OPINION — “U.S. [nuclear] warheads were designed and manufactured until the late 1980s and early 1990s. Since then, we have not designed any new nuclear components. When the warheads needed repair, we remanufactured the existing designs and reused components that we were not able to manufacture. That’s no longer an option. For the [new] W87-1 [warhead], every part will be newly manufactured using well-established design knowledge.”
That was physicist Juliana Hsu, the W87-1 program manager at the Lawrence Livermore National Laboratory (LLNL) as quoted in the laboratory’s magazine, Science & Technology Review (S&TR) of December 2022.
One W87-1 thermonuclear warhead will have the explosive power of 475 kilotons, the equivalent of 475,000 tons of TNT or roughly twenty times more powerful than the Hiroshima atomic bomb.
The first W87-1 warheads are to be carried in an advanced version of the Mark21A reentry vehicle and delivered by the new Air Force Sentinel Intercontinental Ballistic Missile (ICBM). The first nine Sentinel ICBMs are scheduled to be deployed and go on alert in 2030. The remaining of a total planned force of 400 deployed missiles is expected to be completed by the end of 2036.
The article in Livermore Laboratory’s December S&TR first caught my attention with its claim that the W87-1 would mark the first time since the end of the Cold War that the U.S. would “be putting a 100 percent newly-manufactured nuclear warhead into the stockpile.” It drew my further interest as I read further details in the article about development of the warhead. That led me to other sources and discovery of more facts about the building of the W87-1 reentry vehicle and its ICBM delivery system.
A nuclear warhead has thousands of separately machined parts. Many of them involve the use of synthetic polymers, substances that can absorb shock, or be made rigid and maintain precise shapes under severe pressure. Polymers, for example, are used in weapons to bond with explosive materials and melt into a casting or, as in the W87-1, be created as 3D parts by the layer-by-layer technique of printing from a digital model.
Previous nuclear warheads saw Livermore’s weapons designers conceptualize and prototype components and then send their blueprints to the weapons complex production team in Kansas City, Missouri. What’s called the Kansas City National Security Campus (KCNSC) would then produce and assemble non-nuclear components such as firing and other control elements.
For the W87-1, Livermore in early 2022 employed a team of its engineers, physicists, chemists, computer scientists, and production-line experts, called the Polymer Production Enclave, to speed the design-prototype-produce process using a newly constructed, state-of-the-art polymer design and production facility at the Laboratory, according to the S&TR article.
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As a result, W-87-1 polymer-based parts from design to realization became a joint effort between Livermore and KCNSC, where both had procured identical 3D machines, tools, and other production equipment. “Now, the collaborators can simultaneously complete multiple production phases — such as ink processing, [3D] printing, materials characterization, and quality control — and immediately incorporate their findings into upcoming rounds of development and testing,” according to the S&TR article.
Additional collaboration is underway for the W87-1 explosive parts. Here, Livermore works with the weapons complex’s Pantex Plant near Amarillo, Texas, which is the primary facility for the final assembly, dismantlement, and maintenance of nuclear weapons.
A new Energetic Materials Development Enclave at Livermore has been working with Pantex experts to explore new technologies to develop reliable high-explosive parts, some of which could reach maturity for inclusion in the W87-1.
The Laboratory is also working closely with DOD’s Holston Army Ammunition Plant, in Kingsport, Tennessee, which supplies the nuclear weapons complex with explosive materials to perfect the insensitive high-explosive that will serve as the main charge for the W87-1.
The Y-12 National Security Complex in Oak Ridge, Tennessee, focuses on processing and storing uranium and is responsible for producing the radioactive components for the nuclear explosive package. The W87-1 team at Livermore is working closely with Y-12 to modernize technology and production methods for manufacturing such components.
For example, some materials used in Cold War nuclear weapon systems were hazardous and no longer producible in the modern safety environment. Y-12 and Livermore are partnering in the case of one particularly toxic material where Livermore researchers invented an alternative material without a health hazard for workers. Livermore researchers have also developed a manufacturing process using a massive hot press to turn this new material into the needed weapon component. Now, Y-12 has obtained a similar hot press and a joint Livermore-Y-12 team is working to optimize the production process, according to another S&TR article.
