonium program build an integrated schedule consistent with schedule best practices. NNSA generally agreed with the recommendations.

Recommendations for Executive Action

Agency Affected Recommendation Status
National Nuclear Security Administration The NNSA Administrator should direct the W87-1 program to ensure consistent, reliable, and objective assessments of remaining feature and component design decisions in Phase 6.2 by developing study plans for remaining design studies consistent with the guidelines for such plans in NNSA's AOA procedure, including documenting and justifying deviations from best practices. (Recommendation 1)
Closed – Implemented
In February 2023, NNSA officials told us that--consistent with NNSA's guidance for analysis of alternatives (AOA)--it had planned and completed evaluations of trade-offs for remaining major component decisions for the W87-1 warhead that may have a significant cost or performance impact, and that it had documented these assessments in formal studies. NNSA subsequently provided a January 2020 W87-1 trade study guide that the program developed using best practices from NNSA's AOA guidance, in addition to a number of federal, industrial, and academic guidance sources. In February 2023, NNSA also provided us with trade studies for two of the major design decisions discussed in the report. Specifically, NNSA provided us with an August 2020 electrical bus trade study, which included consideration of a digital architecture, and a September 2020 trade study evaluating neutron generators. We reviewed each and determined that they both described how they were conducted consistent with NNSA's AOA guidance.
National Nuclear Security Administration
Priority Rec.
The NNSA Administrator should direct the Office of Defense Programs to revise its program execution instruction to require that design studies for warhead life extension and replacement programs follow AOA best practices, such as by having a study plan, or to justify and document deviations from best practices. (Recommendation 2)
Open – Partially Addressed
NNSA generally agreed with our recommendation and stated that it would revise its program execution instruction to clarify that design studies conducted in the first phase of NNSA's process--known as concept assessment--for warhead modernization activities should incorporate AOA best practices. In September 2021, NNSA issued a revised version of the program execution instruction that partially addressed our recommendation. Specifically, NNSA incorporated references to AOA best practices in some portions of the document, but had not consistently integrated those references throughout, resulting in some ambiguity about how such guidance would be implemented. In April 2022, NNSA officials agreed to further revise the program execution instruction to fully integrate references to AOA best practices, but they could not estimate when the next revision would be published. When NNSA issues its next revision of the program execution instruction, we will evaluate it for consistency with our recommendation.
National Nuclear Security Administration
Priority Rec.
The NNSA Administrator should direct the Office of Defense Programs' plutonium program office to ensure that the integrated master schedule in development for pit production meets NIMS standards, consistent with best practices for schedule development. (Recommendation 3)
In October 2021, NNSA officials stated that NNSA implemented an integrated master schedule for pit production on October 1, 2021. However, in January 2023, GAO found that NNSA's pit production schedule does not meet minimum qualifications to be considered an integrated master schedule, according to GAO's Schedule Guide. In response, NNSA stated that it will continue to refine its integrated master schedule for plutonium pit production to align it with GAO best practices. We will continue to evaluate NNSA's efforts to develop a pit production schedule that meets GAO best practices.
National Nuclear Security Administration The NNSA Administrator should direct the W87-1 program to prioritize the development and documentation of a risk mitigation strategy to address the risk that pit production may be insufficient to meet W87-1 production needs. (Recommendation 4)
Closed – Implemented
In August 2021, NNSA officials described studies that were under development for risk mitigation to the W87-1 program, including risk of insufficient pit production to meet W87-1 program needs. In January 2023, GAO found that NNSA's pit production schedule was not comprehensive, and thus could not be considered reliable. As noted in our report, a reliable pit production schedule is essential to providing assurance of sufficient pits to meet W87-1 program needs. In a February 2023 meeting, NNSA officials told us that NNSA had documented its pit production risk mitigation strategy in an October 2021 study. NNSA officials provided this document subsequent to our meeting, and in our review we determined that the document identified a range of options for managing risks should new plutonium pits not be available in sufficient numbers to sustain W87-1 warhead production.

Full Report

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Analysis of alternativesBest practicesCost and scheduleCost estimatesMissile warheadsNuclear securityNuclear weaponsPlutoniumRisk assessmentSafety