In a Looming Nuclear Arms Race, Aging Los Alamos Faces a Major Test

In a sprawling building atop a mesa in New Mexico, workers labor around the clock to fulfill a vital mission: producing America’s nuclear bomb cores.

The effort is uniquely challenging. Technicians at Los Alamos National Laboratory must handle hazardous plutonium to create the grapefruit-size cores, known as pits. They do so in a nearly 50-year-old building under renovation to address aging infrastructure and equipment breakdowns that have at times disrupted operations or spread radioactive contamination, The New York Times found.

Now, the laboratory is under increasing pressure to meet the federal government’s ambitions to upgrade the nation’s nuclear arsenal. The $1.7 trillion project includes everything from revitalizing missile silos burrowed deep in five states, to producing new warheads that contain the pits, to arming new land-based missiles, bomber jets and submarines.

But the overall modernization effort is years behind schedule, with costs ballooning by the billions, according to the Congressional Budget Office. In 2018, Congress charged Los Alamos with making an annual quota of 30 pits by 2026, but by last year it had produced just one approved for the nuclear stockpile. (Officials have not disclosed whether more have been made since then.)

In August, James Danly, the deputy secretary of the Energy Department, ordered a study of the leadership and procedures involved in pit production and related projects at Los Alamos and the Savannah River Site in Aiken, S.C. That facility was also designated to produce pits but is unlikely to begin before 2032, according to federal officials.

“I have become increasingly concerned about the National Nuclear Security Administration’s ability to consistently deliver on nuclear weapons production capabilities needed to support the national defense of the United States,” Mr. Danly wrote to the agency’s acting administrator. The N.N.S.A., an agency within the Energy Department, maintains the nuclear stockpile and is overseeing the renewal project.

In response to questions from The Times last month, a spokeswoman for the N.N.S.A., the Energy Department and the national laboratory said: “We are fully committed to strengthening the nation’s nuclear deterrent and ensuring the long-term national security of the United States. This commitment includes accelerating our plutonium pit production” at Los Alamos and completing the South Carolina facility, “which are critical for a safe, secure and effective nuclear stockpile.”

To ramp up, PF-4 is undergoing dozens of infrastructure projects. But some major systems in “poor condition” will require repairs and replacements over the next 25 years, a 2020 Energy Department report said.

Complicating the renovation is not only the presence of radioactive materials, every gram of which must be closely tracked, but also contamination. Beyond the sealed steel workstations, called glove boxes, where workers handle plutonium and other nuclear materials, contamination has been found in pipes, unused laboratory rooms, ceilings, a stairway, ladders and basement floors. Those findings have been documented in federal and state reports and weekly inspection records from the Defense Nuclear Facilities Safety Board, a federal watchdog group. The Times also interviewed 30 nuclear experts and current and former employees.

Replacing glove boxes is going slowly, for example, because decontaminating and removing the old models can take weeks for each one. Fifteen water leaks — including one that flooded part of the basement with 4,700 gallons of water and required extensive cleanup — have been reported since 2018. Three spread radioactive particles into nearby spaces, safety inspectors noted.

Since 2018, the lab’s overall work force has grown by 50 percent to nearly 18,000. About 1,000 people in the plant handle nuclear material or perform construction work. Those in the building at the same time have more than doubled, causing congestion in certain areas. A federal report called the increased activity a “very high risk.”

Choreographing dual renovation and production work is intricate. “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, the lab’s deputy operations director, once described the effort.

Terry Wallace, the laboratory’s former director, put it this way in a recent interview: “How do we keep this part going while we upgrade this part and make no mistake? Well, you still have high-hazard material there, so you have to do it extremely carefully, extremely thoughtfully.”

The United States created its stockpile decades ago as a deterrent to nuclear war. Like the U.S., China, Russia, North Korea and other nations are upgrading or enlarging their arsenals amid rising global tensions over nuclear threats. Of the nine countries known to have such arms, the U.S. ranks second, with about 3,700, just behind Russia’s 4,300, according to estimates by nuclear weapons researchers.

Los Alamos became a stopgap solution because the Rocky Flats Plant, in Colorado, which had produced pits for decades, was officially shut down in 1992 for environmental violations. The Savannah River Site was also tapped to make pits, but retrofitting a facility there into a production hub has been repeatedly delayed.

