W93

STRATCOM, the Navy, and the Department of Energy’s (DOE) National Nuclear Security Administration (NNSA) are conducting a Phase 1 concept assessment study of a potential new warhead they’re calling the W93. The key word here is potential. The purpose of a Phase 1 study is to make a preliminary assessment of nuclear weapon design options or concepts, not to nail down details on design, production, manufacturing, or cost. Those things will come later, if the W93 makes it past the Phase 1 and other phase studies. For context, between 1966 and 1985—the height of U.S. nuclear weapons production—59 Phase 1 studies were conducted. Of those, only 19 weapons (32 percent) passed through the next five phases of the Joint DOD and DOE Nuclear Weapons Life Cycle Process and entered into the stockpile.

Although it hasn’t been designed yet, the new reentry body is being called the Mark 7 (Mk7). The Mk7 could differ in size from the current Mark 4 and Mark 5 reentry vehicles, which house the W76 and W88, respectively. “A possible size difference requires NNSA to explore warhead options broader than a life extension of any existing stockpiled warhead type,” explains Bob Webster, deputy Laboratory director for Weapons at Los Alamos.

These “warhead options” are what’s collectively being called the W93. If (and that’s a big if) one of the options moves forward through the entire six-part phase study process, the option will provide STRATCOM and the Navy “a means to address evolving ballistic missile warhead modernization requirements, improve operational effectiveness, and mitigate technical, operational, and programmatic risk in the sea-leg of the triad,” according to a statement by STRATCOM Commander Admiral Charles Richard to the Senate Committee on Armed Services.

“Without a coordinated, joint effort to develop and field the W93/Mk7 as a system, the bulk of our day-to-day deterrent force will be at increased risk in the early 2040s due to aging legacy systems,” Richard continued. “Research and development efforts … must begin immediately to deliver a capability in the 2030s that maintains a credible at-sea deterrent through the 2050s and beyond.”

“This work is critical to the future of the nuclear deterrent,” agrees Mark Suriano, deputy assistant deputy administrator for the NNSA Defense Programs Office of Research, Development, Test, and Evaluation. NNSA—via its national laboratories, plants, and sites—has the sole responsibility to design, develop, certify, and produce nuclear weapons for the United States.

As conversations about the W93 begin, plans to replace the Navy’s aging Ohio-class submarines are also underway. The 2018 NPR ensures Ohio-class SSBNs will remain “operationally effective and survivable” until they can be replaced, one per year, by a minimum of 12 Columbia-class submarines. These next-generation subs are in development, and the first one is scheduled to be deployed by 2031. All 12 are expected to be operational by 2042. So, because the W93 (if it goes forward) wouldn’t enter the stockpile until the mid-2030s, it would have to be compatible with two different boats.

Phase 1 studies typically take 1 to 2 years. During this time, NNSA provides federal oversight and guidance. NNSA ensures the design agencies—Los Alamos, Lawrence Livermore, and Sandia national laboratories—and production agencies are considering all requirements.

As the lead physics design agency—the organization responsible for the design of the nuclear warhead package and some of the nonnuclear components—Los Alamos must consider everything from the number of warheads required per missile to the size, weight, shape, and yield of the warhead. Target sets, target-kill effectiveness, and warhead survivability will also be addressed. Additionally, the Los Alamos design options identified must be able to be produced, delivered, and fielded without any underground nuclear explosive testing.

“The opportunity to be the design agency for the W93 will be leveraged on the great competencies we have developed in conducting modernization work and in supporting the legacy stockpile,” says James Owen, associate Laboratory director for Weapons Engineering at Los Alamos. “The work we’ve done in the past, the work we do each and every day, and the work that stands in front of us are all vital elements in ensuring that we have a safe, secure, and effective nuclear deterrent.”

“At the end of the Phase 1 study, a report on identified designs—warhead and reentry body—and an assessment of whether one or more designs can potentially meet mission requirements is provided to the Nuclear Weapons Council, along with a recommendation to either proceed to Phase 2 or terminate at Phase 1,” Webster explains. (The six-person Nuclear Weapons Council is composed of DOE and DOD senior leaders who direct interagency activities to maintain the U.S. nuclear weapons stockpile.) “In the event it is determined we should proceed, the W93 will have to be programmed in the budget, and that will be passed on to Congress for authorization and appropriation of funds.”