American nuclear weapon facility

After the closure of the country’s prime plutonium manufacturing plant at Rocky Flats in 1992, where 1,000 to 2,000 pits were produced every year, a highly reinforced 236,000 sq-ft facility built at LANL earlier in 1978 became the first Department of Energy (DoE) facility capable of producing plutonium cores.

Although initially established for plutonium research and development, in 2003 the Plutonium Facility Building 4 (PF-4) within Tech Area 55 at Los Alamos produced the nation’s stockpile quality (first war reserve) plutonium. In 2006, Congress instructed the DoE to focus on producing pits at this facility.