S-Site

This building served as a high-explosives storage magazine during the Manhattan Project.

LOS ALAMOS NATIONAL LABORATORY

Quick Facts

Location:

Los Alamos, NM

OPEN TO PUBLIC:

No

MANAGED BY:

Los Alamos National Laboratory

This site is on Los Alamos National Laboratory property and cannot be accessed by members of the public. 

The Manhattan Project brought together forceful personalities, especially in Los Alamos, where strong-willed physicists and rigid military personnel worked to build the first atomic weapons.   

As the idea of an implosion-type weapon gained traction, Project Y had to build more facilities to accommodate the research and development of this new venture. Initial efforts to develop explosives for the weapon started at Anchor Ranch but quickly outgrew the existing facility. In December of 1943, approval came for the development of a new site, Sawmill Site.  

Sawmill Site, abbreviated as S-Site, required a plant for manufacturing explosive casings. David Busbee, a friend of Deak Parsons who joined Project Y as the head of explosives manufacturing, designed the first plant. With a background working with naval ordnance, Busbee created a facility for pouring large castings for a full-scale implosion assembly. George Kistiakowsky, deputy division leader for the implosion program, knew from his experience working with explosives that these large castings would not work. This first plant, in Kistiakowsky’s mind, “was a monstrosity.”  

Eventually, S-Site cast components made of Compound B, Torpex, and Baronal. To house these explosives, workers built additional facilities. The storage magazine still on the site today was the last high-explosives facility built to support Manhattan Project operations at S-Site. Surrounded by an earthen berm to protect the reinforced-concrete floor and walls, the force of an accidental explosion would channel upward through the wooden roof.   

Continue Your Journey 
 

Behind the fence, near S-Site, is V-Site where diagnostic testing of the Fat Man weapon took place.  Learn more about the history of the Manhattan Project by visiting the Bradbury Science Museum! The museum’s interactive exhibits share stories from the project and provide a glimpse of other “behind the fence” historical sites.