A “highly confidential” 266-page document detailing information about civilian nuclear sites and programs was accidentally released to the public last month. While some experts say the lapse does not pose a significant security threat because many of the document’s details had already been made public, others have expressed concern that the unintentional release of such information can provide thieves or terrorists with insider information that can assist their causes.

One of the most serious disclosures appears to center on the Oak Ridge National Laboratory in Tennessee, which houses the Y-12 National Security Complex, a sprawling site ringed by barbed wire and armed guards. It calls itself the nation’s Fort Knox for highly enriched uranium, a main fuel of nuclear arms.

The report lists “Tube Vault 16, East Storage Array,” as a prospective site for nuclear inspection. It said the site, in Building 9720-5, contains highly enriched uranium for “long-term storage.”

An attached map shows the exact location of Tube Vault 16 along a hallway and its orientation in relation to geographic north, although not its location in the Y-12 complex.

The document, which has since been removed from a Government Printing Office website, reportedly contained an exhaustive list of nuclear sites in the United States, but apparently–and fortunately–contained no information about the nation’s nuclear arms stockpile or about the facilities and programs guarding such weapons.