Research Briefs

Why the U.S. Doesn’t Need More Nuclear Pits Right Now

Jun 23, 2020
By:
Bianca Ortiz-Miskimen ‘22
Source:
Woodrow Wilson School

The U.S. Congress is currently debating whether to build and operate a plutonium pit-production factory in South Carolina. It would be the country’s second; the first is in Los Alamos, New Mexico.

Since the end of the Cold War, the Los Alamos National Laboratory has been the sole U.S. center of expertise and producer of “pits,” the critical components at the core of U.S. nuclear warheads. However, production at Los Alamos was shut down in 2013 for safety reasons and is not expected to restart until 2023.

Meanwhile, the Trump administration’s 2018 Nuclear Posture Review requires that no fewer than 80 pits be produced per year by 2030 in order to be able to replace all the pits in U.S. nuclear weapons during the following decades.

The National Nuclear Security Administration (NNSA) has largely lost confidence that Los Alamos can reach this target and plans to divide the pit-production mission with a new facility at the Department of Energy’s Savannah River Site in South Carolina.

A paper written by Frank von Hippel, senior research physicist and professor of public and international affairs, emeritus, at Princeton University’s Woodrow Wilson School of Public and International Affairs argues that building of this new facility should be delayed for a decade or so. He bases this view on three points:

First, the Savannah River Site staff have no pit-production experience. They would need to be trained by Los Alamos staff, who have not yet demonstrated they can successfully manage production at their own site.

“NNSA’s rush forward may result in a debacle on top of a debacle,” von Hippel wrote. “If the experts at Los Alamos can’t manage pit production there, why does NNSA think that they can design and train the staff to operate a pit-production facility at the Savannah River Site? Los Alamos has struggled to produce a small number of pits, even though the lab has spent billions of dollars on pit-production efforts.”

Second, von Hippel questions the U.S.’s need to produce new pits at all. Some argue that older pits will cease being operable as the slow decay of plutonium changes a pit’s mechanical properties. However, experts at the Lawrence Livermore National Laboratory declared that the pits produced at Rocky Flats — a former pit-production plant in Colorado — will continue to be durable for at least 150 years.

“Within a decade, we should have a new lower limit on the functional lives of the legacy pits,” von Hippel said. “If they will indeed last for at least 150 years, as the Livermore experts concluded, then there will be no need for a large production facility to replace them anytime soon.”

Third, NNSA is advocating for the production of more pits in order to construct two new nuclear warheads — the W87-1 and the W93. This is problematic on three fronts, von Hippel said.

One, the plan to replace aging W78 warheads on the U.S. Minuteman III intercontinental ballistic missile requires either W87-0s or the proposed new W87-1s. Given that there are enough stored W-87-0s and the two are almost identical, it is unnecessary to manufacture new ones.

Two, there are strong arms control arguments to retire the Minuteman III’s without replacement given that they are vulnerable and therefore in a dangerous launch-on-warning posture while ballistic missiles on U.S. submarines are invulnerable.

Three, NNSA proposes to replace the warheads on U.S. ballistic missile submarines — the most numerous warheads in U.S. operational stock — with new W93 warheads that contain “insensitive” high explosives to reduce the probability of a plutonium contamination accident. However, without changes in the sensitive propellant in the missile’s third stage — which the Navy has refused to make — changing the warheads would not significantly reduce the hazard.

Decisions concerning the construction of a pit-production facility at the Savannah River site are still up in the air, but von Hippel’s stance is clear.

“We can wait for another decade before we decide on whether the United States requires two pit production facilities,” von Hippel said. “Indeed, we can wait for another decade before we decide on whether we need any new pits at all.”