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Q clearance or Q access authorization is the U.S. Department of Energy (DOE) security clearance required to access Top Secret Restricted Data, Formerly Restricted Data, and National Security Information, as well as Secret Restricted Data. Restricted Data (RD) is defined in the Atomic Energy Act of 1954 and covers nuclear weapons and related materials. The lower-level L clearance is sufficient for access to Secret Formerly Restricted Data (FRD) and National Security Information, as well as Confidential Restricted Data, Formerly Restricted Data, and National Security Information.[1][2] Access to Restricted Data is only granted on a need-to-know basis to personnel with appropriate clearances.

A Q Clearance is equivalent to a U.S. Department of Defense Top Secret clearance.[2] "...the Q access authorization corresponds to the background investigation and administrative determination similar to what is completed by other agencies for a Top Secret National Security Information access clearance."[2]

Anyone possessing an active Q clearance is always categorized as holding a National Security Critical-Sensitive position (sensitivity Level 3).[3] Additionally, most Q-cleared incumbents will have collateral responsibilities designating them as Level 4: National Security Special-Sensitive personnel.[4] With these two designations standing as the highest-risk sensitivity levels, occupants of these positions hold extraordinary accountability, having the potential to cause "exceptionally grave" or "inestimable" damage to the national security of the United States.[5]

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(a) A "Q" access authorization permits an individual access on a need-to-know basis to (1) Secret and Confidential Restricted Data and (2) Secret and Confidential National Security Information including intelligence information, CRYPTO (i.e., cryptographic information) or other classified communications security (COMSEC) information.