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.)

That pace has put the lab -- and especially the building called Plutonium Facility 4, or PF-4 -- under scrutiny by Trump administration officials.

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, South Carolina. 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," Danly wrote to the agency's acting administrator. The NNSA, 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 spokesperson for the NNSA, 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.

Systems for transporting plutonium -- an overhead trolley and the only freight elevator -- have also had outages, so workers have had to manually move nuclear material, which can increase safety risks. Hand-carrying nuclear waste in a stairwell spread contamination and reduced productivity, an inspector reported. The workaround for the elevator put "an extra burden on personnel," according to a July email from Timothy Bolen, a top weapons production official at the lab.

Since 2018, the lab's overall workforce has grown by 50% 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.

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.

America's modernization effort began under President Barack Obama, when Republican senators agreed to endorse a hallmark arms-reduction treaty with Russia, but only if the U.S. updated its nuclear weapons complex. The project accelerated during the first Trump administration when Congress pushed to resume pit production, a capability mostly phased out after the Cold War.

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 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.

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.

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.

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, Missouri, 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.

The NNSA 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 2024 when radioactive particles were found on a pipefitter's equipment, nearby flooring and scaffolding. This past 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.

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 spokesperson 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.

This article originally appeared in The New York Times.