Shifting military requirements changed design of new ICBM pit; first unit delayed

February 17, 2023

By Dan Leone

ALEXANDRIA, VA. — The National Nuclear Security Administration changed the design for the nuclear core of a planned intercontinental ballistic missile warhead late last year, a senior agency official said here Tuesday.

Altering the design of the W87-1 plutonium pit, being developed by the agency’s Lawrence Livermore National Laboratory in California for the Air Force’s planned Sentinel missile, will delay the first copy of the crucial weapon component by about a year, said Marvin Adams, deputy administrator for defense programs at the National Nuclear Security Administration (NNSA).

“The combined team of NNSA, Los Alamos, Livermore and Kansas City, decided last fall on a design change,” Adams said in prepared remarks at the Exchange Monitor’s annual Nuclear Deterrence Summit.

But the change, made in response to what Adams called a late-breaking shift in military requirements, may also have hastened the day that the semi-autonomous DOE nuclear weapons can make the cores en masse.

“The [pit] design was always going to be a challenge and the original design was there when there were still potential military requirements on the table that were later removed,” Adams said in response to a question from the Monitor. “So the removal of those military requirements kind of late in the game opened the door to simplify the design and make it more manufacturable.”

The NNSA’s burgeoning plutonium pit production complex is supposed to include a pair of factories that can cast at least a combined 80 pits annually.

Right now though, the agency can only cast between five and 10 development pits annually at Los Alamos. The lab is splitting between making these practice pits and upgrading its PF-4 Plutonium Facility to make at least 30 pits a year.

The Savannah River Site in Aiken, S.C., meanwhile, is preparing the partially built Savannah River Plutonium Processing Facility to make at least 50 pits a year. When that facility is done — 2036 is the likely date, according to an independent project review of the facility completed in 2021 and referenced in the explanatory text of the 2023 National Defense Authorization Act — it could quickly be tapped to handle a surge load in excess of the minimum 50 a year, NNSA administrator Jill Hruby said here Tuesday.