10 CFR § 1016.13 - Protection of Restricted Data in storage.
(a) Persons who possess Restricted Data pursuant to an Access Permit shall store the Restricted Data classified matter when not in use in a locked storage container or DOE-approved vault to which only persons with appropriate access authorization and a need to know the information contained have access. Storage containers used for storing classified matter must conform to U.S. General Services Administration (GSA) standards and specifications.
(b) Each permittee shall change the combination on locks of his safekeeping equipment whenever such equipment is placed in use, whenever an individual knowing the combination no longer requires access to the repository as a result of change in duties or position in the permittee's organization, or termination of employment with the permittee or whenever the combination has been subjected to compromise, and in any event at least once a year. Permittees shall classify records of combinations no lower than the highest classification of the classified matter authorized for storage in the safekeeping equipment concerned.