Office of Classification
U.S. Department of Energy
19901 Germantown Road
Germantown, Maryland 20874-1290

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With the advent of nuclear weapons and their enormous destructive capability, the United States recognized the need to establish a special classification system to ensure that its nuclear secrets were well protected. On August 1, 1946, President Trumansigned the Atomic Energy Act of 1946 which established the category of classified information known as "Restricted Data" (RD). This Act gave the Atomic Energy Commission (now the Department of Energy (DOE)) unilateral authority over thisinformation. The 1946 Act was superseded by the Atomic Energy Act of 1954 which established another category of classified information known as "Formerly Restricted Data" (FRD) for which DOE and the Department of Defense have joint responsibility. This pamphlet provides a brief orientation to the RD and FRD classification system.

Restricted Data is defined by the Atomic Energy Act as all data concerning:

  • Design, Manufacture, or Utilization of Atomic Weapons
  • Production of Special Nuclear Material (Uranium and Plutonium)
  • Use of Special Nuclear Material (SNM) in the Production of Energy

A Few Examples of RD are:

Nuclear Weapons Design Information

  • Specification and Amount of Nuclear Material
  • Dimensions, Sketches, Drawings, and Blueprints
  • Materials or Weapon Parts
  • Detonation Systems (Amount of High Explosives, Number of Detonators)
  • Safing, Arming, Fuzing, and Firing Systems
  • Nuclear Testing Information

Production of SNM

Uranium Enrichment Technology

  • Gaseous Diffusion
  • Gas Centrifuge
  • Laser Isotope Separation
Production Reactors and Related Technologies
  • Fuel and Target Technology
  • Chemical Processing of Tritium and Plutonium
Allocations to Weapons Programs

Use of SNM in the Production of Energy

  • Naval Reactors
  • Military Reactors
  • Space Reactor Power Systems

The Atomic Energy Act of 1954 recognized the need to make certain atomic energy information more accessible to the United States military. It provided for the transfer of information primarily dealing with the military utilization ofatomic weapons from the RD category to another category of classified information. This category of information became known as "Formerly Restricted Data." Although the word "formerly" implies the information may no longer be classified, it shouldbe noted that Formerly Restricted Data remains classified.

Formerly Restricted Data is defined by the Atomic Energy Act as:

  • Classified information which has been removed from the Restricted Data category after DOE and the Department of Defense have jointly determined that it relates primarily to the military utilization of atomicweapons, and can be adequately safeguarded as national security information.

A Few Examples of FRD are:

Nuclear Weapon

  • Stockpile Quantities
  • Safety and Storage Information
  • Yields and Effects
  • Storage and Deployment Locations (Foreign and Domestic, Past and Present)

(i.e., National Security Information (NSI) as defined in Executive Order 12958) . . .

  • RD/FRD is classified under the Atomic Energy Act -- NSI is classified under Executive order.
  • RD/FRD is not subject to automatic declassification and requires review prior to declassification -- NSI is automatically declassified on occurrence of an event or date unless specifically exempted or theduration is extended.


Documents containing RD/FRD are exempt from automatic declassification and must be reviewed by DOE prior to release.

All RD/FRD documents should be marked with one of the three classification levels --Top Secret, Secret, or Confidential. They should also contain one of the following warning notices:

Restricted Data Stamp

Formerly Restricted Data Stamp

Some documents may have special markings that indicate they probably or potentially contain RD/FRD such as:

  • CNWDI (Critical Nuclear Weapons Design Information)
  • NOFORN (No Foreign Dissemination)
  • Sigma Category
  • Weapon Data

Warning: The absence of RD/FRD markings, particularly on historical documents, does not ensure that RD/FRD is not present. Much RD/FRD information is found in documents without the RD/FRD warning notice or any additional markings to indicate thepresence of RD/FRD.

We have tried to provide you with a brief description of the RD/FRD classification system. Hopefully, this information will assist you in recognizing potential RD or FRD information present in documents you may be reviewing for classification ordeclassification. If you have documents that contain information concerning areas discussed in this pamphlet and you are unsure of their classification status, please contact DOE for assistance.

Additional information and/or training may be obtained by contacting:

Office of Classification Outreach Coordinator
(301) 903-7567


Office of Classification Training Coordinator
(301) 903-7566

November 1995

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