Until then, it all comes down to Los Alamos.

“Is it the best place to do it?” Mr. Wallace, the former director, asked. “Well, it’s the only place.”

The Pit Factory

The laboratory, where J. Robert Oppenheimer oversaw efforts to develop the world’s first atomic bombs, spreads across 40 square miles in northern New Mexico. It is circumscribed by federally protected forests and archaeological sites, the towns of Los Alamos and White Rock and the San Ildefonso Pueblo, home to a Native American tribe.

The lab has to guard against perils inside and outside its buildings. Much of the property is blocked off to the public. Canyons plunge on either side of PF-4, or the plant, as workers call it. Around it are security checkpoints, armed guards and armored vehicles with mounted turrets.

Three wildfires whipped through the area in recent decades. One in 2000 burned 7,600 acres of lab property, damaging or destroying 100 structures. Since 2020, New Mexico has designated Los Alamos County as a high wildfire risk, which the lab says it mitigates through tree thinning and careful monitoring.

Because the region is home to multiple faults, the plant and some equipment have been buttressed against earthquakes. But the safety board, which advises Congress and the Energy Department, has repeatedly questioned whether the building could contain the plutonium and keep it from endangering the public if a quake triggered a fire. The facility does not have the highest-graded ventilation system.

When PF-4 opened in 1978, it was a state-of-the-art building dedicated to research, not production. Its age is now a liability, an Energy Department report said. As the nation’s sole facility for plutonium surveillance, research and manufacturing, the building, the document warned, is “a single point risk of failure for the majority of defense-related and non-defense plutonium missions within the United States.”

PF-4 also performs special tasks done nowhere else. It assesses America’s stockpile of plutonium pits, most made in the 1980s, to ensure they haven’t degraded and will work as designed. It dilutes the nation’s surplus plutonium for disposal and creates power sources for NASA’s space rovers, using a different form of plutonium from the kind in weapons.

The plant also produced a small run of plutonium pits left unfinished when Rocky Flats shuttered. But in 2011 a worker lined up eight rods of plutonium side by side for a photo, a configuration that could have set off a dangerous radiation pulse.

That incident prompted an exodus of frustrated safety experts at the lab, which led to a production shutdown in 2013 that lasted until 2017. That year, Los Alamos was the only nuclear site given a failing rating in an Energy Department report card. Since resuming plutonium operations, the lab’s safety record now ranks “good.”

When Congress designated Los Alamos as a pit production site in 2018, the plant became the linchpin in a sprawling nuclear complex. Lawrence Livermore National Laboratory, in California, designed the pits and the new W87-1 nuclear warhead, the first in decades. A Kansas City, Mo., site is making some components of the warhead, which is intended to arm Sentinel intercontinental ballistic missiles, being produced by Northrop Grumman.

Because the U.S. stopped making new plutonium in 1992, workers now salvage the metal from the pits of retired weapons, held at the Pantex Plant near Amarillo, Texas.

After impurities are removed at PF-4, the material is combined with another metal to create an alloy. Workers heat and cast the alloy into hollow half-spheres, or hemishells, which they weld together and smooth. If the pit were uniformly compressed by explosives in a warhead, a nuclear blast would result.

Refining the pit-making process for a new design has taken years of testing and development, said the lab’s director, Thomas Mason, at a town hall in January. There is “rigorous quality assurance that goes into making sure that the pits we produce meet the needs,” he said.

The N.N.S.A. gave production efforts at the lab an “excellent” rating last year, and Los Alamos says it will meet its annual 30-pit quota by 2028.

A Series of Breakdowns

At the plant, workers wear protective clothing and gear. Monitors detect radiation, and everyone inside the building must wear a badge that tracks cumulative external exposure. When exiting the plant, employees pass through full-body scanners to check for radioactive particles.

While the Energy Department provides reports for all exposed workers at Los Alamos every year, it does not break down how many were at the plant. When plutonium enters the body through inhalation, an open wound or ingestion, it can circulate for decades, potentially causing cancer and other diseases. At least eight plant workers since 2018, seven of whom were handling heat source plutonium for NASA, had confirmed cases of bodily intake, according to safety reports.

