Rocky Flats Plant – Building #991 (Plant D)/Building #991

AddressRocky Flats Environmental Technology Site, Hwy. 93, Golden 80402
QuadLouisville, 1965 (1979)
SectionS10 & 11; T2S, R70W
Elevationc. 6000
SourceHistoric Building Inventory Record #5JF1014.42, 1995, Colorado Historical Society.
Initialdate1998-12-28 00:00:00-07
HistoryDesigned and built by the Austin Co. of Cleveland, Ohio, in 1952, this 40,780 sq. ft. building housed the final assembly of weapons components, testing, and inspection. It is a rectangular concrete building set on a concrete foundation. Two wings extend from the east and west sides. The vaults are constructed of reinforced concrete up to 30" thick, and are completely underground. In 1952, vaults #998, #997, and #996 were constructed. Operations began in 1952 with the first production shipped in 1953. Vault #999 was constructed in 1956. It is the only building at the Rocky Flats Plant that is capable of handling off-site shipments of Special Nuclear Materials. In 1957, production began on the new Part IV weapons design, so the pit assembly was moved to Building #777 from this building. After 1957, Building #991 became used increasingly for shipping, receiving and storage.