K-25 Small Portal/Checkpoint

The K-25 Small Portal checked in thousands of workers in its day.

NPS/BURGHART

Quick Facts

Location:

Oak Ridge, TN

MANAGED BY:

Department of Energy

Oak Ridge’s massive K-25 Gaseous Diffusion Plant, the largest building in the world during the Manhattan Project, required an efficient method of allowing thousands of workers in and out of the top-secret facility on a daily basis. 

One of over a dozen armed security checkpoints within the K-25 complex, the Small Portal allowed for the thousands of K-25 workers to move in and out of the gaseous diffusion plant on a daily basis, ensuring that workers were accounted for and that no unauthorized persons could access the top-secret facility. These checking stations were vital in maintaining K-25’s efficiency and secrecy from the Manhattan Project through the Cold War. 

Continue Your Journey

The Small Portal, along with the nearby Big Portal, are the only two remaining portals within K-25. The K-25 site was deactivated in 1987 and 12 portals were demolished after 2010, along with the majority of K-25’s original structures. For a wealth of information on K-25's history, please visit the K-25 History Center.