Renovation activities have also spread contamination in the building at least a dozen times in recent years, including work on an industrial waste pipe in August last year when radioactive particles were found on a pipefitter’s equipment, nearby flooring and scaffolding. This August, workers spread high levels of contamination in the basement, where bags of radioactive equipment had been improperly disposed and were leaking oil.

While the federal government owns the lab, a private contractor, Triad National Security, led by Battelle, a scientific nonprofit that runs seven other national labs, has managed Los Alamos in affiliation with the University of California and Texas A&M since 2018.

Among its biggest projects is removing approximately 90 old glove boxes and installing new versions fortified against earthquakes. The effort won’t be finished until the 2030s, a Government Accountability Office report said in 2023. The stainless steel chambers can weigh as much as four tons and are connected to other boxes, supply and waste systems. Before removing the boxes, workers wipe them down with decontaminants, enclose them in tents and cut them out for disposal.

Water leaks or spills near nuclear materials can also pose hazards, spreading contamination or in, rare cases, setting off a harmful burst of radiation.

In March last year, water from an overflowing decontamination shower spread radioactive particles in adjacent rooms and the basement. In July 2021, 200 gallons of water poured through the ventilation system into an inactive glove box, then spilled onto floors and eventually into the basement, dispersing contaminants.

The July leak was among four safety incidents that led the N.N.S.A. to withhold $1.5 million from Triad’s contract in 2021 because of “a significant lack of attention or carelessness,” the agency said. Triad routinely “focuses on human errors,” the agency added, “rather than on the conditions that make those errors more likely.”

The plant’s trolley system, which inspectors describe as a “critical piece of infrastructure,” has broken down at least three times since 2018. The system involves buckets that travel overhead on a mechanized clothesline through a metal channel, transporting plutonium and other materials and waste across the plant.

Buckets have sometimes tipped over, spilling contents inside the channel. The cable on which they travel has also snapped. There were monthlong outages in June 2020 and May 2024, and to keep pit production moving, workers had to manually bag nuclear material. This year, the buckets were redesigned and some electrical components upgraded.

The ventilation system has also shut down at times because of outdated parts, according to federal reports. In 2022, the safety board said that shutdowns and repairs caused serious work disruptions. While the safety board has recommended making significant enhancements to the ventilation system, the N.N.S.A. instead opted for more limited upgrades, citing taxpayer costs and other priorities.

In coming months, it is unclear how much outside safety scrutiny Triad and other lab contractors may face. The bipartisan Defense Nuclear Facility Safety Board, which oversees on-site inspectors at Los Alamos and five other facilities, now has only one member instead of the requisite five.

Meanwhile, lab officials have signaled that they intend to increase productivity at the plant. “It can’t be down for any reason,” John Benner, then a weapons production manager, said last year.

In an email to The Times, a spokesman for the safety board wrote that it was factoring the “increased tempo of operations” into its “robust safety oversight.” But if a quorum isn’t restored, the board “cannot elevate its safety concerns” to the Energy Department in “a binding way,” he said. Whether the Trump administration will appoint new members remains uncertain.

The New Brinkmanship

Soon after returning to the White House this year, President Trump said there was no reason to build new nuclear weapons, adding that countries were spending “a lot of money” on them that could be put to better use. While addressing the United Nations In September, he spoke of the need to stop developing them. ”If we ever use them,” he went on, “the world literally might come to an end.”

Later that month, before a gathering of military leaders, he boasted how America had “newer” and “better” nuclear weapons than other nations — a bit premature, since none of the U.S. next-generation arms are yet operational. Russia never lost its ability to produce plutonium pits, and China is estimated to have doubled its arsenal since 2020.

The rising nuclear brinkmanship has raised alarms among weapons control experts, scientists and prominent global figures including the U.N. secretary general, António Guterres.

Uncertainty surrounding the New START treaty, the last remaining arms control accord between the U.S. and Russia, is adding to their concerns. Mr. Trump and Russian President Vladimir V. Putin have recently expressed interest in extending it for one more year, after it expires in February 2026, but that would not bind any other countries.

Meanwhile, the Trump administration is pressing on with the modernization.

“We’ve built one in the last 25 years,” the energy secretary, Chris Wright, said of pit-making efforts in an interview with Fox News in March, “and we’ll build more than 100 during the Trump administration.”