10 CFR §1016.15

1. (a)When, because of their nature or size, it is impracticable to safeguard classified matter containing Restricted Data in accordance with the provisions of §§ 1016.13 and 1016.14, a security area to protect such classified matter shall be established.
2. (b)The following controls shall apply to security areas:
   1. (1)Security areas shall be separated from adjacent areas by a physical barrier designed to prevent entrance into such areas, and access to the Restricted Data within the areas, by unauthorized individuals.
   2. (2)During working hours, admittance shall be controlled by an appropriately cleared individual posted at each unlocked entrance.
   3. (3)During nonworking hours, admittance shall be controlled by protective personnel on patrol, with protective personnel posted at unlocked entrances, or by such intrusion detection system as DOE approves.
   4. (4)Each individual authorized to enter a security area shall be issued a distinctive badge or pass when the number of employees assigned to the area exceeds thirty.