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U.S. Air Force

A U.S. Air Force illustration of the Sentinel, a new intercontinental ballistic missile design.

How to Make a ‘War Reserve’ Nuclear Bomb

The dark art of crafting nuclear ‘pits’ was almost lost. Now it’s ramped up into a multibillion dollar industry.

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Sometime in the next few months a technician at Los Alamos National Laboratory, using an arc welder, will seal together two half-domes of plutonium, creating a “pit,” a seven-pound ball the size of a grapefruit, which, if tucked into America’s newest nuclear warhead and triggered above Times Square, would destroy most of Manhattan and kill more than 1.2 million people.

The bomb is part of a $1.7 trillion plan to rebuild the U.S. nuclear arsenal. The new pit, and hundreds like it, are being made for the W87-1, a new warhead designed to sit atop the Sentinel, a new intercontinental ballistic missile design that will replace all 400 Minuteman III missiles that have been on alert in silos across the Upper Midwest for the last five decades.

Not since the Manhattan Project, the crash program during World War II to invent the atomic bomb, has so much money and urgent energy been spent by the United States to create a weapon of mass destruction. In a paradox of nuclear madness, production of the W87-1—each one with a yield of around 400 kilotons, twenty times larger than the bombs that destroyed Hiroshima and Nagasaki—is breathing life into the U.S. Nuclear Security Enterprise (NSE), the agency that makes nuclear weapons and runs the planes, missiles, and submarines that deliver them.

The warhead “is reinvigorating and transforming the production complex such that NSE can once again produce all of the components typically required for modern nuclear warheads,” according to the Lawrence Livermore National Laboratory, which designed the W87-1. “This work will give the nation expanded options for maintaining an effective nuclear deterrence posture for decades to come.”

Earlier this year, at the annual Nuclear Deterrence Summit in Washington, D.C., there was a palpable sense of excitement at the return to Cold War strategies of shoring up our nuclear arsenal. Today, with what some call the two-peer problem—Russia and China—and the specter of nuclear-armed rogue nations and terrorists, the NSE is racing against what-if targets. The language is aggressive. Opposition is largely mute. Congress has opened the tap. The NSE is hiring, training, building, and spending billions a year.

At Los Alamos, the urgency can be seen inside Plutonium Facility Building 4, known as PF-4, the only building in the United States where plutonium pits are made. Working around the clock, technicians are dismantling old contaminated glove boxes—the laboratory apparatus that allow technicians using built-in gloves to work with toxic or volatile substances inside a sealed chamber—before a new shift of workers arrives to install shiny new steel glove boxes for work on the new pits.

“The best analogy I can come up with is that we are overhauling and upgrading a plane during flight with a load of passengers on board,” Mark Davis, associate lab director for weapons production at Los Alamos, told a crowd at the deterrence summit in 2023. “Decontamination and removal of old equipment is ongoing at PF-4 for clearing space for the new equipment that is to be designed and manufactured and installed. Decontamination removal and installation usually occur during second and third shifts in the same rooms where pit production and other work occurs during the day.”

The process of turning plutonium into a bomb is a dark art—an alchemy invented in 1945 on the same New Mexico mesa. Wizards of physics and math who divined the immense energy locked within its atoms, together with master machinists, created the first atomic bomb, “Trinity,” and its copy, “Fat Man,” which destroyed Nagasaki with the power of twenty kilotons, or 20,000 tons of TNT. These two plutonium bombs produced enough heat and radiation to ignite, or trigger, the kind of fusion fire present in the sun.

One year later, as Baby Boom children were teething, Los Alamos blew up a similar plutonium bomb named “Baker” on Bikini Atoll. Its twenty-one-kiloton underwater eruption captured both the bounty of nuclear power and America’s intent to weaponize it.

During the Cold War, Los Alamos produced ninety-four different nuclear weapons—bigger, smaller, deadlier, more accurate. Many were thermonuclear, or hydrogen bombs, whose design, first revealed to the public by Howard Morland in this magazine in 1979, was theorized during the Manhattan Project. In 1952, Los Alamos, using a plutonium pit as a trigger, detonated its first thermonuclear bomb. That same year, the United States built the Rocky Flats Plant, a plutonium pit factory outside Denver. It produced 1,000 pits a year.

The hands-on, metallurgical master craft of fashioning pits was almost lost, though, when Rocky Flats was raided and closed in 1989 by the FBI for massive environmental crimes—the year the Soviet Union began to collapse, ending the Cold War. The NSE fell into a funk, reduced to cleaning up its messes and “stockpile stewardship.”

In 1993, the Department of Energy instructed Los Alamos to begin producing a limited number of plutonium pits. But it took a decade to produce a pit that met the Rocky Flats quality standard—“War Reserve”—a pit guaranteed to work when inserted into the “nuclear explosive package” of a weapon. Pits that met that standard were marked on their surface with a one-inch-wide, diamond-shaped stamp applied with indelible ink, a practice that began at Rocky Flats in the 1950s, Steven Horak, a Los Alamos spokesperson, tells The Progressive.

Around the year 2000, it was discovered that hundreds of boxes of documents, including notebooks, welding procedures, and technical illustrations, rescued from Rocky Flats were stored in a vault at the Denver Federal Center. “It’s like that last scene of Raiders of the Lost Ark,” said Joe Watts, a Los Alamos project manager, in the lab’s account of the finding. “The boxes were gradually moved, and the contents digitized.”

The Rocky Flats documents proved invaluable: “Standing up pit production at Los Alamos from the Rocky Flats archive is like being asked to recreate the Sistine Chapel from da Vinci’s drawings,” said Bob Putnam, former program director for pit manufacturing at Los Alamos.

