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An Overview of the ... Restricted Data and Formerly Restricted Data Classification System

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

Table of Contents
Where It All Began
Restricted Data
Formerly Restricted Data
How RD/FRD Differ From Other Classified Information
Additional Markings

Where It All Began

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 Truman signed 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 this information. The 1946 Act was superseded by the Atomic Energy Act of 1954 which established another category of classified information known as "Formerly Restricted Data" (FRD) for which DOE and the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

R estricted 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

Formerly Restricted Data

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 of atomic 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 should be noted that Formerly Restricted Data remains classified.

F ormerly 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 atomic weapons, 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)

How RD/FRD Differ From Other Classified Information

(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 the duration 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:

Additional Markings

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 the presence 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 or declassification. 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 Declassification Outreach Coordinator
(301) 903-7567


Office of Declassification Training Coordinator
(301) 903-7566

November 1995