B&W Y-12, a limited liability enterprise of the Babcock and Wilcox Company and Bechtel National Inc. was selected to operate the Y-12 National Security Complex for the National Nuclear Security Administration (an independent agency of the US Department of Energy) in 2000. The Y-12 National Security Complex is a manufacturing facility, and its programs include manufacturing and reworking nuclear weapon components, dismantling nuclear weapon components returned from the national arsenal, serving as the nation’s storehouse of special nuclear materials, preventing the spread of weapons of mass destruction, and providing special support to other programs. The Y-12 complex was part of the original Manhattan Project, with the mandate to process uranium for the first atomic bomb. Construction of Y-12 began in February 1943, and enriched uranium production started in November 1943. The Y-12 National Security Complex manufacturing facility stretches across about eight hundred acres, with more than 575 structures that contain more than seven million square feet of floor space.