As lab managers unsealed and combed through the boxes, Los Alamos “became like monasteries in the Dark Ages that preserved the knowledge” to produce plutonium pits, Robert Webster, deputy director of weapons at Los Alamos, told reporters in a press tour last year.

In 2014, the Nuclear Weapons Council, which oversees U.S. nuclear weapons, told Congress that the military needed “at least” eighty new pits a year. A year later, in its National Defense Authorization Act, Congress mandated their production and subsequently set a deadline of 2030 for thirty pits at Los Alamos and fifty at the Savannah River National Laboratory near Jackson, South Carolina. That deadline is the driving force behind today’s urgency.

“The reestablishment of pit production capabilities is the largest and most complex infrastructure undertaking at NNSA since shortly after the Manhattan Project,” Jill Hruby, administrator of the National Nuclear Security Administration, told the Strategic Weapons in the 21st Century Symposium on April 18. “Our current total estimated acquisition cost range for pit production is $28-37 billion . . . . I know that’s a lot of money . . . . Los Alamos is on track to diamond stamp the first fully qualified War Reserve pit for the W87-1 this year. We anticipate Los Alamos achieving the capability to produce the thirty pits per year envisioned by the two-site plan in or near 2028, with increased manufacturing rate confidence as we install equipment through 2030.”

The United States will never need to make plutonium again. During the Cold War, nuclear reactors at Hanford, Washington, produced more than sixty tons of plutonium. Some 14,000 pits, made by Rocky Flats, each bearing the War Reserve diamond stamp, are warehoused in Pantex, Texas.

As Los Alamos cranks up its program, pits are brought from Pantex, torn apart, and subjected to pyrochemistry, which removes impurities. The metal is then heated into a hot syrup and poured into molds, creating two halves of a sphere. These are welded together. This process is done in rows of connected glove boxes, the plutonium moving from one to another in an overhead trolley system, and dumbwaiters that raise and lower it.

Today at Los Alamos, hundreds of people work at the plutonium factory, some of them making plutonium heaters for space vehicles. But on the pit side, fewer than ten people in the world are trained or are being trained to perform final pit assembly, which must be done by hand inside a large, walk-in glove box, wearing multiple layers of personal protective equipment to prevent plutonium contamination. These master machinists and welders hold Q clearances and undergo annual physical and mental exams. It can take up to four years to train them.

Working inside a glove box is no easy feat, according to a profile of Sheldon Apgar, who has worked in them and is now a glove box problem solver. “Imagine putting your big, heavy winter gloves on, picking up a sewing needle off a table, and threading it at arm’s length in front of you,” he explains. “That would be easier than some of the things that glove box workers have to do in a glove box.”

The first woman to ever assemble pits, beginning in 2013, said that it takes her thirty minutes to an hour to make a pit. “Everything is by touch, by feel,” she told Scientific American. “It’s peaceful in the glove box.”

Outside the glove box, however, the rush to make the W87-1 is anything but peaceful. That welder sits at the apex of an enormously complex pyramid of parts, processes, politics, and potential problems, any one of which could bring the plan to a halt.

Reestablishing pit production from scratch has proved to be challenging. The loss of institutional memory, combined with the hiring of 4,000 new employees, has left the lab with a workforce that has “between zero and five years of experience,” Los Alamos’s Davis said. While trainees fashion “development” or practice pits, “build failure mechanisms are increasingly well understood and build quality is increasing.”

Weekly reports from the on-site representative of the Defense Nuclear Facilities Safety Board tell of myriad issues that have cropped up, including numerous glove breaches, broken equipment, and even radiation leaks. “Just yesterday, they wrote a case of a newly trained radiological technician who started work last August, and did work from August 21 to September 7 without a dosimeter,” Dylan Spaulding, a senior scientist in global security at the Union of Concerned Scientists, tells The Progressive. “I have serious concerns about the integrity of the training.”

Meanwhile, even more fundamental questions are being raised. Scientists debate whether new pits are really needed when existing pits might last for decades. And the need for the W87-1 and the Sentinel missile itself is being questioned because of rising costs and its vulnerability as a land-based, easily targeted weapon. The Pentagon reported in July that the missile’s estimated cost has risen 81 percent over budget to $141 billion.

In New Mexico, two longtime watchdog organizations, the Los Alamos Study Group and Nuclear Watch New Mexico, list dozens of reasons to not make pits at Los Alamos: waste disposal, radiation deposits, earthquake potential, cost and schedule overruns among them.

“Every dollar spent at LANL [Los Alamos National Laboratory] on this program is wasted,” wrote Greg Mello of the Los Alamos Study Group. “Every drum of waste produced in the process need not have been produced. Every career spent making these pits, or supporting the work, is a career that could have been spent building a sustainable, moral, responsible future. The LANL pit production program is a symptom of pure arrogance, greed, and management failure at the highest levels of government.”

“Plutonium pits have become almost iconic in the discussion of whether we should have nuclear weapons,” wrote Thom Mason, the Los Alamos director. “There are certainly people who wish that we didn’t have nuclear weapons. In fact, there are a lot of people who work at Los Alamos who wish that we didn’t have nuclear weapons . . . . Unfortunately, the nuclear deterrent is as relevant as it has ever been.”

As America’s nuclear train chugs forward, it is virtually certain that if the Sentinel missiles containing the Los Alamos pits are in their silos by the early 2030s, as planned, they will inflame an arms race that is already underway, while posing—if we’re lucky—nothing more than an apocalyptic threat in a new Cold War.