The W87-1 will also contain newly produced plutonium pits that serve as the triggering device for thermonuclear weapons by initiating the secondary nuclear reaction. Los Alamos National Laboratory (LANL) has restarted U.S. pit production and there are plans for an additional pit production capability to be established at the Savannah River Site (SRS) near Aiken, South Carolina. The project has had problems. And so the goal, which had been that the two facilities would produce 80 pits a year by 2030, has been pushed back to reach that level sometime after that date.
Livermore designers are working closely with LANL and SRS personnel to establish pit specifications for the W87-1 warhead. Assessment of the potential pits and eventual certification issues will be tested at the Nevada National Security Site, 65 miles west of Las Vegas, as well as at Livermore’s Site 300 and LANL’s test facility.
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Meanwhile, at Livermore, modeling and simulation for the W87-1 are being handled by the Sierra high-performance computer. Eventually, when it comes into service sometime this year, those tasks will be taken over by El Capitan, an exascale supercomputer which is projected to offer more than 15 times peak computer capability over Sierra.
While Livermore is designing and will assist in producing the W87-1 warhead, the Air Force has responsibility for both the Mark21A reentry vehicle (RV) and the Sentinel ICBM.
The Mark21A reentry vehicle, after being released from the Sentinel ICBM, will carry the W87-1 warhead through the atmosphere and back down to earth. The Mark21A is being developed by the Air Force along with Lockheed Martin.
In July 2022, a first flight test for a prototype Mark21A failed because the Minotaur rocket carrying it exploded 11 seconds after it was launched from Vandenberg Space Force Base in California. The Air Force fiscal 2024 budget request now before Congress carries an extra $48 million for the Mark21A program to add another prototype test to one already scheduled for early next year.
The lost test was designed to “demonstrate preliminary design concepts and relevant payload technologies in [an] operationally realistic environment,” according to an Air Force Nuclear Weapons Center press release.
The Mark21A, according to budget documents, will include a high velocity nose tip; arming and fuzing assembly; aeroshell forward section, body section, and rear cover; plus a radio frequency subsystem with antennas.
Last month, the Air Force as part of the development process, sought information from industry partners for what it termed “development of advanced countermeasures for current and future reentry vehicles.” The service specified they are interested in “enhancements in accuracy, lethality, survivability, etc.”
The Air Force Sentinel ICBM program is being done with Northrop Grumman as the main contractor. The current plan calls for eventually acquiring 642 missiles to support testing and then replacement of all 400 Minuteman III missiles that are currently deployed across Colorado, Montana, Nebraska, North Dakota, and Wyoming. The overall Sentinel program also requires upgrades to the launch facilities, launch control centers, and other supporting infrastructure, according to the Congressional Research Service.
The fiscal 2024 Air Force budget has some $3.7 billion to continue developing and testing the Sentinel system that includes funds for flight systems, command and control and launch systems, including missile launch silos, launch control centers, and other ground infrastructure. There is another $500 million for advanced procurement of some elements.
Last March 3, the Air Force and Northrop Grumman conducted the first in a series of open-air static fire tests that will help validate the design and performance of Sentinel’s three-stage propulsion system. Tested was the Stage-1 solid rocket motor, the largest of Sentinel’s three stages and the first to fire upon missile launch.
The program expects Sentinel’s first flight and full functional tests, currently scheduled for fiscal years 2024 and 2025, to further validate progress.
A Government Accountability Office (GAO) Weapon Systems Annual Assessment released last week, said that the Sentinel program “entered development without fully maturing its critical technologies, increasing risk of costly and time-intensive rework if problems emerge later in development.”
GAO also cautioned, “Sentinel’s large program scope – development of new technologies, modification of existing systems, upgrades to property, establishment of new infrastructure – combined with its size –hundreds of facilities and operations that extend across the nation – further adds to its complexity.”
Putting together the W87-1 warhead, the Mark21A reentry vehicle, and the Sentinel ICBM — and having the first nine ready for deployment by 2030 — appears to be quite a challenging task.
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