10 C.F.R. § 1046.18
PF personnel must have the access authorization for the highest level of classified matter to which they have access or SNM which they protect. The specific level of access authorization required for each duty assignment must be determined by the site security organization and approved by the local ODFSA. At sites where access authorizations are not required, SPOs must have at least a background investigation based upon a national agency check with local agency and credit check with maximum duration between reinvestigations not to exceed 10 years. This background investigation must be favorably adjudicated by the applicable Departmental field element. Those SPOs who have access to Category I or Category II quantities of SNM as defined by DOE or with access to credible roll-up potential to Category I according to site-specific determination must have and maintain a DOE "Q" access authorization.
10 C.F.R. § 1046.18