A personnel security clearance is an administrative determination that an individual is eligible for access to classified information of the same category as or lower than the clearance being granted. No one will be given access to classified information or be assigned to sensitive duties unless a favorable personnel security determination has been made of his/her loyalty, reliability, and trustworthiness. The initial determination will be based on a personnel security investigation (PSI) appropriate to the access required or to other considerations of the sensitivity of the duties assigned. Only the following personnel are authorized to request PSIs on personnel under their jurisdiction: Director, Central Adjudication Facility Commanders and commanding officers Chiefs of Recruiting stations Request for PSIs must be kept to the absolute minimum. Reliance on PSIs as a means of identifying problem personnel security cases will be avoided. Special attention is to be given to eliminating unnecessary and duplicate reports. PSIs will not be requested to resolve allegations of a suitability nature for the purpose of supporting personnel administrative decisions or disciplinary procedures independent of a personnel security determination. The Defense Investigative Service (DIS) or the Office of Personnel Management (OPM) conducts or controls all PSIs for the DON. DON elements are prohibited from conducting PSIs without a specific request from DIS to support its investigative responsibilities. TYPES OF INVESTIGATIONS The term personnel security investigation describes an inquiry by an investigative agency into an individual's activities for the specific purpose of making a personnel security determination. Investigations conducted for other purposes may have an impact on security clearances or assignments to sensitive duties, but are not PSIs. The following are some of the types of investigations. See Department of the Navy Information and Personnel Security Program Regulation, OPNAVINST 5510.1, for more information on PSIs. National Agency Check A national agency check (NAC) consists of a check of the files of a number of government agencies for pertinent facts bearing on the loyalty and trustworthiness of the individual. Examples of agencies checked are the FBI and the Defense Central Index of Investigations. The NAC conducted on a first-term enlistee in the Navy or Marine Corps is called an entrance NAC (ENTNAC). The primary reason for the ENTNAC is to determine the suitability of an individual for entry into the service. If a service member reenlists after a break in active service greater than 12 months, an NAC (not an ENTNAC) is requested. Background Investigation The background investigation (BI), conducted by DIS, is much more extensive than a NAC. It is designed to develop information as to whether the access to classified information by the person being investigated is clearly consistent with the interests of national security. It includes an NAC and probes deeply into the loyalty, integrity, and reputation of the individual. Special Background Investigation The special background investigation (SBI) is an investigation conducted by DIS, with extended coverage of the individual's background to provide a greater depth of knowledge than a BI. The scope of an SBI is 15 years or since the 18th birthday, whichever is shorter. At least 2 years will be covered, except that no investigation is conducted prior to the subject's 16th birthday. CLEARANCE ELIGIBILITY Eligibility for a security clearance is limited to members of the executive branch of the U.S. Government or to employees of the DOD contractors, under the Defense Industrial Security Program. Occasionally, it is necessary for the DON to clear persons outside the executive branch of the government. Only U.S. citizens are eligible for security clearances. Non-U.S. citizens may be considered for limited access authorization. Classified information is made available to appropriately cleared persons only when it is necessary in the interests of national defense and the individual requires the information to carry out 11-5