Los Alamos produced the first plutonium pits, the cores of nuclear weapons, in 1945, during the Manhattan Project led by J. Robert Oppenheimer. Since the end of World War II, Los Alamos performed limited pit production for research purposes with a short production campaign from 2007 to 2011 in support of the W88 warhead.
From 1952 to 1989, the majority of plutonium pits for U.S. nuclear weapons were manufactured at the Rocky Flats plant near Denver, Colorado, while Los Alamos continued to advance its plutonium research and development. When Rocky Flats closed in the early 1990s, PF-4 at Los Alamos became not just the premier plutonium facility in the nation, but the only one. That’s why NNSA has designated Los Alamos with the mission to recycle plutonium from old pits to make new ones to fulfill the requirements of the Department of Defense.
Today, the Laboratory is laying the groundwork for manufacturing new pits that are bound for a weapon already in the stockpile, the W87-1 nuclear warhead. Los Alamos National Laboratory remains the only place in the country where pits can be made. This critical mission endures as the driving force for national security through deterrence.
We now know more about plutonium aging and decay, and how the changing properties of a plutonium pit could affect the performance of a nuclear weapon. That knowledge has led the U.S. to choose to replace the aging plutonium pits in many weapons as a precaution. The U.S. recycles plutonium from old pits, removing the aging and decay products then reuses that plutonium to make new ones. This recycling process uses several old pits to make a new pit. That means the number of pits in the nation's stockpile is actually decreasing even as we work to ensure its reliability.
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Learn more about plutonium pits, nuclear deterrence, and LANL’s Plutonium Facility
